Ctenocephalides felis (the cat flea) is the most common ectoparasite of dogs and cats worldwide. In the United States and Europe, pet owners spend more than 1 billion dollars and 1.1 billion euros respectively on flea control products. The development of novel products, such as selamectin, fipronil, imidacloprid, nitenpyram, and insect growth regulators/juvenile-hormone analogues has revolutionized the approach to flea control in pets. Studies on the biology of fleas have revealed that both male and female fleas must feed to reproduce. Males feed within an hour of finding a host and females feed within 5 minutes, and both will feed for up to 25 minutes. In addition, the larval stages of fleas, which are present in flea excreta, can be killed by contact with and/or ingestion of these newer parasiticidal agents. The application of spot-on therapies to the neck is supported by studies documenting that the largest number of fleas are found on the head and neck. Selemectin, fipronil, and imidacloprid provide effective flea control for at least 1 month and often longer. Modern flea control programs advocate on-animal treatment only. One of the newest findings is that flea allergy dermatitis (FAD) can be managed through flea control. The severity of clinical signs will dictate the level of flea control needed, but in brief, products that kill rapidly (e.g., nitenpyram) and prevent flea feeding (e.g., deltamethrin shampoo, permethrins) are most effective. Fipronil, selamectin, and imidacloprid also decreased pruritus and lesion scores in dogs with FAD. Currently there is no evidence of the development of insecticidal resistance.

COMMENTARY: This is a well-written review of current flea control products. The authors summarize the major efficacy studies, with the bottom line being that all such products are effective for at least 1 month. The most important change in flea control over the past decade has been the shift from treating the animal and the environment (inside and outside) to just treating the animal. Given the increasing concern about human exposure to chemicals and insecticides and the uncertainty of risks of long-term exposure, this is an important change.

Advances in the control of Ctenocephalides felis (cat flea) on cats and dogs. Rust MK. TRENDS IN PARASITOLOGY 21:232-236, 2005.