Histomonas Meleagridis - Pathogenicity

Pathogenicity

H. meleagridis is the causal organism of histomoniasis of gallinaceous birds. It induces extensive and severe necrosis of the tissues of the mucosa and submucosa of cecum and parenchyma of the liver. The lesions are sometimes exacerbated by other pathogens such as Escherichia coli and coccidia. The symptoms appear within 7–12 days after infection and include depression, reduced appetite, poor growth, increased thirst, sulphur-yellow diarrhoea, listlessness, drooping wings, and unkempt feathers. The symptoms are highly fatal to turkeys, but affect less damage in chickens. However, outbreaks in chickens may result in high morbidity, moderate mortality, and extensive culling, leading to overall poor flock performance. Concurrence of Salmonella typhmurium and E. coli was found to cause high mortality in broiler chickens. Young birds particularly of 3–12 weeks olds are most susceptible. Generally the symptoms are profound in turkeys while chickens are usually asymptomatic.