Naegleria australiensis: experimental meningoencephalitis in mice

Abstract

Naegleria australiensis was recently described as a new species of free-living amoeba pathogenic for mice. Infections of human brain by the free-living amoebae N. fowleri and Acanthamoeba spp. are well known. We here describe the clinicopathological features of experimental infection of the central nervous system of mice by N. australiensis. Weanling mice were inoculated intranasally and intracerebrally. The involvement of the nasal mucosa, olfactory neuroepithelium and lobes, cerebrum and cerebellum was detected in haematoxylin-eosin stained paraffin-embedded sections. Amoebic trophozoites sparsely located throughout the central nervous system were shown better by the immunoperoxidase method. Cysts were not detected. The histopathological changes differ from those produced by N. fowleri, especially in the degree of severity. They may be confused with those caused by Acanthamoeba spp. which usually produced subacute and chronic encephalitis with a prolonged clinical course.

Isolation and identification of Acanthamoeba species related to amoebic encephalitis and nonpathogenic free-living amoeba species from the rice field

“…Literature reviews had indicated nonpathogenic amoebas such as N. australiensis and Vannella spp. may cause diseases in animals (De Jonckheere et al. 1983; Dyková 2005).…”

“…Literature reviews had indicated nonpathogenic amoebas such as N. australiensis and Vannella spp. may cause diseases in animals (De Jonckheere et al 1983;Dyková 2005). Mice experimentally infected with N. australiensis developed subacute meningoencephalitis comparable to that caused by Acanthamoeba spp.…”

“…Other free-living amoebae such as Naegleria australiensis and Vannella spp. may also cause diseases in animals and human (De Jonckheere et al 1983;Dyková 2005). The genus Acanthamoeba is a group of nearly 25 named species that have a worldwide distribution (Booton et al 2005).…”

Diagnostic moléculaire d’une méningoencéphalite amibienne primitive à l’occasion d’un cas fatal en Guadeloupe

“…ITS1 sequences of different N. fowleri types l'espèce la plus étroitement apparentée à N. fowleri, bien qu'elle ne soit pas pathogène, et elle est considérée comme un indicateur de la présence possible de N. fowleri [7]. N. australiensis est pour sa part pathogène pour la souris [4,5,15], mais n'a encore jamais été détectée dans les infections humaines [7].…”

Assessing the Risk of Primary Amoebic Meningoencephalitis from Swimming in the Presence of EnvironmentalNaegleria fowleri

“…For example, no case of PAM associated with N. australiensis or N. italica has so far been described among humans, although these species are pathogenic for mice (15). Moreover, while many studies (6,9,18,34,39) have shown the presence of anti-N. fowleri antibodies in humans, these have not been found in laboratory animals; this may explain the greater resistance among humans.…”