Abstract
Members of the genus Naegleria are free-living amoebae that are widely distributed in water and soil environments. Moreover, Naegleria fowleri is a pathogenic amoeba species that causes a fatal disease in the central nervous system known as primary amoebic meningoencephalitis (PAM) in humans. Since most reported infections due to N. fowleri are reported in recreational waters worldwide, this study was aimed to describe the presence of these amoebic genus in Mexicali Valley irrigation channels of recreational use. A total of nine water samples were collected and processed by triplicate, in nine different sites of the Valley. After filtering and culturing the samples, plates were examined, and the observed amoebae were morphologically identified at the genus level. In addition, the pathogenicity of these amoebic isolates was checked, and molecular characterization was performed by PCR/sequencing. The results revealed the presence of Naegleria spp. in all the channels sampled. Finally, molecular identification confirmed the presence of five different species of Naegleria: N. fowleri, N. australiensis, N. gruberi, N. clarki and N. pagei. The presence of these protists, particularly N. fowleri, should be considered as a potential human health risk in the region.
Highlights
Free-living amoebae (FLA) are widely distributed protists in nature
Four Naegleria isolates were able to kill 100% of infected mice used in their pathogenicity test; such isolation corresponded to CRES2, CRES3a, CRES3b and CRES4b (Table 3)
Sequences and phylogenetic analysis from these isolates, N. fowleri and N. australiensis were identified in the studied irrigation channels (Table 4)
Summary
Free-living amoebae (FLA) are widely distributed protists in nature. Some species are causative agents of a fatal brain infection in humans, including Naegleria, Acanthamoeba, Balamuthia and Sappinia [1,2,3]. Naegleria fowleri is a free-living thermophilic amoeboflagellate that causes primary amoebic meningoencephalitis (PAM) [1,2]. PAM is a rapidly spreading and fatal disease with a fatality. Infection of the brain occurs after amoebae reach the nasal cavity and invade the nasal mucosa. Amoebae penetrate the nasal epithelium and migrate by the olfactory nerves through the cribriform plate to invade the brain and meninges. The disease is rare; new cases are being reported every year in the world [5,6]
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