Public health experts are watching for cases of Chikungunya virus to spread in the United States.
The virus is a mosquito-borne illness and can cause a bad headache, fever and severe joint pain.
It is rarely fatal, but the joint pain can last more than a month in some cases.
The virus has been spreading in the Caribbean and South America and experts say it is likely to reach other countries, including the U.S.
There have been more than a dozen cases diagnosed in the U.S., but those people had traveled to other places where the virus is more prevalent.
Other than trying to stay way from mosquitoes, there is no specific treatment or way to prevent the virus.