Efficacy of measures to control caprine arthritis-encephalitis in dairy herd with high clinical and serological prevalence

Abstract

This study examined the effectiveness of control measures for caprine arthritis-encephalitis in a herd with 431 dairy goats in an intensive rearing system. All animals older than six months were initially tested by agar gel immunodiffusion (AGID) and separated into seropositive and seronegative. Control measures were implemented for two years and ten months. Five serological examinations were subsequently performed two by AGID and three by the Western Blot (WB) technique. In these tests, animals that tested negative in the previous serological examination were evaluated along with those older than six months which had not yet been examined. The effectiveness of control was evaluated based on the incidence of the disease. Seroconverted animals were stratified according to age, physiological status and dam serology. For the effect of time, logistic regression was performed at the 5% significance level, with values converted into likelihood. General incidence and incidence as a function of age and physiological status were evaluated by analysis of variance, with means compared by Tukey’s test at 5% significance. The ratio test was used for incidence and physiological status, and the agreement between the AGID and WB tests was determined by the Kappa coefficient. Animals that seroconverted and were born to positive dams were compared with those born to dams negative at birth by the Chi-square test, and the same was applied for the number of discarded animals. Initially, 54.24% (179/330) positive and 257 seroconverted animals were identified after the start of control. Higher incidence occurred in the animals aged between 13 and 36 months and in lactating does. Seroconversions among offspring of seropositive dams were higher than in the offspring of seronegative dams (p < 0.001). High infection rates were identified in the sires. The obtained results were not satisfactory, as the measures did not help to prevent new cases, indicating that there are moments of infection yet to be elucidated. On farms that aim to control the disease, the following measures are required in addition to those already recommended: use of diagnostic tests with less frequency; application of high-sensitivity tests in the offspring; immediate separation of kids from dams at birth; separation of kids according to the serological status of the dams; inclusion of kids from unsupervised births in the group of kids from positive dams; and keeping positive and negative animals on different farms or greatly distanced. In herds for which there is an intention to establish control, it is important to determine whether the productive losses associated with the disease are greater than the costs of implementing more efficient measures.

Influence of caprine arthritis encephalitis on milk production and quality along the lactation curve in primiparous dairy goats

“…The fact that extensive farms have a lower disease rate may be related to the few tests performed due to the cost of exams and the animals' hardiness. As reported by Alcindo et al (2020), the economic impact must be considered in the establishment of preventive measures such as testing the herd and separating seropositive animals, demonstrating the worldwide and national importance of studies related to the disease.…”

“…The CAE virus is transmitted mainly via colostrum and milk from infected animals and through contact with secretions such as the saliva and semen of positive animals (Souza et al, 2013;Hasegawa et al, 2017), and hence the importance of early diagnosis, isolation and disposal of infected animals as a way of preventing vertical and horizontal transmission in the herd (Konishi, Nagura, Takei, & Fujita, 2011). According to Alcindo et al (2020), who evaluated the effectiveness of adopting control measures in dairy cattle with confirmed occurrence of CAE and its impacts on the incidence of the disease, as the animals grow older, even if some of the recommended control protocols are established, the likelihood of their remaining seronegative decreases over time. Thus, early identification, through periodic tests, and the separation of these animals from the herd can contribute to reducing future losses.…”

Inquérito sorológico de lentivírus de pequenos ruminantes e Toxoplama gondii em caprinos leiteiros de Zabelê, Cariri Ocidental, Paraíba, Brasil

“…A efetividade dessas medidas apresenta sérias implicações quanto a sua eficácia em rebanhos com soroprevalência intermediária e alta, como observada em três rebanhos do estudo, contribuindo pouco para a redução de novos casos (Alcindo et al, 2020), além disso o controle de doenças infecciosas nos rebanhos Paraibanos é dificultado devido ao baixo nível de escolaridade dos criadores e insuficientes e/ou inadequados investimentos e assistência técnica para o desenvolvimento da atividade (Guilherme et al, 2017;Alves et al, 2022). Isso evidencia-se quando analisamos os resultados de pesquisa realizada em 150 rebanhos de quinze município do Cariri Ocidental, Semiárido Paraibano, onde a frequência de caprinos soropositivos foi de 8,1% (153/1890) com presença de focos em 42,7% (34/150) das criações.…”

“…Nos rebanhos com intenção de estabelecer programa de controle do LVPR, deve-se levar em consideração os custos para a sua implantação (gastos com exames laboratoriais periódicos, reposição de animais, mão de obra, instalações e medicamentos), e avaliar se as perdas produtivas associadas à doença são maiores do que os custos incorridos na implementação de medidas mais eficientes (Reina et al, 2009;Azevedo et al, 2018;Alcindo et al, 2020).…”

“…Entre as doenças responsáveis por prejuízos na caprinocultura, destacam-se as lentiviroses de pequenos ruminantes (LVPR) (Azevedo et al 2018;Alcindo et al 2020), caracterizadas por artrite crônica com aumento do volume articular, mastite intersticial endurativa, levando a redução da produção, alterações respiratórias, leucoencefalomielite aguda em cabritos e emagrecimento crônico progressivo (Hasegawa et al, 2016;Wolf, 2021), e a toxoplasmose, causada pelo protozoário Toxoplasma gondii, responsável por casos de infertilidade, abortos, natimortalidade e debilidade nos rebanhos (Silva et al, 2015;Rego et al, 2016;Oliveira et al, 2022). O consumo de subprodutos caprinos (carne e leite), sem o tratamento térmico adequado, é uma importante via de infecção do T. gondii ao homem, além da possibilidade de transmissão transplacentária (Djurković-Djaković et al, 2019).…”