Description of Pathogen Acanthamoeba are a genera of free-living amebae that can cause localized infection of the central nervous system (CNS), respiratory tract, skin, eyes, and disseminated disease. Nearly 25 named species and at least 20 genotypes of Acanthamoeba have…
Description of the Pathogen Naegleria fowleri is a free-living ameba that causes primary amebic meningoencephalitis (PAM). , It is the only known species of the genus Naegleria pathogenic to humans amongst over 40 other identified species. Two other species, N.…
Before 1985, few human microsporidial infections had been reported. Since then, the number of cases has increased dramatically because of recognition of this pathogen in patients infected with HIV. Although most reported infections have occurred in HIV-infected people, the organism…
Description of the Pathogen The genus Leishmania comprises vector-borne protozoan parasites that cycle asexually between the digestive tract of the sand fly as a motile flagellated promastigote and, in a wide range of vertebrate hosts (e.g., rodents, canids, hyrax, humans),…
Cystoisospora belli (formerly Isospora belli ) has been renamed and included in the Cystoisospora genus. Both C. belli and Cyclospora spp. infect the small intestine and have been implicated in diarrheal disease. C. belli, which first was linked with disease…
Giardia intestinalis is a flagellated protozoan that infects the duodenum and upper small intestine. Giardia is the most commonly identified enteric parasite in the US and Canada. Infection can be asymptomatic or associated with a variety of intestinal manifestations. Factors…
In addition to Entamoeba histolytica ( Chapter 263 ), amebae that can be found in the human intestinal tract include other species of Entamoeba ( E. dispar, E. moshkovskii , E. bangladeshi, E. coli, E. hartmannii, E. polecki), Endolimax nana…
Entamoeba histolytica is a “tissue-lysing” ( histo = tissue, lytic = lysing) ameba that can cause disease ranging from asymptomatic colonization to diarrhea, colitis, and liver abscess. It was first discovered in 1875 by Fedor Aleksandrovich Lösch, who described amebic…
Endolimax nana is a single-celled parasite of the colon. Although considered nonpathogenic, infection with E. nana is an indicator of exposure to fecal contamination and often is seen in fecal samples positive for other common parasitic intestinal protists. Description of…
Human disease caused by Cryptosporidium was first described in 1976 and became recognized increasingly during the HIV epidemic. Improved detection of oocysts in feces has shown Cryptosporidium to be a common cause of diarrhea in both immunocompetent and immunocompromised hosts.…