U.S. intelligence analysis of patterns of infectious diseases and impacts

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After the Second World War, antibiotics and vaccines were hoped to become the end of most infectious disease. Increases in the rate of acquired drug resistance in pathogens, and a slowing of the rate of development of new treatments, proved this overoptimistic. Other factors including expanded trade and travel, the overuse of antibiotics, and other factors made the outlook a good deal more bleak. According to the 1999 NIE, [1] Still, there is both the promise that Variola major virus, the cause of smallpox, has been eradicated from the wild; there remains the fear that a culture exists other than in the two authorized facilities, and could be used as a biological weapon.

  • Infectious diseases remain a leading cause of death. Of the estimated 54 million deaths worldwide in 1998, about one-fourth to one-third were due to infectious diseases, most of them in developing countries and among children globally.
  • Infectious diseases accounted for 41 percent of the global disease burden measured in terms of Disability-Adjusted Life Years (DALYS) that gauge the impact of both deaths and disabilities, as compared to 43 percent for noninfectious diseases and 16 percent for injuries.
  • Although there has been continuing progress in controlling some vaccine-preventable childhood diseases such as polio, neonatal tetanus, and measles, a White House-appointed interagency working group identified at least 29 previously unknown diseases that have appeared globally since 1973, some incurable, including HIV/AIDS, Ebola, and hepatitis C virus. Most recently, Nipah encephalitis was identified. Twenty well-known diseases such as malaria, tuberculosis, cholera, and dengue fever have rebounded after a period of decline or spread to new regions, often in deadlier forms.
  • These trends are reflected in the United States as well, where annual infectious disease deaths have nearly doubled to some 170,000 since 1980 after reaching historic lows that year, while new and existing pathogens, such as HIV and West Nile virus, respectively, continue to enter US borders.

Economic, social, and political impact

The persistent infectious disease burden is likely to aggravate and, in some cases, may even provoke economic decay, social fragmentation, and political destabilization in the hardest hit countries in the developing and former communist worlds, especially in the worst case scenario outlined above:[2]

  • The economic costs of infectious diseases--especially HIV/AIDS and malaria--are already significant, and their increasingly heavy toll on productivity, profitability, and foreign investment will be reflected in growing GDP losses, as well, that could reduce GDP by as much as 20 percent or more by 2010 in some Sub-Saharan African countries, according to recent studies.
  • Some of the hardest hit countries in Sub-Saharan Africa--and possibly later in South and Southeast Asia--will face a demographic upheaval as HIV/AIDS and associated diseases reduce human life expectancy by as much as 30 years and kill as many as a quarter of their populations over a decade or less, producing a huge orphan cohort. Nearly 42 million children in 27 countries will lose one or both parents to AIDS by 2010; 19 of the hardest hit countries will be in Sub-Saharan Africa.

The relationship between disease and political instability is indirect but real. A wide-ranging study on the causes of state instability suggests that infant mortality--a good indicator of the overall quality of life--correlates strongly with political instability, particularly in countries that already have achieved a measure of democracy. The severe social and economic impact of infectious diseases is likely to intensify the struggle for political power to control scarce state resources.

As a major hub of global travel, immigration, and commerce with wide-ranging interests and a large civilian and military presence overseas, the United States and its equities abroad will remain at risk from infectious diseases.

  • Emerging and reemerging infectious diseases, many of which are likely to continue to originate overseas, will continue to kill at least 170,000 Americans annually. Many more could perish in an epidemic of influenza or yet-unknown disease or if there is a substantial decline in the effectiveness of available HIV/AIDS drugs.
  • Infectious diseases are likely to continue to account for more military hospital admissions than battlefield injuries. US military personnel deployed at NATO and US bases overseas, will be at low-to-moderate risk. At highest risk will be US military forces deployed in support of humanitarian and peacekeeping operations in developing countries.
  • The infectious disease burden will weaken the military capabilities of some countries--as well as international peacekeeping efforts--as their armies and recruitment pools experience HIV infection rates ranging from 10 to 60 percent. The cost will be highest among officers and the more modernized militaries in Sub-Saharan Africa and increasingly among FSU states and possibly some rogue states.
  • Infectious diseases are likely to slow socioeconomic development in the hardest-hit developing and former communist countries and regions. This will challenge democratic development and transitions and possibly contribute to humanitarian emergencies and civil conflicts.
  • Infectious disease-related embargoes and restrictions on travel and immigration will cause frictions among and between developed and developing countries

