Homeopathy/Draft

Homeopathy or homoeopathy is a system of alternative medicine. The term derives from the Greek hómoios (similar) and páthos (suffering). Homeopathy is based on "the principle of similars", which asserts that substances known to cause particular symptoms can also, in low and specially prepared doses help to cure diseases that cause similar symptoms. This principle, which is accepted by homeopaths, is not accepted by mainstream medicine or by conventional scientists.

Homeopathy's basic principles were first described by a German physician, Samuel Hahnemann (1755–1843), who observed that a medicine sometimes evoked symptoms similar to those of the illness for which it was prescribed. In homeopathic theory, every person has a "vital force", with the power to promote healing and maintain good health (the term "vital force" is akin to qi in traditional Chinese medicine). In this theory, the symptoms of a disease reflect efforts of the vital force to counter infection, or to resist damage from environmental toxins or from various stresses. Homeopathic treatment attempts to strengthen this "vital force" with the aid of remedies, which are extremely small doses of drugs diluted in water or ethanol and dispensed in pills or liquid form. Remedies are chosen according to their ability (in large doses) to provoke the very symptoms that the remedy is intended to heal. Homeopaths believe that this vital force is akin to what physiologists would call a person's overall "defense system".

"Classical homeopathy" refers to the original principles in which individual remedies are chosen according to the overall physical, emotional, and mental symptoms that the sick person is experiencing, rather than only the diagnosis of a disease. "Commercial" or "user-friendly" homeopathy refers to the use of a mixture of remedies in a single formula, generally chosen for their ability to treat a specific disease. Homeopathy is practiced worldwide by many licensed practitioners, including some conventional medical physicians.

Contrasting views of homeopathy and conventional medicine
The theory underlying homeopathy is not considered to be plausible by most contemporary scientists working in academic institutions in Europe and the USA, and in key respects, the treatment advice offered by homeopaths is in fundamental disagreement with conventional medicine.

Most homeopaths believe that the fundamental causes of disease are internal and constitutional, and that infectious disease is not just the result of infection but also of susceptibility. This leads them to seek to avoid conventional drug treatments that suppress symptoms. Mainstream physicians accept that some disease is indeed a disturbance in normal function, whether due to external, genetic, or internal reasons. However they consider that most disease can be attributed to a combination of external causes (such as viruses, bacteria, toxins, dietary deficiency, physical injury) and physiological dysfunction (including genetic defects and mutations such as those which trigger cancers). They often use drugs simply to suppress the symptoms of a disease (to alleviate the pain, injury and distress that they cause). However, the main goal of medical treatment is to eliminate the causes of the disease, and drugs that address the causes of disease eliminate symptoms by removing the disease, not by merely opposing the symptoms.

The fact that there is no established mechanism of action for homeopathy makes it difficult to study, and this remains a stumbling block to its acceptance by medical and scientific institutions, although, as homeopaths point out, there are some accepted medical treatments for which the mechanism of action remains unknown. Some materials scientists, physicists, and other scientists have investigated how homeopathic medicines might work,

The basics of homeopathy
The underlying concept of homeopathy is "like cures like"—a principle described by Hippocrates more than 2,000 years ago and which has been used in various medical systems since then, in many diverse cultures throughout history. "Like cures like", the "Law of similars", and related maxims are common in anthropological literature.

Historical origins
For the early Greek physician Hippocrates of Cos (c. 450 BCE - 380 BCE), the four "humors" (blood, black bile, yellow bile and phlegm) were the key to understanding disease. His ideas persisted through the writings of Galen (131-201 CE) until at least 1858, and Rudolf Virchow's theories of cellular pathology. Diseases, it was thought, were the result of an "imbalance" of the humors, and physicians of the day focused on restoring that balance, either by trying to remove an excess of a humour, or by suppressing the symptoms. "Bloodletting, fever remedies, tepid baths, lowering drinks, weakening diet, blood cleansing and everlasting aperients and clysters (enemas) form the circle in which the ordinary German physician turns round unceasingly", wrote Hahnemann while translating into German the Treatise on Materia Medica (1789) by the Edinburgh physician William Cullen.

After 1783, disillusioned with the medicine of the time and the many toxic effects of its treatments, the German physician Christian Friedrich Samuel Hahnemann (1755-1843) gave up his medical practice and devoted himself to the translation of medical books, as he was conversant in nine languages. Cullen had written that cinchona bark (which contains quinine) was effective in the treatment of malaria because of its bitter and astringent properties. Hahnemann questioned these assertions because he knew that other substances were as bitter and astringent, but had no therapeutic value in this deadly disease. Being an avid experimenter, Hahnemann took cinchona bark himself and saw that the symptoms that it causes were similar to the symptoms of the diseases for which it was prescribed. Hahnemann then experimented with other substances and found that the symptoms that they caused were again similar to the symptoms of the diseases for which they were prescribed. This led him to formulate the 'Principle of Similars', expressed by him as similia similibus curentur or 'let likes cure likes'. He used this principle to develop a new system of health care, which instead of the often toxic and ineffective drugs offered by conventional physicians, employed more gentle alternatives, at low doses, designed rationally to supplement the body’s natural healing powers. He believed that diseases were caused by "spirit-like derangements of the spirit-like power that animates the human body", and that effective healing called for medicines that would supplementing this vital force.

Hahnemann named his system of health care "homeopathy" (meaning "like disease") and coined the term "allopathy" ("different than disease") to refer to conventional medicine of the day, because its drugs were sometimes "similar," sometimes "opposite," but usually simply "different" to the symptoms of the sick person. .

Hahnemann strove to find the lowest doses at which his remedies would still be effective, as he thought this the best way to avoid any adverse side-effects. To his surprise, it seemed that reducing the dose did not diminish the effectiveness sof his treatments. Indeed, on the contrary, he concluded that his remedies worked better and better the more he diluted them, particularly if he “potentized” them between each stage of dilution by vigorous shaking (succussion). Homeopathy became inextricably linked with this process of ultradilution – dilution of substances to such an extreme degree that in most homeopathic remedies ‘’not even a single molecule of the original substance remains.’’ Hahnemann's explanation for how higher potencies could be more efficacious was that the friction involved in succussion might release some hidden curative power. He wrote in 1825: "The effect of friction is so great, that not only the physical properties, such as caloric, odour, etc., are thereby called into life and developed by it, but also the dynamic medicinal powers of natural substances are developed to an incredible degree".

