Babesia and Bartonella DNA Found in Five Young People After Death

He had once been fit and well. Years later, he was living with fatigue, pain, memory difficulties and psychiatric symptoms. In time, he was forced to withdraw from university.

When the 27-year-old died, six years of illness and specialist treatment had not returned him to health.

Tests conducted after his death detected DNA from two species of Babesia - minute parasites that infect red blood cells - as well as Bartonella henselae, the bacterium responsible for cat-scratch disease.

His case was among six examined in a postmortem study prompted by families who continued to look for explanations for their children's illnesses. Researchers found DNA from either, or both, of these groups of microbes in five of the individuals.

The findings, however, left one central issue unresolved: whether these infections had any part in their illnesses.

Postmortem Babesia and Bartonella findings

The people studied were between 14 and 30 years old. Each had lived with chronic illness and experienced suicidal thoughts or behaviour.

Four died by suicide, one died through medical assistance in dying, and one died from a serious condition marked by excessive immune activation.

After hearing about work by Edward Breitschwerdt and his colleagues on Bartonella and neurological illness, their parents contacted the infectious disease researcher at North Carolina State University. They provided medical records and arranged for postmortem specimens to be sent to his laboratory.

Several of the individuals had been tested or treated for these infections during their lives, meaning the investigation was not the first evidence of infection in every case.

Initial testing in the laboratory did not provide clear results. The researchers examined 125 DNA extracts taken from blood, laboratory blood cultures, tissue and other bodily fluids. Quantitative PCR screening, which looks for specific genetic sequences, produced negative results in every initial test.

The team then used digital PCR, a technique that splits samples into numerous tiny reactions, and detected weak signals in some specimens. However, none met the study's cut-off for a positive result.

Further targeted testing and DNA sequencing - which reads genetic material to identify organisms - supplied confirmation. Babesia DNA was found in four people, two of whom had multiple species. B. henselae DNA was confirmed in two people. One individual had both, making five in total.

Control samples used to check for contamination were negative. A faint signal for Borrelia, a bacterial group that includes pathogens causing Lyme disease, could not be verified through sequencing.

How Babesia and Bartonella may be acquired

These microbes enter the body by different routes. Babesia may be transmitted through tick bites, which can also spread other disease-causing microbes.

B. henselae can be passed on by scratches from cats carrying fleas. According to the US Centers for Disease Control and Prevention, there is no evidence that ticks transmit Bartonella to people.

The next issue was whether the detected DNA indicated an infection that was still active at the time of death.

When asked if the findings could separate active infection from remaining DNA, Breitschwerdt recognised that the matter is scientifically debated. He said, however, that finding a known pathogen's DNA in clinical specimens is medically accepted as evidence of "active infection".

Clinical interpretation nevertheless depends on context. Guidelines from the Infectious Diseases Society of America state that PCR tests for Babesia microti, one of the parasite species detected, may stay positive for months or more than a year after standard treatment, including once symptoms have cleared.

Persistent DNA does not usually mean treatment has failed.

What the study cannot establish

Finding these infections does not prove that they caused the psychiatric symptoms or deaths of the young people.

How might an infection influence the mind? A review referenced by the researchers outlines two potential pathways: microbes may affect the nervous system directly, or the body's immune response may alter brain function.

The researchers suspect inflammation may be a link between infection and some symptoms experienced by these young people, but the postmortem results cannot demonstrate that sequence of events.

"This was an observational study, not a prospective case-controlled study," Breitschwerdt told ScienceAlert.

"I think the best interpretation is that infections with vector-borne pathogens that have evolved to induce persistent infections in animals and human patients are not a current diagnostic consideration in patients with chronic illnesses or neuropsychiatric symptoms."

The families had specifically requested the testing, and the study included no comparison group. Consequently, its results cannot determine whether these infections occur more often among people with suicidal symptoms.

The samples also differed in type and in when they were collected, with some taken days after death. All six individuals had been given antimicrobial medication, which may have reduced the likelihood of detection. Movement of bacteria after death may likewise have influenced the blood cultures.

Breitschwerdt says considerable evidence and research funding will be required to establish whether persistent infections make a causal contribution to suicidality. He is calling for a national centre to investigate chronic infections in people whose illnesses remain unexplained.

"We need an initiative similar to the start of the National Cancer Institute," he says.

The paper states that Breitschwerdt and Ricardo Maggi co-founded Galaxy Diagnostics, which offers Bartonella testing, and that they hold leadership positions at the company. Co-author Henry Lindner is related to one of the individuals in the study.

For these families, the work has provided molecular evidence to investigate further. Whether the infections help account for what happened to their children is still unknown.

The research appears in Parasites & Vectors.

If this story has raised concerns or you need to talk to someone, please consult this list to find a 24/7 crisis hotline in your country, and reach out for help.

This article was fact-checked by Fiona MacDonald and edited by Fiona MacDonald. Although we take pride in our process, we are only human. If you notice an error, please let us know.