Ticks Hold the Key to Heartland Virus

Heartland virus discovered in ticks in Missouri

(RxWiki News) As if Lyme disease wasn't enough, people now have a brand new reason to keep tick bites at bay.

A new study from researchers with the Centers for Disease Control and Prevention (CDC) has detected the rare Heartland virus in Missouri ticks. This virus, which was previously unknown, infected two people in 2009.

The CDC recommends people take steps to protect themselves from tick bites.

"Wear long sleeves and pants to help prevent tick bites. "

According to the authors of this new study, the beginnings of the research date back to June 2009, when two men in northwestern Missouri were both admitted to a regional hospital with similar symptoms.

The men both lived on farms in the same region of Missouri, but the farms did not neighbor each other. They both reported recent exposure to and removal of embedded ticks. 

The CDC reported that the patients presented flu-like symptoms. They experienced fatigue, fever, loss of appetite and diarrhea. Tests showed that the patients had low counts of platelets — cell fragments which help the blood to clot.

Doctors initially suspected ehrlichiosis, a disease spread by ticks. When medicine used to treat ehrlichiosis did not help the two men, special tests were run.

After testing the patients, doctors determined that they were both suffering from a novel Phlebovirus — a family of viruses often passed through the bites of mosquitos, sandflies and ticks. The new virus was named the Heartland virus.

For the new study, lead author Harry M. Savage, PhD, of the CDC, and team collected a total of 56,428 ticks during April, June and August 2012.

Ticks were collected from 12 different sites (including the farms of both 2009 Heartland virus patients) in four different Missouri counties.

Three different tick species were identified, but most of the ticks found (97.5 percent) were of the species Amblyomma americanum, or the lone star tick (named for its coloration, not for an association with the state of Texas).

After testing the ticks, the researchers found evidence of the virus in ticks gathered from one of the farmer's properties and from a conservation area.

The strain Dr. Savage and team identified in the ticks was 97.6 percent identical to the strain identified in the human farmers in 2009.

The samples consisted of a large number of nymphs, or young ticks. At one site with positive results, the authors estimated that 1.99 nymphs per 1,000 were infected with the Heartland virus.

Dr. Savage and team also collected 758 mosquitos, but no evidence of the virus was found in these insects. 

"It's the first time anyone has found it in the wild, in the environment," said Dr. Savage in an interview with NPR News. "It means the virus is yet another tick-borne disease in the US — and another reason to prevent getting bit."

According to the CDC, people can prevent tick bites through a number of methods, including wearing long-sleeved shirts and pants, and using insect repellent. 

The presence of ticks in the yard can also be reduced by regularly clearing brush, tall grasses and leaf litter from areas surrounding homes, the CDC reported. 

More research is needed to understand how the virus is spread and to determine if the Heartland virus is present in a wider geographic area.

This study was published online July 22 by the American Journal of Tropical Medicine and Hygiene.

The study received financial support from the CDC's Division of Vector-Borne Diseases. No conflicts of interest were reported. 

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Review Date: 
July 23, 2013