SURVEILLANCE OF INFLUENZA A VIRUSES IN AVIAN AND CANINE SPECIES IN YANGON AND NAY PYI TAW, MYANMAR

Abstract

This dissertation contains influenza surveillance programs conducted in two animal species, poultry and dogs, in Myanmar. In poultry, the study included virological and serological influenza surveillances. In dogs, the study included virological and serological influenza surveillances as well as epidemiological analysis (association study). In poultry, 14-month influenza surveillance program was conducted in Live-bird Markets (LBM) in Yangon and Namkham, Myanmar. One thousand two hundred and seventy-eight (1,278) swab samples were collected from chickens (n=703), ducks (n=380), and environments (n=195) and tested for influenza A virus (IAV). The occurrence of IAV in poultry was 5.71% (73/1,278). Interestingly, three IAV subtype H9N2 were isolated from chicken in Namkham, upper Myanmar. Genetic analysis of the IAV-H9N2 revealed that the viruses posed low pathogenicity characteristics and closely related with IAV-H9N2 isolated from China during 2013-2015. For serological surveillance in poultry, 8-month influenza surveillance program was conducted in Yangon LBM during February to September 2016. Six hundred twenty-one (621) serum samples were collected from chickens (n=489) and ducks (n=132). The occurrence of IAV antibodies was 12.8% (80/621). Out of 80 ELISA-positive samples, 9 samples were subtyped as H5N1 and 15 samples were subtyped as H9N2 by HI test. In dogs, 12-month influenza surveillance program was conducted in Yangon and Nay Pyi Taw areas, Myanmar. The study was conducted in dogs in four townships of Yangon and Nay Pyi Taw during June 2014 to May 2015. The occurrence of canine influenza A virus (CIV) in dogs was 21.2% (43/203) by real-time RT-PCR. It is noted that no virus could be isolated from dogs. For serological surveillance in dogs, the occurrence of CIV antibodies was 11.8% (24/203). In association analysis of CIV infection in dogs, the results showed that the occurrence of CIV infection in dogs was statistically significant associated with respiratory symptoms (p=0.004; OR=2.92; 95% CI=1.387 – 6.143), poor body condition score (p=0.015; OR=3.02; 95% CI=1.319 – 6.895), season of sampling (p=0.001; OR=8.31; 95% CI=3.224 - 21.426), and vaccination against influenza viruses (p=0.008; OR=9.69; 95% CI=1.283 - 73.24). In association analysis of CIV antibodies, the results showed that the occurrence of CIV antibodies was statistically significant associated with respiratory symptoms (p=0.009; OR=3.16; 95% CI= 1.291 – 7.735) and season of sampling (p=0.001; OR=4.583; 95% CI= 1.804 – 11.645). In this study, the presence of respiratory symptoms and poor body condition scores were statistically significant correlated with test results of RT-PCR and ELISA (p<0.05). In conclusion, this dissertation reported the molecular characteristics of IAV H9N2 in Myanmar, and epidemiological information of CIV infection in dogs in Myanmar. Our findings provide insight information regarding influenza A virus infections in animals. Therefore, routine surveillances and genetic characterization of IAVs in animals should be conducted at local, regional and national levels to monitor the emergence of IAVs in animal population. Public health awareness of IAV infection in humans in Myanmar should be provoked to a higher extent and surveillance of IAV infection at human-animal interface is deemed necessary. Collaborative works are needed between authorities to minimize the spread of IAVs across the regions. Findings and recommendations from this study will be useful for prevention and control measures of IAV infections in Myanmar in the future.