Confronting a Public Health Threat in the Great Outdoors

Whether mowing your lawn or hiking in the woods, any outdoor activity carries with it some risk that you will be bitten by a tick or mosquito carrying a pathogen that can cause a potentially serious disease.

While many of us have been educated about the importance of covering up, using insect repellants, and checking our bodies for ticks after being out in nature, there are still many unanswered questions about preventing and treating Lyme and other vector-borne diseases. Public health agencies, ranging from the local level to the Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO), face a shortage of public health entomologists with the necessary expertise to tackle these challenges.

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UMass Amherst is leading a regional effort to close knowledge gaps and test evidence-based solutions for more effective control of ticks and mosquitoes across New England. In 2022, the CDC designated a New England Center of Excellence in Vector-Borne Diseases (NEWVEC) at UMass, funded by a $10 million, five-year grant. NEWVEC is directed by Stephen Rich, UMass Amherst professor of microbiology, with Andrew Lover, assistant professor in the School of Public Health and Health Sciences, as deputy director, and Guang Xu, research professor of microbiology, a co-investigator, along with a multidisciplinary group of scientists at the University of Rhode Island, Northern Vermont University, Western Connecticut State University, the University of New Hampshire, Dartmouth College, and the University of Maine.  

Rich said NEWVEC aims to “bring to bear the talents of a diverse group of experts to answer important questions around vector-borne diseases, in order to help pest control groups and public health agencies use their limited resources to the greatest effect.” This network of researchers meets weekly to compare data and notes.

Moreover, said Rich, when it comes to vector-borne diseases, “What happens in northern Vermont and Maine is likely somewhat different than what happens in southern New England, and rural areas differ from urban and suburban areas. We want to incorporate understanding of all those different ecosystems and make sure the responses are catered to the specific needs of a region.”

In addition to fostering collaborative operational research, NEWVEC is working to train the next generation of public health entomologists and create a “community of practice,” connecting researchers with state and local public health agencies, tribal organizations, Lyme disease groups, private pest control operators, and public and nonprofit landowners who promote outdoor activities.

Shifting Landscapes

UMass Amherst has been a leader in research and education related to entomology, the biological science focused on insects, dating back to its early days as an agricultural college in the 19th century. The university awarded its very first PhD in entomology. Back then, entomologists were primarily concerned with the problems insects posed to crops. But in the second half of the 20th century—as UMass was expanding and diversifying its programs beyond agriculture—certain insects emerged as carriers of pathogens that could infect humans. Lyme disease, carried by ticks, was first discovered in New England in the 1970s. Other vector-borne diseases, such as West Nile virus and Eastern Equine Encephalitis, followed.

“There’s a very, very rich history of entomology at UMass, and we’re trying to resurrect that to confront these public health challenges today,” said Rich.

Vector-borne diseases can cause a range of symptoms which, in some cases, linger for years or even decades. Blood-sucking ticks transmit more vector-borne diseases than any other arthropod on the continent, with activity highest in New England, where changing weather patterns mean tick season is nearly year-round.  

Lyme and other vector-borne diseases are also believed to be significantly underreported. In recent years, about 40,000 new cases of Lyme disease have been reported annually in North America (exceeding the number of new reported cases of HIV and AIDS each year), yet the CDC estimates the actual number of people infected could be as much as ten times higher.

Above: Guang Xu, UMass Amherst research professor of microbiology and NEWVEC co-investigator, demonstrates a "flagging" technique. The white flag is swept across vegetation and ticks, thinking the flag is a deer, grab onto it. From there, they can be collected for research purposes.

Research to Enhance Tick Prevention

Presently, the best option for mitigating the public health impacts of Lyme and other vector-borne diseases is prevention. Yet, unlike many other diseases, the goal of “herd immunity” cannot be achieved through human vaccination because vector-borne diseases are transmitted by insects, not person to person. That means, said Rich, “Vaccines are part of the solution, but they’re not going to solve the whole problem."

In addition, while local and regional agencies have historically carried out mosquito control efforts by spraying in areas where the insects are known to breed, tick control requires more of a patchwork approach by individuals and agencies. According to Lover, the two broad areas of tick prevention are personal protection—such as wearing long pants, using repellants, and doing tick checks with outdoor activity—and yard-based interventions, including clearing vegetation, wood chipping, and professional pesticide application.

NEWVEC’s first big research undertaking, known as Project ITCH (“Is Tick Control Helping?”), aims to improve understanding of best practices for individuals and families to protect themselves from ticks at home. In the first phase of the project, going on now, the researchers are surveying residents across New England about what they’re doing on their properties to reduce the incidence of ticks and tick bites. In the second phase, they will study whether these efforts are effective at reducing tick-borne illnesses. The results of Project ITCH will be used to educate the public about best practices.

The UMass researchers are also interested in understanding how much tick exposure occurs on residential properties compared to other settings, like hiking trails and sports fields. Lover and Rich have been studying the location of tick exposures using small GPS devices carried by participants who have and have not had recent tick-borne disease. 

"Figuring out where people are being exposed will help us develop more effective and targeted messaging to the public on how to protect themselves,” said Lover. “For example, we could post QR codes at trailheads with information on the level of tick activity on that trail.”

Other NEWVEC research focuses on testing novel approaches and products to protect against ticks. For example, Rich’s lab recently studied the effectiveness of new “spatial repellants” that create a type of force field that alters and slows ticks’ progress toward their target. In addition, NEWVEC researchers at the University of Rhode Island are working to develop new bee-friendly acaricides that kill ticks while sparing pollinator populations.

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Beyond prevention, NEWVEC's researchers also aim to better understand Lyme disease, including why it causes long-term symptoms in a subset of patients.  

“There are some people who get Lyme disease, take a two-week course of antibiotics, and never have another problem. Other people have long-term consequences and, in some cases, are sick for years,” said Rich. “We don’t know why that is, but the hunch is there may be other pathogens involved. There are always new viruses being discovered in ticks.”

In his research, for example, Xu found Hartland virus and Bourbon virus in ticks on Long Island. These pathogens were previously thought to be mainly found in the Midwest. NEWVEC researchers are also discovering new species of ticks in the region. “I think this center will help us provide an early warning system about new ticks species and pathogens, and the risks they pose to humans,” said Xu.

NEWVEC researchers are also pursuing tick-prevention strategies focused on deer, which are vital breeding sites for ticks. The explosion of ticks in New England over the past few decades can be traced to increases in deer populations. “Besides hunting, we’re trying to figure out ways to make the deer targets for interrupting the breeding of ticks,” said Rich.

Rich recently published a study in the journal Vector-borne and Zoonotic Diseases that demonstrated for the first time that the blood of the white-tailed deer kills the corkscrew-shaped bacterium that causes Lyme disease. Understanding exactly how the deer’s blood kills the bacteria could ultimately lead to new strategies for preventing and treating Lyme disease in humans. Watch Rich discuss this research on WCVB NewsCenter 5.

Training the Next Generation of Public Health Entomologists

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UMass students, from the undergraduate to the PhD level, contribute to NEWVEC’s research in a variety of ways, including in the lab, the field, and on public health messaging. Local high school students also assist through a partnership with the Northampton-based nonprofit, Collaborative for Educational Services.

On the education side, NEWVEC is working to build capacity in UMass’s public health major—the second largest major at the university—for studies in public health entomology. “This area has been highlighted by CDC and DPH [Department of Public Health] as a major gap in their hiring,” said Lover.  

“This center will provide a good opportunity to develop the next generation of entomologists,” said Xu.

This story was originally published in May 2023.