Published: August 26, 2013
Residents of the Northeast and the Midwest know that ticks can carry the bacteria that cause Lyme disease. What most don’t know is that the same family of black-legged ticks can also cause other diseases that are even more dangerous.
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The worst is Powassan disease, which generally kills about 10 percent of its victims and leaves half the survivors with permanent neurological damage. Only 15 cases of this rare disease have been found in New York State in the last nine years, but there is no treatment and 5 of the patients have died. Fortunately, only a small percentage of ticks in New York are infected with the Powassan virus — between 4 percent and 6 percent at sites in the hardest-hit counties, Dutchess, Putnam and Westchester. By contrast, the Lyme bacterium has been found in 35 percent to 75 percent of the ticks at sites in those areas.
Three other diseases — anaplasmosis, babesiosis and illnesses caused by a newly detected pathogen, Borrelia miyamotoi — are transmitted by the same ticks and can, to varying degrees, cause severe disability and sometimes death. In rare cases a single tick could make a person sick with several diseases at the same time, greatly complicating diagnosis.
Senator Charles Schumer, Democrat of New York, recently urged the Centers for Disease Control and Prevention to allocate resources for research to understand the Powassan virus, create a treatment and learn how to prevent further spread. It would make sense to control this virus before it becomes a major threat.
Meanwhile, Lyme disease remains the most widespread tick-borne disease in the United States. Some 30,000 cases are reported annually to the C.D.C., but most cases go unreported because the symptoms are mild or mimic other diseases. The C.D.C. recently estimated that there may be 300,000 cases a year in this country, making Lyme “a tremendous public health problem.”
There are huge gaps in what scientists know about how best to diagnose, treat or prevent the disease. Researchers have identified the bacteria, known as spirochetes, that cause Lyme and the black-legged ticks that can transmit the disease from rodents and deer to humans. But they know very little about prevention. There is no vaccine on the market, so health authorities can do little but advise taking sensible precautions against tick bites, like wearing long sleeves and pants, using insect repellent and looking closely for ticks to remove after spending time outdoors. (Even infected ticks don’t always transmit the bacterium, especially if they are removed quickly.)
Lyme disease is best treated if caught early, when antibiotics can head off the worst consequences. But the early flulike symptoms, like fever, headache and fatigue, are so common that people may not realize they have Lyme. There is no reliable diagnostic test to identify Lyme disease within the first month after the tick bite.
Although most cases are relatively mild and easily cured, some victims are left with lasting injuries, like joint pain, persistent fatigue or neurological damage. There is controversy over whether these long-lasting effects can be attributed to Lyme disease or may have been caused by something else that does not respond to the antibiotics used against Lyme disease.
Senator Richard Blumenthal, Democrat of Connecticut, has introduced a bill that would establish an advisory committee in the Department of Health and Human Services to help set priorities and coordinate federal programs for Lyme and other tick-borne diseases.
With little certainty about the best ways to address the problem, researchers ought to conduct trials of promising approaches to controlling rodents and deer that harbor the Lyme bacteria, study ways to kill the ticks themselves with fungi and plant extracts that are lethal to black-legged ticks but safe for wildlife, and develop new tests that can identify patients at the early stages of Lyme disease.