Lymphatic filariasis: the importance of screening all peripheral blood smears in low power for detection of asymptomatic cases

Abstract

Lymphatic filariasis caused by the mosquitoborne, lymphatic-dwelling nematodes Wuchereria bancrofti and Brugia malayi is still a common tropical parasitic disease and 120 million people are affected in the world, of which two-third are in Asia. They cause high morbidity and mortality among humans. Irreversible “elephantiasis” is the major clinical manifestation for LF. Detection of microfilaria in peripheral blood is important. In addition to simple thick and thin blood smear tests, concentration techniques are used: mainly density gradient centrifugation, haemolysis and filtration of the blood through a polycarbonate membrane, which retains the parasite. Diagnosis has been revolutionized with the availability of circulating filarial antigen (CFA) tests which are easy to perform but are costly. Diethylcarbamazine (DEC) is the drug of choice for treating lymphatic filariasis. In the light of this information, hereby presenting a case series of 4 asymptomatic patients who were diagnosed with filariasis on peripheral blood smear examination. The article emphasizes the importance of low power scanning of every peripheral blood smear, especially when the laboratory is not facilitated with costly methods to detect microfilaria.