Bartonella quintana: Putting the re-emerging in emerging infection

Introduction

Trench fever was a defining feature of World War I. Notables like A.A. Milne, author of Winnie-the-Pooh, and fantasy writer JRR Tolkien were treated for trench fever. But surely trench fever did not just appear in the European trenches of World War I and then disappear after. What’s the rest of the story?

Before World War I, Way Before

While infections caused by body lice can be dated back 10,000 years, there is no DNA evidence that B. quintana, the bacteria we now know caused trench fever, was the causal pathogen of previous outbreaks of louse-borne disease for that entire time period.

Nonetheless, going back to  a tooth 4,000 years ago, recent research is finding more confirmation of a long history for B. quintana. A 2020 study confirmed B. quintana DNA in 19.3% of dental samples collected from nine archeological sites that spanned 1900 years. That is, from the first to the nineteenth century. In more recent centuries, pathogenic DNA was more commonly found in soldiers than in civilians.

World War I

“Trench fever” was first described in 1915, during World War I. The name was given to the condition by soldiers and only later picked up by medical professionals. Soldiers and civilians experienced an inexplicable relapsing fever, often accompanied by intense leg pain. Probably more than one million people were affected. At one point, 1 in 5 soldiers seeking medical care had symptoms of trench fever.

Trench fever is now known to be caused by Bartonella quintana, a bacteria that is spread by lice. Humans are a reservoir host for this pathogen. The bacteria are most commonly transmitted from the fecal matter of lice through an open wound or scratch.

Find out more about the history of common species of Bartonella.

Another Verse, Not Quite the Same

Today, some 100 years after World War I, Bartonella quintana is associated with conditions like endocarditis, lymphadenopathy, and bacillary angiomatosis. Bartonella species infections are the most common cause of culture-negative endocarditis.

Why do today’s infections look so different from the trench fever of World War I? One reason may be a change in recognizing what conditions are caused by B. quintana. World War I soldier were known to suffer from heart conditions, often thought to be caused by war stress or what today we would call PTSD. Perhaps those heart conditions were undiagnosed B. quintana infections.

Another reason may be a change in who is exposed to body lice and other potential vectors. These are no longer soldiers in war trenches, but communities with overcrowding and a lack of access to hygiene. Trench fever got so bad that soldiers were cleaned before being allowed to travel home. But many individuals also live in places where B. quintana infections are a risk.

A 2022 study explores the effects lice and Bartonella quintana have on people today. The study was performed by testing blood and serum samples from patients in the Denver, CO, area. The researchers found DNA evidence of Bartonella quintana infection in 14 patients, most of whom had been affected by homelessness. About 43% of individuals with DNA evidence of B. quintana showed signs of endocarditis. B. quintana infection has been repeatedly shown to be a risk of homelessness.