Rabies kills more than 25 000 people each year in India,1 where stray dogs are mainly responsible for transmission.2 Almost half a million people receive prophylaxis after being bitten.3 Documented cases of dogs outliving their victims in India and other developing countries suggest a possible chronic excretor state for the virus, which complicates the standard management.

Examples of such cases include a dog that remained alive for one month after biting a man, who died of rabies.4 After the death of another patient from rabies the dog that bit him was kept under observation at the Pasteur Institute, Coonoor, from 1966 until it died three years later.5 Prolonged investigations were possible: 913 saliva samples were tested by the fluorescence antibody technique and animal inoculation test, and rabies virus was isolated on 14 …