Tick-borne anaplasmosis on the rise in Warren County

By Kris Parker

Health officials in Warren County have issued a public warning after a surge in cases of anaplasmosis, a rare disease carried by ticks.

In a press release distributed this week, Warren County Health Services reported a four-fold increase in cases of anaplasmosis, a disease caused by bacteria transmitted through tick bites. Anaplasmosis, while easily treatable, can lead to severe health consequences if left untreated. 

The county straddles the Adirondack Park’s southeastern boundary and includes communities along the south and west shores of Lake George.

Warren County has documented 40 cases of anaplasmosis this year so far. Only 9 cases were reported during the same timeframe last year, with 39 cases reported by the end of the year. According to the press release, the 40 cases represent more than twice the number of combined cases documented during the same periods in 2018 and 2019.

The increase reflects larger trends affecting the Adirondacks in recent years as a changing climate expands the habitable range of ticks.

“This isn’t unexpected. The pattern has been established in other parts of the state but the risk here is we just aren’t prepared for it,” said Lee Ann Sporn, a professor at Paul Smith’s College who researches ticks. “We’ve been barking about this for a few years now.”

Early symptoms of anaplasmosis include fever, chills, severe headaches, muscle aches, nausea, vomiting, diarrhea and loss of appetite. These symptoms appear between one to five days after a bite and are usually mild to moderate. Early treatment with antibiotics can prevent further escalation.

If treatment is delayed, or if a person has other underlying health concerns, more severe symptoms can arise, which include respiratory failure, organ failure, bleeding problems or even death. Further complicating matters in the era of COVID-19 is the similarity between early symptoms of each disease, increasing the risk of misdiagnosis. 

“We want people to be aware and be able to suggest it to their doctors,” Sporn said. 

Blacklegged ticks (Ixodes scapularis), also known as deer ticks, are the dominant tick in the area and used to be considered rare in the Adirondacks. As global temperatures continue to rise, the local climate has begun to shift in subtle but perceptible ways. Over the last half century, the region has become increasingly wetter and warmer, resulting in milder winters, amongst other things, creating conditions that have allowed ticks to spread to higher elevations. Ticks exist in higher densities at lower altitudes, but are now occasionally recorded at altitudes of up to 2,000 feet. 

“The ticks are expanding in the region, so you can predict that if climate conditions become more favorable to ticks, they will expand,” said Curt Stager, a natural science professor at Paul Smith’s College. “Winter has gotten shorter and milder over the last century and it will continue to do so. It is the perfect storm.”

Ticks thrive in forested areas with humidity and heat. New York’s epicenter for ticks has traditionally been the Capital Region, though the parasites are now expanding outwards, both geographically and in density. Besides warming, reforestation and growth in deer populations can assist in the expansion as ticks typically feed on deer and small mammals. 

“Climate change is probably driving most of the expansion in the region,” Sporn said. “There are more hosts to feed on and more opportunities to be looking for a host if the conditions are right.”

Ticks have a two-year life cycle and only feed three times during their life. Young ticks are called nymphs and they feed during the summer months, with June and July considered the highest risk period for humans and pets. The two-year cycle has led to a pattern of expansion that Sporn describes as a staircase, rather than linear, with every other year showing an increase in tick density and people reporting cases of anaplasmosis. 

“We expected this year to be higher,” she said. “We’ve noticed that odd numbered years are reporting more cases.”

Nymphs are also hard to detect, as they are roughly the size of a poppy seed. Adult ticks feed during the months of October and November. In the winter, ticks usually enter a hibernation-like state when temperatures reach freezing.

While Lyme disease is still a much greater risk than anaplasmosis, the numbers of ticks carrying anaplasmosis is increasing in the Adirondacks. Additionally, not all strains of anaplasmosis are harmful to humans. Unfortunately, the ticks collected by researchers have shown to be carrying the strain that is harmful to humans.

“This is the special thing; we have the strain harmful to humans, which is different from what is usually found on ticks in western New York,” Sporn said. “It is unclear why we have this “bad” strain but it could be related to wildlife populations — deer versus small mammals — that ticks feed on.” 

The first cases of ticks with anaplasmosis in Warren County were documented in 2012. Since that time, Essex County, just to the north, has become the county with the most documented cases, with the first reported in 2015. Roughly 10% of ticks are currently found to be carrying anaplasmosis in Essex county.

Tick-bite prevention strategies include wearing light-colored clothing for easier visual detection, wearing long pants and sleeves, avoiding dense woods and brush, using repellent, checking your clothing and body, and bathing after being outdoors.