A high rate of neurological complications following Semple anti-rabies vaccine

A fatal case of encephalitis due to Semple (phenolized sheep-brain) anti-rabies vaccine prompted a search for neurological complications among 722 recipients of 2 vaccine batches administered in Bangkok, Thailand in June and July 1984. A review of all patients admitted with neurological symptoms from June through August 1984 to the 5 major teaching hospitals in Bangkok found 6 cases (0.83%), including the index case, who had received the vaccine. Rabies infection was ruled out in all 6 cases. 4 patients had meningitis, and 2 had meningo-encephalitis. Only the index case was fatal; the other patients recovered without neurological sequelae. The rate of neurological complications after receiving Semple vaccine was therefore a minimum of 8.31 cases per 1000 persons vaccinated (1:120). This complication rate was about 25 times higher than the overall complication rate of 0.33 per 1000 (1:3018) determined from 14 previous reports. The fatality rate was 1.39 per 1000 (1:722), about 15 times higher than the rate of 0.09 per 1000 (1:10805) calculated from the previous studies. It is urgent to find economically feasible alternatives to Semple vaccine.