Updated June 2026
NCCID Disease Debriefs provide Canadian public health practitioners and clinicians with up-to-date reviews of essential information on prominent infectious diseases for Canadian public health practice. While not a formal literature review, information is gathered from key sources including peer-reviewed literature, the Public Health Agency of Canada (PHAC), the USA Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO).
Questions, comments and suggestions regarding this debrief are most welcome and can be sent to nccid@umanitoba.ca
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Questions Addressed in this debrief:
- What is Bartonella quintana?
- What are the clinical features and complications of Bartonella quintana?
- How is Bartonella quintana transmitted?
- What is the epidemiology of Bartonella quintana?
- How is Bartonella quintana diagnosed and treated?
- What is the risk for Canadians?
- What prevention and control measures can be taken?
What is Bartonella quintana?
Characteristics and Causes
Bartonellosis is a group of infectious diseases caused by bacteria within the Bartonella genus. These bacteria are fastidious, aerobic, gram-negative cocci/small rods, and are hemotropic. The bacteria invade erythrocytes and the lining of blood vessels where they then proliferate. There are at least 22 known vector-borne species, 14 of which are known to be zoonotic. Bartonella species are transmitted by several arthropod vectors, including sandflies, fleas, and lice. Bartonella quintana is primarily associated with transmission by the human body louse (Pediculus humanus corporis). This disease debrief is specific to the species Bartonella quintana – also known as “trench fever” because of the high levels of recorded cases among soldiers in the trenches during World War I. B. quintana infection is increasingly recognized as a re-emerging infection of public health importance in Canada.
Pathogen Safety Data Sheets: Infectious Substances – Bartonella quintana – Health Canada
Bartonella quintana Characteristics and Clinical Management – Emerging Infectious Diseases
About Bartonella quintana – Centres for Disease Control and Prevention
What are the clinical features and complications of Bartonella quintana?
Signs and Symptoms
Characteristic symptoms of B. quintana are headaches, maculopapular rashes on the trunk and abdomen, papular lesions, and a sudden onset of chills and relapsing fever. Bone pain (mainly occurring on the neck, shins, and back) as well as enlargement of the spleen or liver may also occur. Relapsing febrile episodes may occur over a period of days to weeks.
Culture-negative endocarditis can also occur with B. quintana, typically involving the mitral and aortic valves; it carries a high risk of embolization. Bartonella species are among the leading causes of blood culture-negative endocarditis. In immunocompetent persons, febrile symptoms generally occur approximately 15-25 days after infection. While the infection is most often self-limiting among individuals with a healthy immune system, relapsing illness and chronic bacteremia have been reported. In some patients, less common clinical presentations such as endocarditis and bacillary angiomatosis may occur.
Pathogen Safety Data Sheets: Infectious Substances – Bartonella Quintana – Health Canada
Bartonellosis – National Organization for Rare Disorders
Bartonella quintana Characteristics and Clinical Management – Emerging Infectious Diseases
Bartonella, a common cause of endocarditis: a report on 106 cases and review – Journal of Clinical Microbiology
Case series of Bartonella quintana blood culture-negative endocarditis in Washington, DC – Journal of Medical Microbiology
Severity and Complications
Severe complications of B. quintana infection include infective endocarditis, chronic bacteremia, embolic complications, and bacillary angiomatosis. Bartonella species are among the leading causes of blood culture-negative endocarditis. Endocarditis caused by B. quintana may occur in persons without previous valvular injury and is associated with substantial mobidity and mortality. Global mortality estimates for Bartonella-associated endocarditis have been reported at approximately 12%. A recent Canadian retrospective review reported a mortality rate of 19% among published Canadian cases, which the authors suggested likely reflects the disproportionate number of severe infective endocarditis cases compared with other manifestations of B. quintana infection.
Many patients with Bartonella endocarditis do not present with fever, which may contribute to delayed diagnosis. Endocarditis associated with Bartonella infection is frequently diagnosed using tissue obtained during heart value replacement procedures due to the difficulty of diagnosis using routine blood culture methods.
Bacillary angiomatosis is characterized by neovascular skin proliferation and occurs most commonly in persons living with HIV or other immunocompromising conditions. Lesions are typically elevated, vascular, and prone to bleeding, and may be surrounded by a scaly ring-like border. In immunocompromised patients, bacillary angiomatosis may become severe and can be fatal if left untreated.
Known risk factors for severe disease include body lice exposure, people experiencing homelessness, alcohol use disorder, crowded living conditions, and limited access to hygiene and laundry infrastructure. Cases of B.quintana endocarditis and bacillary angiomatosis have also been reported in immunocompetent persons. Recent Canadian reports have highlighted severe disease, including infective endocarditis, among populations experiencing barriers to housing, sanitation, hygiene, and healthcare access.
