Histomoniasis in Leghorn Pullets on a Florida Farm

Abstract

Recurrent outbreaks of histomoniasis in flocks of 4-to-6-week-old white leghorn pullets is reported. In a typical outbreak, 5% of the pullets were stunted and listless with unkempt feathers. Mortality ranged from 2 to 3%, and the cull rate was approximately 2%. Ceca of affected chickens contained caseous cores. Histological examination of the ceca revealed fibrinonecrotic ulcerative granulomatous typhlitis associated with numerous histomonad trophozoites in the cecal wall. The outbreaks of histomoniasis were associated with heavy parasitism of pullets by Heterakis gallinarum. Litter had not been completely removed from the houses for the past 10 years, providing a constant source of Histomonas-infected larvated Heterakis ova.

Rapid transmission of the protozoan parasiteHistomonas meleagridisin turkeys and specific pathogen free chickens following cloacal infection with a mono-eukaryotic culture

“…In the present study, no clinical signs and mortality were recorded in the SPF chickens. In comparison, there are many reports in the literature that document outbreaks with varying mortality in young chickens (Milks, 1908;Eriksen, 1925;Tyzzer, 1934;Bayon, 1937;Hungerford, 1937;Bishop, 1938;Goedbloed & Bool, 1962;Ivanics et al ., 1984;Gerth et al ., 1985;Reece et al ., 1986;Mü ller, 1990;Homer & Butcher, 1991;Ganapathy et al ., 2000;Esquenet et al ., 2003). Furthermore, Desowitz (1951) reported the highest mortality during the first 2 weeks after infection of commercial chickens, and the infection status of the birds varied by age.…”

“…In general, mortality rates in chickens are somewhat lower in comparison with those reported for turkeys. However, recent reports underline the importance of the disease for chickens, especially for birds kept under free range conditions or on farms with low or inadequate disinfection procedures (Homer & Butcher, 1991;Hafez et al , 2001;Esquenet et al , 2003;Cortes et al , 2004).…”

Infectivity ofHistomonas meleagridisin ducks

“…This apparent contradiction between carriage and clinical signs of blackhead may partly explain the lack of correlation between moderate to severe clinical signs sometimes observed on farms and poor lesions identified in experimental infections. This phenomenon has already been described in chickens (Homer & Butcher, 1991). Probably, other exacerbating circumstances may exist under field conditions, such as highly virulent histomonad strains, the presence of other pathogens (coccidia, helminths, bacteria or virus), physiological particularity or feeding of host species, husbandry practices, and so on.…”

“…To attempt to explain the disparity between clinical signs observed in different species, it is essential to investigate the parasite dissemination in the host body. Indeed, it seems that in ducks, in guinea fowl (Lund & Chute, 1972b) and sometimes in chickens (Homer & Butcher, 1991), the parasite remains in the caecal lumen and never invades the liver, contrary to what is usually observed in turkeys. The biological meaning of this difference underlines the need for further studies using other methods of investigation.…”

Observations on the occurrence ofHeterakis gallinarumin laying hens kept on soil

“…H. gallinarum infections linked to histomoniasis have been well documented in chickens (Homer and Butcher, 1991;Permin, 2003). However, little is known about the prevalence of H. gallinarum in chickens in Italy, since available reports are mostly restricted to partridges and pheasants (Rizzoli et al, 1999;Tampieri et al, 2005).…”