symptomatic illness and that the incubation period for such illness can be relatively long. This model for AIDS transmission is consistent with findings described in an investigation of a cluster of sexually related AIDS cases among homosexual men in southern California [CDC, MMWR, December 10, 1982].
One week later, the CDC reported four additional cases of AIDS in children (all less than two years old) (CDC, MMWR, December 17, 1982). None of the four infants were known to have received any blood or blood products. The mother of one was a prostitute and IV drug user; two were the children of Haitian immigrants; and one was the child of an IV drug user mother who had died of immune deficiency. According to the report, although the nature of the immune function described in the four cases was unclear, it was possible that these infants had AIDS and that the death of one of the mothers from PCP was probably secondary to AIDS. The CDC further stated that although the etiology of AIDS remained unknown, a series of epidemiological observations suggested it was caused by an infectious agent (CDC, MMWR, December 17, 1982).
The similar patterns of transmission of AIDS and hepatitis B and the latency period in both diseases led the medical and scientific community to discount the hypothesis that "poppers" were the cause of AIDS (CDC, MMWR, November 5, 1982; Panem 1988). A few months later, some physicians, scientists, and consumers of blood and blood products endorsed the theory that blood products may be transmitting the infectious agent. Others, however, were unconvinced and continued to hypothesize that the cases in hemophiliacs may have been due to immune suppression from using AHF concentrate (FDA, BPAC, 1983; Foege 1983; Aledort, Bove, Osborn interviews). They were skeptical because of the small number of known diagnosed cases among hemophilia patients compared to the number who were exposed to blood products.
Evidence for heterosexual transmission of AIDS appeared on January 7, 1983, when the CDC reported immunodeficiency in two female sexual partners of men with AIDS. The editorial note contained in this MMWR stated that
… epidemiological observations increasingly suggest that AIDS is caused by an infectious agent. The description of a cluster of sexually related AIDS patients among homosexual males in southern California suggest[s] that such an agent could be transmitted sexually or through other intimate contact. The present report supports the infectious-agent hypothesis and the possibility that transmission of the putative "AIDS agent" may occur among both heterosexual and male homosexual couples. At this time, CDC has received a total of 43 previously healthy females who have developed PCP or other opportunistic infections typical of AIDS [CDC, MMWR, January 7, 1983].
On the same date, the CDC also reported on the occurrence of AIDS in 16 prison inmates. All inmates were reported to have had a history of chronic IV drug use. The report added weight to the hypothesis that AIDS was caused by