Hawaii’s Big Island has declared a localized state of emergency because of the growing outbreak of dengue fever, with over 250 cases confirmed over the past several months.

Hawaii County Mayor Billy Kenoi declared the state of emergency, while Hawaii Governor David Ige said he supported the efforts, but would not issue a statewide emergency.

Dengue fever usually causes flu-like symptoms, though can develop into the deadly dengue hemorrhagic fever.

The State Department of Health and the County of Hawai‘i have been working together to stop an outbreak of dengue, a viral illness spread by mosquitos.

The dengue virus is transmitted to humans by the bite of an infected mosquito. Two of the mosquitos that transmit the virus are found on Hawai‘i Island, the Aedes aegypti and Aedes albopictus.

Dengue moves around the world by travelers. Visitors or residents infected with dengue coming or returning to Hawai‘i from other countries may infect local mosquitoes, as happened in an outbreak on Maui in 2001 that spread to O‘ahu and Kaua‘i before ending in 2002. Dengue is found routinely in 100 countries worldwide.

The most effective way to avoid dengue is to avoid mosquito bites through personal protection and reducing mosquito habitats by eliminating standing water near your home or workplace.