First Case In California Of Mosquito-Borne Dengue Not Related To Travel Reported In LA County

The Pasadena Public Health Department is reporting the first confirmed case of dengue not related to travel in California.

Dengue is a viral infection spread to people through the bite of an infected mosquito. The infected person is a Pasadena resident who is said to be recovering. Officials did not release any additional information.

The person who contracted the virus sought medical care after feeling ill in September. Their health care team recognized potential symptoms of dengue and alerted the Pasadena Public Health Department. A blood test by the Centers for Disease Control and Prevention confirmed the resident was infected with the dengue virus on Oct. 20. The resident did not travel to a country where dengue is endemic, health officials said.

“Dengue virus is a human-only disease,” said Dr. Dr. Matthew Feaster, an epidemiologist with the city of Pasadena. He stressed that it is not contagious from person to person. “With vigilance and proper treatment we can remove an infected person from the community. Prevalence and incidence in the U.S. is low to no cases, meaning this is a very rare occurrence.”

In Los Angeles County, dengue cases are typically only seen in travelers who have visited countries where dengue is found.

Most people who get dengue won’t have symptoms. But for those who do, the most common symptoms are high fever, headache, body aches, nausea and rash. Most recover in a week or two.

There are some risks, however. A pregnant woman already infected with dengue can pass the virus to her fetus during pregnancy or around the time of birth. People who develop severe dengue may need hospital care. In severe cases, dengue can be fatal, according to the World Health Organization.

The risk of local exposure remains low as dengue can only be transmitted through infected mosquitos; to date, increased testing of mosquito pools have not identified any mosquitos infected with dengue.

Above normal rain plus high temps equal more mosquitos

Still, this has been a particularly bad mosquito season.

“At the peak of our season we were catching four times the average for the mosquito population," said Jason Farned, district manager for the San Gabriel Valley Mosquito and Vector Control District. "Those population increases were due to the additional rain, those summer thunderstorms we were adding more water to the environment. And also the continued warm temperatures throughout the nights, traditionally the night time temperatures tend to drop in the fall where we’re still seeing warmer temperatures so that has extended the mosquito season longer than we generally see."

Farned said the district will continue testing mosquitos for dengue until the mosquito season ends. "We’re expecting over the next few weeks the temperature is going to drop and nature will help us out in controlling the mosquito populations,” he said.

How do dengue viruses spread?

Dengue viruses are spread to people through the bite of an infected Aedes species mosquito. These mosquitoes also spread Zika, chikungunya and other viruses.

According to the CDC, most outbreaks in the continental U.S. have been relatively small and limited. Local spread has been reported in Arizona, Florida, Hawaii and Texas.

In June, European health officials announced an uptick in locally acquired cases of dengue, which is also surging in Central and South America, as well as in many parts of Africa, Asia and the Pacific Islands.

The best way to avoid dengue: do everything you can to prevent mosquito bites. Use insect repellent, especially during dawn and dusk.