[Submicroscopic Plasmodium spp. Infections in Febrile Patients in Togo]

Submicroscopic Plasmodium infections, mostly undetected by routine diagnostic techniques, represent a potential reservoir that contributes to the continued transmission of malaria in the community. To achieve the World Health Organization's goal of malaria elimination, it is therefore essential to identify all parasite carriers and treat them effectively with recommended antimalarial drugs. The aim of this study was to estimate the proportion of submicroscopic Plasmodium spp. infections not detected by microscopy in symptomatic patients with suspected malaria attending health centers in Togo, and to identify the factors associated with it.

A cross-sectional study was conducted between September 2021 and January 2022 and between July and December 2022 in three health facilities in Togo. Each patient suspected of having malaria had a capillary blood sample taken for detection of Plasmodium species by thick blood film/blood smear (TBF/BS) and PCR. A logistic regression model was used to evaluate the factors linked to the parasitic results.

A total of 553 participants were selected, 44.6% of whom were female, with a median age of 25 years (± 2 years). The proportion of Plasmodium spp. infections detected by TBF/BS was 25% and by PCR 29.1%. The frequency of submicroscopic Plasmodium spp. infections detected by PCR in patients with negative microscopic TBF/BS was 5.5% (23/415) [95% CI: 3.7-8.2], and P. falciparum was the most common species (83%, 19/23, 95% CI: 60-94). Participants from the Anié and Kouvé sites were more likely to have submicroscopic infections.

This study provides preliminary data on the incidence of submicroscopic Plasmodium infections in Togo.