Study on Acanthamoeba spp. in Mosquitoes of Taiwan
Date Issued
2016
Date
2016
Author(s)
Shen, Yu-Chun
Abstract
Free-living amoebae (FLA) are ubiquitous in soil and water, and can complete their life cycle without host. These opportunistic microbes can infect human host and cause severe human diseases, such as fatal encephalitis, keratitis, and infections of skin, lung and sinus. Previous study in Brazil indicated that 90.0% (54/60) of pooled samples (10 larvae) of Aedes aegypti larvae were detected with FLA, and 78.3% (47/60) of pooled sample were detected with genus Acanthamoeba. Whether the distribution of FLA in mosquitoes or not is still unknown. According to Taiwan Centers for Disease Control’s reports, the FLA related diseases in Taiwan are mainly caused by Acanthamoeba and the case number of amebic skin abscess was highest in Taoyuan City which compare to other cities with unknown source origin. In this study, mosquito larvae were collected from agricultural fields in Taoyuan City and were detected with Acanthamoeba by molecular method. The positive rate, species gene diversity and seasonal difference of Acanthamoeba were also analyzed. In this study, five species of Acanthamoeba, including A. hatchetti (identity: 100.0%; 416/416), A. griffini (identity: 99.5%; 417/419), A. castellanii (identity: ≥ 99.3%; 413/417), A. polyphaga (identity: 98.0%; 395/403) and Acanthamoeba sp. (identity: 99.3%; 406/409) were identified from water samples in ditch and a small pool. In the field surveillance, the total positive rate of Acanthamoeba in mosquito larvae and pupae in Taoyuan City was 9.2% (23/249). The positive rate in different Districts were 62.5% (5/8) in Pingzhen District, 14.6% (6/41) in Taoyuan District, 14.2% (2/14) in Guanyin District, 9.8% (5/51) in Daxi District, 8.1% (3/37) in Yangmei District, 5.0% (1/20) in Guishan and 3.2% (1/31) in Longtan. Luzhu (0/3), Zhongli (0/7), Dayuan (0/16) and Xinwu District (0/21) were not detected with Acanthamoeba. Positive rate of Acanthamoeba between Districts was significant different (p=0.005). The proportion of mosquito pupae in all samples was 15.7% (39/249). There were 6 positive samples in mosquito pupae. The positive rate of Acanthamoeba in Culex species, Aedes species and Armigeres species were 12.3% (17/138), 6.8% (5/73) and 2.6% (1/38), respectively. Positive rate in Culex between Districts was significant different (p=0.003), but positive rate in Aedes (p=0.540) and Armigeres (p=1.000) was not significant different between Districts. And positive rate of Acanthamoeba between three mosquito genus was not significant different (p=0.133). 23 isolates of Acanthamoeba species were detected in this study. They belonged to three kinds of Acanthamoeba and two of them were pathogenic to human, including Acanthamoeba sp. T4 and A. castellanii. The sequence Identity were 100.0% (419/419) and 99.8% (416/417) respectively. The former were from water sample, and the latter were from pupae of Aedes albopictus, larvae and pupae of Culex quinquefasciatus. Mosquito adults were not detect with Acanthamoeba. Prevalence of Acanthamoeba was mainly in spring and summer, and the positive rate were 18.8% (6/32) and 9.4% (17/181), respectively. Acanthamoeba were not detected in autumn and winter, when heavy rain, typhoon Chan-Hom and Soudelor appeared. There was no significant difference in positive rate of Acanthamoeba between four seasons (p=0.084), but there was a significant decrease after spring (p=0.011). Acanthamoeba were discovered in mosquito larvae and pupae in Taoyuan City. People who working in the agricultural fields need more notice to their hand hygiene after using the water from water containers. The potential dispersal of Acanthamoeba by mosquitoes need further research.
Subjects
Free-living amoeba
Acanthamoeba
mosquito
SDGs
Type
thesis