Investigation of the Role of Healthy Dogs as Potential Carriers of Rabies Virus

Abstract

To investigate whether healthy animals are potential carriers of rabies virus in China, 153 domestic dogs were collected from a rabies enzootic area, Anlong county in Guizhou Province, and monitored for 6 months. Initially, findings of rabies virus antigen in the saliva of 15 dogs by an enzyme-linked immunosorbent assay (ELISA) test suggested they might be carriers. These 15 dogs were kept under observation for 6 months. None of the dogs showed any clinical signs of rabies during the observation period. Moreover, using the ELISA test alone, detection of rabies virus antigen in saliva of some animals was not consistent during the observation period. However, none of the saliva samples collected either at the time of acquisition or during the observation period was found to be positive for rabies virus RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). Furthermore, neither viral antigen nor viral RNA was detected in the brain samples collected at the time of euthanasia. These results do not provide support for the contention that healthy dogs act as carriers in rabies. Caution is urged when preliminary and nondefinitive tests, such as ELISA, are used to infer clinical status related to rabies.

Molecular Epidemiology of Reemergent Rabies in Yunnan Province, Southwestern China

“…Previous studies showed that in rabies-endemic areas, some apparently healthy dogs are infected with RABV ( 22 , 33 ). In the present study, of 1,162 brain samples from apparently healthy dogs in rabies-endemic areas, 40 (3.44%) were confirmed to be infected with RABV, which indicates that the virus will be disseminated by local dogs in any village containing even 1 rabid dog (Figure 3).…”

Reemerging Rabies and Lack of Systemic Surveillance in People’s Republic of China

“…Unfortunately, this possibility remains highly speculative. Although some investigators have questioned reports of a carrier state in dogs ( 17 ), an author reported RABV isolation from brains of healthy dogs ( 6 ). Carrier dog RABV isolates were even characterized at the molecular level in 1996 ( 15 ).…”

“…In a report by Zhang ( 17 ), 15 dogs that were diagnosed as positive by ELISA were confirmed to be negative by the standard direct fluorescent antibody (DFA) method. Explanations for these contradictory findings include misidentification of infected dogs, detection of RABV early in the prodromal course once it has reached the central nervous system after infection and incubation, and inadequate diagnostics.…”

Rabies in Asia: The Classical Zoonosis

“…Low rabies antibody has also been reported among Canadian Inuit (Eskimo) hunters (Orr et al 1988). The existence of asymptomatic rare dog virus carriers has been the subject of several controversial papers (Zhang et al 2008).…”