Abstract
The genus Naegleria, of the free-living amoeba (FLA) group, has been investigated mainly due to its human health impact, resulting in deadly infections and their worldwide distribution on freshwater systems. Naegleria fowleri, colloquially known as the “brain-eating amoeba,” is the most studied Naegleria species because it causes primary amoebic meningoencephalitis (PAM) of high lethality. The assessment of FLA biodiversity is fundamental to evaluate the presence of pathogenic species and the possibility of human contamination. However, the knowledge of FLA distribution in Brazil is unknown, and to rectify this situation, we present research on identifying Naegleria spp. in the Monjolinho River as a model study. The river is a public Brazilian freshwater source that crosses the city of São Carlos, in São Paulo state, Brazil. Five distinct sampling sites were examined through limnological features, trophozoites culturing, and PCR against internal transcribed spacer (ITS) regions and 5.8S rRNA sequences. The results identified N. philippinensis, N. canariensisi, N. australiensis, N. gruberi, N. dobsoni sequences, as well as a Hartmannella sequence. The methodology delineated here represents the first Brazilian Naegleria spp. study on a freshwater system. Our results stress the urgency of a large scale evaluation of the presence of free-living amoebas in Brazil.
Highlights
Naegleria is a genus that comprises single-celled, heterotrophic protists that are widely distributed in natural environments [1,2,3]
dissolved oxygen (DO) Monjolinho, and temperature measurements that were in situ along
The samples were collected along the Monjolinho river, which passes through the city of São
Summary
Naegleria is a genus that comprises single-celled, heterotrophic protists that are widely distributed in natural environments [1,2,3]. The 47 species identified up to now exist as free-living amoebas (FLAs) with a bacteria-based feeding habit and binary fission division [4]. They transform from trophozoites to the cyst stage as a resting form [5]. A third stage, commonly biflagellate, can be formed to seek a better surrounding [6]. The known exceptions are Naegleria indonesiensis, N. chilensis, N. paradobsoni and N. neochilensis for which a flagellate form has never been identified [4]. Naegleria is described as an amphizoic genus, as four species are able to thrive as free living organisms and as parasites: Naegleria fowleri, Naegleria australiensis, Naegleria philippinensis and Naegleria italica [7,8,9]. Since N. fowleri withstands higher temperatures, as found in geothermal sources and heated recreational aquatic systems, the species has been classified as thermophilic [3,10] with the Pathogens 2020, 9, 90; doi:10.3390/pathogens9020090 www.mdpi.com/journal/pathogens
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