Brief Overview about Protozoa Contaminating Drinking Water or Protozoal Diseases Transmitted Through Drinking Contaminated Water

Abstract

Background: The first published report of Cyclospora infection in humans can probably be dated to 1979. Ashford described coccidian organisms causing diarrhea in two children and a woman in Papua New Guinea and concluded that they could be a coccidian of the genus Isospora. In 1991 and 1992, Ortega and collaborators characterized this controversial organism as a new coccidian species capable of infecting humans and belonging to the genus Cyclospora. In reports published in 1993 the name Cyclospora cayetanensis (C. cayetanensis) was proposed. Cyclospora infection is characterized by anorexia, nausea, flatulence, abdominal cramping, diarrhea, low-grade fever and weight loss. Cyclospora infection induces several pathological alterations of the intestinal epithelial tissue, which include; focal vacuolization at the tips of the villi of the surface epithelium, loss of the brush border, and alteration of cells from a columnar to cuboid shape. In addition, the intestinal architecture may show variable degrees of villous atrophy and crypt hyperplasia, characterized by shortened blunted villi and increased crypt length. Human cryptosporidiosis is caused by the infection with the Apicomplexa protozoan of the genus Cryptosporidium. Cryptosporidium hominis (C. hominis) and Cryptosporidium parvum (C. parvum) are among the commonest species of this genus. Humans are the only natural hosts for C. hominis, while C. parvum infects bovines as well as humans. Some studies indicate that C. parvum exhibits geneticpolymorphism, with one genotype infecting only humans and another infecting humans, cattle, and mice. At present, the infection of Cryptosporidium has been reported in more than 70 countries. The world-wide prevalence of Cryptosporidium infection in man ranged from 0 % to 86%. The highest prevalence was found in Mexico, Nigeria, Bangladesh and Republic of Korea among general residents, patients, school children and healthy population.