Contributing factors

The legendary Four Horsemen of the Apocalypse, Conquest, War, Famine and Death, have gained allies against the health of the world. Not even the Horseman of Death, riding a pale horse, needs to journey at the pace of a fast horse, when an infection can leap to an air traveler. The SARS outbreak came uncomfortably close to such a scenario.

When white horses bearing corrupt officials intent on enriching themselves, funds that might have gone to water purification, public health, and immunization become lost.

The red horse bearing War can drive refugees before it, spreading disease from a failed state. Epidemiologists had driven polio into a few remote areas, and there was hope that it might join smallpox in extinction. When Somali refugees became ill with polio in a Kenyan displaced persons camp, the shock went beyond East Africa.

It may take a crossbreeding of horses to produce a biological weapon with no safeguards against spread. While this is much more difficult than many suggest, the technologies exist.

Conflict

Detection and control of emerging infectious diseases in conflict situations are major challenges due to multiple risk factors known to enhance emergence and transmission of infectious diseases. These include inadequate surveillance and response systems, destroyed infrastructure, collapsed health systems and disruption of disease control programs, and infection control practices even more inadequate than those in resource-poor settings, as well as ongoing insecurity and poor coordination among humanitarian agencies. [3]

Bioterrorism

The probability of a bioterrorist attack against US civilian and military personnel overseas or in the United States also is likely to grow as more states and groups develop a biological warfare capability.[1] Although there is no evidence that the recent West Nile virus outbreak in New York City was caused by foreign state or nonstate actors, the scare and several earlier instances of suspected bioterrorism showed the confusion and fear they can sow regardless of whether or not they are validated.[4]

One of the challenges of detecting bioterrorism is that while automated aerosol detection equipment exists, it can cover only limited physical areas, such as high-value targets or troop concentration. In a civilian population, the first warning of covert terrorism is apt to come from clinicians that can compare many cases. An emergency room is one obvious place for comparison, but the availability of electronic health records, from which data from many office encounters can be extracted, with due regard for privacy, and searched for patterns.

Multidrug resistance and coinfection

Another reason for the increased danger of infectious diseases is antibiotic resistance, especially multidrug resistance. By themselves, bacteria can transfer the genes for resistance to a specific antibiotics. Improper medical use, where antibiotics are not needed for the actual problem but expose other bacteria to be selected out as resistant, or where patients do not take the full prescribed course, are significant sources of new forms. Use as an agricultural growth stimulant is generating resistant forms. While researchers continue to develop new classes of antibiotics, the rate of development is slower than the emergence of resistant forms.[5][1]

War and other factors are spreading resistant forms. In the US, Acinetobacter strains were previously seen only in immunosuppressed patients, but Acinetobacter baumanii has been a common, and drug-resistant, infection in military patients from Iraq and Afghanistan.[6]

Spread through rapid transportation

The increase in international air travel, trade, and tourism will dramatically increase the prospects that infectious disease pathogens such as influenza--and vectors such as mosquitoes and rodents--will spread quickly around the globe, often in less time than the incubation period of most diseases. Earlier in the decade, for example, a multidrug resistant strain of Streptococcus pneumoniae originating in Spain spread throughout the world in a matter of weeks, according to the director of WHO's infectious disease division. The cross-border movement of some 2 million people each day, including 1 million between developed and developing countries each week, and surging global trade ensure that travel and commerce will remain key factors in the spread of infectious diseases.<[1]

Technology, medicine, and industry

Although technological breakthroughs will greatly facilitate the detection, diagnosis, and control of certain infectious and noninfectious illnesses, they also will introduce new dangers, especially in the developed world where they are used extensively. Invasive medical procedures will result in a variety of hospital-acquired infections, such as Staphylococcus aureus. The globalization of the food supply means that nonhygienic food production, preparation, and handling practices in originating countries can introduce pathogens endangering foreign as well as local populations. Disease outbreaks due to Cyclospora spp, Escherichia coli, and Salmonella spp. in several countries, along with the emergence, primarily in Britain, of prion diseases such as Bovine Spongiform Encephalopathy, or "mad cow" disease, and the related new variant Creutzfeldt-Jakob disease (nvCJD) affecting humans, result from such food practices.