In 1830, the first homeopathic schools opened, and throughout the 19th century dozens of homeopathic institutions appeared in Europe and the USA. Apart from his ventures into homeopathy, Hahnemann had been a prominent and respected public health reformer, and the Medical Society of the Country of New York had given him honorary membership. However, a few years later the society rescinded this when they realized the "ideological and financial threat" that homeopathic medicine posed. In 1844, the first US national medical association - the American Institute of Homoeopathy - was established.

One reason for the growing popularity of homeopathy was its relative success in treating people suffering from the infectious disease epidemics that raged at the time. Cholera, scarlet fever, typhoid fever, and yellow fever were rampant and killed large numbers of people. But death rates in homeopathic hospitals were commonly much lower than in the conventional medical hospitals, whose cures – purging, blood-letting and mercury treatments, were often worse than the diseases themselves, and did nothing to combat them.

Homeopathic "provings" and remedies
Homeopathic practitioners derive their remedies from provings, experiments in which volunteers are given substances (usually in single-blind or double-blind trials), the effects of which are recorded in both books (called materia medica and repertories ) and software. The symptom complexes that these substances cause are subsequently used to compare with a patient's symptoms in order to select, as the appropriate remedy, the substance whose effects are closest to the patient's symptoms - the "similimum".

Today, homeopaths use about 3,000 different remedies, from animal, plant, mineral, or synthetic sources. It is a convention that the first letter of the Latin-derived name of such preparations is capitalized. When the source is well-defined, the traditional name rather than chemical, pharmacologic designation or biological nomenclature, is preferred, such as Natrum muriaticum rather than sodium chloride.

A few homeopaths use more esoteric substances, known as "imponderables" because they are said to originate from electromagnetic energy "captured" by ethanol or lactose, such as "X-Ray" or "Magnetic North" (north pole of a magnet).

In the USA, the Homœopathic Pharmacopœia of the United States is the approved reference for homeopathic remedies. This reference is approved by the Food and Drug Administration (FDA), the governmental agency that regulates drugs. According to the FDA, FDA regulates homeopathic drugs in several significantly different ways from other drugs. Manufacturers of homeopathic drugs are deferred from submitting new drug applications to FDA. Their products are exempt from good manufacturing practice requirements related to expiration dating and from finished product testing for identity and strength. Homeopathic drugs in solid oral dosage form must have an imprint that identifies the manufacturer and indicates that the drug is homeopathic. In 1938, the federal Food, Drug, and Cosmetic Act became law in the USA. The chief sponsor of this bill was Senator Royal Copeland, a homeopathic physician, and the bill gave the FDA the power to regulate drugs. In this process, it gave legal recognition to the "Homeopathic Pharmacopeia of the United States" as a compendium of drugs. In contrast, non-homeopathic drugs for which a New Drug Application (NDA) is required must be accompanied by approved evidence of safety and efficacy; simple listing in a reference is not sufficient.

Most homeopathic remedies are available over-the-counter and do not require a doctor's prescription. However, paticular homeopathic remedies may need a doctor's prescription if the dosage is in a non-potentized dose (in Europe, a medicine has to be diluted at least 1:10 three times to be deemed homeopathic). In the USA, if a homeopathic remedy claims to treat a serious disease such as cancer it can only be sold by prescription. Only products sold for so-called “self-limiting conditions”--colds, coughs, fever, headaches, and other minor health problems that will eventually go away on their own--can be sold without a prescription (over-the-counter).

Homeopathic remedies can be purchased or used in several different ways (single medicine, homeopathic formula or complex medicines, and a limited number of external applications). Remedies for internal consumption come either in pill form or as liquid.

Preparation of homeopathic remedies
The most characteristic &mdash; and controversial &mdash; principle of homeopathy is that the efficacy of a remedy can be enhanced and its side-effects reduced by a process known as 'dynamization' or 'potentization', whereby liquids are diluted (with water or ethanol) and shaken by ten hard strikes against an elastic body ('succussion'), to get the next, succeeding higher potency. For this, Hahnemann had a saddlemaker construct a wooden 'striking board', covered in leather on one side and stuffed with horsehair (it is displayed at the Hahnemann Museumin Stuttgart). When insoluble solids such as oyster shellare used for remedies, they are diluted by grinding them with lactose ('trituration'). The original serial dilutions by Hahnemann used a 1 part in 100 (centesimal; $$'C'$$ potencies), or 1 part in 50,000 ( Quintamillesimal; $$'LM' or  'Q'$$ potencies). The dilution factor at each stage is 1:10 ('D' or 'X' potencies) or 1:100 ('C' potencies); Hahnemann advocated $$30C$$ dilutions for most purposes (i.e. dilution by a factor of 10030 = 1060). The number of molecules in a given weight of a substance can be calculated by Avogadro's number; the chance that there is even one molecule of the original substance in a 15C solution is small, and it is very unlikely that one molecule would be present in a $$30C$$ dilution. Thus, homeopathic remedies of a high 'potency' contain just water, but water that, according to homeopaths, retains some essential property of one of the substances that it has contacted in the past.

Similia similibus curentur: the law of similars
Similia similibus curentur or 'let likes cure likes', means that a remedy can cure a disease/problem, if the presenting symptom syndrome is similar to what it can produce in the 'crude' drug form.

Today, two notions, vaccination, and hormesis, are used as analogies for homeopathy's law of similars and the use of small doses.

Vaccination
Emil Adolph von Behring (1854-1917), who won the first Nobel Prize in medicine in 1901 for discoveries that led to vaccines against tetanus and diphtheria, and who some consider to be the father of immunology, asserted that vaccination is, in part, derived from the homeopathic principle of similars.

In spite of all scientific speculations and experiments regarding smallpox vaccination, Jenner’s discovery remained an erratic blocking medicine, till the biochemically thinking Pasteur, devoid of all medical classroom knowledge, traced the origin of this therapeutic block to a principle which cannot better be characterized than by Hahnemann’s word: homeopathic.

Although homeopathic remedies and vaccinations both use low doses of active ingedients, there are important differences. First, the doses used in homeopathic remedies are always very much lower than used in vaccines. Second, vaccines produce a measurable immune response (e.g., immunoglobulin production). Some homeopaths might say these are applications of the principle of similars, but these conventional treatments involve application of measurable doses of substances, at levels known to activate mechanisms of cellular response. Homeopathic preparations above the $$24X$$ ($$12C$$) potencies do not contain enough molecules to activate any known metabolic or signalling pathway.

