COMPARABILITY OF TREATMENT GROUPS AND RISK-FACTORS FOR PARASITEMIA ATTHE FIRST ANTENATAL CLINIC VISIT IN A STUDY OF MALARIA TREATMENT AND PREVENTION IN PREGNANCY IN RURAL MALAWI

The problems of Plasmodium falciparum infection in pregnant women have been described in numerous sub-Saharan African countries, but the fre quency of parasitemia at the first antenatal visit and risk factors fo r infection have not been fully investigated. During a prospective ant imalarial treatment and prophylaxis trial in pregnant women in Malawi (three groups receiving a chloroquine regimen and one group receiving a mefloquine regimen), we examined women at their first antenatal clin ic visit to evaluate these issues and to verify that subjects in the s tudy treatment/prevention arms were similar. Among 4,127 women with en rollment blood smear results, 1,836 (44.5%) were parasitemic. The high est infection rates and densities were observed in primigravidas (66% infected, geometric mean parasite density [GMPD] = 1,588 parasites/mm( 3) of whole blood), followed by second pregnancies (46% infected, GMPD = 615 parasites/mm(3)) and subsequent pregnancies (29% infected, GMPD = 238 parasites/mm(3)), (P < 10(-6) for both infection prevalence and density, by chi-square test for trend). Significant risk factors for parasitemia at first antenatal clinic visit in a multivariate model in cluded low gravidity, high transmission season, no use of prophylaxis before first antenatal clinic visit, young age (< 20 years), human imm unodeficiency virus (HIV) infection, low hematocrit, short stature, an d second trimester (compared with third trimester). Women in the diffe rent treatment an-ns of the study were generally similar in many chara cteristics; statistically significant differences, where present, were small. Targeting malaria control efforts to women in their first or s econd pregnancy and during the high transmission season will be an imp ortant strategy to reach most parasitemic women and minimize resource expenditure. Women infected with HIV had a 55% increased risk of paras itemia at their first antenatal clinic visit and may represent an addi tional important risk group whose numbers may hr increasing and who ma y benefit from identification and management for malaria.