AIDS and HIV infection outside the United States

Within 3 years after the syndrome was recognized in the United States, cases of AIDS were reported from every continent. By November of 1997, more than 1.7 million cases had been reported from 197 countries to WHO (Table 409-4) . WHO also estimates that >60 milion people would be infected with HIV by the end of century.

AIDS case reporting from developing countries is much less complete than in industrialized countries and, because the developing world is most heavily affected by HIV/AIDS, WHO estimates that the number of reported AIDS cases worldwide are less than 15% of the total estimated number of AIDS cases that have occurred throughout the epidemic. Extensive HIV serosurveys in Africa, South and Central America, and parts of Asia provide evidence that AIDS case reports greatly underestimate the magnitude of the HIV problem in many countries in these regions.

Modes of transmission of HIV are similar throughout the world, but the relative frequency varies considerably between countries and regions. In North America, Europe, Australia, New Zealand, and some areas of South America, the majority of HIV infections first occurred in homosexual men and IDUs; heterosexual and perinatal transmission initially resulted mostly from transmission from IDUs and their partners. In most countries in Africa and some in the Caribbean and Central America, most HIV infections have occurred through heterosexual transmission.

HIV seroprevalence rates are highest in urban prostitutes and sexually active young adults. High rates of infection in young women translate into a substantial amount of perinatal transmission. In some areas of Africa, pediatric HIV infection has significantly increased already high infant mortality rates. In many developing countries, transfusion of HIV-infected blood remains a substantial problem because of inadequate blood banking and serologic testing capacity. Reuse of nonsterile needles and syringes and other medical practices have caused major HIV outbreaks in the former Soviet Union and Romania. In Asian countries such as Thailand and India, emergence of HIV infection as a major public health problem began in IDUs and prostitutes, but rapidly spread more widely through heterosexual transmission to other young adult populations. India is now the country believed to have the highest number of HIV-infected persons, with an estimated 2 to 5 million people currently infected.

In Eastern Europe and the newly independent states of the former Soviet Union, HIV infections are rapidly increasing, primarily in association with injecting drug use. In yet other countries, primarily in the Middle East, Asia, and the Pacific region, HIV has not yet been recognized as an important public health problem. The future course of HIV in these countries may depend on their ability to anticipate and respond to the problem; it can be approximately predicted by the extent and pattern of sexually transmitted and transfusion-associated infections and the extent of injecting drug use that currently exists in each country.