Toxoplasma gondii: infection among shelter and stray cats in Rio de Janeiro, Brazil

Abstract The aim of this study was to identify possible infection of Toxoplasma gondii among cats in a shelter and a set of condominiums in the city of Rio de Janeiro, through changes to the cats’ serological status between two different times in 2014 and 2015. One group was made up of captive cats at the municipal shelter and the other comprised stray cats that circulated in condominiums in the city. On the first occasion, cats were caught and tagged through application of microchips; in this manner, blood samples were obtained from 261 captive cats and 172 stray cats. On the second occasion, blood samples were obtained from 94 captive cats and 56 recaptured stray cats. The serological diagnosis was made by means of the indirect hemagglutination assay (IHA) and indirect immunofluorescence reaction (IFAT) (cutoff ≥ 64). The frequency of T. gondii infection among the captive cats was 24.5% and among the stray cats, 18%. With the second analysis, it was possible to verify modifications to the serological status of anti-T. gondii antibodies, in 18% of both populations of animals. The presence of seroconversion shows that infection was possibly occurring in the region at the time of the study.

摘要 本研究旨在通过对比2014年与2015年两个不同时间点猫只的血清学状态变化，调查里约热内卢市内某动物收容所以及多栋公寓社区中猫的弓形虫（Toxoplasma gondii）潜在感染情况。试验分为两组，一组为该市公立收容所内的圈养猫，另一组为在市内公寓社区活动的流浪猫。首次采样时，研究人员通过植入微芯片对猫只进行捕获并标记，共采集261只圈养猫与172只流浪猫的血液样本。第二次采样时，分别采集到94只圈养猫与56只重捕的已标记流浪猫的血液样本。本研究采用间接血凝试验（indirect hemagglutination assay, IHA）与间接免疫荧光试验（indirect immunofluorescence reaction, IFAT）进行血清学诊断，临界值（cutoff）≥64。结果显示，圈养猫的弓形虫感染率为24.5%，流浪猫的感染率为18%。通过第二次采样分析，可确认两种猫群中各有18%的个体出现抗弓形虫抗体的血清学状态变化。血清转换现象表明，研究开展期间该区域存在弓形虫活动性感染。