THE ROLE OF REGULATORY T CELLS IN THE CONTROL OF PARASITE GROWTH AND CLINICAL OUTCOMES FOLLOWING CONTROLLED HUMAN MALARIA INFECTION IN SEMI-IMMUNE KENYAN ADULTS

Loiasis is a vector-borne parasitic disease caused by the filarial nematode Loa loa and transmitted by the tabanid vectors from the genus Chrysops. Loa loa infection is associated with clinical manifestations such as pruritus, migratory transient edema, passage of adult worm in the bulbar conjunctiva, retinal damage, glomerular damage, albuminuria, pleural effusion, hydrocele, and endomyocardial fibrosis. Data reporting the occurrence of spontaneous encephalopathy associated with loiasis are very scanty. Severe adverse events occurring post-ivermectin administered in the framework of the fight against onchocerciasis and/or lymphatic filariasis in loiasis co-endemic areas have been closely associated with very high L. loa microfilariaemia. Different regimens have been used to lower L. loa microfilariaemia before definitive treatment, and many discrepancies have been reported. We report the case of a patient who was admitted to a health facility and hospitalized for 34 days for altered consciousness, blurred vision, headache, and chills. After other potential diagnoses were eliminated, the patient was confirmed with encephalopathy due to loiasis and referred to the Centre for Research on Filariasis and other Tropical Diseases (CRFilMT). On admission at CRFilMT, the patient was harboring 28,700 microfilariae per milliliter of blood (mf/mL), and after four 21-day courses of 400 mg daily albendazole, the L. loa microfilariaemia lowered to 5,060 mf/mL. The patient was then treated with ivermectin 3 mg and a total clearance of microfilariae was observed, with satisfactory clinical evolution and no adverse event. This case study further confirmed that albendazole is effective against L. loa, but might necessitate a longer course.