By Patricia Houser
For Nature’s Sake
Patricia Houser
The way we shape our landscapes has come back to bite us – literally.
Lyme disease cases in the US have tripled in the past 20 years, which makes it the “most common infection in North America transmitted from animals to people,” according to the January 2022 issue of Science Magazine. Research has confirmed that, as our climate has warmed, more disease carrying ticks are becoming active in the winter months and more species of ticks, with new diseases, are migrating to the Northeast.
That means right now, in February, ticks are already outside and ready to find a mammal to feed on in Orange and Milford. Dr. Goudarz Molaei, chief scientist at the Connecticut Agricultural Experiment Station, has said while the state lab used to get at most 50 ticks submitted for testing between December and March, they now see close 800 ticks in the same period.
Climate change worsens the risk of tickborne illness, but Lyme disease didn’t start with the climate crisis. Nor was it invented in a laboratory. In fact, researchers at Yale School of Public Health found that the bacterium which causes Lyme disease has existed in North America for at least 60,000 years. While Lyme disease has existed in animals for millennia, the crossover to humans seems to have become most notable in the past 50 years or so, with the moniker “Lyme disease” prompted by a cluster of cases in children and adults in the mid-1970s in Lyme, Connecticut.
Why then did Lyme disease shift from animals to humans in significant numbers when it did and where it did, bursting into public health consciousness in the last quarter of the 20th century?
The answer is summarized on the Connecticut Department of Public Health’s website: “The emergence of Lyme disease in Connecticut is attributed in large part to changes in land use…[that] favor expansion of habitat that supports ticks and wildlife and therefore transmission of tick-borne diseases from animals to people.”
Our sprawling style of growth, with commercial strips and leafy neighborhoods interspersed with fragments of forest, enables certain types of wildlife to survive and even thrive while other species disappear. In those distorted ecosystems, some of the species that thrive also foster an increase and spread of ticks and disease.
We are living, then, in an era when diseases that have lived in nature a long time, including Lyme disease and COVID-19, have jumped to human populations. As we combat those diseases and seek to prevent new ones, it can help to explore basic information on some of the animals and plants that play a role in the environmental settings where Lyme disease is rising.
For instance, the white footed mouse, the most common small mammal in much of the Northeast, is a key “reservoir” of disease and a favorite feeding station for ticks; a mouse may carry as many as 100 ticks without being harmed itself. The mice, however, tend to carry several diseases in their blood, including the bacterium that causes Lyme disease, and, as it turns out, they are highly successful at transmitting those diseases to ticks.
Deer cannot transmit Lyme disease to ticks. Rather, their importance is that they feed a lot of ticks at one time and help the population grow. A single deer can support hundreds of ticks while also transporting them between forests and lawns.
Still another feature in our landscapes that can worsen tickborne disease risk is the invasive plant called the Japanese barberry. Wildlife biologist Dr. Scott Williams of the Connecticut Agricultural Experiment Station explained in an interview that the barberry shrub provides a uniquely hospitable setting for ticks. The shrub creates a reliably shaded space with a high relative humidity for moisture-loving ticks. Williams and his colleagues have found that eliminating Japanese barberry from forested areas can reduce the number of Lyme disease-infected ticks in those areas by as much as 80 percent.
For a few further basics consider the quiz and answers below:
1. Which of the following tick species is, by far, the most common in Connecticut?
a) The black-legged tick (also called the deer tick)
b) The lone star tick
c) The American dog tick
d) The Asian longhorned tick
2. Which of the following disease organisms has been found in ticks tested by the New York Upstate Medical University testing lab at Syracuse in the past several years?
a) Anaplasmosis
b) Babesiosis
c) Bartonella
d) Lyme disease
e) All of the above
3. According to the Centers for Disease Control, in which life stage are ticks most likely to transmit Lyme disease to humans?
a) Larval stage
b) Nymph stage
c) Adults
4. True/False: In 2021 an investigative news report showed that a popular flea and tick collar was responsible for nearly 1,700 pet deaths.
Answers:
- a) The black-legged tick. Out of more than 5,000 ticks sent by Connecticut residents to the state laboratory for testing in 2021, roughly 77 percent were black-legged, 19.2 percent were dog ticks, 3.7 percent were lone star ticks, and 0.2 percent were Asian longhorned ticks.
- e) All of the above.
- b) Nymph stage. Northeastern University has reported that nymphs are responsible for 85 percentofall tick-borne diseases. Black-legged ticks in the nymph stage are roughly the size of a poppy seed, which makes them especially difficult to detect; they are most active between late May through August.
- True. A follow-up congressional investigation found that certain pesticides in flea and tick collars caused 2,500 pet deaths and roughly 100,000 illnesses. In October 2022, the EPA announced a ban on a type of flea and tick collar containing a chemical linked to neurological damage in children. A guide to safer alternatives can be found on the non-profit National Resources Defense Council webpage, “Flea and Tick Products Directory.”