The prevalence of Blastocystis hominis as an enteric pathogen in human seems not to be associated with gender and living environment, and that Blastocystis hominis is more common in stool samples of the patients with diarrhea, especially with chronic diarrhea or obstinate diarrhea. When patients with diarrhea infected by Blastocystis hominis, their cellular immune function decreases, which make it more difficult to be cured.

The clinical symptoms of clonorchiasis are non-specific, and the main evidences for diagnosis of clonorchiasis should be provided by etiologic examination, B-mode ultrasonography and clinical history. The infection of clonorchis sinensis is related to occupations, bad eating habits and lack of knowledge about prevention of the disease.

Cyclospore cayetanensis infection is present in Anhui, China and it was confirmed to be a new pathogen associated with children diarrhea, adults obstinate diarrhea and diarrhea in immunocompromised individuals. Among all the infected individuals, adult obstinate diarrhea patients and immunocompromised individuals are common. Feces examination of oocysts and serological examination of the specific antibody will be of much help in the diagnosis of Cyclospore cayetanensis infection.

H pylori infection is associated with occurrence and development of gastric and duodenal carcinomas. Furthermore, it is also associated with histological type and locations of gastric and duodenal carcinomas.

There are two infection peaks in infection of Cryptosporidium parvum and its infection can be found more often in infants, patients with diarrhea or immunodeficiency, and in rural areas. Subclinical infection is the main manifestation and might be easily misdiagnosed. When the therapeutic effectiveness is low for diarrhea, the infection of Cryptosporidium parvum should be considered, concerning their age and immune function.