First identification of Microsporidia MB in Anopheles coluzzii from Zinder City, Niger.

BACKGROUND: Malaria, a disease transmitted by Anopheles mosquitoes, is a major public health problem causing millions of deaths worldwide, mostly among children under the age of 5 years. Biotechnological interventions targeting parasite-vector interactions have shown that the microsporidian symbiont Microsporidia MB has the potential to disrupt and block Plasmodium transmission. METHODS: A prospective cross-sectional survey was conducted in Zinder City (Zinder), Niger, from August to September 2022, using the CDC light trap technique to collect adult mosquitoes belonging to the Anopheles gambiae complex. The survey focused on collecting mosquitoes from three neighborhoods of Zinder (Birni, Kangna and Garin Malan, located in communes I, II and IV, respectively). Collected mosquitoes were sorted and preserved in 70% ethanol. PCR was used to identify host species and detect the presence of Microsporidia MB and Plasmodium falciparum infection. RESULTS: Of the 257 Anopheles mosquitoes collected and identified by PCR, Anopheles coluzzii was the most prevalent species, accounting for 97.7% of the total. Microsporidia MB was exclusively detected in A. coluzzii, with a prevalence of 6.8% (17/251) among the samples. No significant difference in prevalence was found among the three neighborhoods. Only one An. coluzzii mosquito tested PCR-positive for P. falciparum. CONCLUSIONS: The results confirm the presence of Microsporidia MB in Anopheles mosquitoes in Zinder, Niger, indicating its potential use as a biotechnological intervention against malaria transmission. However, further studies are needed to determine the efficacy of Microsporidia MB to disrupt Plasmodium transmission as well as its impact on vector fitness.

Plasmodium falciparum kelch13 polymorphisms identified after treatment failure with artemisinin-based combination therapy in Niger.

BACKGROUND: Artemisinin-based combination therapy (ACT) is the most effective treatment for malaria, and has significantly reduced morbimortality. Polymorphisms associated with the Plasmodium falciparum Kelch gene (Pfkelch13) have been associated with delayed parasite clearance even with ACT treatment. METHODS: The Pfkelch13 gene was sequenced from P. falciparum infected patients (n = 159) with uncomplicated malaria in Niger. An adequate clinical and parasitological response (ACPR) was reported in 155 patients. Four (n = 4) patients had treatment failure (TF) that were not reinfections-two of which had late parasitological failures (LPF) and two had late clinical failures (LCF). RESULTS: Thirteen single nucleotide polymorphisms (SNPs) were identified of which seven were non-synonymous (C469R, T508S, R515T, A578S, I465V, I437V, F506L,), and three were synonymous (P443P, P715P, L514L). Three SNP (C469R, F506L, P715P) were present before ACT treatment, while seven mutations (C469R, T508S, R515T, L514L, P443P, I437V, I465V) were selected by artemether/lumefantrine (AL)-five of which were non-synonymous (C469R, T508S, R515T, I437V, I465V). Artesunate/amodiaquine (ASAQ) has selected any mutation. One sample presented three cumulatively non-synonymous SNPs-C469R, T508S, R515T. CONCLUSIONS: This study demonstrates intra-host selection of Pfkelch13 gene by AL. The study highlights the importance of LCF and LPF parasites in the selection of resistance to ACT. Further studies using gene editing are required to confirm the potential implication of resistance to ACT with the most common R515T and T508S mutations. It would also be important to elucidate the role of cumulative mutations.