Cluster of Cases of the Acquired Immune Deficiency Syndrome

I was sitting in a performance of The Normal Heart tonight, wondering what it must have been like to be gay in New York in the early 80s and to know that your gay friends are dying in numbers, but to have no idea why. I remembered this 1984 article in which investigators made a tentative guess that AIDS had something to do with sexual contact. At this time the scientific community was groping in the dark. Before this, there had been a major study by the CDC (late 1981) concluding that “a large number of sexual partners was the most important risk factor among… homosexual men”. It was not known that unprotected sex was how the virus is transmitted. Actually, it was not even agreed that AIDS is caused by a virus.

Study Plan

The study was prompted when a small number of AIDS patients reported that they had had sexual contact with other patients. The original plan was to interview 19 Kaposi’s Sarcoma patients from Los Angeles and Orange County and map out their sexual network. The characteristics of those patients that were linked through the network would then be compared to those of patients that were unlinked. Participants who had had sexual contact with each other less than 5 years before getting ill were considered linked in the network (e.g. 0 and NY15 are linked in the diagram). All the participants of the study were asked to list all the people that they had had sex with in the preceding 5 years and investigators checked these lists against each other. When a non-Californian, “Patient 0” was found to link AIDS patients from Southern California to other cities, the study was expanded to include other cities.

Differences didn’t say anything

At the end, 40 AIDS patients (see diagram) from different cities were found to be linked and 208 were unlinked. A comparison of the linked and unlinked patients didn’t really lead to insight about the disease: linked patients “were significantly more likely to be white and to have only Kaposi’s sarcoma… linked patients were significantly more likely… to have met sexual partners in bathouses, have been frequent users of inhaled amyl or butyl nitrite [poppers], and have participated in the sexual practice of ‘fisting'”. Other than these differences, linked and unlinked patients were similar.

Latent Period Provides Clue

It was only when they tried to estimate the latency (amount of time from infection to symptoms) that the investigators edged closer to figuring out how AIDS works. They looked at participants that had had sex with only one other participant (there are 20, spot them in the diagram). This was so that they could accurately measure the time from that sexual contact to the first symptoms. Of these 20, they eliminated those that had had sex with the partner for a period of more than 30 days. Again, this was done so that it would be easier to measure the latent period. Only 9 patients remained that had had sex with only one other patient for a period less than 30 days. Of those 9, 3 showed symptoms at the same time, or later than their sexual contact, and 6 showed symptoms after their sexual contact had become ill. This supported the hypothesis that AIDS is transmitted through some infectious agent. (Had some of the 9 patients shown symptoms before the only people they had had sex with, it would be much harder to argue that the 6 were infected by their contacts).

Modest Conclusion

“Although the cause of AIDS is unknown, it may be caused by an infectious agent that is transmissible from person to person in a manner analogous to hepatitis B virus infection; thorugh sexual contact, through parenteral exposure by intravenous drug abusers who share needles, though blood products… The existence of a cluster of AIDS cases linked by homosexual contact is is consistent with an infectious-agent hypothesis.”

*Auerbach. D et. al. 1984 March. The American Journal of Medicine. Vol 76


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