Targeted surveillance of potential zoonotic respiratory and enteric viruses in dogs in bangkok, Thailand

Abstract

Human-dog interface poses a risk of transmission and spread of zoonotic viruses. The objective of the thesis entitled is to survey and genetic characterize zoonotic viruses in dogs and humans who have high-risk occupations and in close contact with dogs. This thesis contains 8 topics. The results of the first to third topics were the surveillance of respiratory viruses in dogs including Canine Parainfluenza type 5 (CPIV-5), Canine influenza virus (CIV) and Coronavirus (CoV). The nasal swab samples were collected from dogs with respiratory signs during 2015-2018. The results showed that the occurrence of CPIV-5, CIV and CoV were 5.6% (32 /571), 1.4% (8/571) and 13.1% (75/571), respectively. The genetic analysis of CPIV-5 showed that Thai CPIV-5 were closely related with CPIV-5 from China and South Korea but they were different from Human PIV-5. The genetic analysis of CIV showed that Thai CIV subtype was pandemic H1N1/2009. The Thai CIV was closely related to pandemic H1N1/2009 infected in swine and human. This result suggested that dogs can be infected with pandemic H1N1/2009, which is reverse zoonotic event. The genetic analysis of CoV showed that canine respiratory coronaviruses (CRCoVs) were grouped into betacoronavirus which closely related to human CoV (HCoV-OC43) and bovine CoV. Thai CRCoVs were different from canine enteric coronaviruses of the genus alphacoronavirus. The TMRCA analysis indicated that Thai CRCoV was estimated to separate from HCoV-OC43 and BCoV with the most recent common ancestor since 2004. The results of the fourth to seventh topic were the surveillance of gastroenteric viruses in dogs including Kobuvirus (KoV), Norovirus (NoV), Rotavirus (RoV) and Canine parvovirus type 2 (CPV-2). These viruses can cause gastroenteric disease. Since some viruses have been reported zoonotic transmission. The rectal swab samples were collected from dogs with gastroenteritis signs. The occurrence of KoV, NoV, CPV-2, and RoV in dogs were 17.6% (54/307), 11.1% (2/18), 29.9% (133/444) and 0.7% (5/710), respectively. The genetic analysis of KoV in dogs showed that Thai-KoVs were closely related to KoV from China. The genetic analysis of NoV showed that Thai-NoVs in dogs belonged to genotype GII.Pe-GII.4 Sydney which is the common genotype causing NoV outbreaks in humans in Thailand. In this study, canine NoVs were detected from dogs living on the same premises with the confirmed human NoV case suggesting human-to-canine transmission. The genetic analysis of CPV-2, this study is the first report of CPV-2c in dogs and cats in Thailand. The genetic analysis of RoV showed that the genotype G3P[3] was a predominant genotype of RoV in dogs in Thailand. The pattern of genetic constellation of Thai RoVs was G3-P[3]-I3-R3-C3-M3-A9-N2-T3-E3-H6, which never been reported in dogs. The TMRCA analysis showed that Thai-RoV was estimated to separate from bat, human, and dog RoVs and subsequently generating novel RoV G3P[3]. The result of the eighth topic was the surveillance of respiratory and enteric viruses in human. Nasal swab, stool samples and questionnaire interview were obtained from 100 participants who had high-risk occupations and in close contact with dogs. The nasal swab samples were tested for influenza virus, parainfluenza virus and coronavirus, while stool samples were tested for coronavirus and rotavirus. The result of this study showed that CoV could be detected from two participants, while none of the other viruses (IAV, PIV and RV) could be detected. The genetic analysis of CoV showed that the human CoV belonged to alphacoronavirus of HCoV- 229E. The questionnaire interview showed that 52% of workers reported that they concern about the risk of zoonotic infection from dogs. Only 8% of participants reported using of gloves when working/contracting with sick dogs. However, this study involved a relatively small population with on one time sample collection. Therefore, a large population shoulde be perfprmed. The conclusion of this thesis, there are potential zoonotic respiratory and enteric viruses circulating in dogs in Thailand. Moreover, the genetic analysis of the viruses indicated that the viruses are rapid evolving especially after introduction of novel virus in the population and/or interspecies transmission. The information will be useful for people who have high-risk occupations such as veterinarians, vet assistants and owners. Moreover, these results provide information of the status, distribution, genetic characteristics of the viruses for the effective prevention and control of respiratory and enteric zoonotic viruses in dogs in Thailand.