NMDOH warns of West Nile after detection in Bernalillo County mosquitos

A female mosquito from the Culex family, which is the biggest vector in spreading West Nile virus in New Mexico, public health officials said. (Courtesy of Centers for Control and Prevention)

BY: DANIELLE PROKOP
Courtesy of Source NM

New Mexico health and veterinary officials urged the public to prevent mosquito breeding and protect against bites after officials detected the West Nile virus in insect populations in Bernalillo County last week.

Mosquitos, which require blood for their breeding cycle, spread West Nile virus by biting infected birds and then biting humans or horses—mostly in the summer. No vaccines exist for people, nor do specific treatments for the infection.

No West Nile cases in humans have emerged so far, New Mexico State Public Health Veterinarian Erin Phipps told Source NM.

“We typically start to see cases in July and August,” she said. “We have not yet seen a case this year, but that’s not unusual. It’s a little too early to stay if that portends a more mild season.”

New Mexico has had more than 500 recorded cases of West Nile since 2005, and at least one death recorded in all but two of the years. New Mexico’s most severe year occurred in 2023, with 80 recorded cases and eight deaths. While multiple species of mosquito can spread the disease, the Culex family of mosquito, which can live anywhere in the state, is the main culprit.

The majority of people who experience the infection have no symptoms, while about 10% to 20% of people experience fevers, muscle aches or headaches.

“Those are often undiagnosed because they mimic any other common illness,” Phipps said.

Only about 1% of the cases progress to a more severe stage, called a neurologic infection, Phipps said, which causes seizures, disorientation and profound weakness, potentially leading to permanent disability or even death.

“While it’s relatively rare, it’s very serious so we encourage everyone to take the prevention measures that they’re able to to decrease their risk of infection,” Phipps said.

An approved vaccine does exist for horses, which can also suffer brain swelling or other complications from contracting the disease. The New Mexico Department of Agriculture reported 19 cases of West Nile in horses in 2023, resulting in six fatalities.

“Vaccinating horses against West Nile virus is one of the most effective steps owners can take to protect their animals during mosquito season,” New Mexico State Veterinarian Dr. Samantha Holeck said in a statement. “Prevention through vaccination is far safer – and often less costly – than trying to treat the horse after infection.”

New Mexico state law delegates mosquito control to municipal and county officials, but Phipps said residents can take some additional measures to minimize bites and breeding spaces for the insects. Those include wearing loose-fitting clothing, using insect repellents and avoiding being outside at dusk and dawn.

Mosquitos can lay eggs in very small bodies of standing water — think the amount in a bottle cap — and larvae can transform into adults in as soon as a week. Phipps encouraged changing standing water at least every week, and removing any debris that could collect water.

“Now is the perfect time to start thinking about West Nile, because prevention is key,” Phipps said.