The tick-borne parasitic disease, Babesiosis, can be a serious disease, particularly in those with weakened immune systems or those without a spleen; however, researchers at the Yale School of Medicine have developed a novel combination therapy that not only clears the infection but also prevents the recurrence that often occurs with existing treatments.
The study was published online June 6 in The Journal of Experimental Medicine.
For their study, the Yale-led team first tested in mice with diminished immune systems four drugs that are currently used in the form of two combinations to treat human babesiosis. Only one of those drugs, atovaquone, was effective in attacking a target enzyme that, when mutated, allows the parasite to develop resistance. Using the mouse model, the team observed efficacy with a fifth drug (ELQ) that involves a similar mechanism of action as atovaquone but at a different enzyme target site. They decided to test the two drugs in combination.
The researchers found that the combination of atovaquone and ELQ-334, at low doses, cleared the infection and prevented recurrence up to 122 days after treatment.
“This is the first radical cure against this parasite,” said Choukri Ben Mamoun, associate professor of infectious diseases. “The novelty of the study was identifying a combination therapy that will both kill the parasite and also paralyze the target enzyme, making it nearly impossible for the parasite to develop resistance.”
The finding is significant since babesiosis is increasing and up to 19% of the ticks and up to 42% of the mammalian hosts (mice and other rodents) that carry the bacteria that cause Lyme disease is co-infected with B. microti.
With this finding, Ben Mamoun and his co-authors can take the next step and pursue studies of the combination therapy in people. “We are developing a better analog for ELQ that will be used in clinical trials. That’s what our future studies will focus on — identifying a better ELQ that could be added to atovaquone. We could test the safety of the compound in humans,” he said.
Babesiosis is a parasitic disease of the red blood cells which can be found worldwide: however, most documented cases have been found in the United States. Most human infections are attributed to the species, Babesia microti, while other species are less often seen in zoonotic infections.
The parasite is typically transmitted through a tick bite, Ixodes scapularis in the U.S., from late spring to early fall. It can also be transmitted through blood transfusions and this is not restricted by geographical regions.
Depending on host factors (people without a spleen, immunocompromised) the disease can range from asymptomatic to life threatening.
Symptoms if present typically appear as non-specific flu like symptoms, fever, chills, body aches, and hemolytic anemia.
After getting infected, the presence of symptoms is variable depending on the host and parasite factors. Typically after tick borne transmission symptoms appear in one to three weeks and it may be weeks to months post blood transfusion.
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