It’s high season for Lyme in the Hudson Valley

Female black-legged tick

John Burroughs wrote, “I go to nature to be soothed and healed, and to have my senses put in order.” Many of us feel the same way, which is why Lyme disease is so insidious: Embedded within the cure is a mysterious new ailment, which can be easily knocked out with a round of antibiotics or cause permanent neurological damage. The months of June and July are the height of tick season and, though it’s hard to eliminate the chance of being bit by a tick without avoiding the woods altogether, there’s a lot we can do to reduce the likelihood of getting Lyme.

It’s mostly undiagnosed.

There were 28,000 diagnoses of Lyme disease in the United States during 2015, but the Centers for Disease Control and Prevention (CDC) estimate that the true number of infections is ten times that — around 300,000.

It’s the height of Lyme season

This could be one of the worst years yet.

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Scientists have been predicting for a while that 2017 would be a bad year for Lyme disease. It started with a bumper crop of acorns in 2015. For reasons still unclear, oak trees overproduce acorns every so often in what’s called a “mast year.” The following year, 2016 in this case, the population of acorn-eaters increases, as well as the ticks that prey upon them. Of particular interest is the white-footed mouse, which is an especially effective spreader of Lyme disease because ticks that attach to it have high infection and survival rates. (Mice don’t groom themselves while possums, just as likely to be bit by ticks, groom so fastidiously that each one kills thousands of ticks per year.)

The most dangerous ticks are smaller than you might think.

The black-legged tick life cycle is two years long and includes three stages: larva, nymph and adult. At each stage, the tick takes a blood meal. Eggs hatch in summer and the larva get their first meal, drop off and overwinter, molting into a nymph during the next spring. They take their second meal in the late spring/early summer, grow into adults and get their last meal in the fall or early the following year, with females laying eggs the following spring.

According to the CDC, most humans are infected with Lyme disease by nymphs, which are much smaller than adults. Adults are a little larger than a sesame seed while nymphs are about the size of a poppy seed. Adults carry Lyme as well but are much easier to spot and remove.

The black-legged tick, from l-r: larva, nymph, adult male, adult female

 

“Deer tick” is a bit of a misnomer.

Click to view a printable pdf of essential tick knowledge

The black-legged tick, Ixodes scapularis, was first described in 1821.  When Lyme disease was discovered in the 1970s, scientists decided that the tick responsible for the infections was a new species, Ixodes dammini, commonly called “deer tick” because of the association of Lyme-carrying ticks and deer in the suburban Northeast. By the early ’90s, it was determined the ticks were all part of Ixodes scapularis.

Most life-forms have various common names whose origins are far from scientific. In this case, the popularity of the name “deer tick” and the assumption that Lyme disease correlates chiefly with white-tailed deer oversimplifies the situation. As Richard Ostfeld, a disease ecologist with the Cary Institute of Ecosystem Studies in Millbrook, writes in Lyme Disease: The Ecology of a Complex System, deer are as common (or more common) in many areas of the country that have yet to see Lyme disease. While it’s true that deer serve as important hosts for the ticks, they’re a very poor reservoir for the Borrelia burgdorferi bacteria that causes Lyme. Deer whose blood contains the pathogen infect only one percent of larval ticks who feed upon them. Compare that to white-footed mice, chipmunks and shrews, all of which infect more than 50 percent.

The white-footed mouse is one of the best reservoirs for the bacteria that causes Lyme disease – much better than deer!

Ostfeld’s book is devoted to the many variables at play. The disappearance of wolves in the Northeast, for example, and the resulting influx of coyotes, led to a drop in the fox population. Foxes are major predators of the rodents who serve as some of the best reservoirs of Lyme. When they’re around, the population of the rodents and their willingness to roam over a wider area is decreased. Settlement patterns are another factor. Large unbroken forests supporting a wide variety of animals (including predators) were less conducive to the spread of Lyme than the suburban and ex-urban pattern of leaving small slices of forest with dense undergrowth as buffers between homes. The latter offer relatively safe spaces for rodents and plenty of cover for ticks while, in the former, rodents are kept in check and ticks attach to a wider variety of hosts — many of which are less likely to transmit Lyme and more likely to kill the ticks while grooming.

The disease is radiating out from its northeastern epicenter

Climate change could be a factor.

The Environmental Protection Agency recently added Lyme disease to its list of climate change indicators. Though Lyme is expanding in all directions, not just north, it’s thought that milder temperatures have acted as an accelerant by allowing more ticks to survive and more time for them to be active.

If you spot and remove a tick the same day, you probably won’t get infected.

Ticks take their time attaching and feeding. According to the CDC, if you remove a tick within 24 hours, you’re unlikely to get Lyme.

When you’re outdoors during tick season, use a repellent that contains DEET. (If you’re against using that particular chemical, the EPA has a handy online tool for choosing repellents with different active ingredients.) When hiking, stay on the center of the trail, avoiding leaf litter and tall grass. When you get back home, take a shower and use a mirror to check yourself for ticks. If you find one, remove it with tweezers, gripping as close to the head as possible. If the head breaks off, that’s OK, there’s no increased risk of infection by leaving it in. The body will reject it like a small splinter in a few days.

It’s not recommended that you see a doctor before symptoms like the bull’s eye rash (present in 70-80 percent of cases), headache, fever, muscle or joint aches manifest. Doxycycline is the most common antibiotic treatment.

The black-legged tick has a two-year lifecycle (CDC)

Killing ticks

There are ways to kill ticks before they can get you. The most effective method is to attract would-be hosts, like mice, using bait boxes. When the mice enter the box, they’re coated with an insecticide similar to what’s found in commercial flea and tick treatment for pets. Going after ticks on one’s own property isn’t very effective, though, since infected ticks from beyond can freely come and go. That’s why The Tick Project, a five-year study by the Cary Institute and Bard College, is using bait boxes as well as other means in 24 neighborhoods of 6-10 blocks. The study aims to determine if a coordinated attack on this scale is effective or not.

What about a vaccine?

With Lyme on the march, and diagnosis and treatment often tricky, the obvious question is: What about a vaccine? Actually, there used to be one. Lymerix was released in 1998, but was withdrawn only four years later following low sales and negative media coverage of lawsuits filed by individuals who said it caused arthritis, among other symptoms. A comparison of the rate of arthritis in those who had the vaccine and the general population later revealed no significant difference, but by then the market had dried up. Currently, you can get a Lyme vaccine for your dog but not for yourself. More human vaccines are in development, but as anti-vaccine sentiment has only grown during the last 15 years, the chances of widespread adoption seem low.

 

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