Rabies Antibody Seroprotection Rates Among Travelers in Nepal: “Rabies Seroprotection in Travelers”

Abstract

Rabies preexposure immunization is recommended for international travelers who are at risk for exposure to rabid animals, especially in areas where postexposure treatment may be limited. Rabies antibody seroprotection rates among international travelers has not been previously investigated. To assess preexisting rabies seroprotection among travelers presenting to a health clinic in Nepal. A prospective convenience sample of international travelers evaluated at a health center in Kathmandu, Nepal during a 2-month period. Subjects were eligible for inclusion if they had received rabies preexposure vaccination within the previous 5 years. Demographic information and vaccination records of rabies preexposure prophylaxis were obtained. Consenting subjects provided serum for rabies antibody measurement measured using the rapid fluorescent focus inhibition test. A dilution greater than or equal to 1:5 (0.5 IU/mL) was considered positive. Data were analyzed using chi-squares and two-sample t-tests with unequal variances. A total of 43 patients consented to enroll. Complete data were available for 38 patients. Subjects had received human diploid cell vaccine (HDCV) or purified Vero cell rabies vaccine (PVRV) vaccine, either via the intradermal or intramuscular route. All patients had adequate antibody titers except one, who had a titer below 0.5 IU/mL. There was no statistically significant relationship between antibody titer and type of vaccine, route of administration, time since vaccination, number of vaccinations, or patient age. Among 38 travelers to Nepal who had received documented preexposure rabies HDCV or PVRV vaccination series, 37 demonstrated adequate titers of > or =0.5 IU/mL and would be considered boostable if exposed to rabies virus. One traveler had a titer of <0.5 IU/mL. Type of vaccine, method of administration, number of vaccinations, and time since vaccination did not influence rabies antibody titer. Rabies vaccination with HDCV and PVRV vaccine was effective in stimulating adequate seroprotection in this sample of travelers.