One of the most common criticisms leveled against those of us who feel that something must be done immediately to prevent further spread of HIV disease is the charge that HIV disease has not exploded into the general heterosexual population as had been predicted during the early stages of the epidemic. The fact that the HIV epidemic in the West appears to be largely limited to homosexuals, IV drug users, blacks and Hispanics seems to somehow justify the continued failure of public health authorities to introduce the use of standard public health measures to try to stop further spread of the illness.
One of the most intriguing questions that has plagued concerned investigators is: "Why is the HIV epidemic primarily a heterosexual disease in Africa while in the West, even after 14 years, the epidemic has not yet spread widely into our sexually active youth?"
One explanation for this apparent discrepancy might be the fact that public health authorities are not routinely testing the promiscuous youth of Western nations. The last major HIV testing of college students in America was carried out back in 1988-1990, and to my knowledge has not been repeated. The blind testing of newborn children, however, has shown that the epidemic does not appear to be spreading rapidly into the general white population, and is only spreading slowly in the black and Hispanic communities of America.
The reason for the apparent discrepancy between the epidemic in Asia and Africa, and in the West, is best explained by the work done by Dr. Max Essex, Chairman of the Harvard AIDS Institute. In a paper delivered at the International AIDS Society in June 1995, Dr. Essex stated that there are two separate HIV epidemics in the world today - one epidemic in sub-Saharan Africa and Asia, and the other epidemic in the West. In Africa, depending upon the region where HIV testing is carried out, between 1 in 5 and 1 in 10 young adults are currently HIV infected. In the West, on the other hand, testing of young adults has revealed that only between 1 in 3000, and 1 in 5000 are currently infected. Thus, according to Dr. Essex:
"The risk of HIV infection among heterosexuals is 500- fold greater in Africa than in the West, at least until now."
Although acknowledging that some researchers have attributed this discrepancy to sexual behavioral patterns, or to the frequency of associated sexually transmitted diseases in Asia and Africa, Dr. Essex expressed his personal belief that the primary difference between the two epidemics lies in the subtypes of the HIV viruses involved. He noted that the predominant subtype of the virus in Western countries is HIV-1 B, while in Thailand it is HIV-1 E, in India it is HIV-1 C, and in Africa still other subtypes of the virus. Dr. Essex stated that subtypes HIV-1 E and HIV-1 C are predominantly spread via vaginal intercourse, and are up to 100 times more infectious than HIV-1 B. One of the problems that America faces today is that all of our public health concepts of the communicability of HIV-1 are based upon our knowledge of the spread of HIV-1 B, while the rest of the world has different subtypes of the virus. Pointing out that it is only a matter of time before one or another of the more virulent forms of the HIV-1 virus spreads to the West, Dr. Essex expressed his concern over the future of the epidemic. He urged that every effort be made to develop a vaccine as soon as possible to head off the same sort of disaster in the West that now afflicts Asia and Africa. In those countries, the epidemic is decimating their populations. Dr. Essex concluded his paper with the following admonition:
"Finally, it would be ridiculously shortsighted to assume that the more heterosexually-efficient non-B subtypes will permanently remain outside the West. Aggressive education and the development of an effective vaccine seem more important than ever."
Copies of Dr. Essex's paper are available from the Harvard AIDS Institute, 665 Huntington Avenue, Boston, MA, 02115, or from HIV-Watch.