Mithridatization and hormesis
Mithridatization (which is not a term used in contemporary science or medicine) may be a better metaphor than vaccination, for the process claimed to take place in the course of an homeopathic treatment. Mithridatization is the chronic administration of subtoxic doses of a toxin, in an attempt to strengthen the defenses of an individual, in prevention of an actual intoxication. It is believed that the Roman emperor Mithridate used this technique to protect himself from his enemies.

There are multiple mechanisms of tolerance, although the effects of frequent small doses can vary. A herpetologist who receives many small doses of snake venom may indeed become tolerant to them. A beekeeper, however, may become hypersensitive to the venom and, after receiving a sting, go into anaphylaxis. This type of response to small, not necessarily precisely measured, dose is not predictable on an individual basis. Allergic desensitization uses tightly controlled doses, increased based on clinical results.

Multiple mechanisms are involved in tolerance to opioids, but, in treating chronic pain, the increasing dose requirement may be due to an increase in the pain rather than actual tolerance.

Both mithridatization and homeopathy might be considered as instances of hormesis, which describes the phenomenon that many chemicals at high concentrations have opposite biological effects to those at low concentrations.

Dynamisation
The law of similars was re-introduced by Hahnemann after centuries of oblivion, and the principle of dynamization (or potentiation/potentization) was another of his discoveries. Hahnemann was not simply a respected physician of his day but also a respected chemist. Mixing, stirring, and shaking are common practices of chemists. Some historians suggest that Hahnemann saw that the efficacy of his remedies was greater in patients he had met in their homes. In Hahnemann's time, the mode of transportation was horseriding. He hypothesised that the agitation during the travel was responsible for the enhanced efficacy. Thus the notion of dynamization was born.

Some scientists have suggested that dilution and vigorous succussion (shaking in a particular way) makes the substance "imprint" the water or ethanol used for diluting. Others have reported that the vigorous shaking of the water in glass bottles can cause small amounts of silica fragments or “chips” to fall into the water, and suggest that these silica fragments might interact with the medicinal solution , but homeopaths generally believe that the remedies are not influenced by the silica.

Many homeopathic remedies are however avalaible as solid preparations -"pillules" of lactose and/or sucrose, intended as inert cores which are transformed into homeopathic drugs by impregnating them with a dilution of homeopathic stock solutions, or in powder form (impregnated lactose). These preparations contain no water.

Professional homeopaths: who are they?
There are no universal standards for homeopathic education, so licensing and regulation varies from country to country, and state to state within each country. In some countries, all (or virtually all) professionals that use homeopathic treatments are MDs (such as France, Spain, Argentina, Colombia), some countries have exclusively homeopathic medical schools (India, Pakistan, Mexico), some countries have naturopathic medicine colleges in which students are taught homeopathy as part of their curriculum (Germany has its "heilpraktica"/health practitioners; the US, Canada, and Australia have naturopathic medicine schools that include homeopathy along with their usual studies) and some countries certify "professional homeopaths" who have attended homeopathic schools and who then pass independent examinations that grant them "certification" as homeopaths. In the US, MDs and DOs are eligible for this certification, though there is also a separate certification process available only to MDs and DOs (there are similar choices of certification available in the UK for medical doctors, who've done at least MBBS).

A typical homeopathic visit
As homeopathic remedies can be prescribed by such a varied array of practitioners, from naturopaths, acupuncturists, chiropractors, pure homeopaths to medical doctors, the gathering of information may be different depending on the professional. Trained homeopaths place emphasis on the patient's symptoms as well as the person's psychological state in choosing a homeopathic remedy. Practitioners of classical homeopathy gather this information from what they call a comprehensive interview with the patient. Generally, a typical homeopathic interview can last from 15 minutes to two hours, with 5 to 45 minute follow-up consultations.

Health professionals who practice homeopathy take a medical history, and then take a homeopathic history. They also perform a basic physical examination, with additional examination of body parts or systems that may be associated with a symptom, diagnostic imaging and tests from the clinical pathology laboratories as suggested by the differential diagnosis, questions raised by the history, and physical examination.

To determine which remedy to prescribe, classical homeopaths place more emphasis on the way a person experiences whatever disease they have more than the name of the disease s/he has. They give higher priority to the unique syndrome of symptoms of the patient than the objective results of conventional medical tests.

When considering the person's symptoms for constitutional treatments, some categories of change are identified as important: "(1) emotions; (2) mentation; (3) specific physical functioning; (4) general physical changes; (5) perception of self; (6) relationships; (7) spirituality; (8) lifestyle; (9) energy; (10) dream content and tone; (11) well-being; (12) perceptions by others; (13) life relationships; (14) a sense of freedom or feeling less 'stuck'; (15) sleep; (16) coping; (17) ability to adapt; (18) creativity; and (19) recall of past experiences."

After the homeopath conducts a thorough interview (and physical exam, when appropriate), the homeopath consults homeopathic textbooks called repertories and materia medica to find a medicine that is known to cause, if given in overdose to experimental subjects, a similar syndrome of symptoms that the sick person is experiencing. Today, the vast majority of homeopaths use expert system software that contains homeopathic repertories and materia medica to find the individually chosen medicine for the sick person.

A "repertory" is a large textbook or database of various physical and psychological symptoms and the list of medicinal substances that have been found to cause and/or cure each individual symptom. A repertory has separate chapters on symptoms of the mind, head, eyes, ears, nose, and each part of the body, as well as a chapter of "general symptoms" which are systemic symptoms. In addition to listing individual symptoms, various characteristics of each symptom are listed, each with their own list of medicinal agents that have been found to cause and cure it. Further, whatever factors (called "modalities") that may aggravate or ameliorate a specific symptom or a generalized condition are listed, along with their respective medicines known to cause and/or cure it.

A "materia medica" (Latin for "materials of medicine") is a book that lists various medicines used in homeopathy and the various physical and psychological symptoms that each medicine has been found (in a problem/disease) to cause in overdose and/or cure in homeopathic doses.

The challenge of homeopathic practice is to find the medicine that most closely fits the unique and overall syndrome of symptoms that the sick person is experiencing.


 * A physician qualified in homeopathic and allopathic methods, after diagnosing a chronic condition that does not have consistently effective allopathic treatments, may prescribe a homeopathic remedy which he feels may be more effective and is likely to have fewer side effects than allopathic drugs.
 * Homeopaths recognize that trauma can be a surgical emergency, but may use homeopathic remedies adjunctively.
 * Homeopaths disagree with mainstream medicine about the role of immunization and chemoprophylaxis for infectious diseases.
 * Situations for which homeopathic practitioners commonly prescribe remedies include asthma and acute bronchitis. For these conditions, homeopathic remedies are often prescribed not only to alleviate chronic symptoms, but also to treat acute attacks.

