MOTHER-TO-CHILD HIV TRANSMISSION

HIV infection in children is mainly the result of a mother-to-child tr ansmission. The contamination during pregnancy is well known but intra partum vertical transmission may also occur through ascending infectio n, blood exchange between mother and child, or direct contact with vag inal or cervical secretions. In addition HIV can be transmitted via br east milk. The reported rates of vertical transmission are highly vari able: 14,4% in a European study, 18,3% in a French survey, 20 to 25% i n the USA, 35 to 50% in Africa. It is unclear whether such a large var iation of the rate of transmission is due to methodological difference s or to different distributions of risk factors in the populations. Th ere are some known predictive factors of HIV transmission such as low CD4 cells count, positive p24 antigenaemia and elevated concentrations of virus. The role of other factors is still debated: prematurity, vi rus (CMV, HTLV-1, HVB, HVC), C section prior labour, rupture of membra nes. The prevention of HIV infection in infants is mainly based on con tra-indication of pregnancy in infected women, desinfection of the vag ina at the beginning of labour, early protection of the newborn by avo iding skin lesions and immediate washing, preventive treatment by zido vudin during pregnancy.