Human Immunodeficiency Virus Type 1
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HIV (Human Immunodeficiency Virus) is an infectious human retrovirus that causes AIDS (Acquired Immunodeficiency Syndrome. It is primarily a sexually transmitted disease. Currently, HIV/AIDS kills approximately 2-3 million people per year, primarily in developing countries. Currently, in the U.S. there are approximately 500,000 people infected with HIV.
Pathophysiology
After exposure, the virus invades and replicates in immune cells near the site of infection. It quickly spreads to regional lymph nodes and via the blood stream to the rest of the body. During this stage the patient may experience Acute Retroviral Syndrome, a vague flu-like illness. The patient is often asymptomatic for the first 5-10 years after infection. By that time, untreated, progression to AIDS in inevitable, except in a small subset of patients.
Clinical syndromes
Primary HIV infection
| sensitivity | specificity | |
|---|---|---|
| Fever | 88% | 50% |
| Malaise | 73% | 58% |
| Myalgia | 60% | 74% |
| Rash | 58% | 79% |
| Headache | 55% | 56% |
| Night sweats | 50% | 68% |
| Sore throat | 43% | 51% |
| Lymphadenopathy | 38% | 71% |
| Arthralgia | 28% | 87% |
| Nasal congestion | 18% | 62% |
Acquired Immune Deficiency Syndrome
Transmission
HIV is primarily spread by sexual contact. Most early infections in the United States were via homosexual sex, and to a lesser extent via intravenous drug use and blood transfusions; most current infections in the world are via heterosexual contact and vertical transmission from mother to child.
HIV can be found in various body fluids, however its highest concentrations are found in semen, blood, and vaginal secretions. It can also be found in breast milk; however exclusive breastfeeding tends to protect against HIV transmission.[2]
Other less likely means of transmission exist, though are rare. There are no confirmed cases from contact with the saliva, sweat or tears of an infected person.
Blood exposure
Mothers infected with HIV transmit the virus to their baby in utero, during childbirth. Mother-to-child transmission can be significantly reduced by the proper use of antiretroviral agents.
Less commonly, contact with infected blood causes HIV transmission. This can occur in health care providers (HCPs) or others exposed to infectious bodily fluids. Transmission is facilitated by breaks in the skin or direct contact with mucosal tissues, such as those found in the eyes, mouth, anus, or vagina. Early in the epidemic, blood transfusions were a significant source of HIV transmission.
Sexual contact
| Risk of transmission per act | |
|---|---|
| Unprotected receptive anal sex with a known seropositive partner |
0.82% |
| Unprotected receptive anal sex with a partner of unknown serostatus |
0.27% |
| Unprotected insertive anal sex | 0.06% |
| Receptive oral sex | 0.04% |
A cohort study of monogamous, heterosexual, HIV-1-discordant couples in Uganda found that the "overall, unadjusted probability of HIV-1 transmission per coital act is 0·0011...higher viral load and genital ulceration are the main determinants of HIV-1 transmission."[4]
Diagnosis
HIV Test
Treatment
Treatment issues are complicated by issues of poverty and education. In communities with adequate resources, HIV infection is treatable with highly active antiretroviral therapy (HAART). This therapy effectively prevents progression to AIDS in many patients, however there are many side effects to treatment, and resistance is a serious issue.
Clinical practice guidelines based recommend to treat if ony of the following are true:[5]
- CD4 cell count is less than 350/microL.
- Among patient with CD4 cell count > 350/microL, treat if
- high plasma viral load (eg, >100,000 copies/mL)
- rapidly declining CD4 cell count (>100/microL per year)
- active hepatitis B or C virus infection
- cardiovascular disease risk
- HIV-associated nephropathy
Prognosis
A multinational cohort study has found that since the introduction of highly active antiretroviral therapy, "mortality rates for HIV-infected persons have become much closer to general mortality rates." [6]
A second, industry-funded, multinational cohort study has found that with combination treatment, "the average number of years remaining to be lived at age 20 years was about two-thirds of that in the general population in these countries."[7]
Screening
Prevention
Prevention is an issue complicated by issues of poverty and education. Sexual transmission can be effectively prevented by avoiding sexual contact (abstinence), but much of HIV tranmission takes place in marriages or other similar relationships, therefore abstinence is impractical. The most effective method is regular, proper use of latex condoms. A large percentage of those infected are unaware of their disease status, which complicates prevention. Spouses are often infected without their knowledge of their partner's status.
Occupational infection can be prevented with the use of universal precautions and by post-exposure prophylaxis.
Currently, no vaccine is available, and it is not clear if a vaccine will be available any time in the near future.
Prevention in health care settings
The United States Centers for Disease Control and Prevention has summarized the use of universal precautions to prevent the transmission of HIV in health care settings.
In addition, the Centers for Disease Control and Prevention has published guidelines on preventing transmission by use of postexposure prophylaxis.[8]
References
- ↑ Daar ES, Little S, Pitt J, et al (2001). "Diagnosis of primary HIV-1 infection. Los Angeles County Primary HIV Infection Recruitment Network". Ann. Intern. Med. 134 (1): 25–9. PMID 11187417. [e]
- ↑ Coovadia HM, Rollins NC, Bland RM, et al (March 2007). "Mother-to-child transmission of HIV-1 infection during exclusive breastfeeding in the first 6 months of life: an intervention cohort study". Lancet 369 (9567): 1107–16. DOI:10.1016/S0140-6736(07)60283-9. PMID 17398310. Research Blogging.
- ↑ AEGiS-AIDSWeekly: Per-Contact Risk of HIV: Odds Don't Tell Whole Story - August 9, 1999. Retrieved on 2008-07-02.
- ↑ Gray RH, Wawer MJ, Brookmeyer R, et al (April 2001). "Probability of HIV-1 transmission per coital act in monogamous, heterosexual, HIV-1-discordant couples in Rakai, Uganda". Lancet 357 (9263): 1149–53. DOI:10.1016/S0140-6736(00)04331-2. PMID 11323041. Research Blogging.
- ↑ Hammer SM, Eron JJ, Reiss P, et al (August 2008). "Antiretroviral treatment of adult HIV infection: 2008 recommendations of the International AIDS Society-USA panel". JAMA 300 (5): 555–70. DOI:10.1001/jama.300.5.555. PMID 18677028. Research Blogging.
- ↑ Bhaskaran, Krishnan; Osamah Hamouda, Mette Sannes, Faroudy Boufassa, Anne M. Johnson, Paul C. Lambert, Kholoud Porter, for the CASCADE Collaboration (2008-07-02). "Changes in the Risk of Death After HIV Seroconversion Compared With Mortality in the General Population". JAMA 300 (1): 51-59. DOI:10.1001/jama.300.1.51. Retrieved on 2008-07-02. Research Blogging.
- ↑ The Antiretroviral Therapy Cohort Collaboration (2008). Life expectancy of individuals on combination antiretroviral therapy in high-income countries: a collaborative analysis of 14 cohort studies. Lancet DOI:10.1016/S0140-6736(08)61113-7
- ↑ Panlilio AL, Cardo DM, Grohskopf LA, Heneine W, Ross CS (September 2005). "Updated U.S. Public Health Service guidelines for the management of occupational exposures to HIV and recommendations for postexposure prophylaxis". MMWR Recomm Rep 54 (RR-9): 1–17. PMID 16195697. [e]