As discussed in part one of this blog, confusion about the origins of HIV/AIDS often adds to the already extraordinary stigma surrounding the pandemic. Questions such as where did HIV come from, how did it spread, and why was it only occurring in certain populations continue to linger for many people. Fortunately, over the past 30 years the scientific community has compiled a massive canon of sound scientific evidence that clearly demonstrates HIV is the direct descendant of a common virus found in many species of non-human primates. HIV came from monkeys, and then proceeded to pass unnoticed among human populations for decades. Not until the early 1980’s, when young American men began presenting with rare infections and cancers, did the scientific community recognize that an unprecedented, unidentified, and potentially lethal epidemic had taken root.
SIV, the Simian Immunodeficiency Virus, is a natural virus that affects monkeys and apes in the same way HIV affects humans. Though often milder and less pathogenic, SIV progressively weakens a primate’s immune system by attacking white blood cells and potentially causing many of the same AIDS defining illnesses seen in humans1. Recent research shows that SIV has been in monkeys and apes for at least 32,000 years, and possibly as long as 75,000 years2. Certain strains of SIV are genetically very similar to HIV. The most common type of HIV, HIV-1, is directly related to SIV found in chimpanzees, while the more rare HIV-2 corresponds to SIV found in a type of west African monkey called the Sooty Mangabey.
How SIV moved into humans is also well supported by scientific research. Evidence points to bush meat as the primary source of SIV transmission into the human population. Hunting, butchering, and eating monkeys are common practices that present a number of opportunities for primate viruses to pass into humans. Furthermore, a 2004 study shows that various simian retroviruses continue to be prevalent among individuals who prepare & consume monkey meat3. SIV infection has also been well documented in animal handlers and people working with primates in laboratory settings1,3,4. The transmission of pathogens to humans from other species, known as zoonosis, is natural and ubiquitous. Other zoonotic illnesses include ebola, rabies, H1N1 flu, malaria and bubonic plague.
Recent research indicates that HIV was likely initially confined to small, rural communities in parts of central Africa. The eventual spread of the virus beyond isolated communities correlates to the urbanization and infrastructure that came with European colonization2. Railways and roads, urban migration, high density cities, labour camps where monkey meat was a dietary staple, as well as intercontinental travel are factors that worked together to create an ideal environment for the rapid and widespread transmission of HIV.
Through phylogenetic analysis, a process akin to building a family tree of HIV, researchers estimate HIV has been in the human population for approximately 100 years5. Because viruses mutate at relatively constant and known rates, by comparing HIV samples and subtypes, researchers are able to develop timelines based on how far the virus has drifted from ancestral forms 5,6. Looking forward, we can expect to see the phylogenetic origins of HIV increasingly clarified and articulated through emerging research. Recent studies have even suggested links between HIV-related pathogens in present-day lemurs, as well as ancient tigers dating back more than 100,000 years7.
While HIV’s viral ancestors have existed for millennia, the virus remained unknown until relatively recently. Fast forward to 1981 when a handful of young, previously healthy gay men presented to doctors in Los Angeles with a rare infection called pneumocystis carinii pneumonia8. Doctors noted that all patients also had other symptoms of an underlying suppression or deficiency of the immune system. The following year, the Centre for Disease Control and Prevention reported 19 cases of confirmed pneumocystis carinii pneumonia and a rare form of skin cancer known as Kaposi’s sarcoma among young, previously healthy gay men in southern California9.
At this point, the scientific community began to understand that something unknown and increasingly prevalent was occurring. GRID, or Gay Related Immune Deficiency, was the first term used to describe the phenomenon, based on incomplete assumptions about who was at risk or how the illness was being contracted. However, shortly thereafter reports of similar infections were identified among more diverse populations. The illness that would later be coined as AIDS was described as affecting a set of populations sometimes called the 4-H Club: Homosexuals, Haitians, Hemophiliacs and Heroin Users.
