Differences in U.S., Zaire AIDS Patterns Noted

ATLANTA — The recent finding that the AIDS virus may be spread through casual household contacts in the African nation of Zaire has no relevance to the way the disease is transmitted in the United States, an American scientist said Monday.

“To extrapolate our finding to America would be incorrect and wrong,” Dr. Jonathan Mann, assistant for international programs at the Centers For Disease Control, told reporters. “You can’t compare the transmission of the AIDS virus in Zaire to transmission in the U.S.”

Mann, who has spent the last year studying acquired immune deficiency syndrome in Zairian households, was here to address an international conference on AIDS attended by 2,000 scientists from 30 countries.

In his report, Mann described a search for the AIDS virus antibody among members of 46 households in the Zairian capital of Kinshasa in which there was at least one AIDS victim and in a control group of 44 households in which no member of the family had the disease. The presence of the antibody indicates that a person has been exposed to the AIDS virus.

Risk Factors

Excluding the spouses of the AIDs patient, 11% of the rest of the people in the households had antibodies to the virus, indicating that they may have acquired it through non-sexual transmission. In the control families, only 4% had the antibodies.

Mann said it appeared that the more distant the relationship with the AIDS patient within the household, the less likely the transmission of the virus. For example, he said, parents and children of the AIDS patient were more likely to have been exposed to the virus than were more distant relatives in the same household.

Nevertheless, the study also demonstrated that AIDS is transmitted primarily by sexual contact. Although 11% of the non-spouses had been exposed, 72% of the spouses had antibodies against the viruses.

Mann said he could not tell whether the transmission of the virus was person-to-person--by passing the virus through saliva when kissing, for example--or through some other shared risk factor.

He noted that a shared risk factor could exist if family members had all received inoculations with a contaminated needle. Another type of shared risk could exist if insect bites play a role in spreading the disease in Zaire, he said.

Looked at in another way, Mann said, the fact that 89% of people in the households, excluding the spouses, had not been infected despite at least 18 months of close contact with AIDS patients “is additional support for the belief that brief casual contacts to a case are extremely unlikely to result in viral transmission.”

Studies have shown that Zairians living in Kinshasa have a much higher incidence of exposure to the AIDS virus than do Americans--about 4% compared to less than 1% in the United States.

Life style, living conditions, nutritional status, cultural factors and the presence of other infectious diseases, such as malaria, that depress the immune system also differentiate conditions in the two countries, scientists have noted.

In Zaire, AIDS is primarily a disease of heterosexuals, whereas in the United States it is primarily homosexuals who are affected.

In the United States, about 1% of the 9,405 cases reported as of April 8 are among heterosexuals. There are no documented cases of the disease in the United States being acquired through casual contacts with AIDS patients. Researchers say that the number of cases among heterosexuals would be much higher than 1% if transmission were occurring through casual contact.

Increase Inevitable

Dr. James Curran, director of the Centers for Disease Control’s AIDS Task Force, said that although an increase among heterosexuals in this country is inevitable, transmission will not be as rapid as it has been among homosexuals.

Casual contact, he said, “will remain unimportant” as a means of transmission in this country.

Researchers are still far from developing a vaccine against AIDS.

When such a vaccine is developed, Curran said, “it will probably be desirable to vaccinate all Americans” to prevent the spread of the disease.

In another talk Monday, Dr. James Oleske of Childrens Hospital of New Jersey in Newark reported on a study of 40 children who were at high risk of developing AIDS because their mothers were intravenous drug users or spouses of intravenous drug users. Intravenous drug users are one of the high-risk groups for acquiring AIDS.

Although 16 of the children died before they were 6 months old, there has been no evidence of household transmission of the virus among 14 brothers and sisters and nine foster mothers, all of whom showed no evidence of infection by the virus. The children who died are believed to have acquired the virus from their mothers during gestation or around the time of birth.

Oleske said he believes that it is safe for the brothers and sisters of AIDS children to go into foster care. Because some of these children are nearing school age, the state of New Jersey is developing guidelines for how this may be done, he said.

Praise for Researchers

In welcoming remarks to the scientists gathered for the three-day conference, Health and Human Services Secretary Margaret M. Heckler heaped praise on AIDS researchers for making major discoveries that led to the isolation of the AIDS virus and the development of a test to detect its presence in blood.

“Never before in the history of medicine has so much been learned about an entirely new disease in such a short time,” Heckler said.

She said the blood test has made it possible to predict that the number of people who will contract AIDS in the future will be far larger than scientists had the ability to predict before the test.

Curran estimates that between 500,000 and 1 million Americans have been infected and that 10% will develop AIDS.