Evolution and spread of Plasmodium falciparum mutations associated with resistance to sulfadoxine-pyrimethamine in central Africa: a cross-sectional study.

BACKGROUND: Efficacy of sulfadoxine-pyrimethamine, the malaria chemoprophylaxis used in pregnant women, and in children when combined with amodiaquine, is threatened by the accumulation of mutations in the Plasmodium falciparum dihydropteroate synthase (pfdhps) and dihydrofolate reductase (pfdhfr) genes. Data on the prevalence of resistant alleles in central Africa and the new pfdhps I431V mutation, particularly associated with other mutations to form the pfdhps vagKgs allele, are scarce. We explored the frequency and geographical distribution of pfdhps and pfdhfr mutations in central Africa in 2014-18, and assessed the evolutionary origin of the vagKgs allele. METHODS: Samples were collected at 18 health-care centres in seven countries (Angola, Cameroon, Central African Republic, Democratic Republic of the Congo, Gabon, Nigeria, and Republic of the Congo) from patients who showed possible symptoms of malaria between March 1, 2014, and Oct 31, 2018. Samples that were positive for P falciparum were transported to a laboratory in Toulouse, France, and genotyped. The frequency of pfdhfr and pfdhps mutations was studied in 1749 samples. Microsatellites in pfdhps flanking regions and whole-genome analysis compared with parasite genomes from the data-sharing network MalariaGEN were performed on samples carrying the vagKgs allele. FINDINGS: Mapping of the prevalence of single nucleotide polymorphisms and corresponding alleles of pfdhfr and pfdhps showed a substantial spread of alleles associated with sulfadoxine-pyrimethamine resistance in central Africa during the 2014-18 period, especially an increase going west to east in pfdhps alleles carrying the K540E and A581G mutations. A high prevalence of the pfdhps I431V mutation was observed in Cameroon (exceeding 50% in the northern region) and Nigeria. Genomic analysis showed a recent African emergence and a clonal expansion of the most frequent pfdhps vagKgs allele. INTERPRETATION: Reduced sulfadoxine-pyrimethamine efficacy due to increased resistance is a worrying situation, especially because the malaria transmission level is high in central Africa. Although the resistance phenotype remains to be confirmed, the emergence and spread of the vagKgs allele in west and central Africa could challenge the use of sulfadoxine-pyrimethamine. FUNDING: Toulouse Institute for Infectious and Inflammatory Diseases.

Prevalence of asymptomatic malaria in HIV-infected subjects on cotrimoxazole antimalarial prophylaxis attending a tertiary health care center in southern Nigeria: a cross-sectional study.

INTRODUCTION: Co-infection has become a major contributor to increased burden of morbidity and mortality in HIV infection. The aim of this study was to assess the prevalence of asymptomatic malaria in the HIV-infected subjects on antimalarial prophylaxis and provide information to improve management of HIV subjects. METHODS: This was a cross-sectional study with a purposive sampling. Microscopy method was used for the confirmation of malaria parasitemia status. The study was performed in University of Calabar Teaching Hospital, Calabar, Cross River State, Nigeria, a major tertiary health institution within the period of January to June 2016 involving 100 participants. RESULTS: The majority (65%) of the study participants were females. The majority of the studied population belonged to the age range 33-38 years old. Most (45%) of the patients had CD4 count ≥500 cells/µL. The prevalence of asymptomatic malaria was found to be 13% (13/100). The distribution of asymptomatic malaria based on gender and age were found not to be statistically significant (P>0.05). Subjects with CD4 count in the range of 200-499 cells/µL had the highest prevalence (24.39%) of asymptomatic malaria. CONCLUSIONS: Considering that all the studied participants were on antimalarial prophylaxis, it signals a public health concern to employ more intensive preventive methods in addition to antimalaria prophylaxis.

Cysteine-cysteine chemokine receptor 5 (CCR5) profile of HIV-infected subjects attending University of Calabar Teaching Hospital, Calabar, Southern Nigeria.

BACKGROUND: Cysteine-cysteine chemokine receptor 5 is the main HIV co-receptor involved in the virus and cell-to-cell spread. A variant of the CCR5 gene known as CCR5-Δ32 which is a product of 32 base pair deletion in the gene plays critical role in the infection and progression to AIDS. The study was carried out to determine the CCR5 genotype of HIV-infected subjects attending University of Calabar Teaching Hospital, Calabar. METHODS: A total of 100 subjects attending HIV clinic, University of Calabar Teaching Hospital were purposively recruited for this study. DNA was extracted from each sample using the Quick gDNA miniprep DNA extraction kit, Zymo Research. Polymerase chain reaction (PCR) was used in the amplification of CCR5 gene in each DNA in a 9700 ABI Thermo cycler and then resolved on 4% agarose gel electrophoresis. RESULT: Out of the 100 samples assessed, 100 (100%) were homozygous for the CCR5 wild type gene (CCR5-wt), while none (0%) was homozygous for the CCR5-Δ32 (mutant type), and heterozygosity was not observed. CONCLUSION: This study observed absence of CCR5-Δ32 deletion gene among the studied subjects in Calabar, implying lack of genetic advantage in HIV infection and possible rapid progression towards AIDS if other precautions are not checked.

High prevalence of Plasmodium falciparum Pfmdr1 86Y mutant gene in sickle cell disease in Nigeria.

BACKGROUND AND PURPOSE: In areas where malaria is endemic, drug prophylaxis is required for people with sickle cell disease. Chloroquine resistance has been associated with the Plasmodium falciparum multidrug resistance 1 (Pfmdr1) mutant gene. This study tested for the Pfmdr1 86Y mutation in P. falciparum isolates from individuals with sickle cell disease and sickle cell trait, who also underwent hemoglobin genotyping. METHODS: Blood samples were collected from patients presenting with symptoms of malaria in an endemic region. The subjects were screened for hemoglobin genotype using hemoglobin electrophoresis and P. falciparum Pfmdr1 genotyping was carried out using polymerase chain reaction-restriction fragment length polymorphism. RESULTS: 229 subjects, comprising 144 with hemoglobin AA genotype, 57 with hemoglobin AS genotype and 28 with hemoglobin SS genotype, were enrolled in this study. There was no significant difference in the infective rate of malaria in the 3 groups (p>0.05). However, the prevalence of Pfmdr1 86Y was higher in those with hemoglobin SS genotype than in hemoglobin AA and AS subjects (p<0.05). CONCLUSIONS: Uncontrolled use of chloroquine is a major cause of chloroquine resistance in Nigeria. Chloroquine prophylaxis may be the underlying cause of the high prevalence of Pfmdr1 86Y mutant gene in individuals with hemoglobin SS genotype.