The state health department says it is treating the affected area for mosquitoes, though it did not specify where in the county the case was reported.

Health officials warned that the Los Angeles area is seeing more dengue fever cases in people who have not traveled outside the U.S. mainland, a year after the first such case was reported in California.

The disease, while rarely fatal, is painful and debilitating. Officials did not say where in the county the case occurred.

A Panorama City resident has been confirmed with a rare locally acquired case of the mosquito-borne illness dengue, making him the fourth person in the county with the virus this year, public health officials said Wednesday.