The California Department of Public Health (CDPH) is urging the public to protect themselves against mosquito bites, after receiving reports of an increase in dengue fever and chikungunya in Mexico and Latin America.

Public domain image/National Atlas of the United States
Public domain image/National Atlas of the United States

As of December 31, 2014 a total of 155 chikungunya cases have been reported from five Mexican states and more than 26,000 confirmed cases reported in the Caribbean and Central and South America as of January 9, 2015. Last year, 98 cases of dengue and 92 cases of chikungunya were reported in California. All human cases were imported after travel to areas where transmission of those diseases was occurring. Of the reported cases, 23 dengue cases had a history of travel to Mexico.

Dengue and chikungunya viruses are transmitted by Aedes albopictus and Aedes aegypti mosquitoes. These two mosquitoes are aggressive day-biters that can potentially transmit the virus after biting an infected person.

CDPH recommends that individuals prevent exposure to mosquito bites by applying insect repellent containing DEET, picaradin, oil of lemon eucalyptus or IR3535 according to label instructions. DEET can be used safely on infants and children 2 months of age and older.

Mosquitoes bite in the early morning and evening so it is important to wear proper clothing and repellent if outside during these times. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.

Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flower pots, old car tires, rain gutters and pet bowls.


According to the World Health Organization, dengue is transmitted by the bite of a mosquito infected with one of the four dengue virus serotypes. It is a febrile illness that affects infants, young children and adults withsymptoms appearing 3-14 days after the infective bite.

Dengue is not transmitted directly from person-to-person and symptoms range from mild fever, to incapacitating high fever, with severe headache, pain behind the eyes, muscle and joint pain, and rash. There is no vaccine or any specific medicine to treat dengue. People who have dengue fever should rest, drink plenty of fluids and reduce the fever using paracetamol or see a doctor.

Severe dengue (also known as dengue hemorrhagic fever) is characterized by fever, abdominal pain, persistent vomiting, bleeding and breathing difficulty and is a potentially lethal complication, affecting mainly children. Early clinical diagnosis and careful clinical management by trained physicians and nurses increase survival of patients.

Chikungunya is a viral disease transmitted by the bite of infected mosquitoes such as Aedes aegypti and Aedes albopictus. It can cause high fever, join and muscle pain, and headache. Chikungunya does not often result in death, but the joint pain may last for months or years and may become a cause of chronic pain and disability.

There is no specific treatment for chikungunya infection, nor any vaccine to prevent it. Pending the development of a new vaccine, the only effective means of prevention is to protect individuals against mosquito bites.

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