Blackhead Disease: In Vitro Isolation of Histomonas meleagridis as a Potentially Useful Diagnostic Aid

Diagnosis of blackhead disease in poultry or wild game birds can be confirmed by isolating the agent in vitro. The culture medium contains 85% medium 199, 5% chick embryo extract, and 10% sheep or horse serum adjusted to pH 7.8. The test can be read 24-48 (usually 48) hours after the cultures are inoculated. Phase-contrast microscopy facilitates the observation of histomonads in cultures or in cecal scrapings. The identity of the isolant can be further confirmed by rectal inoculation of 2-week-old chicks or turkeys with 1 ml of the culture material.