Experts debate tick numbers, but not danger
As the Island approaches the height of the tick season, experts disagree about the size of the tick population this year.
But public health experts agree that residents and visitors need to protect themselves from these nasty pests and the several diseases they carry. People who spend time outside and in the woods should be particularly vigilant.
"This is definitely the worst tick year I've ever seen," David Simser, Barnstable County Extension Service entomologist, said this week. "It's the year of the bug, all bug populations are up; it's a huge year for ticks."
Mr. Simser said this year both deer ticks and dog ticks seem to be out in record numbers. There is reason to be concerned about both species: both carry serious diseases.
But tick expert Dr. Samuel Telford of the Harvard School of Public Health has a different view.
"The deer tick population this year is delayed. The number of deer ticks found on mice this year is significantly less than it was last year at this time," Dr. Telford said in a telephone interview Tuesday.
He said the cold weather over the past three months has delayed the deer ticks. "June and early July is the biggest time for deer ticks in their nymphal stage, but so far there aren't very many of them."
June and July generally account for most reported cases of Lyme disease, and other tick-borne diseases, but Dr. Telford anticipated that the peak time would be later this year. "People do need to be careful right now, because the nymphal deer ticks are definitely going to be coming out more and more," he said.
Although the risk of contracting Lyme disease from deer ticks is well publicized, the small insects also transmit other diseases, including babesiosis and erhlichiosis.
The larger wood tick, sometimes referred to as a dog tick, has been implicated in recent Island outbreaks of tularemia, also called rabbit fever. Wood ticks can also transmit Rocky Mountain spotted fever, though this is rarely found here.
Some areas of the Vineyard are hotter than other places, Mr. Simser said, when it comes to tick populations. He said he encountered a surprisingly large number of deer ticks up-Island. After a recent walk on property managed by The Trustees of Reservations in Chilmark, he remarked on the large number of ticks. "I was walking on the paths in Menemsha Hills, and there were huge numbers of ticks. That's definitely an Island tick hot spot."
Dr. Telford agreed that up-Island tended to have larger tick populations. "I've always found Chilmark and Chappy to be the most 'ticky' parts of the Island," he said.
Mr. Simser did not attribute the population explosion to weather. He proposed that it was the result of "a harmonic insect life-cycle…something like the 17-year locusts. This is just a big year for ticks to hatch and reproduce." Dr. Telford did attribute the delay he saw in the deer tick population to the weather, saying, "With a hard winter and low temperatures over the past couple months, you would expect the ticks to be a little behind."
Ticks and public health will be the topic of a forum run by the Martha's Vineyard Hospital tonight. Donna Enos, an infection control nurse at the hospital, and one of the organizers of the forum, said, "I think we're going to see a lot more cases of tick bites more quickly, because the weather is so much better than it was last year. When it gets warm and sunny earlier, people are going to be out in places they never would have wanted to go if it were cold and rainy, places with lots of ticks."
Ms. Enos keeps track of the tick-borne illness infection records for the Island, and says that thus far she has not seen a rise in the number of infections in her data, but expects to soon. "I access that information through a computer system, and the system's about a month behind, so I think I'll see an increase as soon as the system finishes with May."
Not all experts agreed that this year would be worse for deer ticks than other years. "Ticks move into an area, their population grows until a certain point, and then it levels off," Durland Fish, professor of epidemiology at Yale University, explained. "I find it highly unlikely that a place like Martha's Vineyard, with a well established tick population, would have a dramatic increase in the population."
The deer tick population varies dramatically from year to year in one way, Mr. Fish said. "The tick population is much larger in even numbered years than it is in odd numbered years." He said this may be a result of the two-year life cycle of the tick creating two different reproductive groups, one consistently larger than the other group.
Mr. Fish did allow that the number of deer ticks nationwide is probably growing, as ticks are quickly moving into new areas. In addition, the number of cases of Lyme disease and other tick-borne illnesses are increasing nationally, said Mr. Fish. He attributed this to an increase in contact between people and ticks more than an increase in the tick population. "We're seeing the suburbanization of wooded areas. This puts a lot more people in tick-filled areas, and means that people are more likely to get bitten overall."
