Malaria chemosuppression in pregnancy. III. Its effects on the maternal malaria immunity

Abstract

The malaria immune status of pregnant women participating in a malaria prophylaxis study was assessed using their sera reactivity to the R32tet32 antigen. Supervised prophylaxis started early in pregnancy till delivery. Women randomly received either chloroquine once weekly (CQ), or proguanil daily (PROG), or a combination of the two drugs (CQ + PROG). Blood was collected at enrollment, then after 8, 16, and 24 weeks of prophylaxis. Of the 312 women who received prophylaxis for more than 10 consecutive weeks before delivery, anti-sporozoite antibodies were assayed in 232 at enrollment, 258 after 8 weeks, and 254 after 16 weeks. Titres at enrollment were comparable by parity and the residential area. Antibodies in women of the PROG group who were parasitaemic before the assessments decreased with the increasing number of breakthrough and clinical episodes. The converse was true for antibodies in the CQ and CQ + PROG groups. Group differences in the parasite densities would explain this. Parity and placental malaria did not influence titres significantly. Overall, antibodies of the CQ + PROG group decrease significantly with time, possibly due to its long period of aparasitaemia. This suggested interference with the immune responsiveness of the women. PROG, which was equally efficacious, offers better prophylaxis.