Molecular Epidemiology Of Cryptosporidium And Giardia Infection In A Part Of Children And Cattle In Northeast China

Cryptosporidium spp. and Giardia spp are obligate protozoan parasites that infect the gastrointestinal tract of many animals, including humans. In both the developing and developed world, Cryptosporidium and Giardia cause their hosts diarrhea with a significant morbidity and mortality. In immunocompetent individuals, Cryptospori- dium and Giardia parasites can cause acute, self-limiting infection, but in immunocompromised individuals, Cryptosporidium and Giardia parasites can cause severe, chronic, life-threatening disease. The transmission of Cryptosporidium and Giardia usually occurs through the direct fecal-oral route or through (oo)cyst contaminated water or food.Recent studies suggest that Cryptosporidium parvum, Cryptosporidium bovis, Cryptosporidium ryanae and Cryptosporidium andersoni are the major species or genotypes infect cattle. Cryptosporidium parvum and Cryptosporidium hominis are the major species or genotypes infect human. Giardia duodenalis (syn G. intestinalis, G. lamblia) has been implicated as an etiological agent for dairy calves and human diarrhea, worldwide. Cattle are susceptible to infection with two genotypes of Giardia duodenalis: the zoonotic genotype (assemblage A), the livestock genotype (assemblage E). Human mainly are susceptible to infection with two zoonotic genotypes of Giardia duodenalis: assemblages A and B. In Other countries, the prevalence of Cryptosporidium spp and Giardia spp infections in children or cattles had been determined using Molecular Biology method. Such as in Australia, the prevalence of Cryptosporidium spp is 48.1% and Giardia spp is 88.9% in dairy calves. In Canada, the prevalence of Cryptosporidium spp is 27.3% and Giardia spp is 42.0% in dairy calves. In British Columbia, the prevalence of Cryptosporidium spp is 50.5% and Giardia spp is 30.3% in the three Communities.In China, data on the prevalence of Cryptosporidium spp and Giardia spp infections in children or cattles by using Molecular Biology method are limitted.For many years, microscopic examination of fecal samples has been commonly considered to be the"gold standard"for diagnosis of Cryptosporidium and Giardia infections. More specific and sensitive alternative methods (ELISA and IFA) have also been extensively developed over the years. However, the assays mentioned above need to harvest enough oocysts and cysts from feces for detection, sometimes are labor-intensive, time-consuming and less sensitive, and the antibodies utilized in the direct fluorescent-antibody methods were often shown to have cross-reaction with various species of algae in environmental samples Thus, more sensitive and specific assays are required to detect low-level contamination of oocysts and cysts. Nested PCR assays have been introduced as a very sensitive method to detect Cryptospo- ridium spp and Giardia spp in clinical specimens. The advantages of Nested PCR include greater sensitivity, higher specificity, relatively low cost and rapid detection of pathogens. So in the present study, we used Nested PCR assay to detect Cryptosporidium spp and Giardia spp.The use of the small subunit (SSU) rRNA genotyping tools for Cryptosporidium has improved the understanding of the host range of Cryptosporidium species and genotypes, which is useful in epidemiological investigations, assessment of zoonotic transmission, and tracking sources of infection and contamination. Because of the high genetic heterogeneity displayed by Giardia spp. at triosephosphate isomerase (TPI) gene, TPI gene of Giardia was widely used for identification of various assemblages of G.duodenalis. So in the present study, we used the 18S rRNA gene of Cryptosporidium and the TPI gene of Giardia as target gene to detect Cryptosporidium spp and Giardia spp.The prevalence of Cryptosporidium spp infections in a part of cattle in Northeast China by using Nested PCR method was11.3%, C. andersoni, C. bovis, and C. ryanae constituted, 7.31%, 1.33% and 2.99% of the 301 samples, respectively. But in105 preweaned calves, the prevalence of C. andersoni, C. bovis, and C. ryanae was 4.39%, 3.51%,7.89%, respectively.This is the first report of C. ryanae is the major species or genotypes infect preweaned calves in China.The prevalence of Giardia in cattle was 7.64%, subassemblage E XI of Giardia duodenalis, subassemblage E I of Giardia duodenalis, subassemblage E III of Giardia duodenalis, subassemblage E VII of Giardia duodenalis and assemblage A of Giardia duodenalis constituted, 3.32%, 2.33%, 1.33%, 0.33% and 0.33% of the 301 samples, respectively.So subassemblage E XI of Giardia duodenalis is the major species infect cattles in Northeasrt China.In children stools, we did not detect any Cryptosporidium or Giardia,that may be due to the low temperature of Northeasrt China, the living habits and others factors.C. andersoni, C. bovis, C. ryanae and assemblage E of G.duodenalis do not infect human, but assemblageA of G.duodenalis can infect human, so isolates of assemblageA of G.duodenalis recovered from cattles represents a public health risk in terms of the potential for zoonotic transmission in Northeast China.Based on the studies, the epidemic situation of Cryptosporidium and Giardia in cattle and children can be clearly known, which will provide useful information for Molecular epidemiology of Cryptosporidium and Giardia infection in China.