Officials issue warning after discovering dangerous insects for first time in US region: 'Move with people'

Health officials in Northern California are sounding the alarm after a dangerous mosquito species capable of spreading diseases was detected in San Jose, giving more proof of its expanding territory across the state.

What's happening?

The Aedes aegypti mosquito — known for transmitting viruses such as dengue, Zika, chikungunya, and yellow fever — was recently discovered near Kelley Park, according to the Santa Clara County Vector Control District. It's the first detection in that specific area, but far from the only one.

"This year in particular, we've had so many detections throughout new parts of the county," said Taylor Kelly, the district's scientific-technical services manager, to ABC News.

The species, first detected in California in 2013, has now been found in 27 counties statewide and appears to be establishing itself in Northern California after spreading from the southern and central regions. Officials warn that A. aegypti's ability to "move with people" — hitching rides in cars or breeding in small containers of water — makes containing the pest's spread difficult.

Why are mosquitoes in new areas concerning?

Unlike most native mosquitoes, A. aegypti is more aggressive and prefers to bite during the day. Aside from being a nuisance, these insects pose a major public health risk. The species has already been linked to local dengue cases in California, prompting fears of future outbreaks. Beyond adding strain to local health systems, A. aegypti also disrupts ecosystems by outcompeting native species.

Experts say warming global temperatures are likely helping mosquitoes spread into new territories. As heat and humidity rise, conditions become increasingly ideal for the insects to survive and reproduce, expanding their populations into areas that were once too cool to support them. For example, mosquitoes were recently discovered in Iceland for the first time ever — one of the few remaining places in the world where they weren't established.

What can we do to fight the spread of vector-borne diseases?

Local and state agencies, including the California Department of Public Health and the World Mosquito Program, are ramping up surveillance and public outreach. Experts say residents should dump standing water at least once a week to prevent mosquitoes from reproducing and scrub out containers that have collected water. California residents are also encouraged to report bites and take photographs of the mosquitoes, which have black-and-white stripes.

Ultimately, addressing the bigger cause of rising global temperatures is important to prevent our natural ecosystems from permanently changing. Educating yourself on critical climate issues is a good place to start learning about things we can do individually to make a difference, from transitioning to cleaner energy and conserving native plant and wildlife species.

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