Micro-Kolmer complement fixation test for amebiasis.

Knowledge that free-living amoebae are capable of causing human disease dates back some 50 years, prior to which time they were regarded as harmless soil organisms or, at most, commensals of mammals. First Naegleria fowleri, then Acanthamoeba spp. and Balamuthia mandrillaris, and finally Sappinia diploidea have been recognised as etiologic agents of encephalitis; Acanthamoeba spp. are also responsible for amoebic keratitis. Some of the infections are opportunistic, occurring mainly in immunocompromised hosts (Acanthamoeba and Balamuthia encephalitides), while others are non-opportunistic (Acanthamoeba keratitis, Naegleria meningoencephalitis, and cases of Balamuthia encephalitis occurring in immunocompetent humans). The amoebae have a cosmopolitan distribution in soil and water, providing multiple opportunities for contacts with humans and animals, as evidenced by antibody titers in surveyed human populations. Although, the numbers of infections caused by these amoebae are low in comparison to other protozoal parasitoses (trypanosomiasis, toxoplasmosis, malaria, etc.), the difficulty in diagnosing them, the challenge of finding optimal antimicrobial treatments and the morbidity and relatively high mortality associated with, in particular, the encephalitides have been a cause for concern for clinical and laboratory personnel and parasitologists. This review presents information about the individual amoebae: their morphologies and life-cycles, laboratory cultivation, ecology, epidemiology, nature of the infections and appropriate antimicrobial therapies, the immune response, and molecular diagnostic procedures that have been developed for identification of the amoebae in the environment and in clinical specimens.

Amebiasis↗

PubMed2004

Detection and significance of the potentially pathogenic amoeboflagellate Naegleria italica in Australia.

Thermophilic amoeboflagellates in the genus Naegleria include both virulent and benign species. One of the less studied species, N. italica, has not been detected in the environment since the first reports from Italy in the 1980s; its virulence is known only from infection of laboratory mice. Two recent strains from recreational water in Western Australia (AWQC NG960, NG961) were tentatively identified as N. italica from the characteristic mobilities of seven isozymes. Sequences of the 5.8S rRNA gene and its flanking ITS aligned with a 380+bp length of the published sequence for N. italica with 98% identity. Differences from the type strain were confined to ITS2. Shorter alignments (<320 bp) were observed with other Naegleria species, corresponding to conserved regions of the 5.8S gene and ITS. Unlike the European type strain of N. italica, the Australian isolates failed to infect laboratory mice intranasally, confirming that infectivity of this species is variable and often lower than in N. fowleri.

Amebiasis↗