California health officials issued a travel warning for state residents that travel to Mexico and Hawaii due to increased reports of the mosquito borne diseases, dengue fever and chikungunya.


“We want all Californians to be extra careful when traveling to these regions and take steps to avoid mosquito bites,” California Department of Public Health (CDPH) Director and State Public Health Officer Dr. Karen Smith said. “The mosquitoes that transmit chikungunya and dengue are aggressive daytime biters.”

Chikungunya is a viral disease characterized by acute onset of fever and severe joint pain. Dengue, another viral disease, is characterized by high fever, severe headache, muscle and joint pain, rash, and in severe cases bleeding manifestations. For both, treatment is supportive, the disease is not contagious person to person, and there is no vaccine.

For 2015, 164 cases of chikungunya and 90 cases of dengue have been reported in California residents, all with a history of travel to areas where transmission of these diseases occurs. Of reported cases in 2015, 148 (90 percent) chikungunya and 77 (86 percent) dengue cases had a history of travel to Latin America. The number of reported California dengue cases with a history of travel to Mexico has increased in the last three years, with 80 in 2013-2015 compared to 17 in 2010-2012.

Three California residents have acquired dengue during the recent outbreak in the Big Island in Hawaii. There have been no cases of chikungunya and dengue acquired locally in California.

CDPH recommends that travelers prevent exposure to mosquito bites by wearing protective clothing and applying insect repellent containing DEET, picaridin, oil of lemon eucalyptus, or IR3535 according to label instructions. DEET can be used safely on infants and children two months of age and older. In addition, make sure that your hotel or lodging has air conditioning or doors and windows with tight-fitting screens to keep out mosquitoes.

Chikungunya was first introduced to the Caribbean in late 2013, and by Nov. 30, 2015, over 25,000 confirmed cases were reported from the Caribbean and Central, South, and North America, including over 9,000 cases in Mexico. Dengue transmission has also been prevalent throughout Latin American countries in recent years, and the risk of dengue is present in several Mexican states, including Baja California Sur (where Cabo San Lucas and La Paz are popular tourist areas).

If you have returned from an affected region and have fever with joint pain or rash within the two weeks following your return, please contact your medical provider and tell the doctor where you have traveled. If your doctor suspects chikungunya or dengue, please protect yourself against mosquito bites until you recover. This will prevent spread of the virus to mosquitoes and potentially humans here in California.