Recognizing that GRID was an inappropriate description, the term AIDS, or Acquired Immune Deficiency Syndrome, entered the vernacular. It is interesting to note that AIDS was defined before anyone even knew what caused it. Until the 1983 discovery of HIV as the pathogen that leads to AIDS related illness, very few people had any idea what were or were not risks for contracting this new and alarming disease making headlines across the country. With the eventual discovery of HIV, scientific knowledge progressed in leaps and bounds towards understanding specifically how the virus is transmitted and which activities involve risk. And the rest is history. Or is it?
Unfortunately, because HIV was first identified in the gay male community, some people continue to assume that sexual preference or identity has something to do with individual risk. On the contrary, the most recent 2009 epidemiological data show that 51% of all new HIV infections globally were among women10, and heterosexual transmission accounts for the majority of all new HIV diagnoses in Alberta11. Furthermore, some people believe that HIV/AIDS is a result of activities or lifestyles which may be judged or moralized. Looking forward, part of addressing the stigma associated with HIV/AIDS lies in helping people understand that this is not a gay plague, a moral punishment, or a government conspiracy. Only when we are able to move past the value based judgments and taboos surrounding HIV/AIDS, will we be able to effectively address the pandemic.
This article was written by AIDS Calgary Awareness Association's Community Engagement Coordinator.
Sources
1. Centre for Disease Control and Prevention. (1988). Perspectives in disease prevention and health promotion guidelines to prevent simian immunodeficiency virus infection in laboratory workers and animal handlers. 37(45):693. Retrieved June 13, 2011 from http://wonder.cdc.gov/wonder/prevguid/m0001303/m0001303.asp
2. Worobey, M. et al. (2010). Island biogeography reveals the deep history of SIV. 1. Science. 329(5998):1487. Retrieved June 13, 2011 from
http://www.sciencemag.org/content/329/5998/1487.abstract
3. Wolf, N.D. et al. (2004). Naturally acquired simian retrovirus infections in central African hunters. Lancet. 363(9413):932. Retrieved June 13, 2011 from
http://www.ncbi.nlm.nih.gov/pubmed/15043960
4. Reitz, M.S. et al. (1992). On the historical origins of HIV-1 (MN) and (RF). AIDS Research and Human Retroviruses. Republished 8(9) 2009. Retrieved June 13, 2011 from
http://www.liebertonline.com/doi/abs/10.1089/aid.1992.8.1539
5. Worobey, M. et al. (2008). Direct evidence of extensive diversity of HIV-1 in Kinshasa by 1960. Nature. 455:661. Retrieved June 13, 2011 from
http://www.nature.com/nature/journal/v455/n7213/abs/nature07390.html
6. Abecasis, A.B. et al. (2009). Quantifying differences in the tempo of human immunodeficiency virus type 1 subtype evolution. Journal of Virology. Vol. 83(24):12917. Retrieved June 13, 2011 from
http://jvi.asm.org/cgi/content/abstract/83/24/12917
7. Bambara, R.A. et al. (2010). A sequence similar to tRNA3Lys gene is embedded in
HIV-1 U3–R and promotes minus-strand transfer. Nature Structural & Molecular Biology
17:83. Retrieved June 13, 2011 from
http://www.nature.com/nsmb/journal/v17/n1/full/nsmb.1687.html
8. Centre for Disease Control and Prevention (1981). Pneumocystis pneumonia - Los Angeles. Morbidity and Mortality Weekly Report. 30(21). Retrieved June 13, 2011 from http://www.cdc.gov/mmwr/preview/mmwrhtml/june_5.htm
9. Centre for Disease Control and Prevention (1982). A cluster of Kaposi's sarcoma and pneumocystis carinii pneumonia among homosexual male residents of Los Angeles and range counties, California. Morbidity and Mortality Weekly Report. 31(23). Retrieved June 13, 2011 from http://www.cdc.gov/mmwr/preview/mmwrhtml/00001114.htm
10. Joint United Nations Programme on HIV/AIDS. (2010). UNAIDS report on the global AIDS epidemic 2009. Retrieved June 13, 2011 from http://www.unaids.org/en/dataanalysis/epidemiology/2009aidsepidemicupdate/
11. Alberta Health and Wellness. (2010). HIV and AIDS in Alberta–2009 annual report. Retrieved June 13 from http://www.health.alberta.ca/documents/STI-HIV-AIDS-Report-2009.pdf
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