Cats are only able to spread Bartonella to humans if it is on their claws (or possibly teeth). Fleas are the chief reason that cats carry this bacteria since it is primarily spread by the bite of a flea. In order for a cat to transmit this infection to a person they must scratch at the fleas and pick up flea feces containing Bartonella on their claws. If there are no fleas then there will be no spread of the infection.
Most cats do not get very sick from Bartonella infection. Unless they have underlying health concerns, infected cats may not act ill at all when they get infected. There are several different tests for Bartonella in cats, each test having several pros and cons, and no test that is recommended as a general screening test. Cats that appear to be sick with a Bartonella-related illness may need more than one of the tests in combination to know what is going on with them. There are antibiotic medications available for cats that are sick from Bartonella and need treatment. The important thing to note is the Bartonella is very common in cats with fleas. In areas that get warm and humid weather which promotes flea reproduction (such as New England) as many as 40% of cats may test positive.
Prevention of cat scratch fever should be primarily aimed at flea control. Fleas are small and can fit through screens. All cats should be on flea control at all times, regardless if they go outside or not. There are currently available several safe products that kill fleas and can be used year-round. Regular use of a recommended flea prevention product can protect your family from Cat Scratch disease. Never use over the counter flea products unless your veterinarian tells you that the product is OK because there are many old-fashioned ones still available that are very toxic to cats.