Farm practices and risk factors which influence the high prevalence of brucellosis in small ruminant flocks in Northeast Portugal.

The region of Tras-os-Montes e Alto Douro in northeast Portugal displayed the highest prevalence of brucellosis in small ruminants of the country. A vaccination programme of the whole population with Brucella melitensis Rev-1 was carried out from 2001 to 2004 in an attempt to reduce prevalence levels and protect public health. Although individual prevalence decreased from 5.6% in 2001 to 0.4% in 2007, several flocks continued to present individual prevalence ≥ 5.0%. Given the multifactorial characteristics of brucellosis, the current study evaluated farming practices and risk factors in flocks with an individual prevalence over 5% by multifactorial correspondence analysis. Results showed that a lack of recognition of the symptoms of brucellosis and lack of Rev-1 vaccination were the main factors contributing to the high individual prevalence of brucellosis in flocks. Other factors such as the consumption of raw milk, presence of dog commingling with animals and use of communal pastures also contributed to the persistence of the disease. Family farms with low economical profit, minimal training/education of farmers, and a scarcity of veterinary support may explain the persistence of factors contributing to the high prevalence of brucellosis. The results of this study highlight several risk factors and farming practices that might have contributed to the maintenance of a high prevalence of brucellosis in flocks with high brucellosis prevalence. These results could be used to adopt new approaches to improve the efficiency of brucellosis eradication programs.

A seroepidemiological survey of mycobacterium avium subsp. paratuberculosis in sheep from North of Portugal / Rastreio seroepidemiológico de mycobacterium avium subsp. paratuberculosis em ovinos no Norte de Portugal

The aim of this study was evaluate the risk factors for Mycobacterium avium subsp. paratuberculosis (Map) seroprevalence in sheep in the North of Portugal. The effects on seroprevalence of several variables such as individual characteristics, management practices, farm characteristics, animal health, and available veterinary services were evaluated. This information was then used in a multivariable logistic regression model in order to identify risk factors for Map seropositivity. Univariable analysis was used to screen the variables used in the logistic regression model. Variables that showed p values of <0.15 were retained for the multivariable analysis. Fifteen variables were associated with paratuberculosis in univariable analysis. The multivariable logistic regression model identified a number of variables as risk factors for seropositivity like sheep pure local and/or a cross of a local breed (OR=2.02), herd size with 31-60 head (OR=2.14), culling during the Spring-Summer season (OR=1.69) and the use of an anti-parasitic treatment such as Ivermectin as the only anti-parasitic medication (OR=5.60). Potential risk factors identified in this study support current recommendations for the control of paratuberculosis.

Neste trabalho efectuou-se o estudo dos factores associados à seroprevalência da infecção ovina por Mycobacterium avium subspecies paratuberculosis (Map). Foram investigadas variáveis como as características individuais, práticas de maneio, características da granja, saúde animal e intervenções de sanidade efectuadas no animal. A análise multivariada de regressão logística foi usada para identificar estes factores associados com a seroprevalência da infecção. De acordo com os resultados da análise univariada associaram-se, com o resultado positivo à infecção (p<0,15), 15 variáveis. Após a aplicação do modelo de análise multivariada encontraram-se quatro factores de risco com significância estatística: rebanhos de raças autóctones e seus cruzamentos (OR=2,02); tamanho do efectivo entre 31-60 animais (OR=2,14); época de abate na Primavera-Verão (OR=1,69); uso de ivermectina como único antiparasitário (OR=5,60). Os potenciais factores de risco identificados neste estudo suportam as recomendações currentes para o controlo da paratuberculose.

Comparação de duas técnicas de isolamento do Mycobacterium avium subsp. paratuberculosis em amostras de fezes de ovinos com suspeita clínica de paratuberculose / Comparison of two techniques of isolation of Mycobacterium avium subsp. paratuberculosis in faecal samples of ovine with clinical suspicion of paratuberculosis

A paratuberculose é uma enterite crônica granulomatosa causada por Mycobacterium avium subsp. paratuberculosis que afeta principalmente os ruminantes. A cultura de bactérias a partir de amostras de fezes e tecidos constitui um dos métodos mais eficazes de diagnóstico, sendo ainda o único método disponível para obtenção de isolamentos e estirpes de micobactérias. Contudo, este método apresenta baixa sensibilidade e requer meses de incubação antes do crescimento de colônias. Neste estudo, utilizou-se a cultura fecal como método de diagnóstico em ovinos de diferentes raças portuguesas, com sinais compatíveis com a doença. Fez-se ainda a comparação entre os meios de cultura Lõwenstein Jensen® com micobactina® J e o de Middlebrook® 7H11 com OADC®, utilizados no isolamento da bactéria. As percentagens de isolamento em cada um os meios foram de 2,0 por cento (6/300) para Lõwenstein Jensen® com micobactina J e 1,0 por cento (3/300) para Middlebrook® 7H11/OADC. As três amostras positivas no meio de Middlebrook® 7H11/OADC também foram positivas no meio de Lõwenstein Jensen® com micobactina J e nenhuma foi somente positiva no meio de Middlebrook® 7H11/OADC. Os resultados deste estudo sugerem que o meio de Lõwenstein-Jensen® com micobactina® J é mais efetivo para a obtenção de estirpes ovinas em Portugal.

Paratuberculosis is a chronic enteric disease of ruminants caused by Mycobacterium avium subsp. paratuberculosis. Culture of bacteria from faeces and tissues samples constitutes one of the most effective methods of confirming the diagnosis of para-tuberculosis and the only method available to obtain strains of mycobacteria. However, this method is less sensitive and requires months of incubation before colony growth occurs. In this study, culture method was used on sheep faeces to diagnose paratuber-culosis in animals with compatible signs of the disease. A comparison of two culture media used to isolation was also investigated. Culture was positive in 2.0 percent of faecal samples. Isolation was obtained using Lõwenstein Jensen® with mycobactin® J, and the Middlebrook® 7H11 with OADC®. The Lõwenstein Jensen® with mycobactin® J was that provided highest amount of isolations. The percentages of isolation in each culture media were 2.0 percent (6/300) to Lõwenstein Jensen® with micobactina J, and 1.0 percent (3/300) to Middlebrook® 7H11/OADC. The three positive samples in Middlebrook® 7H11/OADC were also positive in Lõwenstein Jensen® with micobactina J. In the Middlebrook® 7H11/OADC alone there was no sample growth. The results of this study suggest that culture media of Lõwenstein-Jensen® with micobactina® J is more effective for the isolation of sheep strains in Portugal.