Antibiotics as an agricultural growth stimulant

Many farmers have found they have fewer fatalities and greater meat yield if antibiotics are given to feed animals who show no evidence of disease. [7] Antibiotic use in food animal production has been associated with the emergence of antibiotic-resistant strains of bacteria including Salmonella spp., Campylobacter spp., Escherichia coli, and Enterococcus spp. Evidence from some US and European studies suggest that these resistant bacteria cause infections in humans that do not respond to commonly prescribed antibiotics.

In response to these practices and attendant problems, several organizations (e.g. The American Society for Microbiology (ASM), American Public Health Association (APHA)[8] and the American Medical Association (AMA)) have called for restrictions on antibiotic use in food animal production and an end to all non-therapeutic uses. The European Parliament called for phasing out of antibiotics for non-medical use in feed animals with a total ban as of 1 January 2006.[9] However, delays in regulatory and legislative actions to limit the use of antibiotics are common, and may include resistance to these changes by industries using or selling antibiotics, as well as time spend on research to establish causal links between antibiotic use and emergence of untreatable bacterial diseases.[10]

Inappropriate use of antimicrobial drugs in humans

There is misuse of antimicrobial drugs, antimicrobial being defined as a superset of antibiotics that include disinfectants in both developed and less-developed countries, although the inappropriate treatment varies with the medical standards of the country. [1]

Developed countries: overuse of antibiotics

One study on respiratory tract infections found "physicians were more likely to prescribe antibiotics to patients who they believed expected them, although they correctly identified only about 1 in 4 of those patients".[11] Multifactorial interventions aimed at both physicians and patients can reduce inappropriate prescribing of antibiotics. [12] Delaying antibiotics for 48 hours while observing for spontaneous resolution of respiratory tract infections may reduce antibiotic usage; however, this strategy may reduce patient satisfaction.[13]

Economic development and land use

Changes in land and water use patterns will remain major factors in the spread of infectious diseases. The emergence of Lyme disease linked to reforestation, which leads to increases in deer, and then to increases in deer ticks, the vector. In industrialized countries, deer are substantial traffic hazards, and there are a number of programs in the U.S. to put out deer bait containing oral contraceptives.

In Asia conversion of grasslands to farming encourages the growth of rodent populations carrying hemorrhagic fever and other viral diseases. Human encroachment on tropical forests will bring populations into closer proximity with insects and animals carrying diseases such as leishmaniasis, malaria, and yellow fever, as well as heretofore unknown and potentially dangerous diseases, as was the case with HIV/AIDS. Close contact between humans and animals in the context of farming will increase the incidence of zoonotic diseases--those transmitted from animals to humans. Water management efforts, such as dambuilding, will encourage the spread of water-breeding vectors such as mosquitoes and snails that have contributed to outbreaks of Rift Valley fever and schistosomiasis in Africa.[1]

Global animal trade

Globalization has had an impact on the worldwide animal trade. This worldwide movement of animals has increased the potential for the translocation of zoonotic diseases, which pose serious risks to human and animal health.[1]

The magnitude of the global movement of animals is staggering. In terms of sheer numbers, 37,858,179 individually counted live amphibians, birds, mammals, and reptiles were legally imported to the United States from 163 countries in 2000–2004.

Animals are legally imported into the United States for many reasons. They are used for exhibitions at zoos; scientific education, research, and conservation programs; food and products; and in the case of companion animals, tourism and immigration. Increasingly, however, animals are being imported for a thriving commercial pet trade. In many cases the animals that are imported and traded are of species that are considered exotic (here defined as non-native species, animals not traditionally kept as pets, or both). This can be a risky business, as many shipments include a high volume of wild-caught versus captive raised. For most of these animals, there are no requirements for zoonotic disease screening either before or after arrival into the United States. There have been anecdotal reports of high rates of death among animals in these shipments.

