| Neospora caninum is an obligate intracellular protozoan which can infect a variety of animals.It was discovered in 1984 and was named in 1988.Cattle,sheep,donkeys,pigs act as its primary intermediate hosts,dogs and foxes are the definitive hosts.It is widespread all over the world,mainly through vertical transmission and horizontal transmission,vertical transmission through the placenta is the main route of transmission,and infection can last for many years.Most of the infected animals can have abortion,stillbirths,mummified fetuses and neurological symptoms,resulting in a decrease of the production of milk,which brings significant economic losses to the livestock industry.Chlamydia is a gram-negative obligate bacterium,a prokaryotic microbe that is strictly parasitic in eukaryotic cells.It can cause diseases in humans and a wide range of animals all over the world,resulting in some symptoms such as difficult breathing and high fever in infected humans or animals.It not only can cause a huge economic impact on animals,but also pose a major threat to human health and public health.In the first part of this study,a total of 837 serum samples from farmed wild boars were collected in Jilin Province and specific antibodies to Chlamydia were detected in 332(39.67%)out of 837 serum samples by the indirect hemagglutination assay(IHA).The Chlamydia seroprevalence were different in wild boars from different regions.Of the 332 seropositive samples,60 samples were from Baishan City with 33.71%(60/178)positive rate,97 samples were from Siping City,and the positive rate was 36.60%(97/265),175 samples from Jilin City,the positive rate was 44.42%(175/394),and the regional difference was statistically significant(P = 0.0248).However,there is no statistically significant difference in Chlamydia seroprevalence between different genders(40.00% in male and 39.65% in female),different ages(< 22 days: 37.50%;22–66 days: 38.24%;> 66 days: 40.03%),and different years(2015: 41.08%;2016: 36.60%)in farmed wild boars.The antibodies levels were diverse,with IHA titers of 1:16 in 176 samples(176/332,53.01%),followed by 1:64 in 131 samples(131/332,39.46%),1:256 in 21 samples(21/332,6.33%),and 1:1024 in 4 samples(4/332,1.20%),respectively.This is the first report of the seroprevalence of Chlamydia in Chinese wild boars,providing baseline data for the prevention and control of Chlamydia infection in Chinese wild boars.In the second part of this study,a total of 2187 Tibetan sheep from Gansu Province and Tibet were tested for seroprevalence by enzyme-linked immunosorbent assay(ELISA).The results showed that the total seroprevalence of N.caninum among the examined Tibetan sheep was 8.4%(184/2187).Statistically,the N.caninum seroprevalence in male Tibetan sheep(10.8%)(69/638)was significantly higher than that in the female(7.4%)(115/1549)(P < 0.01).The N.caninum prevalence in Tibetan sheep varied among regions,ranging from 4.4% in Luqu(8/182,95% CI 1.4-7.4)to 9.4% in Tianzhu(90/962),but the difference was not statistically significant(P > 0.05).The seroprevalence in Spring was 8.5%(41/480),11.3%(45/398)in Summer,6.5%(31/479)in Autumn,and 7.7%(29/375)in Winter.This is the first report on the infection of N.caninum in Tibetan sheep,which provides useful data for the prevention and control of N.caninum infection in Tibetan sheep.The third part of the study was carried out to collect 1,181 serum samples of farmed raccoon dogs from Changchun City,Jilin Province and Rizhao,Weihai and Yantai city,Shandong Province,and test for antibodies against N.caninum by competitive inhibition enzyme-linked immunosorbent assay(cELISA).The results showed that 7.96%(94/1181)examined samples were positive for N.caninum antibodies.The positive rates in different regions were 2.83%(3/106)in Jilin City,5.52%(9/163)in Changchun City,8.15%(16/188)in Rizhao City,9.76%(40/410)in Weihai City and 8.28%(26/314)in Yantai City.Although the seroprevalence of N.caninum in different regions was not statistically significant,the seroprevalence of N.caninum in Shandong Province(8.99%)was significantly higher than that in Jilin Province(4.46%)(P < 0.05).The seroprevalence of N.caninum in male and female raccoon dogs were 7.91%(60/759)and 8.06%(34/422),respectively.In addition,the seroprevalence of N.caninum infection in infancy,youth and adult raccoon dogs was 7.32%(21/287),7.93%(36/454)and 8.41%(37/440),respectively.This is the first report of N.caninum seroprevalence in raccoon dogs,providing an important reference for the prevention and control of N.caninum infection in raccoon dogs.The fourth part of the study,specific anti-N.caninum antibodies in donkeys were examined using a commercial competitive-inhibition ELISA kit,and the risk factors of N.caninum infection in donkeys were evaluated.Out of a total of 2,228?donkey sera from Shandong,Henan and Hebei provinces in China,211(9.5%)were found to be positive for anti-Neospora antibodies.Statistical analysis revealed that age(P?=?0.019,OR?=?1.62,95% CI: 1.08-2.44),feeding status(P?<?0.001,OR?=?3.79,95% CI: 2.65-5.43),miscarriage history(P?=?0.006,OR?=?2.56,95% CI: 1.27-4.01),and contact with dogs(P?<?0.001,OR?=?2.69,95% CI: 1.86-3.88)were significant risk factors for Neospora infection in donkeys.This is the first evidence of Neospora infection in donkeys in China. |
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