Bartonella henselae is the gram-negative aerobic bacilli associated with the syndrome of cat scratch disease in immunocompetent humans. Ctenocephalides felis, the cat flea, is the vector for B. henselae. Infection is common in naturally exposed cats and their fleas, and >30% of cats with fleas are bacteremic. The objective of this study was to determine if monthly topical administration of a combination of 10% imidacloprid and 1 % moxidectin would lessen flea transmission of B. henselae among cats. Eighteen cats were housed in 3 groups of 6 cats. Each of the groups were placed in enclosures separated by mesh to allow fleas to pass among groups yet prevent cat-to-cat contact. The middle group of cats was inoculated with B. henselae and infection was confirmed. This group was flanked on one side by a group treated topically with 10% imidacloprid-1% moxidectin monthly for 3 months, and on the other side by an untreated group. Fleas were placed on the B. henselae infected group at periodic intervals. Blood samples were collected from all the cats weekly to detect Bartonella spp via PCR assay, bacterial culture, and serologic assay. B. henselae infection was confirmed in all untreated cats after flea exposure following the confirmed infection in the inoculated group. None of the cats treated with imidacloprid-moxidectin combination became infected. The results showed that a monthly topical administration of 10% imidacloprid-1% moxidectin reduces the flea load and thus prevented flea transmission of B. henselae to treated cats. Therefore, the likelihood of humans acquiring B. henselae infection may be lessened through monthly use of this flea control product in cats. [VT]
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