Typhus

From Ganfyd

Introduction

Multisystem disease caused by Rickettsia infection. Different types, depending on insect vector. Louse borne is described below, associated with R. prowazeki and R. typhi, but see also:

• Tick typhus
• Murine typhus - ie flea borne
• Scrub typhus - ie mite borne

Aetiology

• Rickettsia typhi transmitted by the body louse. The organism was discovered by Howard Taylor Ricketts. Persists in warzones and highland areas of social deprivation eg Ethiopia, Rwanda, Burundi, Andes. The Rickettsia survives in the midgut of the louse, where it can be passed to man by scratching of faeces into the skin, or by inhalation of the faeces, or by ingestion of the crushed louse itself. Tends to be epidemic. Can recur 20 years or more later - Brill-Zinsser disease.

Note that the louse can also transmit louse-borne relapsing fever.

Clinical

There is no bite lesion, cf Lyme disease. After an incubation period of 1-2 weeks, there is a sudden onset of fever, headache, myalgia with rash (which can be purpuric). A vasculitic illness, which may be complicated by encephalitis, pneumonia, acute renal failure, skin gangrene. Mortality rates are 10-40%.

Investigations

Blood tests

Weil-Felix response has poor sensitivity or specificity. Serology is the gold standard.

Radiology

Treatment

Medical

Single dose doxycyline.

Surgical

Prevention

1% Permethrin powder to delouse.

Notification

Statutorily notifiable

External links