Conflict as to when conventional medicine may be necessary
This practice is controversial. Asthma and other respiratory disorders with a seemingly mild initial presentation can actually be a life-threatening condition, and acute attacks, if not treated effectively, can lead to sudden death. According to conventional medical opinion, prescribing homeopathic remedies in these cases may delay the delivery of effective conventional treatment, with potentially serious consequences. Medical organisations advise that there is no evidence that homeopathic remedies are effective in these circumstances, and recommend that they should only ever be used in conjunction with conventional medical treatment. Homeopaths state they heal asthma and bronchitis, and point to studies on asthma

Homeopaths also cite a study where "a homeopathic remedy" has been used to shorten the duration of acute bronchitis and heal a person. This study, however, is from the journal Phytomedicine, which is not specific to homeopathy, and the word "homeopathy" does not appear in the MEDLINE abstract, although it does in the body, since it was funded by a German homeopathic pharmaceutical company. The abstract and MEDLINE indexing terms reference "plant extract", defined in Medical Subject Headings as "Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard", which is called a homeopathic mother tincture. Concentrated plant extracts may be used as mother tinctures, or the starting point for dilution, but such use is not mentioned in the Phytomedicine article, because it did not go into the use of dilutions.

These homeopathic studies deal with small test populations, in the order of tens to hundreds, while conventional trials deal with thousands, and surveillance on the actual use in practice gives data from millions. Conventional medicine also has consistent clinical and pathological definitions of asthma, with considerable customization for individual patient needs but still enough common criteria to allow significant retrospective analysis in large populations. Large studies are difficult because individualized remedy selection is a must in homeopathy; this causes conflict with physicians who expect the statistical power of large studies.

Homeopaths also assert that corticosteroids are immunosuppressant drugs that may provide temporary relief of asthma symptoms but may lead to more serious chronic disease and to increased chances of death. Physicians have learned that life, itself, increases the chance of death. The medical use of corticosteroids is not for symptom relief, but to prevention of inflammation that leads to symptoms. Inhaled corticosteroids, which do not spread through the body and cause widespread effects, but stay on the breathing passages and prevent inflammation, are medically preferred to systemic corticosteroid therapy.

Homeopathic remedies might also be used after an asthmatic episode with the intent to prevent recurrences by improving the natural healing processes of the body.


 * An adequately trained homeopath is expected to recognize symptoms that indicate an acute and potentially fatal condition. Such symptoms as unexplained chest pain of sudden onset, especially with other symptoms suggestive of a major cardiovascular event, ethically will activate EMS for immediate transfer to an appropriate staffed and equipped medical facility. The practitioner is expected to have emergency medical training and equipment appropriate to his or her level of medical training in the place of practice (e.g., dressings and basic airway management tools for an individual with training at the Emergency Medical Technician (EMT) of Basic or higher level, and preferably an automatic external defibrillator and advanced cardiac life support resources generally accepted as appropriate for an office.

Conditions where individualization may not be needed
The treatment of acute ailments or injuries does not need the same depth or breadth of the interview process as homeopathic constitutional treatment. The homeopathic treatment of minor acute ailments still requires individualized treatment. Potentially serious acute ailments may require medical supervision, though homeopathic medicines can be prescribed concurrently/alternatively. One person's symptoms of a common cold or a headache or an allergy will have his/her own unique syndrome of symptoms that will require an individually chosen medicine. People who experience an injury, however, generally need the same healing process to recover from trauma, so clinical experience has led homeopaths to believe that some homeopathic remedies might be routinely useful for trauma.

Selecting individual remedies
Once a case-taking has been conducted, the homeopath may use a detailed index of symptoms called "repertories," and/or a "materia medica", which details the symptoms that each remedy is thought to cause or cure. Many homeopathic textbooks have now been integrated into software and most homeopaths world-wide use some such software. Some homeopaths make quick prescriptions based on "keynotes" -the highlights of the best known characteristics of a remedy.

There is rarely a specific remedy for a disease or ailment in homeopathy, instead, remedies are chosen based on the overall syndrome of the patient, not just by the name of the disease. The homeopath seeks to find the "similimum," that is, the remedy that will cause, in overdose in experimental subjects, the most similar syndrome of symptoms that the sick person is experiencing. One of the fundamental reasons for conflict between mainstream medicine and homeopathy is that homeopathy rejects the concept of common, comparable mechanisms of disease, but seeks underlying mechanisms that allow large-scale validation.

Conflict on individualization
Another area of conflict is the insistence that only homeopaths provide remedies tailored to the individual. Classical homeopathy frowns on the use of multiple concurrent remedies; a major repertory contained approximately 3,000 remedies, presumably used singly. In comparison, the The U.S. Food and Drug Administration Approved Drug Products with Therapeutic Equivalence Evaluations 26th Edition Electronic Orange Book (EOB)4 lists 11,706 approved prescription drugs (RX) with therapeutic equivalence evaluations, [ and] 390 approved over-the-counter (OTC) drugs. They contain 1323 chemically distinct ingredients in measurable quantities, not infrequently used in combination. Since medicine is quite willing to use rational combinations, it is fairly straightforward mathematics shows that there is considerably more potential to individualize medical treatment from the permutation and combination of 1323 chemicals, rather than homeopathic treatment based on largely single use of 3000.

As an indication that medicine constantly reevaluates and rejects things with undue risk and inadequate benefit, the Orange book also contains 8820 approved products that have been discontinued.

As far as defining individualized remedies, the increasingly important field of pharmacogenetics individualizes, but based on reproducible criteria from the patient's genome. While this is a very new branch of medicine, a 2007 study created a network of connections of FDA approved drugs and their active ingredients with known human gene targets. This resulted 1052 drugs targeting 485 proteins, the proteins identifiable from genomic data rather than subjective assessments of symptoms.

Homeopathy in injuries
Homeopaths view injuries in a different manner than they view diseases, because they believe that everybody needs the same type of healing response to injuries, whereas a single disease may produce very different symptoms in different people. Homeopathic treatment of trauma is adjunctive to conventional first aid measures. Some clinical research has shown efficacy of homeopathic medicines in the treatment of select injuries, including mild traumatic head injuries and sprains and strains

Homeopathy as a form of Complementary and Alternative Medicine
Some studies of homeopathy have been funded by the U.S. National Center for Complementary and Alternative Medicine (NCCAM). In NCCAM's taxonomy of complementary and alternative medicine, homeopathy is a "whole system" that is an alternative to the entire medical mode, although it can be complementary to conventional care. The funded studies include:


 * A study on fibromyalgia, which showed clinical benefits from individually chosen homeopathic remedies as well as objective differences in EEG readings in homeopathic and placebo subjects.


