The Day

Tick-borne babesiosis, antibiotic-resistant bacteria on rise in Conn.


A tick-borne parasite and antibiotic-resistant bacteria are increasing in Connecticu­t and across the country.

Babesiosis, which can be fatal, is becoming more common because of warmer winters, which allow the blacklegge­d tick, or deer tick, to survive until spring, according to Goudarz Molaei, director of the tick and tick-borne diseases program at the Connecticu­t Agricultur­al Experiment Station in New Haven.

It’s the same tick that carries Lyme disease and other diseases, such as Powassan fever and anaplasmos­is and accounts for 85% of the ticks in Connecticu­t, Molaei said.

The multiple-resistant strains of Shigella, which was unknown in this country until 2015, now account for 5% of all Shigella infections, according to Dr. Ulysses Wu, chief epidemiolo­gist at Hartford HealthCare.

“We are seeing greater activities of ticks and hosts that ticks feed on, meaning that ticks do not carry the pathogen by themselves; they obtain it from rodents, from white-footed mouse, shrews and other small mammals,” Molaei said.

“And because of some environmen­tal changes, including climate change, the climate is quite hospitable for not just ticks, but also for their hosts,” he said. “And as a result, we are seeing this kind of increased tick activity and increased tick host activity.”

They are most common in the Northeast and upper Midwest, particular­ly Wisconsin and Minnesota, he said.

Because they’ve survived the winter, the adult ticks will be out and sucking blood in April and May, then again in November, while the nymphs, a tiny larval stage, are most active in June, Molaei said.

“So a lot of the babesiosis and other tick-borne disease cases are caused during the month of June because nymphs are small and people easily overlook or cannot find them promptly,” he said. “And these small ticks get a chance to feed and to be engaged in feeding long enough in order to successful­ly transmit the disease agent.”

Lyme disease still is more common. From 2015 to 2021, there were 1,921 cases of babesiosis and 10,667 cases of Lyme disease, according to state Department of Public Health figures.

The infection rate ranged from 6% to 11% for babesiosis and from 28.8% to 38.3% for Lyme disease. An average of 4% of ticks were infected with both. In 2022, the rates were 7.3% and 31.1%, respective­ly.

Because babesiosis is a parasite — the “malaria of the Northeast,” according to Wu — it must be treated with both antibiotic­s and anti-parasitic medication­s. He said it can be dangerous and predicted “a robust tick-borne season” this year.

“It is sometimes fatal, but it’s more dangerous than a lot of the other tick-borne diseases,” Wu said.

“The parasite proliferat­es in red blood cells and increases the number until the number reaches to a point that red blood cells burst and then parasites are released to attack other red blood cells,” Molaei said.

To prevent tick-borne diseases, keep skin exposure to a minimum and do a tick check within two or three hours of being in wooded or grassy areas, he said.

The most vulnerable are those who are immunocomp­romised, Wu said, such as the elderly, people with cancer, HIV or those without a spleen.

Complicati­ons include “acute respirator­y distress syndrome. So you could require ventilatio­n,” he said. “You could have severe anemia, because your red cells are being chewed up. And then people may go into heart failure, renal failure,” inability to clot, as well as shock and coma.

Drug-resistant Shigella

As for Shigella, Wu said, “It’s not only becoming resistant, but some of the Shigella that we’ve seen … since 2015, now they’re starting to see an increase of what they call XDR, extensivel­y drug-resistant Shigella infections. And so the normal antibiotic­s that we would normally use, we cannot use to treat any more.”

While 5% of Shigella infections are XDR strains now, Wu said “the rate itself is also concerning, because obviously without any XDRs before now … who would know what it’s going to be like in five years.”

“And so a lot of this is due to not just overuse of antibiotic­s, but these bacteria have the ability to spread resistance to other Shigella, as well as what we call other enteric organisms as well,” those that infect the gut, he said.

Shigella “usually causes an inflammato­ry diarrhea that can sometimes be bloody, but you get fever, abdominal cramping, the feeling of pain when you defecate as well,” Wu said.

While the infection will resolve itself over time, “antimicrob­ial treatment may be indicated because it can actually prevent complicati­ons, and they actually shorten the duration of the illness as well,” he said.

While it is rarely fatal, there have been 165 deaths among 180 million cases of Shigella worldwide, Wu said. It is more common where there is untreated water and food, or when food handlers are infected, or through fecal-oral transmissi­on, he said.

Those who are homeless or who have HIV or who are men having sex with men are especially vulnerable, he said. Washing hands and safe sex is the most effective way to prevent it, he said.

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