Animals imported for commercial trade represent a substantial risk to human health. In 2003, monkeypox, which is listed in the U.S. Select Agent Program was introduced into the United States when a shipment of African rodents was distributed to various US exotic pet dealers, one of whom housed these animals with prairie dogs. The prairie dogs subsequently became ill and transmitted the infection to 47 humans, including prairie dog owners and veterinary staff caring for the ill animals. There is substantial concern that zoonotic poxviruses may cross into humans.

Exotic pet ownership brings unanticipated risks to agribusiness, wildlife conservation, and the ecosystem. Human tularemia, listed in both the CDC Bioterrorism Agents-Disease list and Select Agent Program. Salmonellosis, also in the CDC Bioterrorism Agents-Disease list outbreaks have been traced back to contact with prairie dogs and hedgehogs.For example, giant African land snails released into farmlands have become agricultural pests. They reproduce rapidly, consume large amounts of vegetation, and are hosts for parasites such as Angiostrongylus cantonensis. The illegal trade of exotic wildlife, with promises of considerable financial return in the underground markets, has disastrous implications for many endangered or threatened species.[14]


References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 , Patterns of Infectious Disease, National Intelligence Estimate 99-17D: The Global Infectious Disease Threat and Its Implications for the United States, January 2000
  2. , Economic, Social, and Political Impact, National Intelligence Estimate 99-17D: The Global Infectious Disease Threat and Its Implications for the United States, January 2000
  3. Gayer,Michelle (November 2007), "Perspective: Conflict and Emerging Infectious Diseases", Emerging Infectious Diseases 13 (11)
  4. Charles PE, et al. (2003 June), "Imported West Nile virus infection in Europe", Emerging Infectious Diseases
  5. Board of Global Health, Institute of Medicine (2003). “6, Emerging Tools and Technology for Countering Resistance”, The Resistance Phenomenon in Microbes and Infectious Disease Vectors: Implications for Human Health and Strategies for Containment -- Workshop Summary. National Academies Press. 
  6. Abbo A, et al. (2005 Jan), "Multidrug-resistant Acinetobacter baumannii.", Emerging Infectious Diseases
  7. Mellon, M et al (2001), 'Hogging It!: Estimates of Antimicrobial Abuse in Livestock'
  8. HCWH Policy Statement on Antibiotics in Food.
  9. Lönnroth, Anna (3 September, 2006). The European Commission's research policy on antibiotic resistance: EU policy on antimicrobial drug resistance. European Parliament Scientific and Technical Options Assessment.
  10. Nelson JM, Chiller TM, Powers JH, Angulo FJ (2007). "Fluoroquinolone-resistant Campylobacter species and the withdrawal of fluoroquinolones from use in poultry: A public health success story". Clin Infect Dis 44: 977–80.
  11. Ong S, Nakase J, Moran GJ, Karras DJ, Kuehnert MJ, Talan DA (2007). "Antibiotic use for emergency department patients with upper respiratory infections: prescribing practices, patient expectations, and patient satisfaction". Annals of emergency medicine 50 (3): 213-20. DOI:10.1016/j.annemergmed.2007.03.026. PMID 17467120. Research Blogging.
  12. Metlay JP, Camargo CA, MacKenzie T, et al (2007). "Cluster-randomized trial to improve antibiotic use for adults with acute respiratory infections treated in emergency departments". Annals of emergency medicine 50 (3): 221-30. DOI:10.1016/j.annemergmed.2007.03.022. PMID 17509729. Research Blogging.
  13. Spurling G, Del Mar C, Dooley L, Foxlee R (2007). "Delayed antibiotics for respiratory infections". Cochrane database of systematic reviews (Online) (3): CD004417. DOI:10.1002/14651858.CD004417.pub3. PMID 17636757. Research Blogging.
  14. Marano, Nina (December 2007), "Commentary: Impact of Globalization and Animal Trade on Infectious Disease Ecology", Emerging Infectious Diseases