Allergy to flea bites

Abstract

• 1. Domestic flea species prevalent in human habitations in the San Francisco Bay area were primarily Pulex irritans (L.) and Ctenocephalides felis Bouché.

• 2. Flea bite tests on human subjects, undergoing routine testing for unclassified allergies, were made with the above-named species plus one additional flea, Pulex simulans Baker, closely related to P. irritans.

• 3. It was found that reactions to flea bites consisted of an extravasated flaring reaction not connected with the hypersensitive state, immediate 20-minute whealing reactions with or without solar erythema, and delayed 24-hour reactions consisting of induration or papule formation with or without accompanying erythema or vesicle formation. Occasional delayed reactions culminated in erythematous multiform-like bullous eruptions in from 48 to 72 hours. Immediate and delayed reactions did or did not accompany each other. In 63% of the positive tests obtained, delayed reactions occurred unaccompanied by immediate whealing or erythematoid reactions. However, only rarely were positive immediate reactions unaccompanied by delayed reactions.

• 4. A larger proportion of male than female subjects exhibited delayed reactions to flea bites. A similar trend was noticeable with respect to immediate reactions but was not statistically significant.

• 5. Younger age groups of both males and females were more sensitive than older age groups to the bites of fleas with respect to the delayed reaction. The same trend was indicated with respect to the immediate reaction but was not statistically verifiable.

• 6. The responses of different individuals to the bites of all three species of fleas were positively correlated; i.e., subjects showing immediate or delayed responses to one species usually exhibited immediate or delayed responses to the two other species.

• 7. In general, the sensitivity of the subjects was greater to bites of P. irritans than to P. simulans or C. felis when measured either by immediate or delayed reactions.