Escalating pyrethroid resistance in two major malaria vectors Anopheles funestus and Anopheles gambiae (s.l.) in Atatam, Southern Ghana

Background: Aggravation of insecticide resistance in malaria vectors is threatening the efforts to control malaria by reducing the efficacy of insecticide-based interventions hence needs to be closely monitored. This study investigated the intensity of insecticide resistance of two major malaria vectors An. funestus sensu stricto (s.s.) and An. gambiae sensu lato (s.l.) collected in southern Ghana and assessed the bio-efficacy of several long-lasting insecticidal nets (LLINs) against these mosquito populations. Methods: The insecticide susceptibility profiles of Anopheles funestus s.s. and Anopheles gambiae s.l. populations from Obuasi region (Atatam), southern Ghana were characterized and the bio-efficacy of some LLINs was assessed to determine the impact of insecticide resistance on the effectiveness of these tools. Furthermore, molecular markers associated with insecticide resistance in both species were characterized in the F0 and F1 populations using PCR and qPCR methods. Results: Anopheles funestus s.s. was the predominant species and was resistant to pyrethroids, organochlorine and carbamate insecticides, but fully susceptible to organophosphates. An. gambiae s.l. was resistant to all four insecticide classes. High intensity of resistance to 5 × and 10 × the discriminating concentration (DC) of pyrethroids was observed in both species inducing a considerable loss of efficacy of long-lasting insecticidal nets (LLINs). Temporal expression analysis revealed a massive 12-fold increase in expression of the CYP6P4a cytochrome P450 gene in An. funestus s.s., initially from a fold change of 41 (2014) to 500 (2021). For both species, the expression of candidate genes did not vary according to discriminating doses. An. gambiae s.l. exhibited high frequencies of target-site resistance including Vgsc-1014F (90%) and Ace-1 (50%) while these mutations were absent in An. funestus s.s. Conclusions: The multiple and high intensity of resistance observed in both malaria vectors highlights the need to implement resistance management strategies and the introduction of new insecticide chemistries

Quality of Sulfadoxine-Pyrimethamine Given as Antimalarial Prophylaxis in Pregnant Women in Selected Health Facilities in Central Region of Ghana

The use of sulfadoxine-pyrimethamine (SP) as an intermittent preventive treatment (IPT) against malaria during pregnancy has become a policy in most sub-Sahara African countries and crucially depends on the efficacy of SP. This study sets out to evaluate the effectiveness of the SP given to the pregnant women in some selected health facilities in the Central Region of Ghana to prevent maternal malaria in pregnant women. A total of 543 pregnant women recruited from 7 selected health centres in Central Region of Ghana participated in the study. Parasite density of Plasmodium falciparum was determined from peripheral blood of the pregnant women using microscopy. High performance liquid chromatography (HPLC) and dissolution tester were used to determine the quality of the SP. Malaria infection was recorded in 11.2% of pregnant women who had a history of SP consumption. SP failed the dissolution test. Pregnant women who did not receive IPT-SP were 44%. Low haemoglobin level was recorded in 73.5% of the pregnant women. The results indicated that SP was substandard. IPT-SP is ineffective in preventing malaria infection

Effectiveness of Intermittent Preventive Treatment in Pregnancy with Sulphadoxine-Pyrimethamine against Submicroscopic falciparum

Malaria infections undetectable by microscopy but detectable by Polymerase Chain Reaction (PCR) (submicroscopic malaria) are common in endemic areas like Ghana. Submicroscopic malaria has been linked with severe pregnancy outcomes as well as contributing to malaria transmission. In this cross-sectional study 872 consenting pregnant women (gestation ≥ 20 weeks) were recruited from 8 hospitals in Central Region, Ghana, between July and December 2009. Malaria infection was detected by microscopy and PCR. Haemoglobin was measured and anaemia was defined as haemoglobin lower than 11 g/dL. Majority of the women, 555 (63.6%), were Intermittent Preventive Treatment in Pregnancy with Sulphadoxine-Pyrimethamine (IPTp-SP) users while 234 (36.4%) were nonusers. The prevalence of malaria by microscopy was 20.9% (182/872) and 9.7% (67/688) of microscopy negative women had submicroscopic malaria. IPTp-SP usage significantly (odds ratio = 0.13, 95% confidence interval = 0.07–0.23, p=0.005) reduced the prevalence of submicroscopic malaria as more nonusers (51/234) than users (16/454) were PCR positive. After controlling for other variables the effect of IPTp-SP remained statistically significant (odds ratio = 0.11, 95% confidence interval = 0.02–0.22, p=0.006). These results suggest that Intermittent Preventive Treatment with Sulphadoxine-Pyrimethamine is useful in the reduction of submicroscopic malaria in pregnancy