Citizen Scientists Offer a Better Understanding of Tickborne Disease

Tickborne disease is typically tracked only when people or animals become sick and the cases are reported to local, state, and national health departments. Even then, some disease instances go unreported.

To offer deeper insight into the potential for both human and animal exposure to tickborne disease, ecologists at Colorado State University (CSU) and Northern Arizona University (NAU) enlisted the help of citizen scientists across the country—and were overwhelmed by the response they received. Their findings were recently published in the journal PLOS One.

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“Normally the approach is to rely on reported disease cases, or to look at ticks in natural habitats,” said Daniel Salkeld, PhD, research scientist in the CSU Department of Biology and lead author of the study. “Our [new] data represent that in-between, middle ground: It shows when people or animals got bitten, and where, and what they got exposed to."

The goal of the study was to collect about 2000 ticks with most expected to come from California’s San Francisco Bay Area—but this goal was exceeded by a mile.

More than 16,000 ticks (90% removed from either humans or dogs) were sent in by citizen scientists from every state—excluding Alaska—and Puerto Rico. Each was tested for various bacteria, including Borrelia burgdorferi, Babesia microti, Anaplasma phagocytophilum, and Borrelia miyamotoi, a recently discovered pathogen not typically tracked by public health officials.

"The overwhelming participation from residents throughout the country and the surprising number of counties impacted demonstrates that a great need exists throughout the country for this information," said Nathan Nieto, PhD, assistant professor in the NAU Department of Biological Sciences and other lead author of the study.

Test results revealed 83 counties in 24 states where ticks carrying Lyme disease—causing bacteria had never been documented.

^{The county level distribution of Ixodes pacificus and Ixodes scapularis based on location data collected by citizen scientists. Counties outlined in red did not have previous records according to the CDC; no records include travel history of the submitter.}

Besides the wealth of data garnered from the ticks, this study also opens up a new way of understanding the spread and reach of ticks and tickborne disease by enlisting the help of citizen scientists.

“For example, we could start to look at what species of ticks are active, when, and where,” Salkeld said. “And how does this differ across the north or south, or the Midwest to California? There could be all kinds of subtle variations.”

The investigators did acknowledge the fact that citizen science—sourced data are not perfect and that some of the study findings could be hampered by human error or lack of access to information.

But with help from the public, investigators can gain insight on a scale unmatched by laboratory or government agency studies, which are usually only able to collect around 100 ticks for a localized study.

New approaches like this could lead to new insights on how diseases spread, as well as human and animal pathogens yet to be discovered.