 * A study on homeopathy for mild traumatic brain injury. This pilot study indicate a significant benefit from the homeopathic treatment but requires large-scale, independent replication.

Scientific basis of homeopathy
See articles on solitons, clathrates, nanobubbles and The memory of water.

There are several theories about how homeopathic remedies may work, but no widely accepted scientific explanation. There are observations about the alteration of water by homeopathic preparations, but no generally accepted theories on how those altered properties would affect biological systems. Some homeopaths and a few scientists have proposed that research on what is called the silica hypothesis (see Memory of water, solitons, clathrates, and nanobubbles that suggest how homeopathic remedies might differ from pure water, and some think that better understanding of hormesis might help also.

Water is not simply a collection of molecules of H2O, it contains several molecular species including ortho and para water molecules, and water molecules with different isotopic compositions such as HDO and H218O. These water molecules as part of weakly-bound but partially-covalently linked molecular clusters containing one, two, three or four hydrogen bonds, and hydrogen ion and hydroxide ion species. In addition, there are always adventitious solutes in liquid water. Even double-distilled and deionized water always contains trace amounts of contaminating ions, and different samples will differ in the contaminants that they contain.

There is some support for the notion that water can have properties that depend on how it has previously been processed (that is, water has, in some sense, a kind of "memory"). The experimental evidence indicates that the "memory" is due primarily to solute and surface changes occurring during this processing. In particular, water, as a result of repeated vigorous shaking, might include redox molecules produced from water, dissolved atmospheric gases and airborne contaminants, silicates - tiny glass "chips", nanobubbles and their material surfaces, dissolved ions, including from the glassware, apart from the original medicinal substance it was diluting. It is theorized that each medicinal substance that is placed in the double-distilled water will interact with the silicate fragments in differing ways, thereby changing the structure of the water. There might also be some effects of successive shaking on water structure - "clustering" of water molecules.

These mechanisms are not mechanisms of memory in any cognitive sense; the term memory here is used as a metaphor, implying only that the past history has a discernible influence on the present properties.

Homeopaths believe that, through these or other mechanisms, water can form and retain some "memory" of the original medicinal substance, and that as a consequence of this memory, it can potently elicit specific and relevant biological effects.

Tests of the efficacy of homeopathic remedies
Cochrane Reviews did a meta-analysis of seven randomized controlled trials, three prevention trials (number of participants, $$N = 2265$$) and four treatment trials, $$(N = 1194)$$. The authors considered only two were statistically adequate, but data from the prevention trials showed no effect. Data from the treatment trials showed enough efficacy that further trials were recommended, but that the remedy could not be recommended for first-line therapy. No homeopathic counterarguments to these specific meta-analyses have been published, but homeopaths often consider large trials invalid because they do not reflect the individualized nature of homeopathic treatment.

In vitro
A systematic review of the in vitro evidence of homeopathic high potencies evaluated 67 experiments (mostly performed on basophils) in 75 publications (1/3 of them replications. Nearly 3/4 of them found a high potency effect, including 12 of 18 studies that scored 6 points or more for study quality and which controlled for contamination. Nearly 3/4 of all replications were positive. The authors concluded that even experiments with a high methodological standard could demonstrate an effect of high potencies, but no positive result was stable enough to be reproduced by all investigators.

In vivo
A meta-analysis of 105 animal trials evaluated the use of homeopathic remedies in the treatment of environmental toxicology. Of these, 28 studies were considered high quality, and positive effects from homeopathic doses were reported 50% more often than no effects. The authors also noted, "experiments using the 'high' dilution range (by our definition those preparations diluted beyond the presence of original substance) had higher quality evaluations than experiments in lower dilution ranges, making their validity more likely. Second, our reevaluation of results from these studies using the raw data showed that over 70% had positive effects."

One group of researchers tested the effects of heavy metals on mice who were given homeopathic doses of these toxic substances after exposure. Using Arsenicum album (arsenic oxide) $$6C, 30C$$ and/or $$200C$$ to treat mice who were exposed to crude doses of arsenic, they found that it significantly reduced the cytotoxic effects of arsenic, including the levels of two liver enzymes which are indicators of liver toxicity and both of which are increased as a result of arsenic poisoning.

Randomized controlled trials in humans
Homeopaths assert that homeopathic remedies generally have to be individually prescribed to a sick person based on the totality of symptoms, not just the disease that he/she has been diagnosed with; they therefore argue that many clinical trials are inappropriate tests for homeopathic treatment, but acknowledge that there are sometimes exceptions to the need for individualization (the experience above with Oscillococcinum is one such exception).

Clinical trials are the "gold standard" for efficacy in mainstream medicine, often creating an impasse with homeopaths who do not find their paradigm compatible with large scale randomized controlled trials.

Some individual RCTs have shown no statistically significant effect, while others indicate a positive difference in people receiving homeopathic treatment. There are single RCTs in favor of homeopathy for a number of other conditions, including: respiratory allergies such as hayfever, asthma and perennial allergic rhinitis, acute otitis media, influenza, childhood diarrhea, symptoms of chronic obstructive pulmonary disease, arthritis, fibromyalgia,  vertigo, varicose veins ankle sprain, bronchitis, chronic fatigue and premenstrual syndrome.

Some trials have been performed that partially meet these criteria, and some of these have reported positive effects. These have not been considered as providing compelling evidence, partly because of deficiencies in trial design, but mainly because of the possibility of publication bias - the phenomenon whereby trials that happen by chance to appear to show a positive outcome are more likely to be published than those which are inconclusive or appear to show a negative outcome. Nevertheless, even if homeopaths distrust clinical trials, some have shown, in small groups, enough positive results to justify larger tests. Positive results came from Taylor and colleagues, writing on their placebo-controlled randomized controlled trial of a homeopathic treatment for allergic rhinitis, concluded " this study has failed to confirm our original hypothesis that homoeopathy is a placebo". Two invited commenters were published alongside, and found the study interesting, but of small size. They urged larger trials, and cited the challenge of doing "large trials that really could change thinking," citing work on influenza by Vickers et al. and Ferley et al., on muscle recovery, as having done large-scale trials. The muscle soreness trial showed no significant effect of homeopathic treatment; $$(N =400)$$ but the abstract did not break out the groups. Effects were measured by formal methods of the runners' subjective soreness.

