An epidemic of a disease with strong similarities to the deadly human immunologic disorder called AIDS has occurred among research monkeys in California and Massachusetts, possibly providing a valuable research tool for investigating human AIDS.
The outbreaks affected some cages but not others, reinforcing researchers' ideas that AIDS (for acquired immune deficiency syndrome) is a transmissible disease caused by a virus or other microorganism spread through close physical contact, according to the Feb. 19 issue of the British medical journal Lancet.
AIDS has been recognized only in the last few years, and is believed to be a wholly new disorder. It has been identified in several human populations, including sexually active male homosexuals, intravenous drug abusers, travelers from Haiti, hemophilia patients who receive frequent blood product transfusions and children of parents in those categories.
As of Feb. 2, the federal Centers for Disease Control in Atlanta had reported more than 1,000 AIDS cases, of which 394 were fatal.
According to the Lancet article, a similar syndrome in 15 months killed 24 out of 64 rhesus monkeys of a caged group at the California Regional Primate Research Center, which is affiliated with the University of California at Davis.
Veterinarian Roy V. Henrickson and his co-workers at the California center said the disease "closely resemble s AIDS in men."
The animals' body defense mechanisms failed, leaving them prey to infections they normally could throw off, including some of the same infections that kill human AIDS victims.
The sick monkeys had swollen glands, diarrhea, fever, anemia, weight loss and wasting and skin disorders, all of which are found in human AIDS victims. All died. But, where most human victims have been male, all 24 monkey victims at Davis were female.
The Davis researchers report that three monkeys developed a cancer, previously unseen at their facility, "which invites comparison with Kaposi's sarcoma," the rare cancer that is killing a high proportion of male homosexual AIDS victims.
Both Henrickson and Norval W. King, associate director of Harvard University's New England Regional Primate Research Center, say they believe that earlier epidemics at their facilities, which resulted in many dozens of monkey deaths, also may have been due to AIDS.
King said in a telephone interview that about 100 monkeys at his facility have died of AIDS-like illnesses, 60 in the last three years, since the advent of human AIDS outbreaks.
Researchers say they fear the apparent outbreaks of AIDS among monkeys may decimate animal stocks essential to a wide range of research efforts. But they see the sick monkeys as a valuable research tool--the first candidate for an animal model of human AIDS--that could provide insight into the immune mechanisms, modes of transmission and possible roles of viral and toxic agents in AIDS.
King and other researchers say they do not know how AIDS entered the monkey colonies. They say they have no evidence that AIDS was communicated to the monkeys by humans, or, conversely, that human AIDS victims were infected by contact with the monkeys. As a result, King said he does not believe animal AIDS is a public threat.