The most prevalent of the tick-borne diseases is Lyme disease, characterized by flu-like symptoms, aching muscles and joints, and sometimes a bull's-eye rash around a tiny deer tick's bite.
Untreated, Lyme disease can have debilitating long-term consequences. In a letter to the editor this morning, Susan Mosler of Chilmark, a chronic Lyme sufferer, strongly urges people to take the risks seriously. "Do not ignore a tick bite," she said.
Reached by telephone, Ms. Mosler said she is a chronic Lyme disease sufferer. "This is a very serious disease. I just want people to take all the precautions," she said.
She advised people to spray with an insect repellent containing DEET, be careful in the woods, and be aware that pets can carry ticks into the house from outside. She said, "Most importantly, if you get a tick bite, no matter what, go to the hospital. I just hope people will learn to take it seriously."
While Ms. Mosler recommended going to the hospital immediately, medical experts said that her advice is unnecessarily alarmist. Ms. Enos explained, "You don't really need to go to the hospital right away. People should remove the tick, and save it in plastic or [on a piece of] tape. They should monitor how they feel for the next three to seven days, and if they get flu symptoms, they should go to the doctor and bring the tick for testing."
Dr. Alan Hirshberg, emergency medicine specialist at the Martha's Vineyard Hospital concurred, saying, " If people are uncomfortable removing the tick, if they don't have the right equipment, or can't reach it, then by all means go to the doctor or the emergency room, but other than that, just remove it and watch the bite for infection."
Though chronic Lyme sufferers, such as Ms. Mosler, suggest immediate testing, Ms. Enos said that is largely ineffective. "Their blood won't show anything on a blood test until at least a month after the bite. If people have symptoms, like a fever and aching joints or the bull's-eye rash, doctors will treat them with antibiotics as a precautionary measure."
In addition to Lyme disease, deer ticks can also transmit babesiosis, and erhlichiosis. Although these are less common than Lyme disease, they present serious risks, if contracted.
Babesiosis is a potentially fatal parasitic disease that also has flu-like symptoms. It is most dangerous in people over 50, or those with weak immune systems.
Erhlichiosis is a bacterial disease that is generally mild, but can be serious and even life threatening in extreme cases. Erhlichiosis is characterized by a sudden high fever, sever muscle and headaches, and sometimes a rash.
The wood tick, noticeably larger than the deer tick, can transmit Tularemia. Small wild animals, mainly rabbits, carry the bacteria that cause the infection. Humans can contract the disease through a bite from a wood tick that has fed on an infected animal, by handling infected animals, or by breathing dust contaminated by the bacteria.
Pneumonic tularemia is thought to occur when bacteria from an infected animal becomes airborne when the dead animal or the ground around it is stirred up during mowing, brushcutting, or excavating. The pneumonic form of disease is the most dangerous and if left untreated has a mortality rate as high as 60 percent.
Ms. Enos stressed that pneumonic tularemia, "is more dangerous and easily contractible. You only need to be exposed to a little bit of the bacteria to be infected through the air." She advised that people mowing wear a facemask to protect themselves, and that people who plan to walk in areas with long grass or shrubs use insect repellent.
As an additional form of protection against ticks, a group, including Mr. Simser, is developing tick prevention devices for your yard. One, the Maxforce Tick Control system is designed to prevent ticks from living on mice. The other system, on which Mr. Simser is currently working, called the 4-Poster, is a structure designed for tick prevention in the deer population. This system uses a bin of corn in the center of a structure with four premetherin-coated rollers. The deer enter the structure, eat the corn, and are coated with the premetherin, an anti-tick compound similar to Frontline, the compound used on dogs and cats, said Mr. Simser.
This evening, Islanders may hear what the experts have to say about ticks and tick-borne disease prevention. The panel includes Dr. Alan Hirshberg, Donna Enos, both of the M.V. Hospital, and Susan Soliva, Epidemiologist from the Massachusetts Department of Public Health. A Portuguese translator will be on hand to assist listeners for whom English is a second language. The forum begins at 6:30 pm in the Oak Bluffs School.
