Prevalence of Neospora caninum in two dairy herds of the IX Region of Chile

La neosporosis ha sido reconocida y descrita como causa de aborto en la mayoría de las áreas ganaderas del mundo. En Chile se demostró la presencia de la enfermedad, sin embargo, muchos aspectos son desconocidos, razón por la cual se estudió la prevalencia de infección medida a través de anticuerpos séricos mediante la técnica de IFA en dos predios lecheros con antecedentes de abortos causados por este parásito. Se consideró a un bovino positivo cuando se evidenció fluorescencia a una dilución de 1:200. El 30,2% (52/173, IC=6,8%) de los animales estudiados en el predio A y el 15,7% (31/198, IC=5%) del predio B presentaron anticuerpos séricos contra el parásito. Los resultados por edades fueron para el predio A de 39,6% (42/106) para las vaquillas y de 15,2% (10/66) para las vacas (c2=10,42, P=0,0012) y para el predio B de 22,7% (15/66) para las terneras, de 17,8% (8/45) para las vaquillas y de 9,2% (8/87) para las vacas. Las terneras y vaquillas positivas del predio B difirieron de las vacas adultas (c2=4,07, P=0,043). Cuatro de los siete caninos existentes en el predio A presentaron anticuerpos contra N. caninum en dilución 1:50. Se discuten los resultados en relación a las posibles vías de difusión de infección en nuestro medio

Neosporosis is an important cause of economic loss in the cattle industry throughout the world. In Chile, it has been recently detected and,. since then, veterinarians and producers have required information about different aspects of the disease. In this paper we present data of the prevalence of the disease in two dairy herds of the IX Region of Chile. A commercial indirect fluorescent antibody test (IFA) was performed at 1:200 dilution for bovine and at 1:50 for canine sera. Results indicate a 30.2% (52/173, IC=6.8%) infection in bovines from farm "A" and a 15.7% (31/198, IC=5%) in bovines from farm "B" (c2 = 10.42, P = 0.0012). In addition, 57% (4/7) of the dogs from farm "A" had antibodies. Differences were observed in each farm as well as amongst age groups: in farm "A" 39.6% (42/106) of heifers and 15.2% (10/66) of cows (c2=10.42, P=0.0012) had antibodies against N. caninum; in farm "B": 22.7% (15/66) of calves, 17.8% (8/45) of heifers and 9.2% (8/87) of cows were positive. There were differences amongst cows, calves and heifers groups (c2=4,07, P=0.043). Although it was not the aim of the study it is discussed if the source of infection could be the cause of the difference in prevalence. In contrast with farm "B"," the higher prevalence in farm "A was related to the group fed also with supplements. How the disease spreads in our environment is unknown, different mechanisms could be involved since in most of the farms the animals spend half of the year under confinement and the other half on pasture. The present article gives values of Neospora prevalence and preliminary data for further studies on this progressively important disease