Researchers from the Yale School of Pubic Health believe human Babesiosis is reaching new regions within the United States. A recent study demonstrated that mice infected with Lyme disease and Babesia could enhance the geographic spread of the disease.

“The findings provide a possible answer as to why human babesiosis is only emerging in areas where Lyme disease is well established,” senior author of the Yale study, Maria Diuk-Wasser, tells YaleNews.

“We found that B. burgdorferi and B. microti co-occur in ticks more frequently than expected, resulting in enhanced human exposure,” Maria Diuk-Wasser, senior author of a study, tells YaleNews.

Unfortunately, like many of the other tick-borne illnesses, Babesia can be difficult to diagnose. Only in early cases, can Babesia parasites be seen inside red blood cells using a thick smear test, according to the Centers for Disease Control and Prevention (CDC).

Typically, a co-infection of Babesia with Lyme disease can increase the severity and duration of illness. In YaleNews, Diuk-Wasser points out that multiple infections “can cause more severe symptoms and sometimes make diagnosis more difficult.” Additionally, he infection cannot be effectively treated with antibiotics such as doxycycline, amoxicillin and azithromycin, which are used to treat Lyme disease, Ehrlichia and Anaplasmosis.

Meanwhile, authors of a 2014 study, published in PLOS One, warn physicians to evaluate patients closely for both Lyme disease and Babesia. “Given that co-infection for these two pathogens can exacerbate symptoms and requires distinct treatment, medical practitioners should be aware of the tendency for B. microti and B. burgdorferi to co-occur when diagnosing and treating tick-borne illness.”

There are over 100 known species of Babesia, a parasite, but only a few warrant concern for humans. Most cases involve Babesia microti and Babesia duncani. The severity of Babesiosis infections can vary, but it can be life-threatening to patients with weakened immune systems and the elderly.

Some individuals can present with flu-like symptoms, which include irregular fevers, chills, sweats, lethargy, headaches, nausea, body aches and fatigue. The disease can cause a specific type of anemia, called hemolytic anemia, since the parasites infect and destroy red blood cells. There are individuals who are asymptomatic, as well.

It’s important to point out that unlike Lyme disease, its been documented that Babesia can be transmitted person-to-person through blood transfusions, making the disease particularly concerning. According to a study published in the September, 2014 issue of Transfusion, “cases of transfusion-transmitted babesiosis have been increasingly recognized. To date, no Babesia test has been licensed for screening US blood donors.”