Researchers from the U.S. Centers for Disease Control and Prevention (CDC) have discovered that almost half of the total number of counties in the United States is now home to hordes of ticks that can carry the dreaded Lyme disease.
In a study featured in the Journal of Medical Entomology, scientists from the federal agency found that varieties of blacklegged ticks infected with the Borrelia bacteria inhabit about 45 percent of counties in the country. This is a significant increase compared to the 30 percent of American counties that had these insects in 1998.
"It's important for people to be aware that there may be ticks in areas where they haven't seen them previously so that they can take steps to help protect themselves and their families," Rebecca Eisen, a researcher from the CDC and the lead author of the study, said.
Eisen and her colleagues stated in their report that the number of Lyme disease infections in the United States has more than tripled since the 1990s.
Lyme Disease
Lyme disease is a form of bacterial infection that is typically spread through the bites of blacklegged ticks, particularly the Ixodes scapularis (deer tick) and the Ixodes pacificus (western blacklegged tick). These insects can often be found living in grassy or wooded areas.
The diseases itself is caused by a strain of bacteria known as Borrelia burgdorferi. Individuals infected with these microorganisms develop symptoms such as headache, fatigue and fever, which can often be confused for symptoms of influenza.
Some patients also develop "bull's eye" rash on the area of their body where they have been bitten by ticks.
Lyme disease can effectively be treated using antibiotic drugs. However, if the infection is not addressed immediately, it can cause patients to suffer long-term cognitive problems, muscle and joint pains and various mood disorders.
Spread Of Disease-Carrying Ticks In The United States
In order to determine changes in tick populations in the country, the researchers examined data collected from various counties.
They discovered that deer ticks are now present in 1,420 out of the total 3,110 counties (46 percent) in the continental United States, while western blacklegged ticks now inhabit 111 of the counties (4 percent).
This equates to a 45 percent increase from figures recorded in 1998 when the insects were reported to live in 1,058 U.S. counties.
The researchers determined that deer ticks have established populations in 842 counties in 35 different states, which is a significant increase compared to the 396 counties across 32 states that the insects inhabited in 1998.
The ticks' stomping grounds were used to be centered in northeastern states, but data suggests that the insects have moved south and west.
Meanwhile, western blacklegged ticks have established themselves in 95 different counties across six states, which is an increase from the 90 counties they inhabited in 1998. The insects, however, remain centered in states along the Pacific coast.
Despite the continued spread of tick populations across the U.S., Eisen explained that the likelihood of contracting Lyme disease differs depending on the number of ticks carrying the Borrelia burgdorferi bacteria, as well as the chances of these insects biting individuals.
How To Avoid Tick Bites
Dr. Keith Berndtson, a disease expert from the Center for Research on Biotoxin-Associated Illness (CRBAI) in Maryland, said that people can help protect themselves from tick bites by spraying their skin and clothing with repellants made with lemon permethrin or DEET.
It is also advisable to wear long sleeves shirts and long pants, especially when going outdoors. Wearing clothes in light-colored fabrics can also help make ticks easier to spot.
Berndtson, who was not involved in the CDC study, said that keeping ticks for disease testing can also help researchers determine whether the insects carried the Lyme bacteria.
Photo: Lennart Tange | Flickr
