For the first time in the U.S., a medical case of tickborne illness caused by an unexpected species of bacteria has been reported, as per the Centers for Disease Control and Prevention (CDC).

The bacteria called Borrelia lonestari is a distant relative of the bacteria responsible for Lyme disease. The pathogen was found responsible for triggering tickborne relapsing fever, which had never been reported before, as per IFLScience.

The disease was discovered in a 75-year-old man from Alabama, according to the CDC-run journal Emerging Infectious Diseases.

Tickborne relapsing fever (TBRF) is a rare infection, which causes symptoms such as recurring fever, headaches, muscle and joint aches, and nausea. Most commonly reported in the western U.S., the infection is usually associated with sleeping in rustic mountain cabins, which are typically infested by rats.

However, TBRF is known to be caused by Borrelia bacteria, and not B. lonestari, until now. It spreads to humans through the bite of infected “soft ticks.”

In 2019, the 75-year-old man, who was studied by the CDC, reported experiencing relapsing fevers, chills, sweating, headache, dizziness, and fatigue - all of which lingered for about a month. The Alabama resident admitted to having removed a tick several weeks before the symptom onset. He was successfully treated with antibiotics at the time.

Initially, doctors found spirochetes in his blood. These are spiral-shaped bacteria often spread by ticks. But after months of investigation, they concluded that the cause of TBRF was B. lonestari.

“This case report sheds light onto the potential of B. lonestari to cause human illness and contributes to the body of knowledge on TBRF," study author Dr. Laia J. Vazquez Guillamet told Infectious Disease Special Edition. “It is the second tick-borne Borrelia species transmitted by hard ticks that have been identified as a causative agent of relapsing fever, being the previous ones [were] transmitted by soft ticks."

It should be noted that the patient was taking immunosuppressant drugs for lymphoma at the time. This means whether he developed TBRF due to B. lonestari’s pathogenicity or the medication increased his susceptibility to infection, cannot be determined.

“In future years, increased awareness of the pathogenic potential of B. lonestari and the use of molecular diagnostics may give us an approximation about the real burden of human illness caused by this bacterium,” Vazquez Guillamet added.

Speaking of bacteria, the CDC recently warned of an extensive increase in the drug-resistant Shigella bacteria responsible for watery and possibly bloody diarrhea. “Given these potentially serious public health concerns, CDC asks healthcare professionals to be vigilant about suspecting and reporting cases of XDR Shigella infection to their local or state health department and educating patients and communities at increased risk about prevention and transmission,” the CDC stated in its advisory.