• Parasites, Hosts and Diseases
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• 제57권3호
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• pp.291-294
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• 2019

Primary amebic encephalitis (PAM) is a devastating central nervous system infection caused by Naegleria fowleri, a free-living amoeba, which can survive in soil and warm fresh water. Here, a 43-year-old healthy male was exposed to warm freshwater 5 days before the symptom onset. He rapidly developed severe cerebral edema before the diagnosis of PAM and was treated with intravenous conventional amphotericin B while died of terminal cerebral hernia finally. Comparing the patients with PAM who has similar clinical symptoms to those with other common types of meningoencephalitis, this infection is probably curable if treated early and aggressively. PAM should be considered in the differential diagnosis of purulent meningoencephalitis, especially in patients with recent freshwater-related activities during the hot season.

• Parasites, Hosts and Diseases
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• 제61권2호
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• pp.183-193
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• 2023

Balamuthia mandrillaris amebic encephalitis (BAE) can cause a fatal condition if diagnosis is delayed or effective treatment is lacking. Patients with BAE have been previously reported in 12 provinces of China, with skin lesions being the primary symptom and encephalitis developing after several years. However, a significantly lower number of cases has been reported in Southwest China. Here we report an aggressive BAE case of a 64-year-old woman farmer with a history of skin lesions on her left hand. She was admitted to our hospital due to symptoms of dizziness, headache, cough, vomiting, and gait instability. She was initially diagnosed with syphilitic meningoencephalitis and received a variety of empirical treatment that failed to improve her symptoms. Finally, she was diagnosed with BAE combined with amebic pneumonia using next-generation sequencing (NGS), qRT-PCR, sequence analysis, and imaging studies. She died approximately 3 weeks after the onset. This case highlights that the rapid development of encephalitis can be a prominent clinical manifestation of Balamuthia mandrillaris infection.

• Parasites, Hosts and Diseases
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• 제51권2호
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• pp.203-206
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• 2013

After bathing at a hot spring resort, a 75-year-old man presented to the emergency department because of seizure-like attack with loss of conscious. This is the first case of primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri in Taiwan. PAM was diagnosed based on detection of actively motile trophozoites in cerebrospinal fluid using a wet-mount smear and the Liu's stain. The amoebae were further confirmed by PCR and gene sequencing. In spite of administering amphotericin B treatment, the patient died 25 days later.

• Parasites, Hosts and Diseases
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• 제49권3호
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• pp.285-290
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• 2011

Naegleria fowleri, a ubiquitous free-living ameba, causes fatal primary amebic meningoencephalitis in humans. N. fowleri trophozoites are known to induce cytopathic changes upon contact with microglial cells, including necrotic and apoptotic cell death and pro-inflammatory cytokine release. In this study, we treated rat microglial cells with amebic lysate to probe contact-independent mechanisms for cytotoxicity, determining through a combination of light microscopy and scanning and transmission electron microscopy whether N. fowleri lysate could effect on both necrosis and apoptosis on microglia in a time- as well as dose-dependent fashion. A $^{51}Cr$ release assay demonstrated pronounced lysate induction of cytotoxicity (71.5%) toward microglial cells by 24 hr after its addition to cultures. In an assay of pro-inflammatory cytokine release, microglial cells treated with N. fowleri lysate produced TNF-${\alpha}$, IL-6, and IL-$1{\beta}$, though generation of the former 2 cytokines was reduced with time, and that of the last increased throughout the experimental period. In summary, N. fowleri lysate exerted strong cytopathic effects on microglial cells, and elicited pro-inflammatory cytokine release as a primary immune response.

