1 Division of Parasitic Diseases, National Center for Infectious Diseases, and International Health Program Office, Centers for Disease Control and Prevention, Atlanta, Georgia; University of Malawi School of Medicine and Ministry of Health, Blantyre, Malawi
The problems of Plasmodium falciparum infection in pregnant women have been described in numerous sub-Saharan African countries, but the frequency of parasitemia at the first antenatal visit and risk factors for infection have not been fully investigated. During a prospective antimalarial 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 clinic visit to evaluate these issues and to verify that subjects in the study treatment/prevention arms were similar. Among 4,127 women with enrollment blood smear results, 1,836 (44.5%) were parasitemia The highest infection rates and densities were observed in primigravidas (66% infected, geometric mean parasite density [GMPD] = 1,588 parasites/mm3 of whole blood), followed by second pregnancies (46% infected, GMPD = 615 parasites/mm3) and subsequent pregnancies (29% infected, GMPD = 238 parasites/mm3), (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 included low gravidity, high transmission season, no use of prophylaxis before first antenatal clinic visit, young age (< 20 years), human immunodeficiency virus (HIV) infection, low hematocrit, short stature, and second trimester (compared with third trimester). Women in the different treatment arms of the study were generally similar in many characteristics; statistically significant differences, where present, were small. Targeting malaria control efforts to women in their first or second pregnancy and during the high transmission season will be an important strategy to reach most parasitemic women and minimize resource expenditure. Women infected with HIV had a 55% increased risk of parasitemia at their first antenatal clinic visit and may represent an additional important risk group whose numbers may be increasing and who may benefit from identification and management for malaria.
Authors’ addresses: Richard W. Steketee, Epidemiology Branch, Division of HIV/AIDS Prevention, National Center for HIV/AIDS, STD, and TB Prevention, Centers for Disease Control and Prevention, Mailstop E-45, 1600 Clifton Road, Atlanta, GA 30333. Jack J. Wirima, University of Malawi School of Medicine and Ministry of Health, Blantyre, Malawi. Laurence Slutsker, Foodborne and Diarrheal Diseases Branch, Division of Bacterial and Mycotic Diseases, Centers for Disease Control and Prevention, Mailstop A-38, Atlanta, GA 30333. Joel E. Breman, Division of International Training and Research, Fogarty International Center, National Institutes of Health, Building 31, Room B2C 39, Bethesda, MD 20892-2220. David L. Heymann, Emerging and Other Communicable Diseases Programme, World Health Orgnaization, 1211 Geneva 27, Switzerland.