Molecular epidemiology of Giardia spp. in northern Vietnam: Potential transmission between animals and humans

Hanako Iwashita; Tetsuhiro Sugamoto; Taichiro Takemura; Asako Tokizawa; Thiem Dinh Vu; Tuan Hai Nguyen; Tho Duc Pham; Na Ly Tran; Hang Thi Doan; Anh Hong Quynh Pham; Tetsu Yamashiro

doi:10.1016/j.parepi.2020.e00193

Molecular epidemiology of Giardia spp. in northern Vietnam: Potential transmission between animals and humans

Parasite Epidemiol Control. 2020 Dec 24:12:e00193. doi: 10.1016/j.parepi.2020.e00193. eCollection 2021 Feb.

Authors

Affiliations

¹ Department of International Affairs and Tropical Medicine, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan.
² International Programs, Japan Anti-Tuberculosis Association, 3-1-24 Matsuyama, Kiyose-shi, Tokyo 204-8533, Japan.
³ Vietnam Research Station, Center for Infectious Disease Research in Asia and Africa, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki-shi, Nagasaki 852-8523, Japan.
⁴ Research Center for Child Mental Development, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka 431-3192, Japan.
⁵ National Institute of Hygiene and Epidemiology, No.1 Yersin Street, Hai Ba Trung District, Hanoi 10000, Viet Nam.
⁶ International hospital Vinmec Times City, 458 Minh Khai, Vinh Tuy, Hai Ba Trung, Ha Noi, Viet Nam.
⁷ Division of Bio-Medical Science & Technology, Korea University of Science and Technology (UST), Daejeon 34113, Republic of Korea.
⁸ Department of Bacteriology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishiharacho, Okinawa 903-0215, Japan.

Abstract

Giardia spp. is detected frequently in humans and animals. Although many studies have been conducted on the epidemiology of giardiasis, there is a scarcity of information on the genetic diversity and the dynamics of transmission of Giardia spp. in Vietnam. The zoonotic potential of Giardia spp. remains elusive. The objective of this study was to determine the genetic diversity of Giardia spp. in both humans and livestock to assess the existence of a route of infection between livestock and humans. Our goal was to assess the role animals play in the epidemiology of human infection in northern Vietnam. In Hien Khanh commune in northern Vietnam, 311 households with 1508 residents were randomly selected for a diarrheal cohort study. Of these, 2120 human diarrheal samples were collected from 1508 residents in 2014 and 2017. Of these, non-diarrheal samples were cross-sectionally collected from 471 residents. At the same site, livestock samples from buffalo, dairy and beef cattle, pigs, and dogs were collected. All stool samples were examined for Giardia spp. by Direct Immunofluorescence Assay (DFA) using fluorescent microscope. DNA extraction, PCR analysis of the 3 genes (bg, gdh, tpi), and sequencing analysis were continuously carried out. A total of 23 animal stool samples, 8 human non-diarrheal samples, and 36 human diarrheal samples were Giardia spp. were positive by PCR using the bg and gdh genes. Giardia spp. assemblage AII and E were detected in both animal samples and human samples in this study site. The detection of assemblage E in human stool samples suggests the first human case report in Vietnam. We assume that the unexpected human infection of all Giardia assemblages including A, B, and E may be due to an environment contaminated with animal and human feces in this village.

Keywords: Assemblage A; Assemblage E; DFA, Direct Immunofluorescence Assay; Giardia spp.; Northern Vietnam; Zooanthroponotic transmission; Zoonotic transmission; bg, beta-giardin; gdh, glutamate dehydrogenase; tpi, triose phosphate isomerase.