Tick numbers are high field research finds
Ticks are out there — in the woods, in the grass, in the underbrush — in higher numbers than researchers from Western Connecticut State University have found in this area over six years of collections and study. And, they’re carrying Lyme disease and a smorgasbord of other afflictions that can cause serious health problems for humans.
“The blacklegged tick transmits the agent of Lyme, babesiosis, anaplasmosis, relapsing fever borreliosis, and Powassan encephalitis,” said Dr. Neeta Connally, director of the Tick-Borne Disease Prevention Laboratory at Western Connecticut State University (WSCU).
The lab at WSCU reports that its weekly sampling for deer ticks shows the highest population level that its researchers have found since 2011, the year they initiated field monitoring of area sites.
Dr. Connally, a Ridgefielder and an associate professor of biological and environmental studies, said samples taken weekly since the beginning of May at sites in Ridgefield, Newtown and Danbury have consistently shown increased levels of nymphal stage blacklegged ticks — commonly known as deer ticks — compared with surveys conducted for similar periods from 2012 through 2016.
The numbers are higher but close to the levels found 2011.
Averaging the numbers of ticks nymphal ticks found at the Ridgefield, Danbury and Newtown sites in collections in the last week of May or first week of June, the WSCU lab found the number of ticks collected per hour averaged: 359 in 2017; 89 in 2016; 229 in 2015; 32 in 2014; 97 in 2013; 114 in 2012, and 318 in 2011.
Field samples from the fifth week of collections showed on average 303% more nymphal deer ticks than in the same week in 2016, and 57% more than in 2015. The numbers showed a surge of 1,021% from the comparable week in 2014, when the number of ticks collected was lowest.
“There are many factors that can affect the number of ticks we see each year,” Connally said. “These include the abundance of tick hosts such as deer and white-footed mice, as well as climatic factors like the amount of rainfall in the spring.”
The tick counts are produced from what researchers often call a “tick drag” and are expressed in the “ticks per hour” numbers.
“We have a summer field crew composed of four people. The field sites are located in public nature preserves,” Connally said.
In Ridgefield, the drags are done at the McManus Preserve on West Mountain off Oscaleta Road and Peaceable Hill Road.
“We drag a one-meter square flannel cloth though the leaf litter for 30-second intervals. The drag cloths are inspected after each drag. We sample for 20 minutes and estimate ticks collected per hour,” she said.
Dr. Connally also participated with researchers in New York and Maryland in a study of the rates ticks are infected with Lyme and other diseases, based on tick collections at numerous sites in the three states in 2011 and 2012 and published in 2015 in the Journal of Vector Ecology.
In 2011 the study found that of 439 nymphal ticks tested in Connecticut, 16.4% were infected by Borrelia burgdorferi, the bacterium which causes Lyme disease, and the infection rate at sites in all three states was 18.5%.
Of 75 ticks collected from Connecticut in 2012 and tested, 9.3% had Borrelia burgdorferi, while the infection rate for 170 ticks collected in the three states was 15.3%.
“It is variable from location to location. But the nymph stage (the active stage right now that we monitor) in our region has varied from about 15-25% carrying Lyme,” Connally said.
Babesiosis, described as “a severe and sometimes life-threatening disease” by the Centers for Disease Control and Prevention (CDC), is caused by a tick-borne parasite that infects red blood cells, Babesia microti. The study found Babesia Microti in 5.9% of 439 ticks collected in Connecticut in 2011, and in none of 75 Connecticut ticks collected in 2012 — although it was found in 15.4% of 39 ticks collected in New York in 2012. The study found 2.5% of Connecticut ticks were co-infected with both the Lyme and Babesiosis pathogens in 2011, though none were co-infected in 2012.
The disease Anaplasmosis is caused by the bacterium Anaplasma phagocytophilum. The study found 3% of ticks collected in Connecticut in 2011 carried the bacterium, and 4% of Connecticut ticks collected in 2012. The co-infection rate with both the Lyme and Anaplasmosis pathogens was 1.3% in 2012, with no co-infected ticks found in 2011.
With ticks carrying pathogens for this variety of diseases, Connally urged people to do what they can to avoid them.
“While we are seeing an especially high number of ticks this season, it’s important to remember that in our region, every year is a risky year for Lyme disease and other tick-associated infections,” Connally said.
“Residents should always be vigilant in protecting themselves from tick bites. Some ways for people to prevent encounters with ticks are to wear long pants and light-colored clothing, check all exposed skin thoroughly after spending time outdoors where ticks are present, bathe shortly after outdoor activity, and dry clothes on high heat after outdoor wear.”
Connally also said that application of insect repellent to the skin and the wearing of permethrin-treated clothing can help people avoid tick bites.
She noted that all repellants should be applied and reapplied according to label directions.
She recommended that pet owners discuss tick prevention measures with their veterinarians.
“You can also spray your yard or have your yard professionally treated by a licensed pesticide applicator,” Connally said. “The most long-lasting and effective types of yard sprays are synthetic pyrethroid products. Natural pyrethrin insecticides (derived from chrysanthemum) or Metarhizium fungus can also be effective but the effect may not be as long lasting.”
Last year Connally received a $1.6-million grant from the Centers for Disease Control to conduct a four-year integrated tick management project that aims to combine findings from tick control research with study of human behaviors to produce more effective strategies to combat the spread of Lyme disease and other tick-borne illnesses.
The study is a collaborative effort between the CDC, Western Connecticut State University, Dr. Connally, and Dr. Thomas Mather, director of the Tick Encounter Resource Center at the University of Rhode Island.
Given the current talk of budget-cutting in Washington D.C., there could be a chance the federal money will be cut off.
“I am hopeful that there will be federal funds available for researchers to continue investigating the prevention of tickborne diseases in the future,” Connally said. “There has been a lot of progress in recent years towards understanding the best ways to prevent people from being exposed to blacklegged ticks in our region.”