• 한국동물위생학회지
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• 제42권4호
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• pp.169-175
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• 2019

Naegleria fowleri, a pathogenic free-living amoeba, leads to a fatal infection known as primary amebic meningoencephalitis (PAM) in human and animals. PAM is an acute, fulminant, necrotizing, and hemorrhagic disease that leads to death in approximately seven days. In this study, we investigate the cytotoxicity of target cells and the secreted molecules of N. fowleri under the non-contact condition. The target cell (U87MG cell) treated with N. fowleri lysates showed no morphological changes and no cytotoxicity. By contrast, the U87MG cells co-cultured with N. fowleri trophozoites under the non-contact condition induced morphological changes and reduction in number. When U87MG cells were co-cultured with N. fowleri trophozoites under the non-contact condition for 30 min, 2 hr, and 4 hr, the levels of cytotoxicity of target cells were 32.3, 35.5, and 37.8%, respectively. Particularly, when the ratio of amoeba to target cells is 10 to 1, the level of cytotoxicity of target cells was 49.7% at 30 min. To show the proteins secreted from N. fowleri under the non-contact condition, we carried out 2D electrophoresis and observed 6 major proteins. Finally, these results suggest that the molecules released from N. fowleri under the non-contact condition induce the cell death and this process is an important step in pathogenesis of N. fowleri.

• Parasites, Hosts and Diseases
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• 제46권4호
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• pp.217-221
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• 2008

Free-living Naegleria fowleri leads to a fatal infection known as primary amebic meningoencephalitis in humans. Previously, the target cell death could be induced by phagocytic activity of N. fowleri as a contact-dependent mechanism. However, in this study we investigated the target cell death under a non-contact system using a tissue-culture insert. The human microglial cells, U87MG cells, co-cultured with N. fowleri trophozoites for 30 min in a non-contact system showed morphological changes such as the cell membrane destruction and a reduction in the number. By fluorescence-activated cell sorter (FACS) analysis, U87MG cells co-cultured with N. fowleri trophozoites in a non-contact system showed a significant increase of apoptotic cells (16%) in comparison with that of the control or N. fowleri lysate. When U87MG cells were co-cultured with N. fowleri trophozoites in a non-contact system for 30 min, 2 hr, and 4 hr, the cytotoxicity of amebae against target cells was 40.5, 44.2, and 45.6%, respectively. By contrast, the cytotoxicity of non-pathogenic N. gruberi trophozoites was 10.2, 12.4, and 13.2%, respectively. These results suggest that the molecules released from N. fowleri in a contact-independent manner as well as phagocytosis in a contact-dependent manner may induce the host cell death.

• Parasites, Hosts and Diseases
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• 제26권1호
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• pp.39-44
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• 1988

비장적출된 BALB/c 마우스에 동종항원으로 면역접종하였을 때 병원성 자유생활 아메바, 즉 점천간출a fowzeri o 359의 감염에 의한 사망률, 생존기간을 항체생성과 관련하여 관찰함으로써 비 장적출이 숙주의 체액성 면역기전에 어떤 영향을 미치는지 관찰하였다. 실험 I군은 비장을 적출하고 면역후 감염, II군은 비장적출후 감염, 여군은 면역후 감염, 사군은 대조군으로서 감염만시킨 군 등으로 구분하여 5~10${\times}$105 아메바를 1주 간격으로 2회 복강내에 주입하여 면역접종하였으며 2회 접종 1주 후에 5~10${\times}$104 아메바를 비강내에 감염시켜 감염 31일까지 관찰하였다. 감염후 사망률은 면역된 I 및 III군에서 각각 38.1% 및 25%로 II군 50%나 IV군 46.4%에 비해 낮았다. 사망한 마우스의 평균 생존기간은 I군 $20.1{\pm}3.6$일, II군 $17.3{\pm}4.5$일, III군 $20.4{\pm}7.0$일 및 비군 $19.6{\pm}7.6$일로 각 실험군간에 차이가 없었다. 감염 31일 후 혈중 IgG 항체가(ELISA치)는 면역군인 I군 및 III군에서 각각 $1.10{\pm}0.29$ 및 $1.31{\pm}0.28$로 대조군의 $0.24{\pm}0.37$보다 훨씬 높았다 (p<0.05). 이러한 성적으로 보아 비장적출 마우스에서 면역후 N. fowleri를 감염시켰을 때 마우스 생존기간의 차이는 없으나 사망률은 면역시킨 군에서 낮아 비장적출후에도 체액성 면역 이 방어기전으로 존재하는 것으로 생각되었다.