Survey shows ‘clear gap’ in US tick surveillance, control
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Tick surveillance and control in the United States are inconsistent, largely because of inconsistent funding, limited infrastructure, lack of guidance and institutional capacity, according to a survey in the Journal of Medical Entomology.
“Our findings highlight a clear gap in our public health infrastructure for the monitoring of ticks and the diseases they spread. 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,” Emily M. Mader, MPH, MPP, of Cornell University’s department of entomology and program manager at the Northeast Regional Center for Excellence in Vector-Borne Diseases, told Healio. “In practical terms, this means that many communities have limited or no information about the ticks that are present in the local environment or pathogens they carry. As a result, many of our communities have a poor understanding of the risk for tick-borne illness.”
Mader and colleagues surveyed 140 vector-borne disease professionals from local, state and country public health and vector control agencies to measure tick surveillance program objectives, control practices, pathogen testing methods, data communication and barriers to program operation and development. They found that less than half of respondents said their jurisdiction had routine, active surveillance; nearly two-thirds reported passive surveillance. The most common surveillance objective was detection of tick presence (76.2%) and the majority of programs supporting tick pathogen testing were in the Upper and Central Midwest (64.3%), Northeast (70.8%) and West (71.4%) regions.
Vector-borne diseases more than tripled between 2004 and 2016, including a doubling of tick-borne diseases. The researchers were surprised to find the issues related to pathogen testing, which is an “essential component of surveillance” that helps researchers identify the risks associated with tick-borne diseases, according to Mader.
“There appears to be a significant barrier for many tick surveillance programs across the country to access pathogen testing services,” she said. “We also noticed the large number of programs that relied on partnerships with academic organizations to conduct tick surveillance and control work. These relationships were important for pathogen testing, personnel supply and funding — they’re very wide reaching.”
Mader and colleagues also found that 26% of respondents said their jurisdiction financially supports or conducts testing of tick samples for disease-causing pathogens. Additionally, just 7% of individuals surveyed said their programs evaluate pathogen presence in animal hosts, such as mice and other rodents, from which ticks acquire pathogens.
Infectious Disease News Editorial Board Member Eugene Shapiro, MD, professor of pediatrics and epidemiology at Yale School of Public Health, noted that, in the U.S., inadequate funding for prevention and surveillance programs greatly hinder tick control measures.
“Because federal grant programs seem preferentially to fund research on molecular biologic issues rather than on either field studies or epidemiologic studies related to ticks, there is much that we don’t know about the biology of ticks. For example, the question may not be, ‘Why are there so many ticks?’ but rather ‘Why aren’t there more ticks?’ That is, the question becomes, ‘What causes ticks to die early?’ — which might provide clues as to how to intervene to control them.’”
Survey results from Mader and colleagues revealed that just 12% of participants said their jurisdiction financially supports or directly conducts tick control. Public health, cooperative extension, mosquito control and agriculture were the most common employment sectors among respondents; 57.1% said their programs work with academic partners to perform tick surveillance.
Mader emphasized that a limitation of the study was the lack of a census or program directory for local or state jurisdictions that could be used for data collection.
“Conducting a similar study in a few years’ time will be interesting to see how having this guidance has influenced program operations. Several states and counties have also started to support formal tick surveillance operations since we distributed the survey,” Mader said. “Learning more about their experiences, both needs and successes, will be helpful to further support this component of our public health infrastructure.”
Perspective
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Paul G. Auwaerter, MD
The U.S. lacks vital information that would help inform decisions about the prevention and treatment of tick-borne diseases. Over the last several decades, tick-borne diseases have increased in incidence and spread geographically into new regions. However, information is based more on human cases rather than looking at the tick populations. If tick populations were more carefully followed, this would help inform clinicians, especially in emerging areas, to be aware of infections that should prompt testing in ill people and concerning trends.
Cooperative programs should be funded to monitor and study vector-borne diseases generally, given the population and climatic changes that impact not only ticks but mosquitos and other animals involved in zoonoses.
Most tick surveillance programs are done on a shoestring, meaning that they are ad hoc or dependent on passive surveillance — ticks are brought to them. Only 12% of those surveyed stated they had direct financial support for tick control. Moreover, the lack of funds also limits public-facing messaging.
This is akin to a hospital lacking infection control protocols and practitioners. A secondary consideration is the growing brain drain because the lack of tick research has meant fewer researchers and entomologists (although ticks are not insects, but arachnids) are entering the field.
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