• Korean Journal of Microbiology
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• v.54 no.2
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• pp.98-104
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• 2018

Naegleria fowleri and Acanthamoeba spp. are free-living amoebas that are widely distributed in natural environments. Although uncommon, infection with these protozoans can cause fatal disease in humans and animals. In this study, in order to select the appropriate method to survey Naegleria fowleri and Acanthamoeba spp. in water samples, four molecular biology techniques and one commercially available kit for real-time PCR were compared. The results indicated that the duplex real-time PCR was the most sensitive, and could be used to simultaneously detect two different free-living amoebas. Using the duplex real-time PCR approach, the two free-living amoebas were surveyed in three local streams in Daejeon, Republic of Korea. The concentrated free-living amoebas were inoculated onto non-nutrient agar plates which had been spread with heat-inactivated Escherichia coli and incubated for 5~7 days. After incubation, gDNA was extracted and used as the template for amplification by duplex real-time PCR. Acanthamoeba spp. and N. fowleri was detected from ten (83.3%) and two (16.6%) of the twelve samples, respectively. As these two free-living amoebas can be fatal, continuous surveillance is needed to track their distribution in the aquatic environment for the drinking water safety.

• Parasites, Hosts and Diseases
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• v.58 no.2
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• pp.191-194
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• 2020

Free-living amoebas (FLAs) can cause severe disease in humans and animals when they become infected. However, there are no accurate survey reports on the prevalence of FLAs in Korea. In this study, we collected 163 tap water samples from buildings, apartments, and restrooms of highway service areas in 7 Korean provinces with high population density. All these buildings and facilities have water storage tanks in common. The survey was separated into categories of buildings, apartments, and highway service areas. Five hundred milliliters of tap water from each building was collected and filtered with 0.2 ㎛ pore filter paper. The filters were incubated in agar plates with heated E. coli at 25℃. After axenization, genomic DNA was collected from each FLA, and species classification was performed using partial 18S-rDNA PCR-sequencing analysis. We found that 12.9% of tap water from buildings with storage tanks in Korea was contaminated with FLAs. The highway service areas had the highest contamination rate at 33.3%. All of the FLAs, except one, were genetically similar to Vermamoeba vermiformis (Hartmannella vermiformis). The remaining FLA (KFA21) was very similar to Acanthamoeba lugdunensis (KA/E26). Although cases of human infection by V. vermiformis are very rare, we must pay attention to the fact that one-third of tap water supplies in highway service areas have been contaminated.

• Korean Journal of Microbiology
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• v.54 no.3
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• pp.237-243
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• 2018

The pathogenic free-living amoebas (FLAs), Acanthamoeba spp. and Naegleria fowleri, can cause fatal infections, including amoebic encephalitis. They are ubiquitously distributed in nature, including in diverse bodies of water. In order to survey Acanthamoeba spp. and N. fowleri in source water in Korea, we used culture-based real-time PCR to detect viable FLAs in 52 source water samples collected between July 2017 and December 2017. Acanthamoeba spp. and N. fowleri were detected in 42 samples (80.8%) and 6 samples (11.5%), respectively. Acanthamoeba spp. were detected at approximately the same frequency in all seasons, but N. fowleri was mainly detected in summer and autumn, with no N. fowleri detected in winter. These results demonstrate that these pathogenic FLAs, especially N. fowleri, which has caused deaths in the United States and China, are widely distributed in the Korean aquatic environment.

• Journal of Environmental Science International
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• v.17 no.10
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• pp.1121-1127
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• 2008

The free-living amoeba and Acanthamoeba sp. are widely distributed in fresh water, soil, air and dust in the world. We studied distribution of amoeba from low Nakdong River(Mulgum and Maeri) and removal efficiency in water treatment process of Busan metropolitan city. During this investigation, water quality showed pH $7.4{\sim}9.6({\pm}1.1)$, water temperature $2.0{\sim}29.0({\pm}17)^{\circ}C$, turbidity $4.8{\sim}27.4({\pm}11.0)$ NTU, chlorophyll-a $10.3{\sim}109.0({\pm}44.3)\;mg/m^{3}$, BOD $1.7\sim4.9({\pm}2.6)$ mg/L, COD $3.1\sim-6.9({\pm}5.0)$ mg/L and total coliform $17\sim920({\pm}200.5)$ MPN/100 mL. The free-living amoeba were detected highly than Acanthamoeba sp., 11 out of 22 in raw water samples were positive (50%) for Acanthamoeba sp. from February 2005 to December 2005. The seasonal characteristics of tree-living amoeba and Acanthamoeba sp. in raw water were mainly distributed through the spring to the early fall. When tree-living amoeba and Acanthamoeba sp. were passed through the water treatment of pilot-plant, approximately 80% was sure to be removed through pre-ozonation, sedimentation, send filtration. 100% was removed after post-ozonation process. All of the isolated amoebas from Nakdong River were Acanthamoeba sp. AC311 18S ribosomal RNA gene with 98% nucleotide sequence homology.

• Parasites, Hosts and Diseases
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• v.60 no.4
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• pp.229-239
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• 2022

The high percentage of Vermamoeba was found in tap water in Korea. This study investigated whether Vermamoeba induced allergic airway inflammation in mice. We selected 2 free-living amoebas (FLAs) isolated from tap water, which included Korean FLA 5 (KFA5; Vermamoeba vermiformis) and 21 (an homolog of Acanthamoeba lugdunensis KA/E2). We axenically cultured KFA5 and KFA21. We applied approximately 1×10⁶ to mice's nasal passages 6 times and investigated their pathogenicity. The airway resistance value was significantly increased after KFA5 and KFA21 treatments. The eosinophil recruitment and goblet cell hyperplasia were concomitantly observed in bronchial alveolar lavage (BAL) fluid and lung tissue in mice infected with KFA5 and KFA21. These infections also activated the Th2-related interleukin 25, thymic stromal lymphopoietin, and thymus and activation-regulated chemokines gene expression in mouse lung epithelial cells. The CD4⁺ interleukin 4⁺ cell population was increased in the lung, and the secretion of Th2-, Th17-, and Th1-associated cytokines were upregulated during KFA5 and KFA21 infection in the spleen, lung-draining lymph nodes, and BAL fluid. The pathogenicity (allergenicity) of KFA5 and KFA21 might not have drastically changed during the long-term in vitro culture. Our results suggested that Vermamoeba could elicit allergic airway inflammation and may be an airway allergen.