The second trial, on influenza, used the objective endpoint of time to return to normal body temperature as the endpoint. They observed that more people in the active drug group $$(N=237)$$ than the control group $$(N=241)$$ had faster recovery $$(17.1% against 10.3%,  P=0.03).$$ While they could not explain the result, they called for "rigorously designed clinical studies."

Meta-analyses on humans
Some authors of meta-analyses have concluded that the placebo response is an inadequate explanation for the positive responses that have been reported in some trials. For example, one review assessed 105 trials, 81 of them positive; the authors concluded that the evidence on balance is trials is positive but not sufficient to draw definite conclusions", and they said that “based on this evidence we would be ready to accept that homeopathy can be efficacious, if only the mechanism of action were more plausible”.

In another review, Linde and colleagues analyzed 89 trials and found a $$mean odds  ratio  of  2.45 (95% confidence interval, 2.05–2.93)$$ in favor of homeopathy. When considering just those trials of “high quality” and after correcting for publication bias, the findings remained significant $$(means odds ratio of 1.86).$$ The main conclusion was that the results “were not compatible with the hypothesis that the effects of homeopathy are completely due to placebo.” The authors later analyzed these trials and concluded that higher quality trials were less likely to be positive than those of lower quality, saying  “There is increasing evidence that more rigorous trials tend to yield less optimistic results than trials with less precautions against bias.”

Cochrane meta-analysis of Oscillococcinum
Oscillococcinum is a commercially available homoeopathic remedy manufactured from wild duck heart and liver that is sold as a remedy for influenza, and which is particularly popular in France. A Cochrane review of seven placebo-controlled studies included: but only two of these provided adequate data for full analysis. Two of the trials were unpublished, according to the New Zealand Guidelines Group, which provides evidence-based reporting on complementary and alternative medicine.
 * three prevention trials (number of participants $$(N) = 2265$$)
 * four treatment trials $$(n = 1194)$$.

The review found "promising" evidence that Oscillococcinum is effective in the treatment of influenza and influenza-like illness, but it was not effective in the preventation of influenza and influenza-like symptoms ($$(relative risk (RR) 0.64, 95% confidence interval (CI) 0.28 to 1.43).$$). The review of research found evidence for a small effect on duration of illness (Treatment reduced the duration by 0.28 days $$(95% CI 0.50 to 0.06).$$). This positive result from this homeopathic medicine was felt to justify further research, but the review concluded that the data were not strong enough to make a general recommendation to use Oscillococcinum for first-line treatment of influenza.

The Lancet controversy
In 2005, the Lancet published a meta-analysis of 110 placebo-controlled homoeopathy trials and 110 matched conventional-medicine trials. A press report on the article, which described the Lancet study as performed by Swiss scientists, who concluded that the only effects of homeopathy were in the mind.

There was considerable criticism of the Lancet article from journals in complementary and alternative medicine. In an editorial referring to the Shang article published by The Lancet, the ''Journal of Alternative and Complementary Medicine asked, One cannot but wonder and inquire, in all seriousness, what drove the editors of one of the most highly respected and influential journals of our time to allow through peerreview and thence to publication, a manuscript that fails totally to provide the information necessary for full independent replication or analysis

While Shang was listed as the lead author, the work was done under the Swiss Complementary Medicine Evaluation Programme (Programm Evaluation Komplementärmedizin, PEK). PEK's review board has protested about political interference in the scientific process, according to Peter Fisher, Director of Research, Royal London Homoeopathic Hospital.

The outcome suggested that the clinical effects of homeopathic remedies might all be placebo effects. The Lancet study is notable as a "global" meta-analysis of homeopathy, not an analysis of particular remedies, i.e. it tested the hypothesis that all of the reported effects of homeopathic remedies are placebo effects. If so, then reports of positive effects reflect publication bias (the tendency to publish results when they show a positive effect but not when they are negative), and the magnitude of such effects should diminish with sample size and study quality. They analyzed an equal number of conventional medicine trials similarly; these showed a real effect of treatment, in that the size of the reported effect was independent of sample size, but the trials of homeopathy remedies did not. The study does not prove that homeopathy is never effective, but is consistent with the interpretation that all reported effects are placebo effects. The Lancet subsequently published a selection of critical correspondence.

Several of these published responses remarked (incorrectly) that the researchers evaluated only those studies that met certain criteria for “high quality” scientific investigations. Of the original 110 trials, 21 of the homeopathic studies fit this definition but only nine of the conventional studies did so. The researchers then considered only those trials that had a large number of patients, as trials with a larger sample size have greater statistical power. They thus compared eight homeopathic trials with six conventional medical trials, even though these trials were only matched as being of large size and good quality. The results of this subanalysis was that the effects observed in the homeopathic trials were no greater than the placebo effects observed in the clinical trials. They suggested that no further research on homeopathy is necessary, while advocates of homeopathy assert that almost all of the eight homeopathic trials used only a single homeopathic remedy given to every subject without the typical individualization of treatment that is commonly used in homeopathic practice.

Advocates of homeopathy assert that this study's emphasis on certain large homeopathic trials lacked external validity, that is, the trials were not consistent with the homeopathic methodology, thereby reducing the meaning of the study's conclusions. Some insight may be gained from a branch of mainstream medicine in which treatment must be far more individualized than any plausible drug trial: surgery. A trial lacks internal validity when the difference in the control and treatment groups cannot be explained only by the specific different treatment. Paradis gives a hypothetical example of a trial of wound irrigation with an antibiotic. The treatment group has irrigation from a prefilled, mechanically operated fluid dispenser, while the control group's irigation is done with a hand-operated syringe filled with saline. The potential differences are obvious; there can even be more differences in full surgery, due to the differences in anatomy, body fat, and other individual variations.

External validity is also called "research validation": can the results of controlled trials be seen in community practice? Purists will say that external validation cannot make up for a lack of internal validity; the external experience is essentially separate from the flawed trial. Arguably, many retrospective clinical studies are based purely on reviewing "external" cases, but an attempt is made to find cases with as much similarity as possible. From the perspective of mainstream medicine, it may appear as if homeopaths want to insist on as much individualization as possible, frustrating even retrospective techniques.

