HIV infection

Abstract

Heterosexual spread of HIV is occurring rapidly in Africa and Asia and WHO predicts that by the year 2000, 15 million women will be infected. Perinatal transmission of HIV now represents the major mode of HIV infection in children and in the USA, HIV is now the commonest congenital infection. About two-thirds of perinatal infections occur during delivery. Estimates of mother-to-infant transmission rates vary from 13 to around 40% and the risk of infection of the infant is increased when maternal viral load is high. Breast feeding increases the risk of transmission. Interventions are now available to reduce the frequency of perinatal transmission: the most dramatic of these is the prophylactic use of the antiretroviral drug, zidovudine, during the third trimester, intravenously during labour and orally to the infant for 6 weeks. Bottle feeding, when it can be safely undertaken, appears to reduce transmission rate by more than 10%. (Breast feeding is thought to account for one-third of all vertical infections.) Rates of infection in infants delivered by caesarean section appear to be half those of infants delivered vaginally but it is by no means clear that infants afforded the protection of prophylactic zidovudine would also benefit from caesarean delivery. Diagnosis of HIV in infants of infected mothers is made difficult by the transplacental transfer of maternal antibody which can persist for 18 months. However, with the use of viral culture and polymerase chain reaction to detect HIV all perinatal infections (in bottle fed infants) should be evident within 3 months of birth. Paediatric HIV runs a bimodal course with disease progressing more rapidly in infants of mothers who themselves have advanced disease. Pneumocystis carinii is the commonest opportunistic infection, most episodes occurring between age 3 and 6 months when HIV infection in many cases may not be suspected or firmly diagnosed. All perinatally exposed infants should be considered for antimicrobial prophylaxis from age 4–6 weeks since Pneumocystis carinii infection should be readily preventable but is very frequently fatal in small infants despite optimal therapy. Heterosexual spread of HIV is occurring rapidly in Africa and Asia and WHO predicts that by the year 2000, 15 million women will be infected. Perinatal transmission of HIV now represents the major mode of HIV infection in children and in the USA, HIV is now the commonest congenital infection. About two-thirds of perinatal infections occur during delivery. Estimates of mother-to-infant transmission rates vary from 13 to around 40% and the risk of infection of the infant is increased when maternal viral load is high. Breast feeding increases the risk of transmission. Interventions are now available to reduce the frequency of perinatal transmission: the most dramatic of these is the prophylactic use of the antiretroviral drug, zidovudine, during the third trimester, intravenously during labour and orally to the infant for 6 weeks. Bottle feeding, when it can be safely undertaken, appears to reduce transmission rate by more than 10%. (Breast feeding is thought to account for one-third of all vertical infections.) Rates of infection in infants delivered by caesarean section appear to be half those of infants delivered vaginally but it is by no means clear that infants afforded the protection of prophylactic zidovudine would also benefit from caesarean delivery. Diagnosis of HIV in infants of infected mothers is made difficult by the transplacental transfer of maternal antibody which can persist for 18 months. However, with the use of viral culture and polymerase chain reaction to detect HIV all perinatal infections (in bottle fed infants) should be evident within 3 months of birth. Paediatric HIV runs a bimodal course with disease progressing more rapidly in infants of mothers who themselves have advanced disease. Pneumocystis carinii is the commonest opportunistic infection, most episodes occurring between age 3 and 6 months when HIV infection in many cases may not be suspected or firmly diagnosed. All perinatally exposed infants should be considered for antimicrobial prophylaxis from age 4–6 weeks since Pneumocystis carinii infection should be readily preventable but is very frequently fatal in small infants despite optimal therapy.