| Toxoplasma gondii, an important obligate intracellular protozoan, can infect nearly all warm-blooded animals globally, including foxes. It is estimated that approximately one third of the human population is chronically infected with T. gondii and some people are symptomatic. Humans are infected by ingesting tissue cysts from under-cooked meat or consuming food and water contaminated by oocysts shed by the infected definitive hosts. It can induce serious diseases in fetus during congenital infection, and can cause a fatal harm to immunocomprimised patients, such as people with cancer and those with AIDS or organ transplant.Cryptosporidium, an important intestinal parasite of humans and animals, has a diverse global distribution and at least 26 species with more than 73 host-adapted genotypes of undetermined species have been identified. Cryptosporidium canis, the common species of Cryptosporidium in dogs, has been found in foxes. On the basis of appearance of human patients among the world nations, Cryptosporidium canis is identified as a potentially zoonotic Cryptosporidium species.Microsporidiosis is a common disease in animals and humans around the world. Enterocytozoon bieneusi is the most common microsporidian species in humans. Many animal species may be a potential source of human microsporidiosis. However, information concerning prevalence and genotypes of E. bieneusi infection in farmed arctic foxes(Alopex lagopus) is scarce. Therefore, the present study examined prevalence, risk factors and genotypes of E. bieneusi in farmed arctic foxes in northern China using a genetic approach.In the first part, a serological survey was undertaken to assess the seroprevalence of T. gondii in farmed arctic foxes in eastern and northeastern China. Antibodies to T. gondii were examined in 1346 farmed arctic foxes using modified agglutination test(MAT). 113(8.39%, 95% CI 6.91-9.87) serum samples were positive to T. gondii at a 1:25 cut-off, with titers of 1:25 in 66, 1:50 in 26, 1:100 in 9, 1:200 in 7, 1:400 in 3, and 1:800 in 2. Seroprevalence of T. gondii infection in male arctic foxes was 8.68%(95% CI 6.75-10.6), which is higher than that in the female arctic foxes(7.95%, 95% CI 5.65-10.26). The prevalence in polar foxes was 7.07%(95% CI 5.14-8.99), which was lower than that in the blue foxes(9.75%, 95% CI 7.49-11.99). The seroprevalence of T. gondii infection in Heilongjiang, Jilin, Liaoning and Shandong provinces were 9.85%(95% CI 5.75-13.95), 9.21%(95% CI 5.54-12.87), 7.37%(95% CI 5.22-9.51) and 8.68%(95% CI 5.66-11.70), respectively. There were no statistically significant differences between T. gondii seroprevalence and subspecies, sex or regions of arctic foxes in the logistic regression analysis(P > 0.05). The results of the present survey indicated that T. gondii infection in farmed arctic foxes is prevalent in China. To our knowledge, this is the first report of T. gondii seroprevalence in arctic foxes in China.In the second part, the present study examined prevalence, risk factors and genotypes of E. bieneusi in farmed arctic foxes. Of 302 fecal samples from farmed foxes, 37(12.25%, 95% CI 8.55-15.95) were PCR-positive for E. bieneusi, and the prevalence was highly associated with the farming mode in that foxes raised outdoors(26.03% positive, 95% CI 18.91-33.15) had a significantly higher E. bieneusi prevalence than those raised indoors. Eleven internal transcribed spacer(ITS) genotypes were identified among the positive samples: four known E. bieneusi genotypes(Peru 8, Types IV, CHN-DC1 and D) and seven novel genotypes(NCF1-NCF7). Genotype NCF2 was the commonest(n=13) and was found in five farms across three provinces(Jilin, Heilongjiang and Hebei). All genotypes belonged to phylogenetic group 1.In the third part, the overall prevalence of Cryptosporidium in arctic foxes was 15.9%(48/302) using nest-PCR, with 12.9% in male(18/139) and 18.4% in female(30/163) foxes, respectively. Cryptosporidium prevalence in different farms varied from 0 to 31.43%. The prevalence of Cryptosporidium infection in different age groups varied from 14.1% to 19.0%. Moreover, foxes from Hebei Province(7.8%, 11/141) had a significantly lower Cryptosporidium prevalence than those from Heilongjiang Province(22.9%, 16/70) and Jilin Province(23.1%, 21/91)(P=0.0015). Sequence analysis of the SSU r RNA gene indicated that all the 48 isolates represented C. canis.The present study characterized T. gondii genotypes in farmed foxes in China for the first time. Brain tissue samples collecting from 264 arctic foxes in Jilin, Heilongjiang and Shandong provinces were used to detect the T. gondii B1 gene by a semi-nested PCR, and the positive samples were genotyped at 11 genetic markers(SAG1, alternative SAG2, 5’-and 3’-SAG2, SAG3, L358, BTUB, c22-8, GRA6, c29-2, PK1 and Apico) by multi-locus PCR-RFLP technology. Twenty-one DNA samples from 264 foxes were T. gondii B1 gene positive(7.96%). Two genotypes(Toxo DB#9 and Toxo DB#10) were identified.This study detected the seroprevalence of T. gondii infection in arctic foxes from eastern China by MAT. We also undertook the epidemiological investigation and genotyping of E. bieneusi and Cryptosporidium of arctic foxes by nest-PCR. This study also genetically characterized T. gondii isolates of arctic foxes in eastern China using PCR-RFLP, and identified the major lineage Toxo DB #9 and another lineage Toxo DB #10 successfully. These results provided basic information for preventing and controlling T. gondii, Enterocytozoon bieneusi and Cryptosporidium infection in arctic foxes in China. |
