All mosquitoes bite.

But it’s the bite from a female Anopheles mosquito that can transmit malaria.

The United States sees roughly 2,000 malaria cases a year, according to the Centers for Disease Control and Prevention. But those are typically individuals who have traveled or lived abroad where malaria transmission often occurs – many from sub-Saharan Africa and South Asia. About 300 Americans experience severe disease annually, and between five and 10 die.

A locally acquired mosquito-borne malaria case hasn’t occurred in the United States since 2003.

Earlier this week, though, the CDC issued a malaria alert after five locally acquired malaria cases – four in Florida and one in Texas – were reported.

“Malaria is a medical emergency and should be treated accordingly,” CDC officials said in the alert.

Malaria is caused by a parasite that typically makes patients sick with flu-like symptoms such as high fever, chills, headache, muscle aches and fatigue.

For most, symptoms begin 10 days to four weeks after infection.

Prompt diagnosis and treatment is critical for preventing severe disease or death. Malaria in pregnant women is a health concern because it’s associated with maternal and perinatal illness and death.

As of June 28, the state has had nine confirmed malaria cases, according to the Colorado Department of Public Health and Environment. All of the Colorado cases were in patients who reported international travel before their diagnosis.

“Current evidence suggests that it is unlikely that Colorado mosquitoes are transmitting malaria at this time,” said AnneMarie Harper, a Colorado Department of Public Health and Environment spokesperson.

For the past five years, Colorado has averaged 22 travel-related malaria cases annually. In the City and County of Denver, there have been between four and seven malaria cases from 2018 to 2022.

Denver has had four, internationally-acquired malaria cases this year – which is on pace with previous years, said Emily Williams, a City and County of Denver Department of Public Health and Environment spokesperson.

While the Denver region hosts the Anopheles species that can technically transmit malaria, the area’s climate isn’t hospitable for completing the mosquito’s life cycle, making infection rare, health officials said.

“We’re definitely more concerned about West Nile than we are about malaria,” Williams said.

The elimination of standing water, wearing insect repellent, limiting outdoor activities at dusk and dawn and mosquito fogging are effective preventative measures against all mosquito species. Coloradans traveling to areas where malaria is common should ask their health care provider about malaria chemoprophylaxis.

Healthy Bites is a recurring update on health care related topics by health reporter Nicole C. Brambila.