Recent Weather Could Breed More Ticks

This month's unusually wet start, followed by the recent hot, humid weather, has created ideal breeding conditions for disease-carrying pests -- like ticks. That could be dangerous according to recent research collaborated on by faculty from Washington & Jefferson College in Washington, Pa. and the University of Pennsylvania, along with researchers from the Centers for Disease Control, finding that the potentially fatal tick-borne illness human granulocytic ehrlichiosis or HGE is on the rise.

Washington & Jefferson Professor of Biology Dr. Richard Dryden, reports that HGE can be fatal in five to 10 percent of the cases, yet doesn't receive the same attention as the more common tick-borne illness, Lyme disease. Dryden and his fellow researchers produced a paper titled "Molecular characterization of Anaplasma phagocytophilum and Borrelia burgdorferi in Ixodes scapularis ticks from Pennsylvania," which was published in the Journal of Clinical Microbiology in April. They found that there is not only a higher percentage of ticks carrying Lyme, but also more carrying HGE, which causes flu-like symptoms and often goes undetected by doctors.

"We found a higher percentage of ticks carrying the human pathogen for Lyme disease, as well as HGE, which was first discovered in 1994," says Dryden. "HGE is more of a problem because most people and physicians are not aware of the disease since it has the same symptoms as a person having the flu. There are a lot of different diseases that all have flu-like symptoms that can be tricky. HGE could be the West Nile Virus of the future. It doesn't need to be reported by private physicians in Pennsylvania and the majority of states to the Centers for Disease Control."

While the majority of ticks Dryden, his students, and fellow researchers have collected are from Presque Isle State Park in Pennsylvania's Erie County, he has also tested ticks from other counties in the state, as well as parts of New Jersey, Maryland, and near Washington, D.C. Of the 263 deer ticks collected at Presque Isle State Park the past two years, 162 -- nearly 62-percent -- tested positive for Lyme disease. Dryden believes that may be the highest concentration of the disease in any study nationwide.

His team found the heaviest concentration of HGE in the southeast. Dryden reports that all 100-percent of the ticks found to be HGE-positive from Erie County are carrying pathogenic strains. Based on his research, he believes there are only two places in the United States that have more ticks carrying HGE than the Lyme pathogen -- with one of them being the Chester/Delaware counties area of Southeastern Pennsylvania. The other is Colts Neck, N.J., where they have tested 41 deer ticks to date and found 15 (36.6-percent) to be positive for HGE, with only seven (17.1-percent) testing positive for the Lyme pathogen. He also reports that Maryland is also heavily infested with ticks that are carrying either the HGE pathogen, the Lyme Disease pathogen, or both.

The researchers have tracked the situation in Presque Isle. In the Fall of 2000, they found 43-percent of the ticks tested positive for Lyme disease, but none were positive for HGE. Then in Fall 2001, they found 66-percent of ticks were positive for Lyme disease, while two-and-a-half percent having HGE.

"That indicated that HGE moved into Erie County in the last year," Dryden says. "Normally when a disease moves in, an organism hasn't had chance to mutate to a non-pathogenic form. We think there are new arrivals that may be coming in on migratory birds. All these areas found high rate of deer ticks near the shore or coastline, so that's why we suspect the pathogens may be coming from migratory birds because they follow along coastlines. Deer ticks have been reported being on migratory birds."

The white-footed mouse had been most responsible for passing the pathogens to the ticks.

Dryden has become an authority on tick-borne disease since taking his first sabbatical in the Fall of 1998, where he spent about two months at the Centers for Disease Control and Prevention in Atlanta, learning how to extract DNA from the ticks and test it for bacteria that sickens humans. Upon returning to W&J, he obtained testing equipment and identified promising students to assist in his research.

While Dryden and his team receive ticks from various sources to be tested for disease, they often collect their own in wooded areas. When they do, they try and remain safe by covering themselves from head-to-foot in white -- except face and hands -- wearing long white shirts, pants, and caps, and using duct tape to seal all possible openings where ticks could get in. They also spray shoes with an insecticide containing deet -- like Off -- to keep ticks from clinging onto their shoes and crawling up their bodies. He and his students also check each other for ticks every 10 minutes.

Dryden offers the following tips for people to avoid being infected by a diseased tick:

* Be aware that ticks could be active from the time the weather gets warm in April, until the first hard frost at the end of October, and the beginning of November. * Wear long-sleeved shirts and long pants, tucking the pant legs down into your socks. * Always wear a cap, since they sometime get on your head and hold onto a hair. * Be aware that ticks sometimes hang on to lower branches of shrubs, so check your entire body. * Spray some insecticide containing deet into your socks and pant legs to keep the ticks from clinging.

"Frost will kill off a lot of them off, although others would move to a warmer place and are able to survive in the skins and fur of deer. The fur acts as an insulator and ticks are able to survive there," says Dryden. "We're able to get loads of ticks off those deer."

Dryden also presented the findings of this study last November at the national American Public Health Association meeting in Philadelphia. One of the students who has worked with him helped write an article for the CDC's Journal of Emerging Infectious Diseases.