What Diseases Can Fleas Carry?

Per the Companion Animal Parasite Council (CAPC), this tapeworm requires a flea as an intermediate host to complete its life cycle. Pets get infected by swallowing an infected flea while grooming, and occasionally a young child does the same by accidentally ingesting a flea. Prevention is straightforward: strict, consistent flea control on the pet and in the environment.

Per CDC, cat-scratch disease spreads to people through scratches or bites from a cat whose claws or mouth are contaminated with flea feces; cats themselves catch the bacteria from flea bites. CDC notes that studies have found Bartonella bacteria in the blood of up to about 1 in 3 healthy cats, particularly kittens, but that testing and treating a cat for it isn't recommended unless the pet is actually sick. CDC's prevention advice centers on flea control, not declawing.

Per CDC, most US cases cluster in southern California, Hawaii, and southern Texas, and reported cases have risen since 2008 in those specific regions — but New Hampshire is not among the states seeing meaningful murine typhus activity. Naming it here is for completeness, not because it's a realistic local risk.

Per CDC, the US averages about seven human plague cases a year, almost entirely in the rural West (northern New Mexico, northern Arizona, southern Colorado, and parts of California, Oregon, and Nevada). It does not occur naturally in the eastern United States, and New Hampshire homeowners do not need to factor it into flea decisions.

Focus on the flea itself rather than a long list of exotic diseases. Consistent pet prevention (a vet decision) plus a professional home and yard treatment removes the pathway for both tapeworm and cat-scratch disease — the two illnesses actually worth planning around here.