Prevalence Of Plasmodium Falciparum Infection Research Articles

Do untreated bednets protect against malaria?

Bednets are thought to offer little, if any, protection against malaria, unless treated with insecticide. There is also concern that the use of untreated nets will cause people sleeping without nets to receive more mosquito bites, and thus increase the malaria risk for other community members. Regular retreatment of nets is therefore viewed as critical for malaria control. However, despite good uptake of nets, many control programmes in Africa have reported low re-treatment rates. We investigated whether untreated bednets had any protective benefit (in October and November 1996) in The Gambia where nets, although widely used, are mostly untreated. Cross-sectional prevalence surveys were carried out in 48 villages and the risk of malaria parasitaemia was compared in young children sleeping with or without nets. Use of an untreated bednet in good condition was associated with a significantly lower prevalence of Plasmodium falciparum infection (51% protection [95% CI 34–64%], P < 0.001). This finding was only partly explained by differences in wealth between households, and children in the poorest households benefited most from sleeping under an untreated net (62% protection [14–83%], P = 0.018). There was no evidence that mosquitoes were diverted to feed on children sleeping without nets. These findings suggest that an untreated net, provided it is in relatively good condition, can protect against malaria. Control programmes should target the poorest households as they may have the most to gain from using nets.

Short report: increased susceptibility to Plasmodium malariae in pregnant alpha(+)-thalassemic women.

The influence of alpha(+)-thalassemia on malaria in pregnancy was assessed in a cross-sectional study of 530 women in Ghana. Plasmodial infections, alpha(+)-thalassemia, serum levels of C-reactive protein, and antimalarial drugs in urine were determined. The alpha-globin genotypes did not correlate with the prevalence of Plasmodium falciparum-infection and parasite densities. However, Plasmodium malariae tended to be more frequent in alpha(+)-thalassemic women (P = 0.05). Excluding women with residual antimalarials, a significant excess of P. malariae was observed in alpha(+)-thalassemic individuals. Febrile responses (P = 0.05) and inflammation (CRP > 0.6 mg/dl, P = 0.06) appeared to be less common in infected alpha(+)-thalassemic women and were also comparatively rare in parasitemic individuals who harbored double species infections with P. falciparum and P. malariae. Plasmodium malariae may influence the pathogenesis of falciparum malaria leading to a low prevalence of inflammation and febrile responses in alpha(+)-thalassemic women.

An evaluation of the effects of intermittent sulfadoxine—pyrimethamine treatment in pregnancy on parasite clearance and risk of low birthweight in rural Malawi

The prevalence of infection with malarial parasites and the incidence of anaemia and delivery of infants with low birthweight (LBW) were investigated in 575 Malawian mothers who received one, two or three doses of sulfadoxine-pyrimethamine (SP) during pregnancy. All the subjects were enrolled at their first antenatal visit and all delivered at hospital. The prevalence of Plasmodium falciparum infection at first antenatal visit was 35.3% in primigravidae and 13.6% in multigravidae (P < 0.001). Mean haemoglobin concentration was significantly lower in primigravidae than in multigravidae (8.8 v. 9.5 g/dl; P< 0.001). Of the 233 women tested for HIV infection, 18.8% of the primigravidae and 23.7% of the multigravidae were seropositive.At delivery, there was no significant difference in parasite prevalence in peripheral or placental blood between women who had received one or two antenatal doses of SP. The multigravidae who had received two doses of SP had higher mean haemoglobin concentrations than those who had received just one (P = 0.009) [this difference was not seen in the primigravidae (P = 0.92)]. However, linear regression analysis indicated that the haematinic supplements given to the subjects contributed more to this increase in haemoglobin concentration than the SP.The mean birthweights were higher, and incidence of LBW lower in babies born to primi- and multi-gravidae who had received two or three doses of SP treatment than those seen in babies born to women who had had just one dose (P < 0.03 for each). The odds ratio for LBW in primigravidae compared with multigravidae decreased from 3.2 to 1.0 as the number of SP doses increased from one to three. The benefit of three doses (compared with none) was equivalent to the population-attributable risk of LBW in primigravidae being reduced from 34.6% to 0%. Subjects who were seropositive for HIV were twice as likely to give birth to LBW babies as the other subjects.The use of SP was not associated with maternal side-effects or perinatal complications. The present results indicate that multiple doses of SP taken during pregnancy will lead to a highly significant reduction in the incidence of LBW in infants born to primigravidae, even if the women have HIV infections. This reduction is observable even when parasite prevalence at delivery is high because of re-infections in late pregnancy; reduction in parasite prevalence earlier in pregnancy, as the result of SP treatment, leads to improved foetal growth.

