Profile of molecular markers of Sulfadoxine-Pyrimethamine-resistant Plasmodium falciparum in individuals living in southern area of Brazzaville, Republic of Congo

Background

Although the seasonal and perennial malaria chemopreventions are not implemented in the Republic of Congo, resistance to Sulfadoxine-pyrimethamine (SP) threatens the intermittent preventive treatment during pregnancy (IPTp-SP) and others treatments using the drug. The objective of this study was to determine the prevalence of molecular markers of P.falciparum resistance to SP in individuals with microscopic malaria infection in the south of Brazzaville.

Methods

Two parallel surveys (health facilities and community-based cross sectional studies) were carried out in urban and rural areas in southern Brazzaville. Between March and October 2021, blood samples were collected from 328 P. falciparum microscopic positive individuals (1–83 years old, and sex ratio female/male of 1.1) to characterize dhfr and dhps genes involved in the P.falciparum resistance to SP. Restriction Fragment Length Polymorphism PCR was used for the detection of mutations within these parasite genes.

Results

High prevalence of mutations was reported within Pfdhfr gene: N51I; 328/328 (100%) ratio (prevalence) [95 CI uncertainty], C59R; 317/328 (96.6 %) [94.1–98.1%], S108N; 326/326 (100%), N164L; 3/326 (0.9%) [0.3–2.7%], and Pfdhps gene: A437G; 292/327 (89.3%) [85.5–92.2%], K540E; 140/327(42.8 %) [37.6–48.2%], A581G; 136/325 (41.8%) [36.6–42.3%]. The quintuple mutant (N51I + C59R + S108N + A437G + K540E) and sextuple mutant haplotypes (N51I + C59R + S108N + A437G + K540E + A581G) were reported for 11/144 (7.6%) [4.3–13.2%] and 5/144 (3.4%) [1.5–7.9%]) of the participants respectively. The K540E and A437G mutants were more prevalent in the rural community; 81/139 (58.3%) [50.0–66.1%] and 135/139 (97.1%) [92.8–98.9%] respectively) than in the urban community; 21/50 (46.3%) [33.7–59.4%] and 47/54(87.0%) [75.6–93.6%] (p = 0.004 and p˂0.0001 respectively)

Conclusion

These results indicate high prevalence of SP resistance mutations within the dhfr and dhps genes of P. falciparum isolates circulating in study sites, which may limit the efficacy of treatments using SP in these settings.