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Return tick-borne typhus: causes, symptoms, diagnosis, treatment
Last reviewed: 05.07.2025
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Tick-borne relapsing fever (endemic relapsing fever, tick-borne spirochetosis, argas tick-borne borreliosis, tick-borne relapsing fever) is a zoonosis, an acute natural focal disease of warm and hot climate zones, transmitted to humans by ticks, characterized by multiple attacks of fever, separated by periods of apyrexia.
ICD-10 code
A68.1. Endemic relapsing fever.
Epidemiology of tick-borne relapsing fever
Tick-borne relapsing fever is a classic natural focal disease. The source of infection is various animals, including rodents, predators, insectivores, reptiles, etc. The main reservoir and specific carrier of the pathogen are argas ticks of the genus Alectorobius. found in deserts and semi-deserts, foothills and mountains, as well as in populated areas (farm buildings, cattle sheds, adobe buildings). Infection occurs during the attachment of an infected tick. Human susceptibility to tick-borne relapsing fever is high. People who permanently live in endemic foci usually develop immunity. Mostly people from other regions get sick (tourists, travelers stopping for rest in ruins, abandoned houses, caves, military personnel).
Tick-borne relapsing fever foci are scattered everywhere except Australia, in areas with hot and subtropical climates. Tick-borne relapsing fever is widespread in many countries of Asia (including the former Central Asian republics of the Soviet Union, as well as in Israel, Jordan, Iran), Africa and Latin America; in Europe it is registered in Spain, Portugal, southern Ukraine, the North Caucasus and Transcaucasia.
The incidence of the disease increases in the spring and summer, which is associated with the greatest activity of ticks-carriers; in countries with a tropical climate, infection can occur throughout the year.
What causes relapsing fever?
Endemic relapsing fever is caused by spirochetes of the genus Borrelia (more than 20 species), which are morphologically identical to the Obermeyer spirochete, but differ from it in antigenic structure and pathogenicity. Most often, tick-borne relapsing fever is caused by the African B. duttoni, the Asian B. persica, as well as B. hermsii and B. nereensis.
Borrelia are not very stable in the external environment.
Pathogenesis of tick-borne relapsing fever
Pathogenesis, pathomorphology, and immunity are identical to those of louse-borne relapsing fever.
Symptoms of Tick-borne Relapsing Fever
Tick-borne relapsing fever has an incubation period that lasts from 4 to 20, most often 11-12 days.
At the site of the tick bite, a pink spot appears after a few minutes, then a nodule (papule) about 5 mm in diameter with a hemorrhagic rim. This is the primary affect, which can persist for up to 2-3 weeks.
The first febrile attack usually occurs suddenly, less often - after a prodrome, the following symptoms of tick-borne relapsing fever occur: high body temperature, chills, severe headache and other symptoms of intoxication, as in louse-borne relapsing fever, but instead of adynamia and apathy, excitement, delirium, hallucinations are characteristic. The attack lasts 2-4 days (less often - several hours), then the body temperature drops sharply, patients sweat profusely, after which the state of health normalizes. The duration of the apyrexia period is from 4 to 20 days. The number of attacks can be 10-12 or more. Each subsequent attack is shorter, and the apyrexia period is longer than the previous one. An irregular alternation of fever attacks and fever-free intervals is possible. The total duration of the disease is several months, but with early administration of antibacterial therapy, the clinical picture is erased, one wave of fever is observed.
During attacks, facial hyperemia and subicteric sclera are observed. Heart sounds are muffled, a decrease in blood pressure and relative bradycardia are characteristic. Abdominal pain and loose stools are possible; from the 3rd day, the liver and spleen moderately enlarge.
In East Africa and some US states, there are cases of severe relapsing tick-borne typhus, while in other regions it usually occurs in a mild or moderate form, which may be due to the biological characteristics of local strains of Borrelia.
Complications of tick-borne relapsing fever
Tick-borne relapsing fever is complicated by other diseases less frequently than louse-borne relapsing fever. These include acute psychosis, encephalitis, uveitis, iridocyclitis, and keratitis.
Mortality and causes of death
Fatal cases are extremely rare, but possible with "African" louse-borne relapsing fever, caused by B. duttoni.
Diagnostics of tick-borne relapsing fever
An important role is played by the epidemiological history (staying in places where ticks are carriers), detection of the primary affect, alternation of febrile attacks with periods of apyrexia.
The final diagnosis is established when Borrelia are detected in the patient's blood (a thick drop stained with Romanovsky-Giemsa is examined). Borrelia may be in small amounts in the peripheral blood, so blood is taken several times a day, preferably during a febrile attack. Diagnostics of tick-borne relapsing fever using an indirect immunofluorescence reaction: specific antibodies in the blood serum are tested starting from the 5th-7th day of the disease. Currently, PCR is successfully used for diagnostics.
A clinical blood test reveals slight leukocytosis, lymphocytosis, monocytosis, eosinopenia, and increased ESR; after several attacks, moderate hypochromic anemia appears.
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Differential diagnostics of tick-borne relapsing fever
Differential diagnostics of tick-borne relapsing fever is carried out with louse-borne relapsing fever, malaria, sepsis, influenza and other diseases accompanied by high fever. Unlike louse-borne relapsing fever, tick-borne typhus is characterized by a lower fever, short duration and multiple attacks, rapid improvement in the patient's well-being after the attack, absence of pain in the spleen and its moderate enlargement, excitation (not adynamia) of the patient, a characteristic type of temperature curve, absence of regularity in the duration of both the attacks themselves and the periods of apyrexia, the presence of primary affect, and a milder course. The similarity between tick-borne relapsing fever and malaria can be so great that only the result of a study of a smear and a thick blood drop stained according to Romanovsky-Giemsa allows establishing a final diagnosis.
What do need to examine?
What tests are needed?
Treatment of relapsing tick-borne typhus
Treatment of tick-borne relapsing fever is carried out in a hospital with the same antibiotics and in the same doses as for louse-borne relapsing fever, until the 5th-7th day of stable normal temperature. If necessary, detoxification treatment of tick-borne relapsing fever is prescribed.
How to prevent tick-borne relapsing fever?
No specific prevention has been developed.
Non-specific prevention of tick-borne relapsing fever consists of destroying ornithod ticks and rodents in outbreaks, wearing protective clothing in tick habitats, and using repellents.
What is the prognosis for tick-borne relapsing fever?
Tick-borne relapsing fever has a favorable prognosis.