African Journal of Parasitology, Mycology and Entomology

Background: In Northern Senegal, previous studies have shown a high occurrence of Schistosoma haematobium x S. bovis hybrids. This study aimed to update their circulation in perennial and seasonal transmission areas. Methods: Schistosoma eggs were collected in 2021 from 118 positive urine samples from 6- to 16-year-old children in the villages of Thiagar and Ndiathene, where schistosomiasis transmission is perennial, and in Niakhar and Khombole, with seasonal transmission. Dra1 Real-time PCR and RD PCR targeting mitochondrial (COX1) and nuclear DNA (ITS2) followed by sequencing were performed to characterize individual parasites. Results: Of the 1176 eggs obtained, only 998 with less than 33 ct at the Dra1 test were selected for RD PCR. Among these, 997 (99.9%) and 1 (0.1%) exhibited, respectively, S. haematobium and S. bovis patterns. Among the 998 COX1 amplicons, we obtained 997 sequences (99.9%) of S. haematobium and 1 (0.1%) of S. bovis (Ndiathene). Of the ITS2 sequences analyzed, 21 (2.1%) showed an S. haematobium x S. bovis hybrid sequence from Central Senegal. The complete genetic profiles showed that 976 (97.8%) and 22 (2.2%) sequences were S. haematobium and S. haematobium x S. bovis. Conclusion: Overall, hybrid prevalence was low and, for the first time, the circulation of S. haematobium x S. bovis hybrids was reported in human populations in Central Senegal. The prevalence of hybrids in the north is low compared with previous studies. The mapping of hybrid strains reinforces our knowledge of their circulation in Senegal. Full article

Background: Malaria control in Senegal relies on antimalarial drugs like sulfadoxine–pyrimethamine (SP) for treatment and chemoprevention. Monitoring drug resistance markers is vital to ensure these interventions’ effectiveness. This study assessed the prevalence of SP resistance markers among pregnant women attending antenatal clinics in Senegal in 2019. Methods: Cross-sectional surveys were conducted during the high-transmission period of 2019 among pregnant women in low- and high-transmission areas. After obtaining consent, three dry blood spots on Whatman paper were collected. Samples were analyzed by real-time Polymerase Chain Reaction (RT-PCR) to detect the Plasmodium falciparum VarATS gene. Positive samples were genotyped by High-Resolution Melting for mutations in the dihydrofolate reductase and dihydropteroate synthase genes. Results: Six hundred samples positive for P. falciparum were analyzed. The population was predominantly young and resided in high-transmission areas. Key resistance mutations were detected at the following rates: PfdhfrII164L (11.7%), PfdhpsS436A (14.8%), PfdhpsA437G (19.0%), PfdhpsA581G (15.2%) and PfdhpsA613S (15.5%). The PfdhpsK540E mutation was not detected. The prevalence of these mutations was significantly higher in high-transmission areas. No significant differences in resistance markers were observed based on SP intake or gravidity. Conclusions: The low frequencies of SP resistance markers and the absence of the Pfdhps K540E mutation suggest that SP remains effective for malaria chemoprevention in Senegal. However, regular surveillance is crucial to monitor and contain any potential resistance of P. falciparum to SP and to track the evolution and spread of resistant parasites within malaria control areas. Surveys in antenatal clinics could be a good strategy for monitoring at low cost the emergence of resistance to SP. Full article