Epidemiology of caprine arthritis encephalitis in Costa Rican dairy goat herds

Abstract

The objective of the study was to determine epidemiological aspects, such as seroprevalence, incidence and risk factors associated to the transmission of the caprine arthritis encephalitis virus (CAEV) in dairy goat breeding herds in Costa Rica. Blood samples were collected between July 2005 and June 2006 from 340 goats in 11 out of 15 goat breeding herds, actively registered with the Costa Rican Association of Goat Breeders (Asociación Costarricense de Criadores de Cabras), located in San José, Heredia, Cartago, Alajuela and Puntarenas. At the time of sampling, a questionnaire was applied to breeders to know how virus transmission practices are handled. Blood samples were analyzed using a competitive ELISA to detect antibodies against CAEV. Overall seroprevalence was 61.2% (CI 95%: 56.0-66.4), ranging between 0.0 and 98.4% at farm level, while cumulative incidence was 32.9% (CI 95%: 25.6-40.2) for a follow up period of 6 months. Significant frequency is observed in management practices that favor the transmission of the virus and reinforce the infection, such as working in an open herding system (OR = 3.64; CI: 2.34-5.66), using the male in natural mating regardless of its serostatus (OR = 3.55; CI: 2.82-4.46), having clinical cases of CAEV (OR = 3.64; CI: 2.34-5.66), not disinfecting the ear tag applicator between animals (OR = 2.30; CI:1.79-2.96), and using milk from goats with mastitis to feed newborns (OR = 2.04; CI: 1.53-2.72). Management conditions found in the studied goat herds favor transmission of the virus, making infection very likely to remain. Therefore, controlling this disease is far from being achieved and, most probable, its effects will continue to have a negative impact on dairy goat herds.