Leishmania infection in a population of dogs: an epidemiological investigation relating to visceral leishmaniasis control

Identification of factors associated with Leishmania infection in dogs is essential for targeting visceral leishmaniasis control actions. Thus, the present study analyzed some of these factors in a population of dogs in a Brazilian municipality, along with the limitations of control strategies implemented there. The association between the exposure variables and occurrences of infection was analyzed through logistic regression models. The disease control interventions were treated qualitatively. Out of the 755 animals examined, 13.6% (103/755) were seropositive. Of these, 23.3% (24/103) were asymptomatic and 76.7% (79/103) presented at least one clinical sign possibly associated with visceral leishmaniasis. With weak associations, purebred, shorthaired, over 5 years of age, male and large dogs were more prone to infection. The latter two variables formed the final regression model and the association with dog size was statistically significant. The control strategies developed presented limitations and a great number of seronegative dogs was culled. The data presented contribute towards better understanding of the dynamics of infection in canine visceral leishmaniasis and indicate that actions aimed towards adequate implementation of Visceral Leishmaniasis control program in Brazilian endemic areas should be prioritized.

鉴定与犬利什曼虫感染（Leishmania infection）相关的影响因素，对于针对性开展内脏利什曼病（Visceral Leishmaniasis）防控行动至关重要。本研究针对巴西某县域内的犬群展开相关影响因素分析，并同步梳理当地已实施的防控策略存在的局限性。研究采用逻辑回归模型（logistic regression models）分析暴露变量与感染发生情况之间的关联，并对疾病防控干预措施开展定性分析。本次共检测755只受试犬只，其中13.6%（103/755）呈血清学阳性（seropositive）。在阳性个体中，23.3%（24/103）为无症状感染，76.7%（79/103）表现出至少一种疑似与内脏利什曼病相关的临床症状。经分析发现，纯种犬、短毛犬、5岁以上犬只、雄性犬只以及大体型犬只的感染风险更高，但上述因素的关联强度均较弱；其中犬只性别与体型最终被纳入回归模型，且体型与感染的关联具有统计学显著性。当地现行防控策略存在明显短板，且存在大量血清学阴性犬只遭到扑杀的情况。本研究数据有助于进一步明晰犬内脏利什曼病的感染流行动态，并提示在巴西利什曼病流行区域，应优先推进内脏利什曼病防控方案的规范化落地实施。