Eight states in the Northeast U.S. are seeing increasing rates of an emerging tick-borne illness called babesiosis, according to a new report from the Centers for Disease Control and Prevention.
From 2011 to 2019, there were 10 states that reported cases of babesiosis, which is spread by the black-legged tick (aka deer tick) and usually causes no symptoms but can result in flu-like illness. Of these 10 states, only two saw decreasing rates during that time period: Minnesota and Wisconsin.
The eight states that saw increases in rates of babesiosis are:
- New Hampshire
- New Jersey
- New York
- Rhode Island
The states that saw the largest increases in babesiosis from 2011 to 2019 were: Vermont (up 1,602% from two to 34 cases), Maine (up 1,422% from nine to 138), New Hampshire (up 372% from 13 to 78), and Connecticut (up 338% from 74 to 328).
Babesiosis is now considered endemic in Maine, New Hampshire and Vermont because they consistently saw "newly acquired cases" every year from 2011 to 2019, the CDC noted. Previous CDC data found babesiosis to be endemic only in the seven other states.
The data show an "increase in tick-borne disease in parts of the U.S. that previously saw few cases," Megan Swanson, an epidemiologist with the CDC’s Division of Parasitic Diseases and Malaria, who co-authored the report, told NBC News.
Overall, the U.S. saw a 25% increase in tick-borne illnesses from 2011 to 2019, per the report. One possible reason for the rise is climate change because ticks thrive in warm climates, NBC News reported.
“The ticks are surviving better in the winter, and so the next spring, you have more ticks to bite more people,” Edouard Vannier, who studies babesiosis at Tufts Medical Center in Boston and wasn’t involved in the report, told NBC News.
What's more, babesiosis may be more common than the new report suggests because it's so often asymptomatic and not all cases are reported to the CDC.
“(It's) is much more of a problem than the general public recognizes and can be fatal, up to 20%, in people who have HIV/AIDS or severe cancer with chemotherapy or individuals who lack a spleen,” Dr. Peter Krause, a senior research scientist at the Yale School of Public Health, who wasn’t involved in the CDC study, told NBC News.
How is babesiosis spread?
Babesiosis — most common in the Midwest and Northeast in both inland and coastal areas — is caused by parasites and usually spread through the bite of a black-legged tick, per the CDC. It's most often carried by young ticks of this species, known as nymphs, which are most active in areas with woods, brush or grass in the spring and summer, in particular late May to early September, per NBC News.
It can be difficult to know if you've been bitten by such a tick because they can be as small as a poppy seed.
Other ways people may get babesiosis include through a blood transfusion from someone with the illness or transmission during pregnancy if the mother is infected.
What are the symptoms of babesiosis?
Babesiosis often does not result in any symptoms, the CDC noted. NBC News reported that up to 20% of adult cases and 50% of pediatric cases are asymptomatic.
For those who do develop symptoms, they can take anywhere from one to six weeks to show, and they're often similar to the flu:
- Body aches
- Loss of appetite
Some people have a higher risk for severe illness from babesiosis than others, according to the CDC. These include people without a spleen, those with a weakened immune system or another serious health condition, and the elderly.
One serious complication of is hemolytic anemia, which can lead to yellowing of the skin and dark urine, the CDC said. Others are low and unstable blood pressure, low platelet count, blood clots, organ malfunction and death.
Krause estimated to NBC News that babesiosis is fatal 1% to 2% of the time. He added that the new CDC report is “an unfortunate milestone in the emergence of babesiosis in the United States. ... More cases means more illness, and actually, some people die.”
Babesiosis can be confused with Lyme disease, as both can cause fever and muscle aches. But babesiosis is usually more severe, even though Lyme disease is much more prevalent, NBC News reported.
“Sometimes the patient will have felt just fatigued and not quite right, maybe a low-grade temp for a week or two, and then all of a sudden they get worse,” Krause told NBC News. “That’s usually not the case with Lyme — you get it and then, bingo, you have the rash and so on.”
Vannier estimated that half of people with babesiosis also have Lyme disease.
How is babesiosis treated?
People who do not have symptoms usually do not require any treatment for babesiosis. For those who do have symptoms, treatment should depend on the individual person's risk of severe illness or relapse, the CDC said.
The most common combination of prescription drugs to patients who have babesiosis symptoms are:
- Atovaquone, an antifungal and anti parasite medication, and azithromycin, an antibiotic
- Clindamycin, an antibiotic, and quinine, an anti-parasite
More severe cases might require blood transfusion, mechanical ventilation or dialysis, among other treatments.
How to prevent tick-borne illnesses
The best way to prevent tick-borne illnesses is to avoid getting bitten by a tick. To do so, the CDC advises:
- Avoid areas where ticks live or take precautions before going in them. These include grassy, brushy or wooded areas.
- Treat clothing and outdoor gear with .5% permethrin or by permethrin-treated clothing and gear.
- Wear long sleeves and pants.
- Use insect repellant containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol or 2-undecanone and is approved by the Environmental Protection Agency.
- Check your clothing pets and gear for ticks when you return indoors. Tumble dry clothes for at least 10 minutes to kill ticks.
- Shower as soon as possible and check your body for ticks, especially under the arms, in and around the ears, in the belly button, back of the knees, the scalp, between the legs and around the waste.
It's also important to remember that tick exposure can occur year-round, even if they’re most active from April to September.