Abstract
A survey of Setaria microfilaria (Mf) in the blood of Japanese Black calves performed between September 2002 and June 2003 in Hiroshima Prefecture revealed a total Mf positive rate of 29/672 (4.3%). The positive rate differed according to season in relation to calf birth month. The largest numbers of Mf-positive calves were born between autumn and winter. Calves born in November, December, January and February had positive rates greater than 10%. Calves born in the spring (April to July), on the other hand, were Mf-negative. The Mf detected was morphologically identified as Setaria marshalli.
