THE BURNED OVER DISTRICT

Ticks have always been a problem in warmer climates and now as our climate warms up their range is reaching farther north than ever before. And the ones coming up are more aggressive than previously and vectors of dangerous diseases.

With the expansion of the suburbs and a push to conserve wooded areas, deer and mice populations are thriving. They provide ample blood meals for ticks and help spread the pests to new regions.

Originally from the Southeast, the lone star tick, for example, is heading north; it can now be found in 1,300 counties in 39 states. The blacklegged tick, also called the deer tick, is expanding its territory, too. In a recent study, Dr. Eisen reported a nearly 45 percent increase since 1998 in the number of counties with blacklegged ticks.

Thomas Mather, director of the University of Rhode Island’s TickEncounter Resource Center, said it used to get reports of three or four lone star ticks in the greater Chicago area each year. Now, it is receiving up to 15.

When a tick species marches into a new region, it poses a double-barreled threat, said Jerome Goddard, extension professor of medical and veterinary entomology at Mississippi State University.

First, the species brings diseases from its original location. Second, the ticks pick up new pathogens from animals in their new ecosystem.

Physicians and patients in a tick’s new home may be less familiar with the diseases it carries. They can overlook symptoms or attribute them to a different cause, delaying effective treatment.

The best known threat is Lyme disease. Cases in the United States increased from about 12,000 annually in 1995 to nearly 40,000 in 2015. Experts say the real number of infections is likely closer to 300,000.

But scientists are finding ticks carry more than just Lyme: At least a third of known tick-borne pathogens were found in the last 20 years. Heartland virus and Bourbon virus, which can prove fatal, were discovered in just the last five years.

Powassan virus, a rare but dangerous pathogen that can cause permanent brain damage or death, can be passed from tick to human in just 15 minutes. It was discovered in 1958, and an average of seven cases are reported each year. Earlier this month, a resident of Saratoga County, N.Y., who had Powassan disease died.

Dr. Gary Wormser, founder of the Lyme Disease Diagnostic Center at New York Medical College, said the most worrisome tick-borne contagion he sees is babesiosis, which can cause malaria-like symptoms and require hospitalization. A few of his patients have died from it; several required intensive care.

Before 2001, babesiosis was not found in Westchester, N.Y. But Westchester Medical Center has diagnosed at least 21 cases in the past year. A study of babesiosis in Wisconsin found a 26-fold increase in the number of cases between 2001 to 2003, and 2012 to 2015.

In places where the lone star tick is gaining prevalence, doctors also are seeing an increase in cases of alpha-gal syndrome, a strange allergy to red meat induced by tick bites.

Alpha-gal is a sugar molecule carried by the lone star tick. When the tick bites a human, it activates the immune system, which starts producing alpha-gal antibodies.

The body becomes wired to fight alpha-gal sugar molecules, which are abundant in red meat. Eating meat can trigger allergic reactions, from an itchy rash to anaphylactic shock.

It would be nice if the government would spend as much money seeking a cure for these diseases as they do on research to weaponize them. But we can delay any though of that until we get a real government in Washington.