They carry a rare bacteria in their mouths and claws which can be passed on to humans - with young children most at risk.
The disease, called cat scratch disease (CSD), is caught by kissing the cute pets or touching their fur and then touching your face.
A survey found contact with an infected cat can cause fever, pustules and in extreme cases, the complications from the illness can be fatal. The bug causes no harm to animals.
Researchers from the Centres for Disease Control and Prevention (CDC), Colorado, carried out a large-scale study over 15 years.
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According the the CDC, the disease is caused by a type of bacteria called Bartonella henselae, which cats can get infected with from flea bites, or droppings getting into their wounds.
Kittens are at higher risk than older cats as they have weaker immune systems.
The disease spreads when an infected cat licks a person’s open wound, or bites or scratches hard enough to break the surface of the skin.
Owners are being advised to wash their hands after touching cats - and to use flea control methods where possible.
Dr Christina Nelson, of the CDC, said: “The scope and impact of the disease is a little bit larger than we thought.
“Cat-scratch is preventable. If we can identify the populations at risk and the patterns of disease, we can focus the prevention efforts.”
Kittens are more likely to carry the bacteria, the experts warned - but cat owners should also be careful about their animals interacting with stray cats where possible.
The disease is relatively rare, with the scientists concluding the annual incidence of cat scratch fever was 4.5 outpatient diagnoses per 100,000 members of the population.
But side effects of the potentially deadly disease are getting worse. The report revealed 12,000 Americans a year succumb to the disease which causes fever, fatigue, headaches and swollen lymph nodes.
Five hundred require hospital attention and, in extreme cases, it can even cause brain swelling and heart infections.
Women and girls accounted for 62 per cent and 55.6 percent of outpatient and inpatient diagnoses, respectively.
Dr Nelson said: “The highest rates of outpatient diagnoses and inpatient admissions for cat scratch disease occur among children five to nine years of age.”
She added: “CSD causes a substantial burden of disease nationwide and disproportionately affects children.
“Because CSD is a zoonotic infection that is maintained and spread among cats by fleas, comprehensive flea control for cats can help reduce the risk for human infection.
“Risk may also be reduced by washing hands after contact with cats, to remove potentially infectious flea faeces that could enter breaks in the skin.
“Furthermore, because cats that hunt outdoors are at substantially greater risk for B. henselae bacteremia, limiting hunting activity of cats may reduce risk for human infection.
“Educational efforts should focus on cat owners, particularly those with children in the household or those with immunocompromising conditions.
“Additional research is warranted to elucidate the reasons for epidemiologic differences noted in this study and risk factors for severe disease.”