Study of Tree-sparrow (Passer montanus) as Natural Spreader of H5N1 Virus

To understand sparrow‘s ability in spreading H5N1 avian influenza virus, especially compared to backyard chicken, we performed an experimental infection study. Nine sparrows and backyard chickens were inoculated with H5N1 viruses isolated from sparrow and chicken. We observed the incubation period, clinical signs, and time of death after the exposure. We also carried out pathological anatomy and examined any histopathologyical changes. The results indicate that sparrows are more resistant to the H5N1 virus infection than chicken. The striking organ changes of sparrows died because of the virus infection were lungs and brains haemorrhage. Lung damage seemed to be the main cause of the chicken's death. Neuronal necrosis and gliosis seemed to cause the torticollis of sparrow. The H5N1 virus isolated from sparrow that was more virulent against sparrow than the virus isolated from chicken indicate the occurrence of sparrow's adaptation with the sparrow virus. Based on the longer incubation period and later time of death of sparrows after the virus infection than of chickens, and their ability to fly, we concluded that ability of sparrow to spread H5N1 virus was higher than that of backyard chicken.