AIDS Epidemic Update January 2008
Decreased Infection Rates And Genetic Studies on The Origins of HIV
The past year has seen new methods in determining HIV infection rates and a new study that determines the origin of AIDS in the United States.
Acquired Immunodeficiency Syndrome (AIDS) was first recognized as a disease by scientists in 1981. To date, a reported 25 million deaths have been attributed to AIDS and its associated opportunistic diseases. AIDS is caused by the Human Immunodeficiency Virus (HIV), a retrovirus with counterparts in other species such as monkeys, cats, and horses.
The AIDS epidemic is believed to have peaked in the late 1990s though world health officials still contend there is much to do. The past year (2007) still saw 2.5 million new infections. In sub-saharan Africa AIDS affects men, women, and children. Elsewhere in the world outbreaks are mostly concentrated to high risk groups, but has been on a rise in heterosexual female partners of high risk group members since 1990 (NY Times 12/90, Journal Watch 1999). High risk groups include intravenous drug users, homosexual men, and sex workers.
New AIDS Infection Rate Estimates
The World Health Organization (WHO) and United Nations AIDS agency reported in November 2007 that the number of global AIDS cases fell from over 39 million to 33.2 million in 2007. This was due to new methodology that deflated previous estimates, mainly revised numbers from India and new data from sub-saharan Africa, the epicenter of the epidemic where AIDS is still the leading cause of death. Previous AIDS numbers were devised by projecting the AIDS rates of certain high-risk groups to the entire population at risk as well as the number of infected pregnant women at clinics. The new numbers include data such as national household surveys. Critics contend that even with revisions the numbers may still be too high and more revisions may be in store in the near future.
The Origin of HIV in America
New information about the origins of AIDS also came to light in 2007. A group involving evolutionary biologist Michael Worobey at the University of Arizona conducted genetic analysis on stored blood samples from early AIDS patients. Haitian immigrants in Miami as early as 1979 suffered from a mystery illness that turned out to be AIDS. The governments had stored the samples and the study was able to use five samples taken from Haitian immigrants in 1982 and 1983 along with 117 other early AIDS patients worldwide.
Other studies had previously suggested that the virus first entered the human population around 1930 in central Africa, most likely from slaughtered chimpanzees infected with the simian AIDS virus, SIV. Worobey’s group ruled out the possibility that HIV came directly to the United States from Africa. They found a 99.8% probability that Haiti was a link between the virus’s trek from Africa to the United States, a path long under debate by researchers. The study found that HIV was brought from central Africa to Haiti by an infected person around 1966, matching earlier estimates, but that HIV was brought into the United States in about 1969, earlier than previously thought. The virus was probably brought in by a single infected immigrant.
Reference
Gilbert, M.T.P. et al., 2007. The emergence of HIV/AIDS in the Americas and beyond. Proceedings of the National Academy of Sciences of the United States of America, 104(47), p.18566-70.