Pathogen Safety Data Sheets: Infectious Substances – Bartonella Quintana – Health Canada
Bartonella quintana infection in Canada: retrospective analysis and trends – Canadian Journal of Infectious Disease and Medical Microbiology
Bartonella, a common cause of endocarditis: a report on 106 cases and review – Journal of Clinical Microbiology
Case series of Bartonella quintana blood culture-negative endocarditis in Washington, DC – Journal of Medical Microbiology
How is Bartonella quintana transmitted?
Reservoir and Transmission
The bacterium is most commonly transmitted by the human body louse (Pediculus humanus). Once the body louse ingests B.quintana, typically from feeding on an infected human, the louse is infected for life. The bacterium proliferates in the intestinal tract of the louse and is excreted in feces. Infected feces can remain infectious for as long as a year, so cases can still arise even after elimination of a louse population.
Transmission to humans occurs when infected louse feces are introduced into damaged skin, mucous membranes, or the conjunctiva through scratching or rubbing.
Humans are the primary reservoir for B.quintana, although other mammalian reservoirs—including cats and other primates–have been proposed.
Pathogen Safety Data Sheets: Infectious Substances – Bartonella Quintana – Health Canada
About Bartonella quintana – Centres for Disease Control and Prevention
Incubation period
The incubation period of Bartonella quintana ranges from 15 to 25 days.
Pathogen Safety Data Sheets: Infectious Substances – Bartonella Quintana – Health Canada
What is the epidemiology of Bartonella quintana?
Global and Historical Epidemiology
Cases of Bartonella quintana have been recorded worldwide, with peaks occurring during both the First and Second World Wars. Since the 1990s, the disease has re-emerged among people experiencing homelessness in Europe and the United States.
Epidemiology in Canada
Recent Canadian studies suggest that B. quintana infection is likely substantially underrecognized in Canada due to diagnostic limitations, asymptomatic infection, limited surveillance, and nonspecific clinical presentations. B. quintana infection is currently not a nationally notifiable disease in Canada, and reporting requirements vary across jurisdictions. Recent authors have suggested that enhanced surveillance and coordinated reporting could improve recognition of disease burden and support public health responses among populations disproportionately affected by barriers to housing, sanitation, hygiene infrastructure, and healthcare access.
A recent Canadian retrospective laboratory study identified more than 30 PCR-confirmed cases between 2017 and 2023, the majority associated with infective endocarditis. Subsequent surveillance has identified additional PCR-confirmed cases, indicating that infections continue to occur on a yearly basis in Canada.
Seroprevalence studies conducted internationally among persons experiencing homelessness have identified evidence of substantial exposure and bacteremia in some populations. Body louse surveillance studies conducted in Canada during 2020–2021 also identified louse-borne pathogens, including B. quintana, among persons experiencing homelessness, supporting concerns regarding ongoing transmission in Canada.
Populations at Increased Risk
Key risk factors include body lice exposure, people experiencing homelessness, crowded living conditions, alcohol use disorder, limited access to hygiene and laundry services, and other structural factors associated with poverty and marginalization. Risk may increase in congregate and unsheltered living environments where access to hygiene infrastructure is limited.
Recent publications have also highlighted the potential importance of inadequate access to water, sanitation, hygiene infrastructure, and overcrowded living conditions as contributing factors for transmission in some Indigenous communities.
Pathogen Safety Data Sheets: Infectious Substances – Bartonella quintana – Health Canada
Bartonella quintana Characteristics and Clinical Management – Emerging Infectious Diseases
Trench fever, rare disease that afflicted WWI soldiers, detected in homeless Winnipeggers – CBC News
Bartonella quintana endocarditis in Canadian Indigenous communities highlights the need for outbreak investigation, vector surveillance and access to water, sanitation and hygiene – The Pediatric Infectious Disease Journal
Including louse-borne Bartonella quintana as a nationally notifiable disease: a step towards health equity – The Lancet Regional Health – Americas
How is Bartonella quintana diagnosed and treated
Diagnosis
Diagnosis of B. quintana infection may be challenging because Bartonella species are fastidious organisms, bacteremia may be intermittent, blood cultures are frequently negative, and serologic cross-reactivity may occur.
