Seroprevalence of Neospora caninum in free-range chickens (Gallus domesticus) from the Americas.

Neospora caninum and Toxoplasma gondii are biologically and morphologically similar coccidians with canids as definitive hosts for N. caninum and felids for T. gondii. Feral chickens have been used as indicators of soil contamination with T. gondii oocysts because they feed from ground. In the present study we studied seroprevalence of N. caninum in free range chickens from different countries in America as an indicator of soil contamination due to N. caninum oocysts. Antibodies to N. caninum were found in sera of 524 (39.5%) of 1324 chickens using indirect fluorescent antibody test (IFAT, titer 1:25 or higher). Seropositive chickens from different countries were: 18.5% of 97 from Mexico, 7.2% of 97 from USA, 39.5% of 144 from Costa Rica, 71.5% of 102 from Grenada, 44% of 50 from Guatemala, 83.6% of 98 from Nicaragua, 58.1% of 55 from Argentina, 34.3% of 358 from Brazil, 62.3% of 85 from Chile, 11.2% of 62 from Colombia, 38.7% of 80 from Guyana, 18% of 50 from Peru and 21.7% of 46 from Venezuela. The results indicate widespread exposure of chickens to N. caninum.