New AIDS Findings to Alert a World at Risk

Some of the mysteries surrounding the transmission of the AIDS virus were removed by extensive new data presented at the International AIDS Conference in Paris last month. Seeking to understand why infection with the deadly virus occurs in some people but not in others, medical detectives called epidemiologists have been finding simple explanations for evidence that at first appeared complex and conflicting.

The candid discussions were remarkable this time; just last November, when an international conference on AIDS in Africa was held in Brussels, many of the African nations represented in Paris cancelled their scheduled reports because of extreme sensitivity about any public associations of AIDS with their continent.

In Paris, the experts could agree that the AIDS infection is fundamentally the same disease everywhere, whether it occurs in a heterosexual woman in Africa, a baby in Haiti, a drug addict in New York City or a homosexual man in Los Angeles. Among all peoples, the AIDS virus appears to be equally contagious. Moreover, it appears to be spread in the same ways: through sexual contact, exposure to tainted blood and from infected mother to child--not by casual contact, insects or poor sanitary conditions.

Before the conference, only nine African countries had officially reported a total of 378 AIDS cases to the World Health Organization. But the international group estimates that a minimum of 10,000 AIDS cases may be occuring in Africa each year, involving more than 20 countries; between 1 million and 2 million Africans may be infected with the virus, also known as HTLV-III or HIV, the “human immunodeficiency virus.” They are infectious to others, but may or may not actually develop infections or tumors as a consequence of damage to their immune systems.

Heterosexual intercourse, not homosexual contact, was shown to be the dominant means of transmitting the virus in African nations and also in Haiti, followed by exposure to contaminated blood. Both male-to-female and female-to-male transmission occurs through vaginal sexual intercourse, according to reports by Dr. Jonathan Mann of the World Health Organization and other international authorities. These reports refute previously held beliefs that homosexual or anal intercourse is necessary for sexual transmission, except in rare instances, or that the disease can be transmitted from men to women, but not from women to men.

Convincing evidence indicated that heterosexual transmission of the AIDS virus can cause AIDS epidemics, just as homosexual transmission has led to epidemics in cities such as San Francisco and Los Angeles or transmission of the virus by intravenous drug users has led to epidemics in New York City and urban areas of Spain, Italy and Ireland.

The epidemiologists now believe the key factor in transmission may be damage to the protective barrier of the skin or genital tissues. Such damage allows blood cells containing the AIDS virus to pass from one person to another. The body’s protective barriers may be damaged from trauma during sexual intercourse or from venereal diseases which cause ulcers, such as herpes, syphilis or chancroid.

Individuals with venereal diseases such as gonorrhea also produce large amounts of infection-fighting white blood cells in their genital organs. The AIDS virus grows and concentrates in such cells. This may explain why people with untreated venereal diseases appear more likely to transmit AIDS than infected individuals who do not have additional illnesses.

In Kinshasa, the capital city of Zaire, about 6.5% of all adults appear to be infected, according to Dr. Bila M. Kapita of the Mama Yemo Hospital. Similar reports have come from other African nations, such as Rwanda, Uganda and Zambia. The experts suggest that once a critical percentage of people who have multiple sexual partners becomes infected, the sexual transmission of AIDS can become self-sustaining.

About 8% of all pregnant women in Kinshasa are also infected with the AIDS virus, leading to the development of virus infections in between 2% to 4% of all newborns, according to Mann of the World Health Organization.

Public health officials use this new knowledge of heterosexual transmission to combat the mistaken belief that AIDS is only a risk for “somebody else.” Dr. James W. Curran of the federal Centers for Disease Control told a Paris press conference, when asked about heterosexual transmission, “In case you aren’t listening, this means you too, gang.”

In Africa, intravenous drug use is not a problem, as it is in many Western countries. But transmission of AIDS commonly occurs by transfusions with contaminated blood, injections with contaminated needles, and scarifications with contaminated ritual skin-piercing instruments. For example in Central Africa, between 5% and 10% of blood donors are believed to be infectious. Most hospitals are unable to screen blood for the AIDS virus.

Many children in Africa also receive, by Western standards, an astounding number of injections, both from practitioners of traditional tribal medicine and from physicians. These are sometimes given because patients and parents expect them, not for medical need.

In Kinshasa, a group of children who were thought to be infected with AIDS by contaminated needles had received an average of 44 injections in the previous three years, compared to an average of 23 injections in a control group of children who were not infected, according to Mann. By comparison, there has been no evidence linking injections given in vaccination and immunization programs with AIDS virus transmission, Mann reported.

Public health officials have long been frustrated in their efforts to eliminate unnecessary blood transfusions and injections in developing countries. Now, they are hopeful that public attitudes can finally be changed, through programs warning people about the risk of acquiring a fatal disease.

An important scientific question, still far from resolved, centers on the origins of the virus. Some leading researchers feel AIDS originated in Africa, in part because diseases related to the virus appear to have first become frequent in the mid to late 1970s, compared to the early 1980s in the United States. Others, including some African physicians, say AIDS could have been imported from Western countries.

Important clues in answering this question may come from further analysis of two recently-discovered viruses from West Africa that are related to the AIDS virus--one found by Harvard University researchers and the other by scientists at the Pasteur Institute in Paris.

Uncertainty about AIDS’ origins is only one of the remaining mysteries that epidemiologists hope to solve in the next several years, including the problem of brain diseases caused by the virus and the extreme variations in the types of infections and tumors that develop in one AIDS patient as compared to another. The progress at Paris provides encouragement that explanations may soon be found.