Thiravat Hemachudha

Failure of rabies postexposure treatment in Thailand

Three failures of postexposure rabies treatment using imported purified duck embryo cell and Vero cell rabies vaccines are reported from Thailand. Reference is made to eight additional previously reported Thai patients, six of whom had received human diploid cell vaccine. An analysis of these cases reveals that there were serious flaws in management in all of these patients. It is stressed that 45% of human rabies deaths in Thailand occur within 20 days of being bitten and 71% are dead within 28 days. This short incubation period does not allow much time to start immunotherapy. Of Bangkok dogs found to have rabies at autopsy, approximately 8% have a rabies immunization history. Once a dog has bitten a patient immunotherapy should not be delayed in countries with a high incidence of dog rabies. Patients with chronic disease, alcoholics and drug addicts may have an impaired immune response to postexposure rabies vaccines.

Immune response to rabies vaccine in Alaskan dogs: failure to achieve a consistently protective antibody response

Previous studies in Thailand and Tunisia have shown that one injection of dog pre-exposure rabies vaccine does not produce a lasting antibody titre in a significant group of animals. We therefore duplicated the Thai study in a small North American community using healthy, owned dogs. A tissue culture vaccine of known high antigenicity was given intramuscularly as one primary injection and antibody titres were determined by the rapid fluorescent focus inhibition test on days 14, 30, 60, 180 and 360. Titres were less than 0.5 i.u./mL in 27% of dogs bled at 2 months, 24% at 6 months, and in 33% one year after the primary vaccination. In rabies endemic regions, it may be hazardous to rely on the previous vaccine history of a biting dog when making post-exposure management decisions. A retrospective study of antibody levels in previously vaccinated dogs in North America also indicated that a single injection of vaccine often failed to result in adequate titres.

Postexposure Treatment of Rabies Infection: Can It Be Done without Immunoglobulin?

The last remaining international manufacturer of equine rabies immunoglobulin (ERIG) discontinued production in 2001. However, ERIG remains an essential biological that has no substitute other than human rabies immunoglobulin (HRIG), which is in short supply and virtually unaffordable in developing countries. Physicians in regions where canine rabies is endemic and neither ERIG nor HRIG is available are providing less-than-optimal treatment to patients exposed to rabies. If no immunoglobulin is available, they have only 1 therapy option: use of a vaccine schedule that produces the highest and, hopefully, earliest neutralizing antibody response. However, treatment failures must still be expected. Early, aggressive wound cleansing and more intensive efforts at canine control and are ever more important. Countries that have the resources to manufacture their own rabies immunoglobulins must be encouraged to do so.

Immune response to rabies vaccine in Thai dogs: A preliminary report

Serum neutralizing antibody to rabies virus was determined in previously unvaccinated Thai pet dogs after receiving one subcutaneous dose of inactivated tissue culture rabies vaccine (Rabdomun, Coopers Animal Health Company, Germany, 4.55 IU ml-1 potency). Geometric mean titres on days 14, 30, 60, 180 and 360 were 2.14, 2.30, 0.45, 0.14 and 0.05 IU ml-1, respectively, by the rapid immunofluorescent focus inhibition test. Titres of neutralizing antibody to rabies virus did not correlate with the age of the dog at the time of vaccination or with the presence or absence of anaemia or blood parasites. Six out of 50 (12%), 11 out of 43 (25.6%) and 13 out of 31 (42%) dogs had no detectable rabies antibody in serum 60, 180 and 360 days, respectively, after vaccination. Three of these antibody-negative dogs were given another dose of vaccine. Antibody reappeared on day 14 but rapidly declined within 60 days. These data suggest that one dose of tissue culture vaccine in dogs by the subcutaneous route of injection is not adequate to maintain rabies neutralizing antibody in serum for 1 year.

Rabies in a Thai child treated with the eight-site post-exposure regimen without rabies immune globulin.

We report the case of a 7-year-old Thai girl that was bitten by a dog. She received prompt wound care followed by eight-site intradermal post-exposure rabies schedule using purified chick embryo vaccine. Treatment followed WHO recommendations for desperate situations where no rabies immune globulin (RIG) is available. The patient died 15 days later with classical symptoms and signs of encephalitic rabies.