Fresh-water amoebae from four aquatic sites in Egypt.

Water samples from four aquatic sites in Egypt were examined for the presence of free-living amoebae. Amoebae were isolated and cultured on 1.5% non-nutrient agar with bacteria. They were studied morphologically and tested for production of flagellated forms, encystment, excystment, nuclear division, temperature tolerance and pathogenicity in young mice (8 - 10 gm). Didascalus thorntoni and Naegleria gruberi were dominant in all surface waters. Naegleria fowleri, Acanthamoeba glebae, A. culbertsoni and A. rhysodes were found in Lower Egypt, while Vahlkampfia avara and V. thornata were found in Upper Egypt. All species tolerated incubation temperatures of up to 36 degrees C except for A. rhysodes which degenerated at 34 degrees C. A. culbertsoni tolerated 38 degrees C but died at 40 degrees C. Amoebae were detected histologically in a necrotic brain tissue from only one mouse which was inoculated with A. culbertsoni.