Co-author: Roderick T. Bronson, D.V.M., Harvard Medical School, Boston, MA
AIDS was recognized in humans in 1981 and simian AIDS was described in 1983-1985. However, researchers anecdotally reported seeing cases of opportunistic infections of AIDS in monkeys much earlier. In a recent article in the American Journal of Public Health,
I explored with co-author Roderick Bronson of Harvard Medical School the history, significance, and implications of these early cases in monkeys. We reviewed the literature and interviewed leading researchers on monkeys and the relationships between retroviruses and opportunistic infections in non-human primates and humans, and clinicians who observed early human AIDS cases.
We found that, beginning in the late 1960s, hitherto unusual outbreaks of what came to be recognized as opportunistic infections of AIDS, including lymphoma, progressive multifocal leukoencephalopathy (PML), leukemia, pneumocystis carinii
pneumonia, cytomegalovirus, and cryptosporidiosis, were seen in monkeys in primate centers in California and Massachusetts and in other laboratories in the United States. At least 23 published papers from1971-1980 reported cases in at least 68 monkeys. Some of these papers explored possible virologic and immunologic etiologies. However, these cases were not connected, and this apparent syndrome in monkeys went unrecognized at the time as did its human analogue.
Some of the reasons that the scientific community didn’t connect these dots included weaknesses in understanding of disease mechanisms (among animals, among humans, and from animals to humans), an absence of evidence of human retroviruses, and a climate of opinion that devalued investigating infectious disease and the immunologic origins of disease. The “epistemological obstacle,” a construct developed by the French philosopher Gaston Bachelard to understand progress and challenges in the history of science, helps to explain important elements of this story: that is, misconceptions within accepted and dominant knowledge at the time blocked understanding of the actual dependent relationship among retroviruses, immunodeficiency, and opportunistic diseases.
In a 1991 paper, Ronald Brookmeyer suggested that 250,000 people were already HIV-infected in the U.S. by 1983. Had clearer understanding of the evidence from monkeys caused human AIDS to be recognized earlier, prevention and treatment interventions might have been implemented sooner, and many lives might have been saved.
Lessons for Future Disease Outbreaks
This story offers a case study of how scientific knowledge develops and is understood – or does not develop and is not understood. It also may offer lessons for public health practice. Attitudes, tools, and conditions have improved and collaboration between animal and human disease researchers has increased, raising hope that tragedies of the scale of the HIV/AIDS pandemic may be avoided in the future. However, to make proper use of the available tools and data, continued vigilance, creative thinking, and interdisciplinary collaboration remain essential. Cooperation and information exchange between veterinary and human disease researchers in a “One Health” approach are especially important.
The zoonotic Ebola and Zika virus outbreaks offer some parallels to the recognition of AIDS but some important differences as well. Since 1976, the infectious agent of Ebola has been known and transmission factors are quite well established. Notably, however, some confusion remains regarding ongoing transmission among animals and from animals to humans. In addition, political rumors regarding the origins of Ebola outbreak weakened the early response in some places. A village chief in Liberia said that “The people from the district came and told us all the signs and symptoms, but we did not believe them…We were thinking the president [Liberian President Ellen Johnson Sirleaf] created it [Ebola] to kill people.” Residents of the Monrovia slum district West Point believed that a “quarantine was really a move to quash an armed rebellion, and had little to do with public health.” As it had in the early years of AIDS in the U.S., politics and other extraneous issues may affect public health responses to epidemics.
With Zika, there has been some uncertainty as to the causal link between the virus and microcephaly and the possibility of sexual transmission, but the Centers for Disease Control and Prevention has so far addressed these issues quickly based on emerging evidence.
Still, public health practitioners and health providers must remain vigilant for any new patterns of disease and the possibility that misinformation could undermine prevention and treatment efforts. Ebola and Zika are not the last infectious disease outbreaks that the world will see. We must heed the lessons of the past and ensure that the tools and skills of surveillance and epidemic response are constantly honed.