[External Quality Assessment of Thick and Thin Blood Smear Slides for the Diagnosis of Malaria in the Lomé and Gulf Health Districts of Togo]

Objective

In sub-Saharan Africa where 90% of malaria cases are concentrated, the control of this disease constitutes a major challenge whose diagnosis by thick and thin smear deserves to be exact and reproducible. The purpose of this study is to assess the performance of thick/thin blood smear in order to improve its implementation process.

Material and methods

This was a descriptive and analytical study that took place from May to June 2017 and involved participating laboratories (PL) coming from public, liberal and confessional sectors in Lomé. A set of 13 blood smear slides of variable parasite densities (PD) with assigned values (AV) of parasite densities and the Plasmodium species assigned was used. The criterion for establishing the parasite densities compliance interval was assigned values ± 25% and the performance rates were compared to the 80% recommended by the WHO for Africa region.

Results

41.9% (13/31) of the PLs had a compliance rate greater than 80% including four with a performance of 100% for the ability to identify the Plasmodium species. For the parasitaemia < 100/μl, 51.6% of participating laboratories had a performance rate less than 80% and for parasitaemia > 2000/μl, 100% of these laboratories had a performance rate greater than 80%.

Conclusion

The evaluated laboratories had insufficient ability for the identification of Plasmodium falciparum and the correct estimation of low parasitaemia. A need to strength the technical skills, adapted to the context of low parasitaemia are essential to improve the biological diagnosis of malaria in Togo.