Severe Trench Fever Infections Among Unsheltered Homeless New Yorkers, 2020–2022

The infection

Bartonella quintana is a bacterium spread by the human body louse. In the United States, homelessness is the main risk factor, likely because of limited access to washing and hygiene facilities. It isn't nationally notifiable, so how often it occurs is unknown.

• Acute infection can cause fever, headache and bone pain; severe forms include long-lasting bacteria in the blood, bacillary angiomatosis and infective endocarditis.
• It's hard to diagnose: the bacterium needs special conditions to grow, so standard blood cultures are usually negative. Blood antibody tests are most common but can cross-react with other Bartonella species such as B. henselae, and molecular tests specific to B. quintana are available at only a few laboratories.
• Once diagnosed, it can be cured with several weeks to months of antibiotics.

Six cases in New York City

In January and April 2023, the city health department learned of two people who had had B. quintana infections in 2022 after living unsheltered, and who had since died — one from the infection, one from an unrelated cause. The department then searched the laboratories of five large hospital networks and reviewed the medical records, finding four more cases from January 2020–December 2022.

All six had been unsheltered recently — four at the time of hospitalization, two within the previous year — with little or no contact with the city's shelter or outreach system, and five had a documented mental health or substance use disorder.

What it means

B. quintana infection can be deadly and costly, with long hospital stays and surgery. The true number of cases is probably higher: people living unsheltered often don't seek care, clinicians are less likely to think of it in milder illness, and it's hard to diagnose in the lab.

For clinicians:

• Ask about housing status to spot patients at risk.
• People experiencing homelessness with mental health or substance use conditions may be less able to use hygiene services — better behavioral health diagnosis and treatment could help prevent louse-borne disease.
• Test patients with a history of unsheltered homelessness and prolonged unexplained fevers, a vasoproliferative skin rash, or culture-negative endocarditis with a molecular test for B. quintana, and consider starting treatment in consultation with an infectious disease physician.

Sources

Based on Shannan N. Rich, Amy Beeson, Leah Seifu and others, "Notes from the Field: Severe Bartonella quintana Infections Among Persons Experiencing Unsheltered Homelessness — New York City, January 2020–December 2022," MMWR, Centers for Disease Control and Prevention; a work of the United States government in the public domain.