SEP 16, 2019 11:05 AM PDT

Ticks May Spread Multiple Diseases in One Bite

WRITTEN BY: Carmen Leitch

The incidence of tick-borne diseases is on the rise, and ticks present a growing threat to public health worldwide. In the United States, ticks caused around 22,000 cases of disease in 2002; cases had risen to 48,610 by 2016, and in 2017 there were 59,349 cases, which includes 42,743 occurrences of Lyme disease. There are many other tick-borne illnesses that impact people, however, and 2017 also saw 7,718 cases of Anaplasmosis/Ehrlichiosis, 7,718 people contracted Spotted Fever Rickettsiosis, and 6,248 patients got Babesiosis.

This study focused on three tick species present on Long Island, which bite people. (Left) black-legged tick AKA deer tick (Middle) American dog tick, (Right) lone star tick. / Credit: Santiago Sanchez-Vicente, Stony Brook University

New work in mBio by researchers at Stony Brook University and Columbia University has shown that three species of ticks that are found on Long Island can carry multiple diseases at once.

"In evaluating tick-borne infection, more than one organism needs to be considered," said senior study author Rafal Tokarz, Ph.D., assistant professor of epidemiology in the Center for Infection and Immunity at the Columbia Mailman School of Public Health. "This study emphasizes the need to focus on all tick-borne diseases, not just Lyme."

In this work, the scientists gathered ticks from several places around the central and eastern parts of Long Island. Seven different tick-borne diseases are present in this area - they are caused by microbes the tick harbors. After looking for twelve different disease-causing microbes in 1,633 individual ticks, the researchers found that over half of the deer ticks (Ixodes) they examined were carrying the pathogen that causes Lyme disease. They also found the microbes that trigger Ehrlichiosis and Babesiosis. Over a quarter of the ticks the researchers studied were carrying more than one disease agent, and could potentially transmit more than one disease during the same bite.

The lone star tick is one type of tick, which spreads southern tick-associated rash illness (STARI). Researchers still don’t know what microbe causes the disease, which is usually treatable with antibiotics. These ticks are aggressive and bite people and animals, and are also known to transmit Ehrlichia bacteria, which causes the disease Ehrlichiosis.

The Centers for Disease Control and Prevention notes that “The distribution, range, and abundance of the lone star tick have increased over the past 20-30 years, and lone star ticks have been recorded in large numbers as far north as Maine and as far west as central Texas and Oklahoma.” This work showed that the lone star tick can be found on Long Island as well.

"Polymicrobial infections represent an important aspect of tick-borne diseases that can complicate diagnosis and augment disease severity," said the corresponding study author Jorge Benach, Ph.D., Distinguished Professor at the Department of Microbiology and Immunology at the Renaissance School of Medicine at Stony Brook University. "Some of the polymicrobial infections can be treated with the same antibiotics, but others require different therapies, thus enlarging the number of drugs to treat these infections."

About the Author
Bachelor's (BA/BS/Other)
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
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