Epidemiology of HIV/AIDS in children.

HIV infection has been a major cause of morbidity and mortality since the first cases of AIDS among children were reported in 1982 in the United States. In 1997, HIV infection was the 11th leading cause of death among children 1 to 4 years of age (Richard Selik, MD, personal communication). Perinatal transmission of HIV accounts for 90% of pediatric AIDS cases and almost all new HIV infections in children. 16 An estimated 6000 to 7000 infants were born to HIV-infected women each year from 1989 to 1995, and more than 16,000 perinatally HIV-infected children have been born since the beginning of the epidemic. 10,29 Considerable advances, especially in the past 5 years, in the understanding of the pathogenesis, diagnosis, treatment, monitoring, and prevention of HIV infection in children have changed the epidemiology of pediatric HIV infection in the United States. The 1994 Pediatric AIDS Clinical Trials Group (PACTG) protocol 076 demonstrated that zidovudine (ZDV) therapy administered to selected HIV-infected pregnant women and their newborn infants reduced the rate of perinatal HIV transmission from 25% to 8% and was the first major prevention breakthrough in the HIV epidemic. 28,61 In 1994, the US Public Health Service (PHS) published guidelines for the use of ZDV to reduce perinatal HIV transmission, and in 1995, the PHS published guidelines for universal, routine HIV counseling and voluntary HIV testing of pregnant women. 19,21,26 The rapid implementation of these guidelines by health care providers and acceptance by HIV-infected mothers has resulted in a dramatic decrease in perinatal HIV transmission in the past 5 years. 50 Observational studies have confirmed the effectiveness of ZDV in decreasing perinatal HIV transmission to as low as 5%. 27,33,35,53,55,59,62 Data on combination therapy for the treatment of HIV-infected mothers and obstetric interventions, such as the use of elective cesarean section, suggest that the perinatal transmission rate could be decreased even more. 32,35,43,55 Other interventions, such as the avoidance of breast-feeding and treatment of concurrent sexually transmitted diseases (STDs), may also contribute to the decrease in the perinatal HIV transmission rate. With these successful interventions, the elimination of HIV infection in children in the United States may be possible, 54 but challenges remain, such as increasing the proportion of HIV-infected women, especially substance-using women, who receive timely prenatal care; making HIV counseling and voluntary testing the standard of care in pregnancy; offering ZDV therapy to reduce perinatal transmission; and ensuring that HIV-infected women and their children receive the appropriate HIV medical care and treatment. Treatment advances with combination therapies, including protease inhibitors, have increased survival of HIV-infected children. The ability to measure HIV viral load in plasma in combination with immune function has increased the ability to monitor the effectiveness of therapy. As a result, more children in the United States are living with HIV infection who need treatment, care, and services. Cohorts of perinatally infected children are aging into adolescence, 64 raising additional prevention and treatment issues, such as acceptance to complex treatment regimens and the prevention of sexual transmission. Worldwide, the effect of HIV infection in children is staggering, with more than 1.1 million children living with HIV at the end of 1997 and thousands of infants born with HIV infection each day. 66 The prevention challenge of the new millennium will be to bring the successes observed in the United States to developing countries. This article reviews the epidemiology of HIV infection among children in the United States, highlighting efforts to prevent perinatal HIV transmission that have already made a significant impact on the HIV epidemic among children and touch on the epidemiology worldwide.