B. quintana can be diagnosed using serological testing to identify antibodies in blood serum, with indirect immunofluorescence commonly used as the reference method. Observation of elevated IgG antibody titers > 1:50 indicate possible Bartonella infection; however, interpretation should be made cautiously due to possible cross reactions
The bacterium can also be detected through prolonged blood culture incubation, direct plating on blood agar media, cocultivation in cell culture, polymerase chain reaction (PCR) testing of blood or tissue specimens, and immunohistochemistry performed on tissue samples. Molecular diagnostic methods, including PCR performed on cardiac valve tissue in suspected endocarditis cases, may improve diagnostic sensitivity.
Healthcare practitioners should consider Bartonella infection in patients with compatible clinical syndromes and epidemiologic risk factors, particularly among persons experiencing homelessness, individuals with body lice exposure, or those living in crowded settings with limited access to hygiene infrastructure.
Because many patients with Bartonella endocarditis may not present with fever, clincians should maintain suspicion for Bartonella infection in cases of culture-negative endocarditis with compatible epidemiologic risk factors.
Pathogen Safety Data Sheets: Infectious Substances – Bartonella Quintana – Health Canada
Bartonella quintana Characteristics and Clinical Management – Emerging Infectious Diseases
Bartonellosis – National Organization for Rare Disorders
About Bartonella quintana – Centres for Disease Control and Prevention
Treatment
While full recovery fromuncomplicated B.quintana infection usually occurs within 1-2 months of infection, relapsing illness, chronic bacteremia, and severe complications such as infective endocarditis have been reported. Antibiotics may be required depending on the clinical presentation.
Combination antimicrobial therapy is often required for severe disease manifestations. Doxycycline in combination with rifampicin has increasingly been used in treatment of chronic bacteremia and infective endocarditis. Doxycycline in combination with gentamicin may also be used in some cases, although gentamicin-associated nephrotoxicity and ototoxicity may limit its use. Prolonged antimicrobial therapy may be required for severe disease manifestations such as endocarditis and bacillary angiomatosis..
Macrolides, including erythromycin, have also been used in the treatment of bacillary angiomatosis.
Other antimicrobial agents with reported activity against Bartonella species include macrolides, tetracyclines, rifamycins, and selected fluoroquinolones, although clinical effectiveness may vary. Reduced susceptibility to fluoroquinolones has been reported. Prompt identification and treatment of body lice infestations is also essential for outbreak control and prevention of ongoing transmission. Oral ivermectin has been used in some outbreak and shelter settings as part of body lice control strategies, particularly where access to laundering and hygiene services is limited. Because body lice primarily inhabit clothing and bedding, control measures should include laundering or hot treatment of clothing, bedding, and linens.
Pathogen Safety Data Sheets: Infectious Substances – Bartonella Quintana – Health Canada
Bartonella quintana Characteristics and Clinical Management – Emerging Infectious Diseases
Facts about Bartonella quintana infection (‘trench fever’) – European Centre for Disease Prevention and Control
What is the risk for Canadians?
B.quintana infection remains infrequently diagnosed in Canada and overall population risk is low. However, the disease is likely underrecognized, particularly among populations experiencing barriers to housing, sanitation, hygiene access, or healthcare access.
Persons experiencing homelessness, those exposed to body lice, and individuals living in crowded or congregate settings may be at increased risk of infection.
What prevention and control measures can be taken?
Prevention and Control
The disease can be controlled through enhanced sanitary and vector-control measures in shelters, among the unsheltered homeless, and in other high-traffic, congregate environments. These measures include:
- Prompt identification and treatment of body lice infestations
- Frequent cleaning and sanitization of living quarters
- Launder clothing, bedding and towels using hot water and dry thoroughly using high heat
- Prompt treatment and covering skin wounds
- Encouraging regular hand hygiene using soap and waterand avoidance of scratching affected areas or rubbing the face
Body lice primarily inhabit clothing and bedding rather than human skin. Control measures should therefore include laundering or heat treatment of clothing and bedding and, where appropriate, use of pediculicides in accordance with local public health guidance. Oral ivermectin has also been used during outbreaks and in shelter settings.
Public health responses should consider the broader social and structural determinants associated with transmission risk, including barriers to housing, sanitation, hygiene infrastructure, and healthcare access.
Healthcare practitioners can control the disease by performing serologic and blood culture testing, even in the absence of clinical signs and symptoms, for those who are homeless or who live in crowded/unsanitary conditions.
Bartonella quintana Characteristics and Clinical Management – Emerging Infectious Diseases
Bartonella Infection (Cat Scratch Disease, Trench Fever, and Carrion’s Disease) – Centers for Disease Control and Prevention
Vaccination
There is currently no vaccine available against B.quintana or other Bartonella species in humans or animalsg, though research into vaccine candidates is ongoing.
Pathogen Safety Data Sheets: Infectious Substances – Bartonella quintana – Health Canada