Malaria misdiagnosis among febrile patients in Senegal: implications for the underestimation of Plasmodium species diversity and malaria burden.

BACKGROUND

Malaria remains a leading cause of febrile illness in Senegal, disproportionately affecting young populations. Test-and-treat remains a key strategy for malaria control but relies on accurate diagnosis and effective treatment. This study evaluated and compared the diagnostic accuracy of malaria among febrile patients in three regions in Senegal with high incidence of malaria.

METHODS

Data from 948 febrile patients were included to compare the diagnosis of malaria between standard of care malaria diagnostics (RDT and Microscopy) and references quantitative and qualitative PCR methods, which discriminates the four major human malaria species.

RESULTS

The analysis showed that PCR detected malaria infection in 75.29% (716/948) of patients, of which 70.25% involved non-falciparum species, including P. ovale, P. vivax, and P. malariae. Microscopy and RDT missed 31.5% and 18.92% of PCR-positive infections, respectively. In addition, half of mono-infections with non-falciparum species were misdiagnosed as P. falciparum by both microscopy and RDT. Furthermore, microscopy failed to detect a high proportion of P. falciparum infections confirmed by PCR, including those with higher parasitemia than the microscopy theoretical limit of detection.

CONCLUSIONS

The study highlights notable limitations and concerns for malaria diagnostic in Senegal, especially for microscopy-detectable P. falciparum parasitemia and non-falciparum infections. As malaria epidemiology trends shift toward mixed-species infections, the solely reliance on microscopy and RDT for the diagnosis of malaria may be critical since missed infections can lead to untreated cases and sustained transmission and impede elimination efforts.