Current topics in protozoal diseases.

The author reviews seven protozoal diseases, emphasizing the current development but also briefly reviewing the basic knowledge in epidemiology, parasitology, clinical features, pathology, and laboratory diagnosis. Cryptosporidiosis, microsporidiosis, and cyclosporiasis, which are newly discovered diseases in humans, and pneumocystosis, toxoplasmosis, and isosporiasis, which are important opportunistic infections in patients with acquired immunodeficiency syndrome, are discussed. The author also presents acanthamoeba keratitis, a disease seen mainly in contact lens wearers that is expected to have a higher prevalence in the near future.