Don’t be surprised if you become one of the hundreds of thousands of New Yorkers expected to be bitten by a tick this summer.
Some experts warn that it could be a particularly bad tick season.
For decades, the major public health threat from ticks in New York has been Lyme disease, transmitted by the black-legged tick, often referred to as the “deer tick,” which generally picks up the pathogen from rodents. But new tick-borne pathogens have been discovered in New York State in recent years, with names like the Bourbon and Heartland virus, and rare tick-borne diseases like babesiosis are infecting more people year after year.
Other tick types are also becoming more common; new species have established themselves in the Bronx and Staten Island.
The developments – new ticks, new pathogens and rising cases of rare diseases – are leading experts to reconsider their advice for avoiding tick bites. For example, a new tick species seems to prefer manicured lawns to shady wooded areas, experts surprise.
Where do all the ticks come from?
You may not remember all the acorns underfoot in the fall of 2021, but that year oak trees produced a record crop. It was a feast for white-footed mice and squirrels. Their populations flourished, making it easier for newly hatched ticks to find a rodent for their first blood meal.
And that, in turn, meant more of those larval ticks survived last year, said Dr. Richard Ostfeld, a disease ecologist who studies ticks at the Cary Institute of Ecosystem Studies.
Now those ticks are ready for their second blood meal. Since April, they’ve been waiting for blades of grass and leaves, their top two legs up – ready to climb aboard the next passing creature.
“This year we are seeing very high numbers of nymphs,” said Dr. Ostfeld, referring to the second stage in a tick’s life.
Drag fabrics and new sign
To calculate tick population data, tick researchers periodically drag a piece of white cloth across the forest floor and count how many ticks grab on.
Recently, new tick species have emerged, such as the Gulf Coast ticks, which are common in the South. How these ticks got to New York isn’t clear, but they likely hitched a ride on migratory birds, said Dr. Waheed Bajwa, who leads the city’s health department’s efforts to control insect and tick-borne diseases.
Over the past five years, health department researchers have discovered a growing number of Gulf Coast ticks at Fresh Kills, once the world’s largest landfill that will soon become a park on Staten Island.
Researchers have found that many ticks from the Gulf Coast on Staten Island carry a pathogen that causes a form of spotted fever. Fortunately, it is a milder form than Rocky Mountain spotted fever, a sometimes deadly tick-borne illness. (Although most common in a few southern states, New Yorkers have been infected in small numbers.)
So far, the Gulf Coast tick doesn’t seem to have transmitted the milder form to New Yorkers, but Dr. Bajwa expects that this will not take long.
“Maybe we’ll see some cases in the future,” he said.
In June 2018, a Yonkers man removed a tick from his right leg and saved it to take to his doctor. It was not a typical New York tick, but rather the Asian long-horned tick, whose arrival in the United States had only been discovered a year earlier.
When health investigators inspected the man’s property, they found more Asian longhorn ticks on his lawn. Unlike other ticks, this species is not deterred by grass clippings or direct sunlight.
It also multiplies at an alarming rate; the female can reproduce asexually and create offspring herself.
In parts of Staten Island and the Bronx, it is already found in “extremely high densities” and appears to be “displacing black-legged ticks,” according to a 2022 health department bulletin.
This tick species, which is reddish-brown in color, has so far not been associated with the spread of human disease in the United States. But in East Asia, it can transmit a deadly hemorrhagic fever.
Tick populations have long been in flux
The lone star tick, known for the distinctive white patch on the female’s back, made its way from the southeastern United States to Long Island perhaps 50 years ago. It is now the dominant tick in parts of Suffolk County and is expanding its range across New Jersey.
It is also relatively ferocious.
“Lone star ticks don’t even wait for you to come over,” says Professor Rafal Tokarz, an epidemiologist and tick researcher at Columbia University. “I’ve seen them crawl to me, crawl to my boots.”
In the Northeast, black-legged ticks were once scarce, outside of Long Island and some islands off the coast of Massachusetts, where deer thrived, according to Durland Fish, a tick expert and retired Yale professor. As the region’s deer population soared, the dramatic inland expansion of this tick began.
But when deer disappear, black-legged ticks decline, Professor Fish said. The reason is simple: Although black-legged ticks feed on rodents when young, the adult ticks often feed and mate on the hides of deer.
A recent vasectomy program on deer on Staten Island appears to have led to fewer cases of Lyme there, Dr. Bajwa said.
How bad will the ticks be this year?
As tick populations change, experts say it’s too early to know which tick-borne diseases are likely to pose a major health threat. Or how Lyme disease rates will change.
Most tick bites do not lead to disease. In New York, less than half of the nymph-stage black-legged ticks carry the pathogen that causes Lyme disease.
“Some people predict at the start of a Lyme season that ticks will be out like crazy, but they’re just conjectures,” says Dr. Gary Wormser, chief of infectious diseases at New York Medical College and an expert on Lyme disease.
Nevertheless, the state health department has decided that one tick check after a day away from home is no longer enough: “Perform a full body check several times a day,” read a recent state health department bulletin. That change was prompted by an increase in a rare tick-borne disease, the Powassan virus. Nationally, there are still only 20 to 45 registered cases per year, but that is an increase from a decade ago.
“Powassan is a game changer for us,” said Jennifer White, who heads the state health department’s division that studies tick-borne diseases. She noted that the virus – which often causes permanent neurological damage – can be transmitted if a tick is attached for even 15 minutes, unlike other tick-borne diseases, such as Lyme, which can take 36 hours.