External validity, used with care, does guide surgical development; many number of surgical techniques seemed promising at first, but, with a larger data base, proved ineffective, while others gained more credibility. For there to be better understanding between homeopathy and mainstream medicine, there must be mutual willingness to converge on a model where a degree of individual treatment is accepted as part of the homeopathic approach, but the need to have some statistical rigor has to be accepted as part of the approach of evidence-based medicine.

Other Meta-analyses
Several meta-analyses evaluating the homeopathic treatment of specific diseases has also found positive results. These studied childhood diarrhea, respiratory allergies , and postoperative ileus.

Are the right things being analyzed?
However, other meta-analyses on homeopathy in a wide range of conditions, have suggested that the effect from a homeopathic remedy was no better than a placebo, although several found that there was justification for further research. Some of the authors suggested that the key thing to study, perhaps more so than yet another placebo-controlled trial of a remedy, are systematic observational studies of the interaction between homeopath and patient, in contrast with the interaction between patient and conventional health care worker.

In conventional medicine, there is concern within the U.S. healthcare economics area about even collecting minimal data on the quality of encounters. One policy study stressed the need not to understand the nature of the interaction, but even to get basic demographics on the encounter; especially in programs servicing low-income populations, there may be little more than billing data. There are a number of trial programs to use nurses and other providers, at a lower cost than physicians, to do case management of chronic disease. Case management interactions may be as long as some of those with homeopaths. It is not unreasonable to note that a number of nursing associations call for more holistic patient interactions than is typical for conventional medicine, and to wonder if the most important lessons from current homeopathy are not the ones primarily studied. Proposals for studying nursing may be relevant.

In one meta-analysis of 6 trials $$(N=556)$$, there were six RCTs, which used different treatments that were difficult to form into a meaningful pool. The authors observed that they used standardized treatment, which probably differs from the homeopathic standard of practice. They observed "There has been only a limited attempt to measure a 'package of care' effect (i.e., the effect of the medication as well as the consultation, which is considered a vital part of individualised homeopathic practice)." The conclusion was that there was not enough useful data, and strongly recommended, in addition to RCTs, collecting "observational data to document the different methods of homeopathic prescribing and how patients respond. This will help to establish to what extent people respond to a 'package of care' rather than the homeopathic intervention alone." In conventional medicine, there have been comparisons where the actual treatment was the same, but the variable was the type of encounter (e.g., short or long, physician specialist vs. generalist, nurse-educator rather than physician).

Another study, conducted by an outspoken skeptic of homeopathy (Ernst) identified 17 useful articles. Six, however, re-analyzed the same major meta-analysis. This major study observed some differences between homeopathic treatment and placebo, but also could find no specific evidence of efficacy for any specific condition. The authors of this meta-analysis defined "evidence" in this context as having at least three independent researchers finding positive results from a specific treatment. Within one year of publication of this meta-analysis, a third independent trial was conducted testing Oscillococcinum in the treatment of influenza. Also, a third trial in the treatment of childhood diarrhea was published (the lead researcher for these trials were the same individual, but the prescribing homeopaths for each trial were different clinicians.) Even though these newer studies helped homeopathic research pass this threshold, the authors of the 1997 meta-analysis still concluded,  "Further research on homeopathy is warranted provided it is rigorous and systematic."

The meta-analysis of 17 papers concluded "Until more compelling results are available, homeopathy cannot be viewed as an evidence-based form of therapy," but strongly recommended formal study "individualized, empathetic and time-intensive approach most homeopaths adopt to healthcare yields good clinical results. This emphasizes the importance of the therapeutic encounter and is in accordance with a wealth of information in this area". In other words, there may be useful information about the methods by which patients interact with homeopath, and that, according to the author, may be a more fruitful area of research than the memory of water. Homeopaths respond to such suggestions that most of the above clinical trials were placebo-controlled, and thus, such studies properly evaluate the "package of care" and still find that the majority of clinical trials have shown a positive result.

Prevalence of homeopathy
While homeopathy is not practised by most of the medical profession it is supported by some physicians and scientists. Some homeopathic treatment is covered by European public health services, including France and Denmark. A pilot study published by the British Homeopathic Society recommended homeopathy as a useful treatment option for  National Health Service (NHS) patients. Five homeopathic hospitals are funded by the NHS and homeopathic remedies are sold over the counter throughout Britain. Two countries which formerly offered homeopathy under their public health services no longer do so: from 2004, homeopathic remedies, with some exceptions, were no longer covered by the German public health service, and in 2005, the Swiss Government withdrew homeopathy and four other complementary treatments, stating that they did not meet efficacy and cost-effectiveness criteria.

In France and Denmark licenses are required to diagnose any illness or to dispense any product whose purpose is to treat illness. In many countries, however, there are no specific legal regulations concerning homeopathy. In Austria, the public health service generally requires proof of effectiveness to reimburse medical treatments, but makes an exception for homeopathy.

Questions about homeopathic theory
Homeopathy was developed at a time when many of the most important concepts of modern chemistry and biology, such as molecules and germs, were understood poorly if at all. While proponents may consider the mechanism of homeopathy to be an interesting side issue, others consider the lack of any plausible mechanism to be a serious problem; they raise the bar for the quality of evidence required before accepting the existence of the phenomenon by citing the common phrase, "Extraordinary claims require extraordinary proof".

In Hahnemann's day, many chemists believed that matter was infinitely divisible, so that it was meaningful to talk about dilution to any degree. Although the hypothesis of atoms can be traced back to the ancient Greeks, their size was not calculated until 1865 (by Josef Loschmidt). There are 6.02×1023 particles in a mole (Avogadro's number, or, in German-speaking countries, Loschmidt's number), so homeopathic dilutions greater than about $$24X$$ or $$12C$$ are virtually certain to contain not even a single molecule of the initial substance. This is recognized by advocates of homeopathy, who assert that the essential healing power of their preparations is not to be found in the chemical action of molecules, but perhaps in the arrangement of the water molecules, giving rise to the expression 'the memory of water'.

The idea of the memory of water is parallel to the idea of vital force. Homeopathic preparations change properties of the water such that they can affect vital force, but, since neither vital force nor the means of affecting it are measurable, the process is not compatible with current scientific testing. Vital force was discarded by the scientific community as more and more life processes came to be describable in purely materialistic terms, and as the medical model of disease came to be focused on the interactions of physiological mechanisms, and external factors, in the body.

There have been occasional reports of effects of highly diluted solutions on organic processes, including on histamine release by basophils. However, attempts to replicate these studies failed. . An extremely biologically active substance such as a specific immunoglobulin, in a modern purified form, may or may not be a reasonable surrogate for a preparation prepared with the chemistry available in the early 19th century.

