Louse-Borne Relapsing Fever: A Disease of Crowding, Spread by Body Lice

A human body louse. Image from CDC's page

Louse-borne relapsing fever (LBRF) is caused by the bacterium Borrelia recurrentis, spread to people by the human body louse — and, rarely, the head louse. Today it occurs in parts of Africa; in the United States, infection is extremely unlikely without travel to a region where it's found.

A history of epidemics

It can be severe; reported death rates vary widely with social conditions, geography and access to treatment.

Symptoms

Symptoms are nonspecific:

• fever
• headache
• chills or shaking
• muscle and joint aches
• nausea

LBRF looks much like soft tick relapsing fever but usually brings fewer relapses. Pregnant women are at high risk of pregnancy loss and may become more severely ill.

How it spreads

B. recurrentis is a spiral-shaped bacterium. Body lice (Pediculus humanus humanus) pick it up by feeding on infected people, then carry it from person to person. People are usually infected when an infected louse is crushed and the bacteria get into a bite wound or scratch. No animal hosts are known.

Outbreaks strike where people are crowded and society is disrupted — refugee camps, for example.

Prevention

Preventing LBRF means preventing body lice:

• Make hygiene possible: provide showers and laundry, especially in shelters and for people without housing — body lice thrive where people are crowded and can't bathe or change clothes.
• Don't share clothing, beds, bedding or towels with someone who might have body lice.
• Wash hot: launder possibly infested clothes and bedding in water above 130 °F (55 °C) and dry on high heat to kill lice and eggs.
• Treat infestations with a pediculicide, a lice-killing medicine.

Sources

Based on "About Louse-borne Relapsing Fever (LBRF)" (January 31, 2025), Centers for Disease Control and Prevention; a work of the United States government in the public domain.