TORONTO -- A new study suggests that trench fever, a disease common during the First World War, has been reported among some Canadians experiencing homelessness.

The study, published Monday in the Canadian Medical Association Journal, found that trench fever was present in certain urban, homeless populations in Canada, with researchers warning that physicians should be aware of the potentially fatal disease.

Trench fever, which is caused by the bacteria Bartonella quintana, is transmitted through body lice. Researchers say the disease was first described during the First World War and was widespread among soldiers.

Symptoms of trench fever include relapsing fevers, muscle aches, headaches, rashes, and pain in the shins.

"Our public health message is that this disease is present in Canada and that people and physicians aren't always aware," University of Manitoba infectious disease physician Dr. Carl Boodman said in a press release.

"It's associated with homelessness and homeless shelters, and physicians should consider B. quintana infection in people who are unwell and have a history of body lice infestation," he added.

The study says trench fever can lead to a heart infection known as endocarditis and can be fatal if left untreated. Researchers note that molecular testing and consultation with infectious disease experts is often required for diagnosis.

According to the study, a 48-year-old man previously visited an emergency department in Manitoba with chest pain and shortness of breath. Researchers say the patient had sought care several times within the past 18 months for "episodes of chest pain and body lice infestation."

Four days after being admitted, the study reported that the patient underwent mitraland aortic valve replacement surgery for "severe valvular damage" to his heart from the trench fever.

Researchers say three additional patients with Bartonella quintana were identified in Winnipeg over a six-month period, all of whom had accessed the same homeless shelter.

The study notes that there have only been these four cases of trench fever detected in Canada over the past 20 years.

However, researchers expect that there are more cases of trench fever in Canada’s homeless populations as the disease "likely remains underdiagnosed."

"Clinicians should consider Bartonella serology, echocardiography and infectious disease consultation when caring for individuals who present unwell with a history of body lice infestation," the study said.

The researched said that more studies are needed to better understand the "true burden" of trench fever among those experiencing homelessness.

Correction:

A previous version incorrectly stated that trench fever killed millions of soldiers during the First World War. In fact, it was widespread but rarely fatal.