Abstract

Retroviruses (mainly H.I.V. 1 and H.I.V. 2) are now largely spread over in Central Africa and Caribbean Islands, particularly in large cities. Their transmission is essentially horizontal and mainly sexual. As a matter of fact, sexual transmission is responsible in about 80% of the cases, leaving only a small percentage to transmission by needle (or by any aggressive material), blood or blood by-products. As far as sexual transmission is concerned, it is essentially heterosexual, in spite of the primary epidemic outbreak in the occidental world that focused interest toward male homosexual group, the first exposed to A.I.D.S. Nowadays we know that heterosexual transmission is important and bi-directionnal, even if transmission female to male has seemed to be more difficult to enlight, as it is common in sexually transmitted diseases. Transmission risk to an heterosexual partner is between 20 and 70%. Virus is present in semen, and in cervico-vaginalis secretions during all menstruation cycle. Vertical transmission, mother to child, through placenta or during delivery is frequent, and is of about 50%. First data on heterosexual transmission have been found in Central Africa, indicating high rates for prostitutes, their "customers", unmarried women with numerous partners, women with an other S.T.D. A.I.D.S. in child has been first described in Haïti and in Zaïre. The very important role played by heterosexual transmission imposed sanitary education and usage of contraceptives which are efficient but difficult to firmly recommended for social and cultural considerations.

PIP:

The retrovirus responsible for AIDS began circulating in Africa during the 1970s. Seroepidemiologic studies in Zaire and elsewhere in Central Africa show infection rates of 6-10%, with urban rates even higher and most rural rates close to zero. The modes of transmission are analogous to those of hepatitis B. Homosexual transmission has probably played a small role in Africa. Most epidemiological studies in Central Africa show that almost all seropositive persons are young sexually active adults, with the most affected age groups 20-30 for women and 30-40 for men. The risk of male to female sexual transmission appears to be about 20%, but increases with prolonged relationships. Sperm is able to induce a chronic immunological stimulation and immune perturbations favoring clinical expression of the infection, especially if the sperm comes in contact with the partner's blood because of erosion of the vaginal or anal mucus. Infection of men by women is harder to demonstrate but it cannot yet be confirmed that there are significant differences related to sex. The virus is present in cervicovaginal secretions during the entire menstrual cycle. Seroprevalence rates among prostitutes in Central Africa have increased steadily and are correlated to the time spent as a prostitute and the annual number of clients. Sexually transmitted diseases that disturb the genital mucus appear to favor infection during heterosexual intercourse. In Zaire, 61% of women and 36% of men with AIDS are unmarried. For both sexes, numerous partners appear to increase the risk of infection. Frequent use of prostitutes increases the risk for men. Transmission from mothers to infants can occur during delivery or transplacentally during any trimester of pregnancy. The risk of transmission from an infected mother appears to be about 50%. HIV infection does not appear to have any specific clinical manifestation in the female genital tract. Some studies suggest that the likelihood of 1st trimester spontaneous abortion or of postnatal mortality is increased in infants of seropositive mothers. The clinical characteristics of AIDS in children are not specific and a positive serological test in necessary to confirm the diagnosis. Prevention of HIV infection in the foreseeable future will require health education and the use of condoms, which gained little acceptance in most of Africa.