Rates of babesiosis, a parasitic disease transmitted by ticks, have risen by an average of 9% each year in the United States from 2015 to 2022. Notably, 40% of those infected were also found to have another tick-borne illness, such as Lyme disease, as revealed by a recent study conducted by researchers at Penn State Health Milton S. Hershey Medical Center and Penn State College of Medicine.
From 2015 to 2022, the number of babesiosis cases in the United States grew at an average rate of 9% annually, with 40% of patients also suffering from additional tick-borne diseases like Lyme disease, according to findings from a study led by researchers at Penn State Health Milton S. Hershey Medical Center and Penn State College of Medicine.
“These results indicate that healthcare providers should be more aware of the possibility of co-infections in patients being treated for babesiosis,” said Paddy Ssentongo, an infectious disease fellow and the study’s lead author. “Ticks are known to carry various pathogens that can lead to diseases like Lyme, anaplasmosis, and ehrlichiosis.”
The research was published today (October 8) in the journal Open Forum Infectious Diseases.
Babesiosis, often called “American malaria,” is caused by the Babesia parasite and spreads through the bites of black-legged ticks. It primarily affects areas in the Northeast and Midwest of the United States, infecting red blood cells similar to malaria, and can cause a variety of symptoms. The U.S. Centers for Disease Control and Prevention (CDC) notes that while not everyone shows symptoms, some people may experience flu-like signs. The disease can be particularly dangerous for older individuals and those with certain health issues, such as weakened immune systems or absent spleens.
“Comprehending the factors that influence, regulate, and control both established and emerging vector-borne diseases is essential for global health efforts,” Ssentongo remarked.
According to the CDC, the occurrence of babesiosis has been on the rise. Ssentongo pointed out that climate change might be a contributing factor. Variations in temperature, rainfall, humidity, and growing seasons have impacted the populations and distributions of ticks and their reservoir hosts, such as deer, resulting in ticks inhabiting broader regions.
The researchers aimed to analyze the current prevalence of babesiosis and the occurrence of Babesia co-infections, in addition to assessing the implications of co-infection on mortality risk. They utilized the TriNetX database, which consolidates clinical data from over 250 million patients, identifying 3,521 individuals diagnosed with babesiosis between October 2015 and December 2022.
The study uncovered a consistent annual increase of 9% in babesiosis cases. Most incidents occurred during summer and predominantly in Northeastern states. Among those diagnosed with babesiosis, 42% were concurrently infected with another tick-borne disease, a figure surpassing previous studies. The majority of these co-infected patients, 41%, had Lyme disease, while smaller percentages were infected with bacteria causing ehrlichiosis (3.7%) and anaplasmosis (0.3%).
Upon investigating whether co-infections heightened the risk of complications or adversely affected patient outcomes, researchers found no significant differences in health outcomes between those with just babesiosis and those with co-infections. However, they did observe a higher mortality risk in the babesiosis-only group.
“The presence of both babesiosis and Lyme disease did not correlate with higher mortality rates,” Ssentongo noted, expressing surprise at this finding. “It’s proposed that having multiple tick-borne infections might enhance the immune response, thus effectively combating infections.”
The variation in outcomes may also relate to treatment strategies for other tick-borne diseases, Ssentongo mentioned. The study indicated that the co-infection group was more frequently given doxycycline, the primary antibiotic for treating Lyme disease, anaplasmosis, and ehrlichiosis, compared to the group solely diagnosed with babesiosis. This raises an intriguing question: Is doxycycline an effective treatment for the babesia parasite as well?
Currently, how babesiosis is treated is contingent upon the severity of the disease. Treatment generally consists of a combination of antibiotics, namely azithromycin and atovaquone. In severe cases, particularly those involving significant organ dysfunction, red blood cell exchange may be an option, although the survival advantages of this method remain insufficiently studied.
“For patients diagnosed with babesiosis, we typically add doxycycline while evaluating for Lyme or other tick-borne diseases, and we have observed improved outcomes with this approach,” Ssentongo stated. He also pointed to other case reports illustrating successful treatment of babesiosis with doxycycline. Nevertheless, further research is needed to clarify the biological mechanisms behind co-infection and its potential influence on treatment protocols.
Preventing tick-borne diseases in the first place is the most effective treatment strategy, according to Ssentongo.
“For those living in areas where babesiosis is common, particularly in the Northeast and Midwest, it’s important to take precautions, especially during summer,” Ssentongo advised. “Use tick prevention methods, wear protective clothing like long-sleeved shirts and pants and light-colored attire, apply tick repellent, and check for ticks after outdoor activities.”
This study is set to be presented at IDWeek, the Infectious Disease Society of America’s annual conference in Los Angeles, California, from October 16-19.
Other authors involved in the study from Penn State include Vernon Chinchilli, distinguished professor of public health sciences; Djibril Ba, assistant professor of public health sciences; Natasha Venugopal, internal medicine resident at Penn State Health Milton S. Hershey Medical Center; and Yue Zhang, a doctoral student in epidemiology.
