Relapsing fever--a forgotten disease revealed

Area of Science:

• Medical Entomology
• Infectious Diseases
• Epidemiology

Background:

• Borrelial relapsing fever historically caused worldwide epidemics, with the term originating in Edinburgh.
• Louse-borne relapsing fever (LBRF) has significantly declined due to improved living standards reducing body louse vectors.

Observation:

• Tick-borne relapsing fever (TBRF), a zoonotic form, remains prevalent in global endemic foci.
• TBRF is a leading bacterial infection in Senegal and a top mortality cause in Tanzanian children.
• LBRF is a major cause of hospital admissions in Ethiopia, linked to high morbidity and mortality.

Findings:

• Relapsing fever is increasingly viewed as an unusual tropical disease, with imported cases reported globally.
• Cases have emerged unexpectedly in non-endemic regions, such as Colorado and Los Angeles, USA.
• The infection is often zoonotic, with vertebrate reservoirs, though East African transmission dynamics are debated.

Implications:

• Understanding the arthropod vector's feeding preferences is crucial for deciphering the life cycle of relapsing fever.
• Continued vigilance and research are necessary to address the persistent threat of TBRF in endemic and newly emerging regions.
• Public health strategies must adapt to the changing epidemiology of relapsing fever, including its zoonotic and imported forms.