| Toxoplasmosis is a parasitic zoonosis caused by Toxoplasma gondii. Since Toxoplasma gondii has a extremely wide range of intermediate hosts, the parasite can infect mammal, including human, birds and cold-blooded animals, etc. Its worldwide distribution damages the health of human and livestock, not to mention the great economic losses it causes. Consumption of raw or partially cooked meat and eggs infected by Toxoplasma gondii is a major route of infection for human. Therefore, the detection of toxoplasmosis in livestock is of an important public health significance. So far, there are more foreign epidemiological investigation of Toxoplasma gondii infection in chicken comparing the ones in our country. And usually in those study, only serum antibody is detected rather than circulating antibody. To know more about Toxoplasma gondii infection of chickens in China, totally1266blood samples of free-range and caged chicken from13provinces were detected for antigen and antibody using ELISA. The samples were kept in-20℃, and with one positive result showed in the detection, Toxoplasma positive infections is considered.The results were listed below:Xinjiang Uygur Autonomous Region positive rate of free-range chicken:16.42%(11/67); Inner Mongolia Autonomous Region positive rate of free-range chicken:27.87%(17/61); Liaoning province, positive rate of free-range chicken:20%(10/50); Shandong province, the positive rate of free-range chicken:42.25%(30/71); Henan province, positive rate of free-range chicken:20%(27/135); Jiangsu province, the positive rate of flat circle chicken and free-range chicken:47.27%(78/165); Anhui province positive rate of free-range chicken:6.67%(4/60); Sichuan free-range chicken scattered positive rate:25.81%(24/93); Chongqing city, the positive rate of free-range chicken:35.71%(30/84); Jiangxi province positive rate of free-range chicken:39.64%(44/111); Fujian province positive rate of free-range chicken:15.63%(10/64); Guangxi Zhuang Autonomous Region positive rate of free-range chicken:38.57%(54/140); Guangdong province positive rate of free-range chicken:26.39%(19/72); Henan province, Xinxiang city, positive rate of caged chicken:2.15%(2/93). The results above indicates there are certain proportion chickens infected by Toxoplasma gondii, and caged chicken is less likely to be infected than soil exposed ones maybe because of feeding mode. The average infection of ree-range chicken26.97%, and in some provinces even higher than40%.To study the relevance among antigen, antibody and parasite isolation, animals were infected with tachyzoite strain RH in various does. In heavy does group,5chicken aged2week were administrated108strain per chicken by intravenous injection, while106and105per chicken were administrated to20as middle and low does group respectively. All the chicken of heavy does group died the next day. Their internal organs were collected and passed to mice, and Toxoplasma would be isolated from all these mice. Neither middle nor low does group caused paroxysm.4days after the passage,5antigen positive but antibody negative chicken from each group were killed with hearts and brain organs collected and made into suspension for passage. The suspension then administrated to mice,6days later the mice died as tachyzoite were found in ascitic fluid and Toxoplasma could be isolated from those mice.10days after the passage,5chicken, positive at both antigen and antibody, from each group were killed with hearts and brain organs collected and made into suspension for passage, and Toxoplasma could be isolated from those mice.21days after the passage, antibody positive but antigen negative,5chicken from each group were killed with hearts and brain organs collected and made into suspension with pepsase for passage, and Toxoplasma could not be isolated from those mice after3times blind passage.32days after the passage, all the rest chicken, negative of both antigen and antibody at that time, were killed with internal organs collected and made into suspension with pepsase for passage, and Toxoplasma could not be isolated from those mice after3times blind passage.In our research100blood samples of free-rang chicken from the same region in Jiangsu Province were detected, and21chicken with positive antibody were brought for parasite isolation. After muriatic acid-pepsase digestion, the tissue suspension was blind passed to asymptomatic mice.10days later, asymptomatic mice were killed and their tissue was made into suspension for blind passage which then proceed once every week. Symptoms were observed in the mouse4days after the3th blind passage with the tissue of chick3, and large number of Toxoplasma tachyzoite were found in the miouse’s ascitic fluid. This mouse died2days later. After more passage and augmentation, chick Toxoplasma was finally isolated. Our research established the foundation for the experiment in the future. |
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