Toxoplasma gondiiInfections in Chickens (Gallus domesticus): Prevalence, Clinical Disease, Diagnosis and Public Health Significance

Abstract

Chickens are considered one of the most important hosts in the epidemiology of Toxoplasma gondii infection because they are an efficient source of infection for cats that excrete the environmentally resistant oocysts and because humans may become infected with this parasite after eating undercooked infected chicken meat. The objective of this study is to review worldwide prevalence of T. gondii infection in chickens and to assess the role of infected chickens in the epidemiology of toxoplasmosis in humans. A very high prevalence of the parasite was found in chickens raised in backyards (up to 100%) and free-range organic (30-50%) establishments.

Seroprevalence and isolation of Toxoplasma gondii from free-range chickens from Espírito Santo state, southeastern Brazil

“…Seropositivity in other farms varied from 20 to 73.7% using a cut-off of 25 in the MAT and this variability is probably related to access of cats to chickens. It is likely that seroprevalence could have been higher if the cut-off value in MAT was lower because in previous studies from Brazil, viable parasite has been occasionally isolated from chickens with a MAT titer of 1:10 or even 1:5 (Dubey et al, 2002;Dubey, 2010b).…”

“…The quality and species of erythrocytes used have also not been standardized. Therefore, it is strongly advised that each IHAT kit should be evaluated according to a gold standard test for detection of anti-T. gondii antibodies in chickens, as MAT (Dubey, 2010b), before use in a survey. The sensitivity of IHAT is dependent on the quality of T. gondii antigen, stability of sheep erthrocytes used, and the need for higher salt concentration while using the test for chicken sera (Frenkel, 1981).…”

“…The Sabin Feldman dye test, the most specific test for diagnosis of toxoplasmosis in humans, does not detect antibodies to T. gondii in naturally or experimentally infected chickens (Dubey et al, 1993). The modified agglutination test (MAT) is currently considered the specific and sensitive test for the detection of T. gondii antibodies in chickens (Dubey, 2010b). However, the commercial kit for MAT is made in France (bioMérieux) and very expensive to import in Brazil.…”

“…Information on serological diagnosis of T. gondii in chickens is limited (reviewed in Dubey, 2010b). The Sabin Feldman dye test, the most specific test for diagnosis of toxoplasmosis in humans, does not detect antibodies to T. gondii in naturally or experimentally infected chickens (Dubey et al, 1993).…”

“…Seroprevalence and genetic diversity of T. gondii isolates obtained from FR chickens from different regions of Brazil was summarized Dubey, 2010b;Soares et al, 2011).…”