Microfilaria: not always associated with eosinophilia

Filariasis is a parasitic infection seen predominantly in tropical and subtropical countries including India. In clinically suspected cases, examining a thick wet mount smear or a buffy coat film is most informative. In unsuspected cases, however, eosinophilia in a peripheral blood smear (PBS) may be the sole indicator of parasitaemia. A few cases of tissue microfilaria with the absence of peripheral blood eosinophilia (PBE) have been reported. Here, we report two cases of microfilaria in PBS in the absence of PBE. A routine screening of the tail end of all PBS at low power magnification is also advised as it may facilitate the detection of asymptomatic cases when there is a normal eosinophil count.