As parts of the United States see increasing populations of ticks and their associated diseases, experts warn that current surveillance and tracking methods aren’t robust enough to combat the growing public health concerns surrounding tick-related vector-borne illnesses.

The US is home to two primary tick species, the blacklegged tick (Ixodes scapularis) in the Midwest and East Coast and the Western blacklegged tick (Ixodes pacificus) in the Western US, according to the Centers for Disease Control and Prevention. When they bite people or animals, ticks can spread pathogens from their saliva.

In a recently published report by the agency, experts say that the geographic distributions of the blacklegged tick are expanding, “putting an increasing number of Americans at risk for acquiring Lyme disease” – the highest spread vector-borne illness in the US – and a number of other diseases including anaplasmosis and babesiosis. Despite a rise in tick-borne illnesses over the last 15 years, the researchers warn in the Journal of Medical Entomology that inadequate funding and standardized surveillance procedures pose potential threats to public health.

"Vector-borne diseases are only going to become an increasing threat in the world, [including] the United States and we really don't know how to address that threat unless we study it,” said lead study author Emily Mader in a statement.

Researchers from Cornell University surveyed 140 professionals at various public health and control agencies who study vector-borne diseases in order to identify methods that public health agencies use to track ticks, as well as barriers they have in providing effective guidance. They specifically looked at tick control practices, how data is communicated, and barriers to creating and running programs. Most detrimental to tick monitoring were insufficient infrastructure and limited guidance on best practices, as well as a lack of institutional capacity.

Less than half of respondents were currently engaged in active tick surveillance (collecting ticks from the environment for testing), while almost two-thirds were employing passive surveillance (members of the public send in tick samples). Active surveillance is the most thorough and detailed method, but also costs more and requires more training.

"The most prevalent barrier to developing and sustaining a tick surveillance program across time is just lack of funding," said Mader.

The researchers add a lack of testing services means that data may be insufficient or poorly representative, putting up a barrier to informing the public about threatening tick diseases in their area. Standardizing survey guidelines specific to the unique behavior and habitats of ticks may help to bridge gaps in knowledge, the researchers conclude.