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Symptoms of relapsing louse typhus.
Last reviewed: 04.07.2025

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Louse-borne relapsing fever has an incubation period that lasts from 3 to 14 (on average 7-8) days.
Symptoms of louse-borne relapsing fever are the basis for clinical classification, which provides for the allocation of latent, mild, moderate, and severe forms of louse-borne relapsing fever. The severity criteria are the height and duration of fever, severity of intoxication, and intensity of hemodynamic disorders.
The overwhelming majority of cases are characterized by a violent, sudden onset with a stunning chill, which after a few hours is replaced by fever and a rapid increase in body temperature to 39-40°C and higher. Occasionally, louse-borne relapsing fever begins with a prodromal period, during which nonspecific symptoms of louse-borne relapsing fever appear: general weakness, fatigue, headaches and joint pain.
Typical symptoms of relapsing louse typhus appear already on the first day: severe headache, muscle aches (especially in the calves), lower back, joints, photophobia, insomnia. Loss of appetite, nausea, vomiting, thirst may occur. Patients become lethargic, apathetic, some have meningeal symptoms. Injection of the sclera, hyperemia of the conjunctiva are observed. Nosebleeds, petechial rash, hemoptysis are possible. From the second day of the disease, the spleen enlarges, which causes a feeling of heaviness, pressure or dull pain in the left hypochondrium. From the 3rd-4th day, yellowness of the skin and sclera appears, the liver enlarges. Shortness of breath, tachycardia up to 140-150 per minute, decreased blood pressure are typical. The tongue is dry, thickly coated with white plaque, acquires a "milky", "porcelain" appearance. Diuresis is reduced.
Hyperthermia persists for 5-7 days, after which the body temperature critically drops to subnormal, which is accompanied by profuse sweating and often a sharp drop in blood pressure up to collapse. The duration of the first attack ranges from 3 to 13 days. During the "crisis", up to 3-4.5 liters of light urine are excreted.
After the temperature returns to normal, the patients' health improves, the pulse slows down, but severe weakness remains.
Louse-borne relapsing fever may be limited to one febrile attack (especially with early antibacterial treatment). In most patients, after 7-10 days of apyrexia, body temperature suddenly rises again and a second febrile attack occurs, similar to the first, but shorter (3-4 days), although often more severe.
In more than half of cases, louse-borne relapsing fever ends with a second attack. Sometimes after 9-12, very rarely - after 20 days after another period of normal temperature, a third attack occurs, even shorter and milder. A total of 4-5 febrile attacks are possible, with each subsequent one being shorter than the previous one, and the periods of apyrexia become longer. Early initiation of etiotropic therapy reduces the number of attacks.
In typical cases, the temperature curve is so characteristic that it is precisely this that allows one to suspect relapsing fever.
The recovery period is long, the patients' health recovers slowly, and general weakness, fatigue, dizziness, and insomnia persist for several weeks after the temperature has finally returned to normal.
Complications of relapsing fever
Specific complications, as with other spirochetoses, are meningitis, encephalitis, iritis, iridocyclitis. The most severe, but rare complication requiring urgent surgical intervention is a ruptured spleen. Nasal and uterine bleeding, hemorrhage in the brain and other organs are also possible. A critical decrease in body temperature by 4-5 °C can be complicated by collapse.
Mortality and causes of death
Mortality with timely antibacterial treatment is about 1% (in the past it reached 30%).