New studies and findings in the area of malaria

AUG 20, 2005 — Malaria data are the focus of recent research from France, Sudan and Sweden.

Study 1: A gene mutation associated with chloroquine resistance is common among pregnant women in Senegal, researchers report.

“The risk of malaria infection is increased during pregnancy, and many countries recommend chloroquine prophylaxis in pregnant women, despite Plasmodium falciparum chloroquine resistance.

“Chloroquine resistance is associated with the pfcrt gene K76T mutation. The aim of this study was to compare the prevalence rate of pfcrt T76 mutation in P. falciparum isolates from infected pregnant and nonpregnant individuals from Senegal,” wrote G. Bertin at the Research Institute for Development, Paris, and colleagues.

According to the authors, “The study was conducted in the rural maternity hospital of Thiadiaye, Senegal, where malaria is seasonal. Sixty-nine P. falciparum isolates from infected women were collected at delivery. These women were part of a cohort study; they were followed from their first antenatal visit and advised to take chloroquine prophylaxis. For each woman, the earliest P. falciparum-infected blood sample was also used. A control group of 49 nonpregnant individuals with asymptomatic P. falciparum infection was enrolled.”

Bertin and team determined that “during pregnancy, prevalence of T76 mutant parasites was higher than in the 49 nonpregnant controls (p<0.001). Among pregnant women, this rate was highest at delivery (p=0.06), and tended to be higher in women who had taken chloroquine prophylaxis, as assessed in urine samples (p=0.08)." "Chloroquine prophylaxis is responsible for increased drug consumption and increased drug pressure that may lead to the selection of drug-resistant parasites," said the researchers. This is the first report showing that "P. falciparum-infected pregnant women harbor pfcrt T76 mutant parasites more often than nonpregnant individuals, and that the prevalence of this mutation is higher at term than earlier during pregnancy," stated Bertin and colleagues. They published their study in the Journal of Antimicrobial Chemotherapy (High prevalence of Plasmodium falciparum pfcrt K76T mutation in pregnant women taking chloroquine prophylaxis in Senegal. J Antimicrob Chemother, 2005;55(5):788-791). Additional information can be obtained by contacting P. Deloron, Institut de Recherche pour le Development, Faculty Pharmacy, IRD, UR010, F-75006 Paris, France. Study 2: According to recent research from Sudan, "Pregnant women are more susceptible to malaria, which is associated with serious adverse effects on pregnancy. The presentation of malaria during pregnancy varies according to the level of transmission in the area." I. Adam and colleagues, New Haifa Teaching Hospital, calculated the prevalence and identified risk factors for malaria among pregnant women in eastern Sudan. Disease in this region, they said, "is characterized by unstable malaria transmission." "The prevalence and possible risk factors for Plasmodium falciparum malaria were investigated in 744 pregnant Sudanese women attending the antenatal clinic of New Haifa Teaching Hospital, eastern Sudan, during October 2003-April 2004. A total 102 (13.7%) had P. falciparum malaria, 18 (17.6%) of these were severe cases (jaundice and severe anemia)," the researchers said. When they applied univariate and multivariate analysis to the data, they found that age and parity were not associated with malaria. Adam and coworkers reported, "Women who attended the antenatal clinic in the third trimester were at highest risk for malaria (OR=1.58, 95% CI=1.02-2.4; p<0.05). Women with malaria had significantly lower mean hemoglobin (9.4 g/dl, 95% CI 9.1-9.7 versus 10.7, CI 10.6-10.8, p<0.05). A significantly lower hemoglobin was observed in those with severe falciparum malaria compared to nonsevere form (8.3 g/dl, 95% CI 7.6-9.1 versus 9.4, 95% CI 9.1-9.7, p(=<)0.05)." The researchers concluded, "The results suggest that P. falciparum malaria is common in pregnant women attending antenatal care and that anemia is an important complication. Preventive measures (chemoprophylaxis and insecticide-treated bednets) may be beneficial in this area for all women irrespective of age or parity." Adam and coauthors published their study in Malaria Journal (Prevalence and risk factors for Plasmodium falciparum malaria in pregnant women of eastern Sudan - art. no. 18. Malar J, 2005;4(1):18). For additional information, contact I. Adam, New Haifa Teaching Hospital, POB 61, New Haifa, Sudan. Study 3: Two doses of sulphadoxine-pyrimethamine reduced prevalence of peripheral and placental malaria parasitemia among young women in two areas of Mozambique. "Malarial infection during pregnancy increases the risks of severe sequelae for the pregnant woman and the risk of delivering a low birthweight baby. The aim of this intervention study was to reduce significantly the prevalence of malaria parasitemia in adolescent parturients in Matola and Boane in Mozambique," reported K. Challis of Sundsvall Hospital, Sweden, and colleagues. The population most vulnerable to malaria in this area is adolescent nulliparous and primiparous women, the researchers said, so a group of 600 young pregnant women comprised the study cohort. They "were randomly chosen in a double-blind manner to one of two regimens comparing the prevailing routine (placebo) for malaria prevention with a two-dose regimen of sulphadoxine-pyrimethamine (SP). The first dose was given at enrollment with a second dose at the beginning of the third trimester. At delivery, maternal and placental malaria parasitemia, as well as birthweight and gestational duration, were analyzed." The initial prevalence "of malaria parasitemia was 35.3% in the placebo group and 30.6% in the SP group. At the second dose, the prevalence of malaria parasitemia in the placebo group and SP group was 19.7% and 8.7%, respectively," reported Challis and team. They said, "This implies a relative risk (RR) of 2.24 with 95% CI (1.34, 3.75). The corresponding figures at delivery were 13.6% and 6.3% with an RR of 2.22 (1.07, 4.60) and in placenta 13.3% and 2.4% with an RR of 4.87 (1.58, 15.0)." The women in the placebo group gave birth to significantly more newborns who developed malaria within 7 days of birth (6.4% in placebo group, 0.7% in treatment group; RR = 6.55 (1.20, 35.7). "Almost all (approximately 98%) of the women studied had Plasmodium falciparum [malaria]; the remainder had P. malariae and P. ovale," according to the report. Challis and colleagues also looked at birthweight and gestation times in the two groups. "The mean birthweight in the SP group was 3,077 g and in the placebo group 2,926 g. The estimated mean difference between the two groups was 151 g with 95% CI (51, 252). The mean placental weight in the placebo group was 596 and 645 g in the SP group, implying a difference of 49 g with a 95% CI (11, 88). The mean gestational duration was 6.1 days longer in the SP group, 95% CI (1.5, 10.6)," they reported. The researchers noted two cases of urticaria and one case of nausea in the placebo group, and said one woman in the treatment group experienced vomiting. None of the babies exhibited any indication of serious side effects from SP. "Two doses of SP were enough to significantly reduce the prevalence of peripheral and placental malaria parasitemia among young nulliparous and primiparous pregnant women in Matola and Boane," the team concluded. Challis and coauthors published their study in Tropical Medicine & International Health (Impact of a double dose of sulphadoxine-pyrimethamine to reduce prevalence of pregnancy malaria in southern Mozambique. Trop Med Int Health, 2004;9(10):1066-1073). For more information, contact K. Challis, Sundsvall Hospital, Dept. of Obstetrics & Gynecology, S-84186 Sundsvall, Sweden. The information in this article comes under the major subject areas of Malaria, Sulphadoxine Pyrimethamine, Pregnancy, Disease Prevention, Epidemiology, Antimalarials. This article was prepared by Malaria Weekly editors from staff and other reports. [gallery link="file" ids="https://sudantribune.com/wp-content/uploads/2005/06/jpg_mosquito.jpg|"]