Cases of West Nile virus were confirmed in San Bernardino County on Tuesday as authorities are warning the public to be cautious.

The infections mark the first locally acquired human cases of West Nile virus in the county this year and have been confirmed in Rialto and San Bernardino, according to the Department of Public Health.

West Nile virus is transmitted to humans through the bite of an infected mosquito.

While many people infected with the virus may have no symptoms, older individuals and those with existing health issues are most likely to develop severe symptoms.

“West Nile virus can cause a serious illness in humans,” said San Bernardino County Health Officer Michael A. Sequeira. “Therefore, I urge residents to take precautions to protect themselves against mosquito bites.”

Those most susceptible to complications from infection include anyone over 50 years old, people with diabetes, cancer, hypertension, kidney disease, those who are immunocompromised, organ transplant recipients, or anyone with a recent history of chemotherapy.

About 1 in 5 infected people will develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash, according to the Centers for Disease Control and Prevention. Although most people can recover, feeling tired and general weakness can last for weeks or months.

Signs and symptoms may include:

– Fever, body aches, rash, nausea, vomiting, and headache.
– Symptoms of severe illness include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis.
– Recovery from severe illness might take several weeks or months. Some effects on the central nervous system might be permanent.
– About 1 out of 10 people who develop severe illness affecting the central nervous system die.

“The risk of infection from West Nile virus typically increases from summer through early fall,” county officials said. “Residents are encouraged to protect themselves from mosquito bites during outdoor activities, especially at dawn and dusk.”

Since there is no human vaccine for West Nile virus, residents are urged to be proactive against mosquito bites by wearing insect repellent. Anyone who experiences a sudden high fever (above 102°F), severe headache, or a stiff neck, should seek medical help right away.

Residents can protect themselves from mosquito bites by taking these precautions:

– Wear shoes, socks, long pants, and long-sleeved shirts that are loose-fitting and light-colored.
-Remove or drain all standing water around your property where mosquitoes lay eggs, including birdbaths, ponds, old tires, buckets, clogged gutters, and puddles from leaky sprinklers.
– Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or holes to prevent mosquitoes from entering the home.
– Use insect repellent that has ingredients approved by the EPA such as DEET, IR 3535, and Oil of Lemon Eucalyptus.
– Report green or neglected pools by calling the San Bernardino County Mosquito and Vector Control Program at 800-442-2283. Press 3 when prompted.

For more information on West Nile virus, to report a standing water source, or to request a courtesy mosquito inspection, visit the San Bernardino County Mosquito and Vector Control Program’s website or call 800-442-2283.