Investigation of the role of healthy dogs as potential carriers of rabies virus.

　　Zhang YZ, Fu ZF, Wang DM, Zhou JZ, Wang ZX, Lv TF, Xiong CL, Zou Y, Yao WR, Li MH, Dong GM, Xu GL, Niezgoda M, Kuzmin IV, Rupprecht CE

　　Vector Borne Zoonotic Dis 2008 Jun 8(3):313-9 [] [] []

　　Healthy-looking dogs from a rabies endemic area of the Guizhou province in China were captured and rabies antigen was detected by ELISA in 15 (10%) of the dogs. RT-PCR tests over 6 months did not confirm the presence of viral antigen, nor did further testing of the brain post-mortem. This is evidence against the increasing trend to suspect that healthy dogs can transmit rabies in China.

　　There have been several reports in the Chinese literature of rabies virus infection of apparently healthy-looking dogs. Questions remain about the quality or interpretation of the methods used in these reports. The possibility that dogs can be 'carriers' of rabies and excrete infectious viruses has been debated for more than 50 years. The consensus opinion is that there is no good evidence that healthy dogs can transmit rabies {1}, but virus may be excreted in the saliva during the prodromal phase of the infection, which accounts for the recommendation to observe possibly rabid dogs for 10 days. A recent report of the detection of rabies antigen in the saliva of Chinese dogs by an ELISA test gave rise to this study, using the same commercial Chinese ELISA test. The work is an unusual collaboration between the Chinese and the American Centers of Disease Control. As rabies infection was not confirmed by alternative tests in saliva or the brain, the authors conclude that the results were false-positive. The ELISA kit was designed, validated and intended for use on brain samples only. It is clearly not suitable for testing saliva. A well-informed up-to-date review of the prevalence, problems and progress in rabies infection and control in China can be found in ref {2}, where the Chinese journal references are available in the paper.