Flea bite hypersensitivity
Definition
Flea bite hypersensitivity is a puritan dermatosis due to an immediate and/or delayed cell mediated response to several proteins present in flea saliva.
Etiology
Hypersensitivity to ctenocephalides felis felis is probably the common cause skin disease in dogs and cats.
Pathophysiology
An immediate type 1 hypersensitivity, a late phase IgE mediated reactions, cutaneous basophil hypersensitivity may all be responsible for the occurrence of Flea bite hypersensitivity.
Clinical presentation
Clinical sign in the dog include a papular, puritan dermatitis of tail head, lower back, perineum, hind limb or umbilical areas and usually a superficial pyoderma. Otitis externa may be present. In the cat symptoms may be similar or include miliary dermatitis, symmetric alopecia or eosinophilic plaque.
Common secondary problem in the dogs include otitis externa and superficial pyoderma and in the cats include eosinophilic plaque and indolent ulcer. Vigilance for these problems as well as flea eradication must be maintained in order to keep purities below its threshold in the flea hypersensitive pets.
Differential diagnosis
Cheyletiellosis, pediculosis, sarcoptic mange, trombiculidiasis, superficial staphylococcal pyoderma, etopic otodectes cyanotic infestation, lynxacarus radovsky infestation, Dermatophytosis.
Diagnosis
Diagnosis is achieved ultimately by resolution of symptoms with flea eradication. Many of newer flea adulticides and insect development inhibitors or insect growth regulators make flea eradication quite feasible. A diagnosis supportive of Flea bite hypersensitivity can made with compatible clinical sign, the presence of fleas or flea dirt, recent evidence of dipylidium caninum or a positive intradermal skin or serum allergy test. Inspect other household pets for a flea is possible.
Evidence of fleas will be difficult to find in patients that have been bathed prior to examination. An animal that displays a negative immediate intradermal skin test (IDTS) with flea antigen still be hypersensitive. Observe delayed intradermal skin test (IDTS) reactions in 24-48 hours.
Management
By virtue of their constant obsessive grooming, puritan animals remove most fleas from themselves. An adult flea survives less than 24-48 hours on allergic animal. Even very minimal exposure may be sufficient to perpetuate purities in the hypersensitive patient. Other animal (especially cats) in the environment may be “carrier”. These animals seed the environment with preadult fleas which then emerge continuously to affect the allergic pets. Topical flea products with repellant activity may be required in many hypersensitive patients. Environmental flea eradication is often necessary as well. A rush immunotherapy protocol over a four month period with ctenocephalides felissalivary antigen shows promise as a therapy for flea bite hypersensitivity in dogs. This proprietary product control clinical sign and purities significantly better than placebo in hypersensitive dogs
( source Flea bite hypersensitivity )
