An ancient soldier's disease is now striking vulnerable populations in our cities
Imagine a disease that affected over a million soldiers during World War I, so notorious it was named "trench fever." For decades, this illness seemed confined to history books—but the bacterium behind it, Bartonella quintana, has quietly resurged in modern Canada. Recent research reveals this pathogen has established a disturbing foothold across the nation, from British Columbia to Quebec, with cases steadily increasing year after year 1 .
A 2024 study identified 33 individuals with confirmed B. quintana infections across seven provinces and one territory, with the highest numbers reported in 2022 and 2023 1 .
This isn't a historical curiosity—it's a contemporary public health challenge disproportionately affecting marginalized populations, particularly people experiencing homelessness and Indigenous communities with limited access to running water 1 .
Bartonella quintana is a formidable intracellular Gram-negative bacterium that survives inside its host's cells 1 . It's transmitted through an unexpected vector: the human body louse (Pediculus humanus corporis) 1 .
The infection spreads when body lice feed on human blood, then defecate. The bacterium-rich louse feces contaminate skin abrasions when scratching occurs, allowing B. quintana to enter the bloodstream 1 .
This transmission mechanism explains why the infection thrives where access to hygiene facilities is limited—among people experiencing homelessness, in overcrowded settings, and in communities without running water 2 .
Body lice differ from head lice in both their habitat (clothing rather than hair) and their disease-carrying potential. While head lice are primarily a nuisance, body lice can carry dangerous pathogens including B. quintana 2 .
Canadian researchers employed a dual approach to understand B. quintana's footprint 1 :
This combination allowed scientists to see both confirmed laboratory cases and clinically reported infections that might not have been tested at the national laboratory.
The research revealed several troubling patterns:
Provinces & territories with infections detected 1
qPCR-positive individuals identified 1
Mortality rate among literature cases 1
| Data Source | Time Period | Number of Cases | Key Characteristics |
|---|---|---|---|
| National Microbiology Laboratory | 2017-2023 | 33 qPCR-positive individuals | Spread across 7 provinces and 1 territory |
| Systematic Literature Review | 1915-2024 | 14 qPCR-positive + 7 probable cases | 19% mortality, all from endocarditis |
While B. quintana originally earned its reputation causing trench fever—a relapsing febrile illness accompanied by headache, bone pain (particularly shin pain), and dizziness—we now know it causes a spectrum of conditions 4 :
The bacterium can persist in the bloodstream for months or even years. One study documented bacteremia lasting up to 78 weeks 4 . This chronic infection often presents with minimal symptoms, allowing the bacteria to spread undetected.
Perhaps the most dangerous manifestation, B. quintana can infect heart valves, leading to life-threatening endocarditis. The 2024 Canadian study identified endocarditis as the cause of all B. quintana-related deaths in the systematic review 1 . This condition often requires valve replacement surgery and prolonged antibiotic treatment.
In immunocompromised patients, B. quintana can cause bacillary angiomatosis—vascular proliferative lesions that resemble tumors in the skin and internal organs 4 .
The classic presentation includes relapsing fever, severe headache, and bone pain (especially in the shins). While historically associated with soldiers, it now primarily affects marginalized urban populations 4 .
| Disease Manifestation | Key Symptoms | At-Risk Populations |
|---|---|---|
| Trench Fever | Relapsing fever, headache, shin pain | Previously soldiers; now marginalized populations |
| Chronic Bacteremia | Often minimal symptoms, prolonged infection | People experiencing homelessness |
| Infective Endocarditis | Heart failure, fever, cardiac murmur | All populations, often with delayed diagnosis |
| Bacillary Angiomatosis | Skin lesions resembling tumors | Immunocompromised individuals |
B. quintana presents significant diagnostic challenges that contribute to underrecognition:
Unlike many bacteria, B. quintana doesn't grow in routine blood cultures incubated for five days 1 . Its intracellular location and slow replication (approximately 3 hours) require specialized culture techniques with prolonged incubation 1 .
Antibody tests for B. quintana often cross-react with B. henselae (the cat-scratch disease agent), making species-specific diagnosis difficult without additional testing 9 .
Modern molecular techniques like quantitative PCR (qPCR) have improved detection capabilities. Recent research has validated qPCR tests targeting specific B. quintana genes with 100% sensitivity and specificity 6 .
The 2024 Canadian study provides the most comprehensive picture of B. quintana infections in Canada to date. Here's how the research was conducted:
Researchers analyzed all B. quintana testing performed at Canada's National Microbiology Laboratory from 2017-2023 for molecular testing and 2008-2023 for serologic testing 1 .
Scientists searched multiple databases (PubMed, Scopus, Embase, Web of Science) for articles published before July 15, 2024, using terms related to B. quintana in Canada 1 .
Cases were classified as confirmed (species identification by qPCR) or probable (serologic positivity with compatible clinical syndrome and epidemiologic risk factors) 1 .
The laboratory analysis revealed:
The systematic review identified an additional 21 cases not captured in the NML data, highlighting how this infection likely remains underdiagnosed 1 .
| Finding | Statistical Significance | Public Health Implication |
|---|---|---|
| Increasing case numbers | p-value = 0.005 | Ongoing transmission across geographic settings |
| Rising test positivity | p-value = 0.036 | Possibly reflecting increased prevalence or testing |
| National distribution | 7 provinces + 1 territory | Not a localized problem |
| Substantial mortality | 19% among literature cases | Need for earlier detection and treatment |
The reemergence of Bartonella quintana in Canada represents more than a microbiological curiosity—it serves as a marker of social inequality 1 . This disease thrives where poverty, overcrowding, and inadequate access to hygiene facilities converge 2 . The steady increase in cases signals ongoing transmission across diverse Canadian settings 1 .
Healthcare providers should consider B. quintana in patients from high-risk backgrounds with compatible symptoms
Expanding availability of molecular testing to improve detection
Addressing the root causes through improved access to hygiene facilities, laundry services, and housing support
As the Canadian research demonstrates, B. quintana is no longer confined to history books but has established itself as a contemporary health concern requiring coordinated medical and public health responses 1 . Understanding this disease represents not just a scientific challenge, but a social imperative.