By David N. Leff

In the East African republic of Malawi (formerly Nyassaland), 15 percent of the sexually active men in urban areas and 30 percent of the women are thought to be infected with HIV-1.

As a Third World country, Malawi can ill afford to treat this epidemic with the sophisticated antiretroviral drugs now available to HIV-positive people in the First World. Hence, the Africans die of AIDS within a few years of disease diagnosis.

In Malawi, HIV is spread almost entirely by heterosexual intercourse. The same mode of infection applies to sexually transmitted diseases (STD), -- mainly gonorrhea, but also chlamydia, trichomonas and syphilis.

A biological common denominator of STDs and HIV is seminal fluid. The semen of men infected with both pathogens carries the virus and the venereal microbes. Yet the role of gonorrhea and the other STDs in expediting the transmission of HIV is only now coming into focus.

Last July, at the international AIDS conference, in Vancouver, Canada, infectious disease specialist Myron Cohen reported to a late-breaking session the early findings of a field trial he conducted in Malawi. It assessed the influence of STDs on the load of HIV-1 virus in the inflamed, semen-discharging urethras of men simultaneously infected with a venereal disease.

Those results showed that aggressive antibiotic treatment of gonorrhea and other STDs cut HIV levels in semen dramatically. Cohen is chief of infectious diseases at the University of North Carolina (UNC), Chapel Hill.

Epidemiologist Rachel Royce, an associate of Cohen's at UNC, told BioWorld Today: "This is a very important finding, because it is the first one to give the biological evidence of what we in epidemiology have observed: That sexually transmitted infections have an impact on the probability of acquiring and transmitting HIV."

Those findings, and the entire field investigation that produced them, appear in this week's The Lancet, dated July 28, 1997, and titled: "Reduction of concentration of HIV-1 in semen after treatment of urethritis: Implications for prevention of sexual transmission of HIV-1."

Impact Of Getting, Spreading AIDS Virus

Cohen, the paper's lead author, observed in a UNC statement: "The more virus in semen, the greater the chance for transmission to someone else. We believe this is more efficient in sub-Saharan Africa and some other areas, because STDs are more prevalent there, and therefore more HIV is transmitted during sex."

At the STD clinic in Malawi's capital city of Lilongwe early last year, a mixed team, primarily of UNC and Malawi specialists, recruited 86 young male patients infected with HIV-1. Two-thirds of them also had gonorrhea; the rest, chlamydia and trichomonas. Another 40 HIV-positive men, and 127 HIV-negatives, served as controls.

The volunteers donated samples of their semen. Then all the STD-positive men, identified by their urethritis, received a course of the antibiotic gentamycin, which cleared up their venereal diseases in two weeks.

Pre- and post-antibiotic semen specimens revealed that HIV-positive men with concomitant STD urethritis had eight times higher concentrations of viral RNA in their semen as did HIV-positives without the venereal urethritis. Yet both virus-infected cohorts had similar CD4 counts and concentrations of viral RNA in their blood plasma.

These HIV titers in semen dropped sharply after antimicrobial therapy dispelled their STD urethritis. Gonorrhea, by far the most prevalent venereal disease in Malawi, lead this drop in seminal virus RNA.

Meanwhile, the baseline titers in control participants remained unchanged.

"This is the first report to come out of our work in Malawi," Royce observed. "We still have a lot of analysis to do from the same data set. For instance, we don't yet know what other factors help determine the respective levels of HIV in semen and in blood; how these two compartments are related to each other."

Another line of inquiry that Cohen's lab is beginning to work on, Royce said, relates to the fact that "none of these Malawi men were receiving treatment for their HIV infection, such as antiretrovirals. What would be the effect of such drugs on the amount of HIV in semen?"

She pointed out that while "gonorrheal urethritis is cleared up, and syphilis and genital ulcers are treated successfully with this dose of antibiotic, it has no impact on getting rid of HIV-1 per se."

Semen Now; Vaginal Secretions Some Day

Royce added that "it would be nice to do a comparable study of the HIV in vaginal secretions of women. Our group happens to have expertise in measuring HIV in semen; it's a lot trickier in women's genital secretions. Several groups around the U.S. are working on this, but the techniques have not yet been perfected."

The Malawi findings, Royce emphasized, have important pay-offs on the American scene: "The transmission of HIV today by same-sex sex is not what's currently infecting the major group of people. Having an STD," she continued, "can affect any human being, regardless of whom they have sex with -- men with men, or men with women."

Moreover, Royce pointed out, "We have a surge of STD going on in the southern U.S., which is where the HIV epidemic is currently moving the fastest. The South is where there's an excess of gonorrhea and syphilis compared to the rest of the nation."

Here the Lancet paper's take-home conclusion applies directly: ". . . the diagnosis and treatment of STDs, especially gonorrhea, in patients with HIV infection, should be a key component of HIV-1 prevention programs." *