Lyme disease still rare, but rising in northern Nevada
Jeniffer Solis
(Nevada Current) Although instances of Lyme disease remain low in Nevada, the number of reported cases of the tick-borne illness has been growing in recent years in Northern Nevada, echoing a sharp nationwide increase in the disease.
In 2024, Washoe County saw a nearly 38% increase in reported Lyme disease cases from the previous year, from eight cases to 11. Reported cases of the illness have increased in Northern Nevada year-over-year since 2020, according to tracking by the Northern Nevada Public Health office.
Public health officials say the true number of cases may be higher due to underreporting. The disease can be difficult to track because symptoms mimic those of other diseases, and only patients with the worst outcomes are usually tested.
Lyme disease is transmitted through the bite of an infected black-legged tick, also known as a deer tick, which must be attached for 24 to 48 hours to spread the illness. During the nymph stage, when they are most active, black-legged ticks are about the size of a poppy seed and are easy to miss.
In about 80% of Lyme disease cases, a “bulls-eye” rash spreads around the site of the tick bite, but without one Lyme disease can be easy to misdiagnose.
Early signs include common influenza-like symptoms including fever, chills, headache, fatigue, muscle and joint aches, and swollen lymph nodes. As the disease develops without treatment, more serious symptoms may emerge. In more severe cases the disease can impact joints, the nervous system and the heart for weeks to months after the initial tick bite. Delays in treatment may also increase the risk for chronic illness.
“Unfortunately, if it is Lyme disease and it goes untreated it can progress to more serious signs and symptoms which can appear months after a tick bite,” said Northern Nevada Public Health epidemiologist Liliana Wilbert.
This year, people in the U.S. are seeking emergency care for tick bites at the highest level since 2017, according to data from the Centers for Disease Control and Prevention.
Lyme disease through the years has been found mainly in the eastern and upper mid-western states of the U.S. But the range of Lyme disease cases has expanded significantly since 1995, according to the CDC — including to places where people are less familiar with the risks and how to prevent the disease.
Milder winters and longer warm seasons have allowed ticks to expand their range, bringing Lyme disease to more areas. Lyme disease-carrying black-legged ticks are mostly active when temperatures are above 45 degrees, and thrive in areas with at least 85% humidity, according to the US Environmental Protection Agency.
“It’s more favorable for the ticks in the northeastern regions and coastal California. It wouldn’t be as favorable here in Nevada. That’s not to say we don’t have ticks that do live here,” Wilbert said.
In July, Carson City Health and Human Services confirmed a case of Lyme disease for a person who had not traveled outside Northern Nevada in the four weeks prior to symptom onset. The CDC also reports that more cases of Lyme disease have appeared along the west coast and in Nevada in recent years.
Still, most cases of Lyme disease reported in Northern Nevada in 2024 were among people who had recently traveled out of the state. Eight of the eleven cases in 2024 had a documented history of travel or recent relocation, some with diagnoses originating from outside the state, suggesting potential exposure in other jurisdictions. The remaining three cases had no identifiable source of exposure, indicating an unknown origin of infection.
In some of those cases people traveled to nearby Northern California, an area a recent study by the Johns Hopkins Lyme Disease Research Center identified as an underreported area not fully captured by traditional CDC surveillance methods.
Wilbert said gaps in data can also make it difficult to track Lyme disease across state borders. For example, case counts are attributed to the individual’s place of residence, rather than the location where the exposure or infection occurred.
That can result in skewed data without clear answers. In Nevada, most reported cases in Nevada were among women at 73%.
“When the cases come to us, they’re typically reported on a lab report,” said Wilbert. “We don’t know why most of them have been women, that is definitely something that it’s interesting.”
To reduce the risk of Lyme disease, the Northern Nevada Public Health Department says it’s crucial to minimize contact with ticks and their habitats, particularly in areas with dense vegetation.
“We highly recommend that people be careful when they go out into wooded areas and go camping or hiking because they’re so easy to overlook and prevention is the key,” Wilbert said.
Recommended precautions include wearing long-sleeved shirts and closed-toe shoes, wearing permethrin-treated clothing, applying EPA-registered insect repellent to exposed skin, and performing daily tick checks. Showering within two hours of outdoor activity can help remove ticks before they attach.