Investigation On Infection Of Raccoon Blood Diseases In Some Areas Of Hebei Province

Babesia,Eperythrozoon and Toxoplasma gondii are common pathogens in fur economical animals.It not only seriously endangers the health of fur animals,brings chronic and continuous effects to farms,but also poses a threat to human health.At present,there are few reports on the infection of these three pathogens in raccoon dogs.A total of 922 raccoon blood samples were collected from some areas of Hebei Province(Qinhuangdao,Cangzhou,Zhangjiakou,Tangshan,Hengshui and Shijiazhuang)from October 2020 to December 2021,and the three pathogens were detected by microscopy,serological methods and PCR techniques,and the test results were as follows:The infection of Babesia was detected using 16S rRNA gene,and the overall infection rate of Babesia was 5.3%(49/922)in 922 samples.Babesia infection was found in all six areas,with the highest infection rate of 7.8%in Hengshui and the lowest infection rate of 2.5%in Zhangjiakou,and there was no significant difference in the infection rate among the six areas(2=4.835,P>0.05);the infection rate was4.7%in spring,5.3%in summer,9.1%in autumn,and 2.9%in winter,and there was a very significant difference in the infection rate among the four seasons(2=15.617,P<0.01).The 49 positive samples were sent for testing,and the sequencing results showed that all 49 samples were B.gibsoni.The 16S rDNA gene of Eperythrozoon was used as the target to design primers to detect the infection of Eperythrozoon in the raccoon dog.It was found that the number of positive samples was 469,and the overall infection rate was 50.9%(469/922).The six regions had different degrees of infection.Among them,Hengshui had the highest infection rate of 66.7%,Tangshan had the lowest infection rate of45.8%,and other regions had the infection rate of 51.2%in Cangzhou,48.8%in Zhangjiakou,50.9%in Shijiazhuang,and 55.7%in Qinhuangdao,respectively.There was no significant difference in infection rates in the six regions(X~2=20.981,P<0.05).The gene sequence of the positive sample was identified,and the sequencing result showed that it had the highest homology with canine Eperythrozoon.In order to compare the differences in the detection of T.gondii between PCR methods and serological methods,288 serum samples were random Ly selected to detect T.gondii infection using the indirect hemagglutination antibody test method for T.gondii,and the serological results showed that 24 positive samples,with a positive rate of 8.3%(24/288),of which 22 were consistent with the PCR detection results,and the positive rate of serological detection was slightly higher than that of PCR detection,but the detection results were not significantly different(2=0.095,P>0.05).Toxoplasma gondii infection was detected by amplification of B1 gene by PCR,and the total infection rate of Toxoplasma gondii in 922 samples was 7.3%(66/922).The highest infection rate was 16.2%in Shijiazhuang and the lowest infection rate was 4%in Tangshan.There was significant difference in the infection rate among the six areas of T.gondii in raccoon dogs(2=28.491,P<0.05).In addition,the infection rate was 7%in spring,5.3%in summer,11.7%in autumn and 4.2%in winter.There was significant difference in the infection rate of T.gondii among raccoon dogs in the four seasons(2=17.306,P<0.01),The results showed that both region and season were the main risk factors for T.gondii infection in raccoon dogs.66 samples with positive PCR results were sent for testing,and the results showed that all 66 were T.gondii B1 gene and had infection in all six regions.