Non-homeopaths question if homepathic theory is logically consistent, pointing out what appear to be inconsistency. The theory assumes that water is imprinted by the properties of molecules that it once came in contact with, even when the molecules are diluted away. If so, then where did the pure water used in this process come from? The water that homeopaths use was once in contact with other chemicals, including chemical wastes, radioactive metals, dinosaur urine, and various poisons. According to this interpretation of homeopathic theory, all water in the world should remember its contact with millions of chemical substances and not just the properties of the chemicals that the homeopath claims will be useful. Homeopaths respond to these concerns by asserting that homeopathic manufacturers, who in each country are regulated as drug companies, use a double-distilled water which may clear the "memory" of past water history.

Medical organizations' attitudes towards homeopathy
In the U.S., the National Center for Complementary and Alternative Medicine (NCCAM), part of the National Institutes of Health, funds research into homeopathy. It states that controlled clinical trials of homeopathy have produced mixed results; in some, homeopathy appeared to be no more helpful than a placebo, but in others, more benefits were seen than expected from a placebo.

NCCAM's acting deputy director, Jack Killen, said, in a Newsweek article, homeopathy "goes beyond current understanding of chemistry and physics." He added, "There is, to my knowledge, no condition for which homeopathy has been proven to be an effective treatment." . Homeopaths say that this is his personal opinion and point to the studies which show that Homeopathy is effective.

Historically, the American Medical Association (AMA) was founded in 1847, three years after the forming of the American Institute of Homeopathy,. From 1860's to the early 20th century, the AMA's ethic code disallowed its members to consult with fellow medical doctors who practiced homeopathy. Although the AMA didn't enforce many of its ethical guidelines, the "consultation clause" was one of the few that was. Today, the AMA is no longer overtly antagonistic to homeopathy. Their current policy statement says: "There is little evidence to confirm the safety or efficacy of most alternative therapies. Much of the information currently known about these therapies makes it clear that many have not been shown to be efficacious. Well-designed, stringently controlled research should be done to evaluate the efficacy of alternative therapies".

Homeopathy is practiced by large numbers of conventional medical physicians through Europe, including 30-40% of French doctors and 20% of German doctors, while 45% of Dutch GPs consider homeopathy efficacious in the treatment of upper respiratory tract infections or hay fever. According to the UK National Health Service (NHS), homeopathy is one of the most popular alternative and complementary treatment modalities. The NHS recognizes that there have been about 200 randomised controlled trials evaluating homeopathy, some show efficacy of treatment and some don't. They conclude, "Despite the available research, it has proven difficult to produce clear clinical evidence that homeopathy works".

Homeopathy in India is formally recognised by the Government (along with Ayurveda, Yoga & Naturopathy, Unani, Siddha) as one of the Indian Systems of Medicine. About 10% of the Indian population solely depends on Homoeopathy for their health care needs.

Safety

 * The highest ideal of cure is the speedy, gentle, and enduring restoration of health by the most trustworthy and least harmful way (Samuel Hahnemann)

Some physicians maintain that homeopathy, like other alternative medicine, is relatively unsafe, because, it in some cases, might delay the conventional, medically proper treatment, if it doesn't work. Homeopaths assert that the side effects from conventional drugs pose a greater risk, which is a major area of conflict: too much emphasis in avoiding a controllable side effect may delay other therapy until the conventional treatment is no longer needed, because the problem/disease may go away on its own. Mainstream physicians, however, do not believe that a responsible, evidence-based drug is more dangerous than the condition it might avert or mitigate, and do not accept the homeopathic argument that appears, to a physician, to be opposed to all non-homeopathic drugs.

The European Union allows homeopathic medicinal products, provided they are prepared according to the European Pharmacopoeia or the pharmacopoeias currently used officially in the Member States. Further the products must be diluted sufficiently so that there is no risk for the patient. In particular, the product may not contain either more than one part per 10&thinsp;000 of the mother tincture or more than 1/100th of the smallest dose of an active substance that requires doctor's prescription. No specific therapeutic indication may be given on the label of the product.

The U.S. Food and Drug Administration's view of homeopathy is that there is no real concern about the safety of most homeopathic products because its dosages "have little or no pharmacologically active ingredients".

Virtually every modern pharmacologist would agree with Hahnemann that the drugs prescribed by conventional physicians of the 19th century were at best ineffective and often dangerous. However, some homeopaths question whether even modern medical drugs are safe and effective. For example, a 2006 survey by the UK charitable trust 'Sense About Science' revealed that homeopaths were advising travelers against taking conventional anti-malarial drugs, instead providing them with a homeopathic dilution of quinine. Even the director of the The Royal London Homeopathic Hospital condemned this:

I'm very angry about it because people are going to get malaria - there is absolutely no reason to think that homeopathy works to prevent malaria and you won't find that in any textbook or journal of homeopathy so people will get malaria, people may even die of malaria if they follow this advice.

A particular concern is that some homeopaths discourage the use of vaccines. Homeopathy is superficially like vaccination, in that vaccines contain a small dose of the 'disease' against which they offer protection (a vaccine is usually made from a bacterium or virus that is either dead or weakened so that it cannot produce symptoms, while still providing enough information to the immune system to generate antibody production).

Many homeopaths oppose vaccination for common diseases, such as measles and chicken-pox, thinking this unneccessary. Some believe that vaccines can even be damaging to health, in part because of the mercury and aluminum in them, in part because the bacterium or virus in the vaccine may neither be dead nor weak enough. Such advice is generally considered irresponsible by public health professionals. Adult herpes zoster infection is a reactivation of childhood chickenpox, which recurs along nerve paths, affects 1 in 3 adults, and can cause chronic, severe nerve pain of postherpetic neuralgia in 10-18% of cases, and eye involvement in 10-25% of cases. Chickenpox immunization prevents adult herpes zoster; a herpes zoster vaccine is now recommended for all adults 60 years and older. Childhood immunization against chickenpox prevents herpes zoster. Measles is not a major killer in the western world, where the vast majority of children are vaccinated against the disease at about two years old. However, in less developed countries the death toll is much higher, and in 1999 there were 875,000 deaths from measles worldwide, mostly in Africa. In 2001, a "Measles Initiative" was initiated involving organisations such as the American Red Cross, UNICEF and the World Health Organization, and between 1999 and 2005 more than 360 million children across the world were vaccinated. By 2005 the death toll had dropped by 60% to 345,000.