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Averting Danger: A Case of Anaphylaxis to Rabavert®
Saturday, March 5, 2016
South Exhibit Hall H (Convention Center)
Sarah W. Spriet, DO, Taylor A. Banks, MD, Cecilia Mikita, MD MPH FAAAAI
Rationale: Rabies post-exposure treatment is a medical necessity. Two rabies vaccines are available in the United States; purified chick embryo cell culture vaccine (PCECV, RabAvert®) and gelatin-free human diploid cell vaccine (HDCV, Imovax®). We report a case of PCECV-triggered anaphylaxis.

Methods: After clinical evaluation, patient and a volunteer control underwent skin prick and intradermal testing to the rabies vaccines, vaccine components, and rabies immunoglobulin. Vaccine challenge was then performed.

Results: A healthy 15 year old male presented to the Emergency Department after a live bat was found in his home, captured, and found to have rabies. Mucous membrane exposure could not be ruled out and human rabies immunoglobulin (Imogam Rabies – HT®) and PCECV were administered. Within minutes, he developed dyspnea, stridor and generalized hives. Symptoms resolved within one hour after treatment with antihistamines and IV corticosteroids and he was referred to Allergy-Immunology.            
      On day 3 post-exposure, patient and control underwent skin prick testing to undiluted PCECV, egg, gelatin, HDCV and Imogam. Skin prick was positive to PCECV and gelatin. Intradermal testing (IDT) using 0.02 mL of 1:100 dilution to HDCV and Imogam was negative. IDT using 0.02mL of 1:10 dilution was negative to Imogam, positive to HDCV; however, considered an irritating dose given identical results in control. Patient tolerated a 10/90 challenge to HDCV and completed post-exposure series using this vaccine.  

Conclusions: Skin test results and successful challenge to HDCV suggest gelatin allergy. Awareness of the potential for IgE-mediated reactions to rabies vaccine is important. Challenge to HDCV should be considered in select patients.