Hypersensitivity to airborne spitting cobra snake venom.
BACKGROUND
Although the cytolytic, neurotoxic, and hemolytic actions of snake venoms are well known, the ability of airborne inhaled snake venom of the spitting cobra to induce asthma in snake handlers has not been reported.


OBJECTIVE
To report the allergenicity of inhaled snake venom in a snake handler who developed increasing hypersensitivity to airborne venom, produced by spitting cobras during public demonstrations.


METHODS
Serum samples were obtained from 2 handlers (our study patient and another snake handler who reported developing wheezing when handling spitting cobras), and desiccated venom was obtained from 9 species to which the handlers were exposed. Serum from an asymptomatic and nonatopic snake handler exposed to the same snake species was used as a control. Phosphate-buffered saline extracts were prepared from the desiccated venom, proteins in the venom extracts were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunoblotting was performed. Inhibition enzyme-linked immunosorbent assays (ELISAs) were performed to demonstrate cross-reactivity.


RESULTS
The study patient had never been previously bitten by a cobra. Wheezing occurred rapidly on inhalational exposure and was reversed by inhalation of salbutamol. The patient had developed IgE antibodies to 9 different snake venoms on Western immunoblots, with major IgE binding proteins of 59 to 63 kDa and 8 to 15 kDa. The cross-reactive nature of the IgE epitopes in the venoms in the different species was also confirmed by 50% inhibition of IgE binding in an ELISA by preincubation with unrelated species. Life-threatening sensitivity of the patient was sustained after a long period of avoidance.


CONCLUSIONS
We propose that aerosolized snake venom be considered a new potential source of allergens that may result in anaphylaxis on subsequent exposure. Further studies of the development of specific IgE sensitization following snakebites and the risks of such sensitization should be conducted on snake handlers, particularly those who demonstrate the spitting species.
Prescott
Ruth A
RA
Department of Immunology, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa. rprescot@uctgshl.uct.ac.za
Potter
Paul C
PC
D000280:Administration, Inhalation; D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects* / Q000737:chemistry / Q000276:immunology; D000420:Albuterol / Q000008:administration & dosage / Q000627:therapeutic use; D000818:Animals; D000906:Antibodies / Q000097:blood; D001993:Bronchodilator Agents / Q000627:therapeutic use; D004546:Elapid Venoms / Q000009:adverse effects* / Q000737:chemistry / Q000276:immunology; D017815:Elapidae / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000188:drug therapy / Q000209:etiology* / Q000276:immunology; D007114:Immunization; D007073:Immunoglobulin E / Q000097:blood; D019570:Inhalation Exposure / Q000009:adverse effects*; D008297:Male; D008970:Molecular Weight; D016273:Occupational Exposure / Q000009:adverse effects*; D012307:Risk Factors; D012909:Snake Bites / Q000276:immunology
D000393:Air Pollutants; D000906:Antibodies; D001993:Bronchodilator Agents; D004546:Elapid Venoms; D007073:Immunoglobulin E; D000420:Albuterol