The amoebicidal properties of chlorine, chlorine dioxide, ozone, and deciquam 222 were examined in axenic conditions. Naegleria spp. were found to be more sensitive to chlorine and chlorine dioxide than Acanthamoeba spp. No marked difference in sensitivity to ozone or deciquam 222 could be detected between the pathogenic (A-1) and nonpathogenic (1501) strains of Acanthamoeba and the pathogenic (MsT) and nonpathogenic (P1200f) strains of Naegleria. Methods of disinfection are discussed with reference to suitability of the disinfectants to real conditions.

Samples of soil and water were taken from the McMurdo Sound-Dry Valley region of Antarctica. Of the 70 samples cultured, 22 yielded amoebae capable of clonal growth at 30°C. None of the isolates was pathogenic for mice. Acanthamoeba isolates appeared to show better survival potential than Naegleria isolates.

No abstract

A sample survey of 9 thermal pools or streams in 3 Health Districts of the North Island of New Zealand was made over a 15-month period to determine the presence or absence of pathogenic free-living amoeba (PFLA) of the genera Naegleria and Acanthamoeba. Concurrent chemical, physical, and bacteriological analyses of the pools were made. Naegleria and Acanthamoeba were isolated in the Rotorua and Hamilton Health Districts but not in the Gisborne Health District. Most PFLA were isolated from water with a high coliform content or soil contamination.

Pathogenic free-living amoebae are common in nature, but few clinical infections by these amoebae have been reported. This has prompted studies of host susceptibility factors in humans. A survey of normal human sera from three New Zealand Health Districts was made; antibodies to pathogenic free-living amoebae were found in all sera, with titers ranging from 1:5 to 1:20 for Naegleria spp. and from 1:20 to 1:80 for Acanthamoeba spp. The antibodies belonged mainly to immunoglobulin G and immunoglobulin M classes. The presence of a specific neutralizing factor against Acanthamoeba spp. but not Naegleria spp. was demonstrated. Possible protective mechanisms are discussed.