BOSTON — A rapid increase in the number of tick-borne illnesses, particularly in the Northeast but in other parts of the country as well, has public health specialists concerned.
Of particular concern is Lyme disease, an illness first identified during an epidemic in Lyme, Conn., in 1975, which sometimes leads to long-term heart disease and arthritis. Since its identification, Lyme disease has been found in 14 states mostly concentrated in the Northeast, upper Midwest and the Pacific Coast.
Also of concern is babesiosis, a generally mild illness that can turn deadly when victims are 60 years or older, especially if their spleens have been removed or are malfunctioning.
"We're beginning to see thousands of cases a year," said Dr. Andrew Spielman, a professor of tropical public health at the Harvard School of Public Health, who is the leading authority on the transmission of these two diseases.
Both are transmitted to humans by the Northern deer tick, which lives its adult life on deer.
The tick's dependence on deer explains why the disease is becoming more common. By the turn of the century, the northern deer had almost been eliminated from the Northeast because the area's forests had been cut down for farming. As farming became less common in the Northeast, the forests regrew and the deer became abundant once again.
Other ticks are spreading common tick-borne diseases such as equine encephalitis, Rocky Mountain spotted fever and canine heart worm, which may be transmitted to humans by mosquito.
"They appear with alarming regularity in New England and some are deadly," said an article in the Health Sciences Report, published by the Harvard School of Public Health. "Disastrous epidemics are possible, in the view of health authorities and Harvard scientists."
"The potential for epidemics of animal-to-man disease is increased by current adaptations by wildlife," said Spielman. "Raccoons and skunks have become more numerous in the cities of the Northeast. Opossums, once seen only in the South, are becoming adapted to New England.
"Even the desert armadillo, host of leprosy, is extending its range into colder and moist regions. The new non-human residents of the Northeast threaten to share their diseases with the human inhabitants."