In relation rto the size of viral inoculum, influenzal infection in ferrets caused by the inoculation of a mouse-adapted subline of PR 8 strain of type A influenza virus was studied. The results are summarized as follows; 1) When ferrets were inoculated with a highly diluted virus (10-7), a small proportion of them experienced inapparent infections and the rest of them escaped the infection. 2) With the increased size of viral inocula, there was a good correlation between the size of infecting does and the frequency of overt infections in ferrets. 3) Nasal tissues were the main locus of viral multiplication in ferrets at 72 hours after viral inoculation. Viral multiplication in nasal tissues was demonstrated only in a small proportion of ferrets which were inocu1ated with a 10-7 dilution of virus; however, when the size of vira1 inoculum was increased above this level, all ferrets had viral growth in their nasal tissues. 4) The involvement of pulmonary tissues, viral growth in those tissues and the development of gross lung lesions were significantly rare. There was no dear-cut relationship between the size of infecting doses and the frequency of such plumonary involvements in ferrets.
Animal ; Carnivora ; Female ; Influenza/microbiology* ; Orthomyxoviridae*

OBJECTIVE: To investigate the prevalence of Echinococcus infections in wild carnivores in Serthar County, Sichuan Province, so as to provide insights into echinococcosis control in local areas. METHODS: Stool samples were collected from wild carnivores in Serthar County, Sichuan Province in May 2021, and the host sources of stool samples and Echinococcus infections were identified using PCR assays. The prevalence of E. multilocularis, E. granulosus and E. shiquicus infections was estimated in different hosts. RESULTS: A total of 583 stool samples were collected from wild carnivores, including 147 stool samples from fox, 154 from wolf, 227 from wild dogs and 11 from lynx. The overall prevalence of E. multilocularis, E. granulosus and E. shiquicus infections was 5.68%, 0.19% and 14.20% in canine stool samples, and no E. granulosus infection was detected in fox stool samples, while the prevalence of E. multilocularis and E. shiquicus infections was 0.68% and 47.62% in fox stool samples (χ² = 88.41, P < 0.001). No E. granulosus or E. shiquicus infection was detected in wolf stool samples, and the prevalence of E. multilocularis infection was 10.39% in wolf stool samples. The prevalence of E. multilocularis, E. granulosus and E. shiquicus infections was 5.73%, 0.44% and 2.20% in canine stool samples (χ² = 12.13, P < 0.01). In addition, the prevalence of E. multilocularis infections was significantly higher in wolf stool samples than in canine and fox stool samples (χ² = 13.23, P < 0.01), and the prevalence of E. shiquicus infections was significantly higher in fox stool samples than in canine and wolf stool samples (χ² = 187.01, P < 0.001). No Echinococcus infection was identified in 11 lynx stool samples. CONCLUSIONS The prevalence of Echinococcus infections is high in wild canines in Serthar County, Sichuan Province. Wolf, wild dog and fox all participate in the wild life cycle of E. multilocularis in Serthar County, and wolf and wild dogs may play a more important role.
Animals ; Dogs/microbiology* ; China/epidemiology* ; DNA, Helminth/genetics* ; Echinococcosis/veterinary* ; Feces ; Foxes/microbiology* ; Lynx/microbiology* ; Prevalence ; Wolves/microbiology* ; Carnivora/microbiology*