An evaluation of the effects of intermittent sulfadoxine-pyrimethamine treatment in pregnancy on parasite clearance and risk of low birthweight in rural Malawi.

The prevalence of infection with malarial parasites and the incidence of anaemia and delivery of infants with low birthweight (LBW) were investigated in 575 Malawian mothers who received one, two or three doses of sulfadoxine-pyrimethamine (SP) during pregnancy. All the subjects were enrolled at their first antenatal visit and all delivered at hospital. The prevalence of Plasmodium falciparum infection at first antenatal visit was 35.3% in primigravidae and 13.6% in multigravidae (P < 0.001). Mean haemoglobin concentration was significantly lower in primigravidae than in multigravidae (8.8 v. 9.5 g/dl; P < 0.001). Of the 233 women tested for HIV infection, 18.8% of the primigravidae and 23.7% of the multigravidae were seropositive. At delivery, there was no significant difference in parasite prevalence in peripheral or placental blood between women who had received one or two antenatal doses of SP. The multigravidae who had received two doses of SP had higher mean haemoglobin concentrations than those who had received just one (P = 0.009) [this difference was not seen in the primigravidae (P = 0.92)]. However, linear regression analysis indicated that the haematinic supplements given to the subjects contributed more to this increase in haemoglobin concentration than the SP. The mean birthweights were higher, and incidence of LBW lower in babies born to primi-and multi-gravidae who had received two or three doses of SP treatment than those seen in babies born to women who had had just one dose (P < 0.03 for each). The odds ratio for LBW in primigravidae compared with multigravidae decreased from 3.2 to 1.0 as the number of SP doses increased from one to three. The benefit of three doses (compared with none) was equivalent to the population-attributable risk of LBW in primigravidae being reduced from 34.6% to 0%. Subjects who were seropositive for HIV were twice as likely to give birth to LBW babies as the other subjects. The use of SP was not associated with maternal side-effects or perinatal complications. The present results indicate that multiple doses of SP taken during pregnancy will lead to a highly significant reduction in the incidence of LBW in infants born to primigravidae, even if the women have HIV infections. This reduction is observable even when parasite prevalence at delivery is high because of re-infections in late pregnancy; reduction in parasite prevalence earlier in pregnancy, as the result of SP treatment, leads to improved foetal growth.

Asymptomatic Plasmodium falciparum infection and poor school performance in primary school children in the Volta Region of Ghana.

This study aimed to evaluate the association between asymptomatic Plasmodium falciparum infection and poor intellectual development in primary school children in the Volta Region of Ghana. This was a cross-sectional study conducted among children from 5 primary schools in 3 districts in the Volta region of Ghana. Questionnaires were administered, and blood samples collected for malaria investigation using Rapid diagnostic test (RDT) and microscopy. School performance was used to assess intellectual development in the children. Arithmetic was the subject of choice for the standardized test. Pearson chi square test was used to evaluate the association between Plasmodium falciparum and poor school performance. Multivariate analysis was used to identify factors independently associated with risk of poor school performance. Out of 550 children, 305(55.45%) tested positive for malaria with RDT and 249(45.27%) positive with microscopy. Children from the Evangelical Presbyterian (EP) primary school in Afegame had the highest prevalence of Plasmodium falciparum infection with both RDT (92, 74.80%) and microscopy (73, 59.35%). Two hundred and fifteen students (39.09%) failed the arithmetic school test. EP primary school in Afegame recorded the highest frequency of poor school performance among the children (53.66%). School performance was significantly associated with RDT malaria diagnosis with failure rate higher among children who were RDT positive (135, 62.79%, p=0.005). Lower mean scores were seen in children with positive RDT result (47.35, [SD 30.85], p=0.021). Plasmodium falciparum infection (RDT) was independently associated with increased risk of poor school performance (AOR, 1.92, p=0.003). An urgent scale-up of malaria control program targeting school-going children in this region is needed to mitigate the possible negative impact of Plasmodium falciparum infection on their intellectual development.