Tick surveillance, control needed in U.S., study shows

The prevalence of Lyme disease and other tick-borne illnesses has steadily increased in the U.S. over the past 20 years. Now, an inaugural nationwide study of tick surveillance and control describes a clear need for more funding and coordination among programs across the country.

Among the coauthors is a Texas A&M AgriLife researcher, Pete Teel, Ph.D., a Regents professor in the Texas A&M Department of Entomology. Teel said that while Texas has monitored and controlled ticks since 1893, a nationwide database is needed.

The study’s authors surveyed 140 vector-borne disease professionals working at state, county and local agencies in fall 2018. Reaching even that many respondents proved challenging, the authors said. No central database of tick-management programs or contacts was available.

The survey’s aim was to learn about programs’ objectives and capabilities for tick surveillance and control. Respondents were also asked whether they tested ticks for disease-causing germs, and about barriers to success.

Nationwide, less than half of public health and vector-control agencies engage in active tick surveillance, according to the survey. Only 12% of the surveyed agencies directly conduct or otherwise support tick-control efforts.

The Lyme disease bacterium is spread through the bite of infected deer ticks, or blacklegged ticks. Photo courtesy of CDC

The study appeared on June 17 in the Journal of Medical Entomology. In addition to Teel, the authors were from Cornell University; University of Florida, Gainesville; University of California, Davis; University of Illinois; and the Centers for Disease Control and Prevention Division of Vector-Borne Diseases. The authors are also affiliated with the CDC’s five Vector-Borne Disease Regional Centers of Excellence.

“Ticks are responsible for the majority of our vector-borne illnesses in the U.S., and our programming does not adequately meet the need in its current form, for both surveillance and control,” said Emily Mader, public health researcher, lead author on the study and program manager at the Northeast Regional Center for Excellence in Vector-Borne Diseases, led by Cornell University.

Texas has a long history of tick surveillance

In Texas, early detection and control have led to discoveries of exotic ticks, Teel said. These efforts kept the ticks from becoming established. 

“These ticks could have introduced several devastating diseases with high risks for humans, livestock and wildlife,” he said. “National databases for the kinds of ticks that are present, and how those populations change with time and space, would be hugely informative for public health and animal health needs.”

Dog ticks can transmit cattle fever and other animal and human diseases. Photo by CDC/James Gathany

Texas has engaged in tick surveillance and control activities since 1893. At that time, the 23rd Texas Legislature established the Livestock Sanitary Commission, which later became the Texas Animal Health Commission. 

“I believe this to be the oldest and longest continuous tick surveillance program in North America,” said Teel. The commission’s aim was to protect livestock from dangerous diseases such as cattle fever.

The resulting state and federal cattle fever tick eradication program eliminated these ticks from 14 states by the 1940s. The program established a permanent quarantine zone along the Texas-Mexico border and has protected the U.S. cattle industry ever since. Statewide tick surveillance activities continue today.

“Today, the data from this program are becoming valuable and complimentary to public health needs,” Teel said. “Collaborations are growing in Texas to share information, improve surveillance and testing, train a new generation of vector biologists, and improve best practices for tick control and tick-borne disease prevention.”

One such collaboration is the Western Gulf Center of Excellence in Vector-Borne Diseases, where AgriLife is a partner. Other collaborators include academic institutions and public health and animal health agencies in Texas, Oklahoma, Arkansas and Louisiana. Led by the University of Texas Medical Branch, the center performs research to expand surveillance for ticks and tick-borne pathogens. The center also trains future scientists and public health practitioners.

Highlights from the nationwide survey of tick-management programs

Less than half of tick-management programs proactively collect ticks in their area 

About two-thirds of respondents, 65%, said their programs engage in passive tick surveillance, such as accepting tick samples submitted by the public. However, only 46% said their programs engage in routine active tick surveillance, such as focused collection of tick samples within their community.

Only a quarter of tick-management programs test ticks for disease-causing germs 

Survey respondents from Texas are among the 26% nationwide who said their jurisdiction conducts or financially supports testing of tick samples for disease-causing pathogens. Only 7% of respondents nationwide said their programs work to detect such pathogens in animal hosts, such as mice, that can pass the pathogens to ticks in their area.

“Pathogen testing is an essential component of surveillance and is needed in order to understand tick-borne disease risk to communities,” said Mader. “There appears to be a significant barrier for many tick-surveillance programs across the country to access pathogen-testing services.”

Capacity for public tick-control efforts is low 

Texas provides financial support for tick control. Yet nationwide, only 12% of respondents said their jurisdiction conducts or financially supports tick control. Those efforts primarily focused on reducing tick presence on animal hosts such as deer and rodents.

Mader said limited resources mean tick-management programs need reliable, proven control methods.

“They are not going to invest in a strategy unless it has been investigated and shown to make a difference in reducing the burden of ticks and tickborne diseases,” she said. “Right now, supporting this research is a major need. These kinds of evaluations often take at least three years to complete and require a significant investment.”

Tick surveillance and control happen in a range of sectors 

The most common employment sectors among respondents was public health, mosquito control, cooperative extension and agriculture. More than half of respondents, 57%, said their programs work with academic partners such as Texas A&M AgriLife to conduct tick surveillance.

Info and data sharing on ticks and public health is lagging 

Less than a quarter of respondents, 23%, said their tick-management programs disseminate information to local health departments. Just 14% report data to the CDC.

Greater support for tick-management programs is critical. Respondents commonly cited the need for stable funding, training for personnel, and standardized, research-based guidance and protocols.

Recent national efforts begin to improve the tick situation

In December 2019, the Kay Hagan Tick Act authorized $150 million to strengthen the nation’s efforts on vector-borne disease. The act included funding the CDC’s Vector-Borne Disease Regional Centers of Excellence for an additional five years, through 2026. In the past two years, the CDC also issued guidance on the best practices for surveillance of several tick species.

These steps address several needs that survey responders had highlighted. The authors said the survey will serve as an important baseline from which to measure future progress and improvement.