Facultad de Medicina Veterinaria y Zootecnia, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Mexico.
Vet Parasitol. 2011 Feb 10;175(3-4):367-71. doi: 10.1016/j.vetpar.2010.10.018. Epub 2010 Oct 16.
The presence of cats in the farms is considered a risk factor for the infection of pigs with Toxoplasma gondii (T. gondii). Cats eliminate oocysts that contaminate food, water and promote the infection of host reservoir such as rodents and birds among others that are also involved in the infection of pigs. The objective of this study was to assess the dynamic of infection of T. gondii in seronegative weaned pigs from weaning to 20 weeks of age from two farms from an endemic region, one with high and low density of cats. A cohort study was performed in 64 pigs, 31 newly weaned pigs on a farm with a high density of cats (FA) and 33 newly-weaned pigs on a farm with a low density of cats (FB). Blood samples were collected every 14 days to determine the presence of IgG antibodies against T. gondii in the serum using an indirect ELISA test. True incidence rate (TIV), cumulative incidence (AI) and relative risk (RR) was calculated. The age of seroconversion was determined by using survival tables; both farms were compared with Long-Rank test. In FA 97.5% of the pigs seroconverted at the second sampling and 100% at the third sampling, while in the FB all pigs seroconverted to the fourth sampling. The TIV was 0.67 and 0.43 for FA and FB respectively, during the first four weeks at risk. A RR of 1.5 (1.04-2.39) was obtained (p<0.05). Animals of the FA had a higher risk of infection compared with the FB, however, all animals included in the study had contact with the agent. Infection with T. gondii was rapidly distributed in both farms, regardless of the relative density of cats observed during the study. These results suggest a high environmental contamination with oocysts in the facilities of both farms probably due to the fact that T. gondii infection is endemic in the area where the farms are located, allow proper establishment of the etiological agent. The points of prevention and control strategies to avoid exposure of pigs to T. gondii in an endemic area should focus on the control of cats and rodents.
猫在农场的存在被认为是猪感染刚地弓形虫（T. gondii）的一个风险因素。猫会排出卵囊，污染食物、水，并促进包括啮齿动物和鸟类在内的宿主储主的感染，这些储主也参与了猪的感染。本研究的目的是评估从断奶到 20 周龄的来自两个疫区农场的血清阴性断奶猪的刚地弓形虫感染的动态，其中一个农场猫的密度高，另一个农场猫的密度低。在 64 头猪中进行了队列研究，其中 31 头是来自高猫密度农场（FA）的新断奶猪，33 头是来自低猫密度农场（FB）的新断奶猪。每隔 14 天采集一次血样，使用间接 ELISA 试验检测血清中针对 T. gondii 的 IgG 抗体的存在。计算真实发病率（TIV）、累积发病率（AI）和相对风险（RR）。通过生存表确定血清转化的年龄；使用 Long-Rank 检验比较两个农场。在 FA 中，97.5%的猪在第二次采样时发生血清转化，100%的猪在第三次采样时发生血清转化，而在 FB 中，所有猪在第四次采样时发生血清转化。在第一个四周的风险期内，FA 的 TIV 分别为 0.67 和 0.43，FB 分别为 0.67 和 0.43。获得 1.5（1.04-2.39）的 RR（p<0.05）。与 FB 相比，FA 的动物感染风险更高，但研究中所有动物都接触过该病原体。无论在研究期间观察到的猫的相对密度如何，T. gondii 感染在两个农场中都迅速传播。这些结果表明，由于该地区存在刚地弓形虫感染的流行，两个农场的设施中都存在高卵囊环境污染，这可能允许病原体的适当建立。在流行地区避免猪接触刚地弓形虫的预防和控制策略的重点应放在控制猫和啮齿动物上。
