Studying these cells could lead to new treatments for diseases ranging from gastrointestinal disease to diabetes.
There may be a vaccine for one subtype of HIV by the turn of the century, but other subtypes will continue to spread rapidly throughout Asia and Southeast Asia, where the greatest rates of increase are being seen today, said Dr. Jeffrey Harris in last week's IAP session on "AIDS in the 21st Century."
Dr. Harris, an associate professor of economics who also holds an MD degree, detailed some of the reasons for the rapid spread of HIV and AIDS in some countries, as well as some possible scenarios for the future course of the pandemic. The most accurate estimates of the number of people infected with the virus are between 1 million and 1.5 million in North America, 15 million to 25 million in Africa and 10 million in Asia and Southeast Asia, where as many as one in 50 heterosexual, sexually active young adults is infected, he said. By the end of the decade, the figure could be as high as one in 15, he added.
The global proliferation of HIV will eventually have consequences for Americans. The important question is not whether transmission is being controlled by needle-exchange programs or safer sex here, but "how long before HIV, which is spreading like wildfire in Southeast Asia, eventually comes full circle and back to the United States," Dr. Harris said. "This is merely a matter of time. there's no reason that the international movement of people isn't going to bring [HIV] virus of all kinds" to this country.
One of the causes of the higher rate of spread in countries like Thailand is the sex industry found there. This industry is driven by supply rather than demand, Dr. Harris said. Many prostitutes in cities such as Bangkok are teenage girls lured from rural areas with promises of jobs in the city, where wages are much higher than in the countryside. The girls expect to be able to send to their families some of the money they earn in factories, but they are instead forced into prostitution.
In India and other countries where depiction of sexuality in movies or other public venues is tightly restricted, there may be more incentive for prostitution as well, Dr. Harris said. "You could make a generalization that it's the suppression of free sex that's driving demand."
In underdeveloped countries in Africa and elsewhere, the disease can be spread through contaminated blood products, because those countries cannot afford the screening equipment and other medical supplies that are routinely used in the United States. In some parts of Africa, blood transfusions are often used to treat anemia because of the scarcity of iron pills, Dr. Harris said.
There are at least 10 subtypes of HIV; type B is most common in the US, while type E is most prevalent in southeast Asia. American researchers are working on a vaccine for type B, but such a vaccine will probably not protect against other forms of the virus, he said. "It's conceivable that you could have one grand HIV vaccine, but the chances are quite likely that it's the opposite."
Dr. Harris predicted that the medical obstacles to a vaccine for one type of HIV would be overcome within three or four years, but that other issues must be dealt with before such a vaccine can be tested and made widely available. "Even if we solve some of the technical problems of developing a vaccine, the social, economic and political problems of trying to test that vaccine on a large scale are really very substantial," he said. For example, monitoring and controlling the behavior of drug-abusing patients at risk for contracting HIV through sharing needles is difficult because of their lifestyle.
The line is already blurring between asymptomatic HIV infection and AIDS itself, Dr. Harris noted. This is because recent research has shown that AIDS is a chronic illness in which the virus actively battles with the immune system from the moment of infection rather than lying dormant for many years as previously supposed. As a result, the term "AIDS" will probably be replaced within five years by "HIV disease" that encompasses all manifestations of infection, he said.
A version of this article appeared in MIT Tech Talk on February 8, 1995.