Version 1: Fortuitous discovery of a microfilaria of the genus Loa loa during a routine blood smear at the Hematology Laboratory of the Mohamed V Military Instruction Hospital in Rabat: A case report

Loiasis is a neglected nematode infestation that is endemic in the rainforests of western and central Africa. The disease is transmitted to man by tabanid flies of the genus Chrysops, and is frequently associated with significant and persistent hyper eosinophilia.

We present a case involving a 28-year-old Cameroonian soldier who underwent a blood examination. The findings revealed hyper eosinophilia with a count of 1500/µl, and no indications of anemia or thrombocytopenia. Analysis of a blood smear, using MGG (May-Grünwald-Giemsa) staining, identified small worms that are indicative of microfilariae of the genus Loa loa.

This case of Loa loa, identified in the hematology laboratory, is one of the rare diagnoses in Morocco. Therefore, biologists need to remain vigilant and carry out a thorough analysis of the blood count and blood smear.