High yield of parasites and prolonged in vitro culture of Histomonas meleagridis.

Dwyer's medium is a frequently employed culture medium for Histomonas meleagridis with rice powder as an essential ingredient. The effect of adding larger quantities of rice powder to the culture medium and the influence of the size of the rice particles on the growth of H. meleagridis was examined. Increasing the amount of rice powder from the standard amount of 10 to 12 mg to 50 to 100 mg per 12.5 ml medium resulted in approximately a 10-fold increase of parasites. Larger quantities of rice powder did not give better yields. The particle size of the rice powder proved relatively unimportant, although the addition of only large rice powder particles (>250 microm) resulted in a somewhat lesser yield. H. meleagridis cultures could be prolonged from approximately 4 days to at least 2 weeks without subculturing by supplementing the culture medium with rice powder only.