Emerging artemisinin resistance is a threat to global malaria control. Mutations in the Plasmodium falciparum Kelch 13 (K13) propeller domain confer artemisinin resistance and constitute molecular markers for its detection and monitoring. We sequenced 222 P. falciparum isolates obtained from community children in the Huye District of southern Rwanda in 2010, 2014, and 2015 to investigate the presence of K13 polymorphisms. No polymorphisms were observed in 2010 but they were present in 2.5% and 4.5% in 2014 and 2015, respectively. In 2015, two isolates showed candidate K13 resistance mutations (P574L and A675V), which are common in southeast Asia and associated with delayed parasite clearance. K13 polymorphisms in southern Rwanda are infrequent but include variants associated with artemisinin resistance. Establishing correlations with local treatment response and in vitro resistance assays are needed in addition to further monitoring K13 polymorphisms in the study area.

BackgroundPlasmodium falciparum infection during pregnancy is a major cause of poor maternal health, adverse foetal outcome and infant mortality in sub-Saharan Africa. Genetic disposition is involved in susceptibility to malaria in pregnancy and its manifestation. MicroRNAs (miRNAs) influence gene regulation including that of innate immune responses. A miRNA-146a rs2910164 G > C single nucleotide polymorphism (SNP) has been associated with increased risks of several diseases, but no data as to malaria are available.MethodsThe association between miRNA-146a rs2910164 and P. falciparum infection among 509 Ghanaian women attending antenatal care (ANC) and 296 delivering Ghanaian primiparae was investigated. Malaria parasites were diagnosed by microscopy and PCR. Leukocyte-associated hemozoin in placental samples was recorded as well. Proportions were compared between groups by Fisher’s exact test, and logistic regression models were used to adjust for possible confounders.ResultsBy PCR, P. falciparum infection was detected in 63% and 67% of ANC attendees and delivering primiparae, respectively. In both groups, two in three women were either heterozygous or homozygous for miRNA-146a rs2910164. Among ANC attendees, homozygosity conferred increased odds of infection (adjusted odds ratio (aOR), 2.3; 95% CI, 1.3–4.0), which was pronounced among primigravidae (aOR, 5.8; 95% CI, 1.6–26) but only marginal in multigravidae. Likewise, homozygosity for miRNA-146a rs2910164 in primiparae increased the odds of past or present placental P. falciparum infection almost six-fold (aOR, 5.9; 95% CI, 2.1–18).ConclusionsThese results indicate that SNP rs2910164 G > C is associated with increased odds for P. falciparum infection in first-time pregnant women who are considered to lack sufficient acquired immune responses against pregnancy-specific strains of P. falciparum. These findings suggest that miRNA-146a is involved in protective malarial immunity, and specifically in the innate component.

Sulfadoxine-pyrimethamine (SP) is the recommended drug for intermittent preventive treatment of malaria in pregnancy in most of sub-Saharan Africa. Resistance to SP is related to mutations in the dhfr and dhps gene of Plasmodium falciparum. This study determined the prevalence of Pfdhfr and Pfdhps polymorphisms found in asymptomatic pregnant women attending antenatal care in Calabar, Nigeria. From October 2013 to November 2014, asymptomatic pregnant women attending antenatal care clinics were enrolled after obtaining informed consent. Malaria diagnosis testing was done using thick and thin smears. Dried blood spot filter papers were collected. Parasite DNA was extracted from the filter papers using a chelex extraction. Extraction was followed by nested PCR and restriction enzyme digestion. P. falciparum infection was detected by microscopy in 7% (32/459) participants. Twenty-eight P. falciparum isolates were successfully genotyped. In the Pfdhfr gene, the triple mutation was almost fixed; S108N mutation was (100%), N51I (93%) and C59R mutations (93%), whereas the I164L mutation was absent. The prevalence of Pfdhps S436A, A437G, A581G and A613S mutations was 82.1% (23/28), 96.4% (27/28), 71.4% (20/28) and 71.4% (20/28) respectively. The K540E mutation was absent. The prevalence of the Pfdhfr triple mutation IRNI was 92.9% (26/28). The efficacy of SP as IPTp in Southeast Nigeria may be severely threatened. The continuous monitoring of SP molecular markers of resistance is required to assess thresholds. The evaluation of alternative preventive treatment strategies and drug options for preventing malaria in pregnancy may be necessary.

