Update on protozoan parasites of the intestine.

The last year has seen new approaches to the diagnosis, treatment, and prevention of protozoal infections of the gastrointestinal tract. Some of the news is not good: new foodborne and swimming pool outbreaks of cyclosporiasis and cryptosporidiosis, respectively, occurred in North America; paromomycin was shown to be ineffective treatment for cryptosporidiosis; and these parasitic diseases continued to have a worldwide impact on human health. On the bright side, there were important advances in the understanding of the pathogenesis of cryptosporidiosis and the diagnosis of amebiasis and giardiasis, and some new leads on the treatment of cryptosporidiosis and refractory giardiasis. Finally, evidence was found of acquired mucosal immunity to amebiasis in Bangladeshi children, offering a guide for the development of an amebiasis vaccine. This review is not intended to be comprehensive, but contains a variety of articles that the authors hope will be of interest to the reader.