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BackgroundSevere and fatal vivax malaria is increasingly reported from India. In Mangaluru, southern India, malaria is focused in urban areas and associated with importation by migrant workers. In Wenlock Hospital, the largest governmental hospital, the clinical, parasitological and biochemical characteristics of malaria patients were assessed.MethodsDuring the peak malaria season in 2015 (June to December), outpatients were interviewed and clinically assessed. Malaria was ascertained by microscopy and PCR assays, concentrations of haemoglobin, creatinine and bilirubin, as well as thrombocyte count, were determined, and severe malaria was defined according to WHO criteria.ResultsAmong 909 malaria patients, the vast majority was male (93%), adult (median, 26 years) and of low socio-economic status. Roughly half of them were migrants from beyond the local Karnataka state, mostly from northern and northeastern states. Vivax malaria (69.6%) predominated over mixed Plasmodium vivax–Plasmodium falciparum infection (21.3%) and falciparum malaria (9.0%). The geometric mean parasite density was 3412/µL. As compared to vivax malaria, patients with falciparum malaria had higher parasite density and more frequently showed impaired general condition, affected consciousness and splenomegaly. Also, they tended to more commonly have anaemia and increased creatinine levels, and to be hospitalized (7.3%). Mixed-species infections largely assumed an interim position. Severe malaria (3.5%) was not associated with parasite species. No fatality occurred.ConclusionIn this study, uncomplicated cases of malaria predominated, with P. falciparum causing slightly more intense manifestation. Severe malaria was infrequent and fatalities absent. This contrasts with the reported pattern of manifestation in other parts of India, which requires the analysis of underlying causes.

BackgroundBlood group O protects African children against severe malaria and has reached high prevalence in malarious regions. However, its role in malaria in pregnancy is ambiguous. In 839 delivering Ghanaian women, associations of ABO blood groups with Plasmodium falciparum infection were examined.MethodsPlasmodium falciparum infection was diagnosed in placental blood samples by microscopy and PCR assays. Present or past infection was defined as the detection of parasitaemia or haemozoin by microscopy, or a positive PCR result. Blood groups were inferred from genotyping rs8176719 (indicating the O allele) and rs8176746/rs8176747 (distinguishing the B allele from the A allele).ResultsThe majority of women had blood group O (55.4%); present or past P. falciparum infection was seen in 62.3% of all women. Among multiparae, the blood groups had no influence on P. falciparum infection. In contrast, primiparae with blood group O had significantly less present or past infection than women with non-O blood groups (61.5 vs 76.2%, P = 0.007). In multivariate analysis, the odds of present or past placental P. falciparum infection were reduced by 45% in blood group O primiparae (aOR, 0.55 [95% CI, 0.33–0.94]).ConclusionsThe present study shows a clear protective effect of blood group O against malaria in primiparae. This accords with findings in severe malaria and in vitro results. The data underline the relevance of host genetic protection among primiparae, i.e. the high-risk group for malaria in pregnancy, and contribute to the understanding of high O allele frequencies in Africa.

In most of India, sulfadoxine-pyrimethamine (SP) plus artesunate serves as first-line treatment for uncomplicated falciparum malaria. In 112 clinical Plasmodium falciparum isolates from Mangaluru, southwestern India, we sequenced molecular markers associated with resistance to SP, lumefantrine, and artemisinin (pfdhfr, pfdhps, pfmdr1, and K13). The pfdhfr double mutation 59R-108N combined with the dhps 437G mutation occurred in 39.3% and the pfdhfr double mutation plus the pfdhps double mutation 437G-540E in additional 24.1%. As for pfmdr1, the allele combination N86-184F-D1246 dominated (98.2%). K13 variants were absent. No evidence for artemisinin resistance was seen. However, the antifolate resistance alleles compromise the current first-line antimalarial sulfadoxine-pyrimethamine plus artesunate, which may facilitate the emergence of artemisinin resistance. Artemether-lumefantrine, introduced in northeastern parts of the country, in the study area faces the predominant pfmdr1 NFD genotype, known to impair lumefantrine efficacy. Further monitoring of resistance alleles and treatment trials on alternative artemisinin-based combination therapies are required.

Abstract. Phagocytosis of malaria pigment (hemozoin) induces increased activity of matrix metalloproteinase (MMP)-9, an endopeptidase involved in cytokine regulation. In this study, we examined whether a common functional MMP-9 promoter polymorphism (rs3918242) affects Plasmodium falciparum infection in pregnancy. Eighteen percent of Ghanaian primiparae carried the minor T allele. It was associated with reduced odds of placental hemozoin and of placental as well as peripheral blood parasitemia. The results indicate that a common MMP-9 polymorphism protects against placental malaria indicating that this endopeptidase is involved in susceptibility to P. falciparum.Pregnant women are a particular risk group for infection with Plasmodium falciparum and malaria. Although commonly asymptomatic at high endemicity, malaria in pregnancy may cause anemia, abortion, stillbirth, low birth weight (LBW), and preterm delivery (PTD), and contributes to high infant mortality. The increased susceptibility of pregnant women, particularly primigravidae, is largely due to parasites expressing specific variants of the P. falciparum erythrocyte membrane protein-1. Parasite adhesion via these variant surface proteins results in the sequestration of infected red blood cells (RBCs) in the placental intervillous space. Sequestration frequently is accompanied by local hemozoin (malaria pigment) deposition and accumulation of inflammatory cells, including monocytes/macrophages. Specific immune mechanisms targeting the pregnancy-associated parasites, particularly parasite-specific antibodies, are low in primigravidae. Only with successive pregnancies, these are acquired, and infection risk and manifestation decrease.