Recurrent typhus is a disease of the spirochaetosis group, including epidemic (lice) and endemic (tick-borne) recurrent fevers. The main signs are multiple febrile attacks alternating with intervals of apyrexia. There is also marked intoxication, skin rashes, hepatosplenomegaly, mild jaundice of the skin and sclera. The detection of spirochetes in the patient’s blood is crucial for confirming the diagnosis of recurrent typhus. Etiotropic therapy is carried out with antibacterial drugs (penicillin, tetracycline, erythromycin, levomycetin, ampicillin).
Disease is an acute infectious disease that has a polycyclic course with alternating bouts of fever and non-sporadic periods. The term “recurrent typhus” refers to two similar etiologically and pathogenetically infections – lice and tick-borne typhus. Both of these diseases combine the morphological properties of pathogens belonging to pathogenic spirochetes of the genus Borrelia, the transmissive mechanism of transmission, and the generality of clinical manifestations. At the same time, differences in the antigenic structure of spirochetes, the epidemiology of diseases and immunological reactions of the body allow us to consider lice and tick-borne recurrent typhus as two independent nosologies.
Disease is an epidemic spirochaetosis, the causative agent of which is Borrelia reccurentis (Obermeyer’s spirochaete). It has a spiral shape with 4-8 curls, high mobility, a length of 10-30 microns and a thickness of 0.3-0.5 microns. By its nature, lice typhus is an anthroponosis, in which a sick person acts as a source of infection. The epidemic danger of the patient is mainly in the febrile period, when the concentration of pathogens in the blood reaches its peak. Carriers of infection are lice – in most cases, clothes, less often – head and pubic. During blood sucking, spirochetes enter the body of lice, where the reproduction of pathogens occurs in the hemolymph.
Infection of a healthy person is possible only when an infected insect is crushed and spirochetes get into areas of damaged skin with scratches, abrasions and other microtrauma. The spread of lousy recurrent typhus is facilitated by unfavorable sanitary and hygienic conditions, large crowding and mass lice of the population (for example, in flophouses, prisons, barracks). During periods of war, recurrent typhus took on the character of epidemics.
Tick–borne recurrent typhus (recurrent tick fever) is an endemic (naturally focal) spirochetosis caused by about 20 species of spirochetes of the genus Borrelia, common in various regions of the globe. According to their biological and morphological properties, these pathogens are similar to Obermeyer’s spirochaetes. The source of the spread of infection are rodents, and the carriers are ticks of the genus Ornithodoros, in whose body spirochetes persist for life and can even be transmitted to offspring. A person becomes ill with tick-borne recurrent typhus after being bitten by infected ticks. The causative agents of tick-borne recurrent typhus are present in the patient’s blood, both during fever and during the non-sporadic period. The disease is common in Asia, Africa, Latin America, Europe (in Spain, Portugal, southern Ukraine), etc. Epidemics are not typical for tick-borne recurrent typhus.
After the expiration of the incubation period (on average 3-14 days), the temperature suddenly rises to 39-40 ° C, accompanied by short-term chills and fever. In the midst of a febrile attack, weakness, insomnia, headaches, arthralgia, pain in the calf muscles are expressed. At fever height, facial hyperemia, injection of sclera vessels, signs of conjunctivitis are noted. Skin rashes may occur, having the character of petechiae, roseoles or macules; nosebleeds. Practically from the first days of recurrent typhus, the spleen and liver increase in size; about 2-3 days, jaundice of the skin and sclera appear; nausea, vomiting, diarrhea with mucus, oliguria occur. The first febrile period with recurrent typhus lasts 5-8 days, after which a period of apyrexia lasting 1-2 weeks occurs.
Between attacks, the condition of patients improves, but weakness, malaise, and decreased appetite persist. After a period of apyrexia, as a rule, a second wave of recurrent typhus occurs with the same clinical symptoms. However, the duration of the second attack is reduced to 3-4 days, and the non-sporadic interval, on the contrary, is lengthened. Usually, attacks of lice recurrent fever are repeated 3-5 times, each time becoming shorter and lighter than the previous one.
Among the most threatening complications is a rupture of the spleen with lethal internal bleeding. It is also dangerous to develop biliary typhoid, which can occur in a typhoid or septic variant. Typhoid variant is characterized by severe jaundice, profuse diarrhea, hemorrhagic rash, fever during apyrexia. The septic variant proceeds with the development of numerous abscesses of internal organs, myocarditis, pneumonia, osteomyelitis. With the development of biliary typhoid, fatal outcomes are frequent. The disease of recurrent typhus during pregnancy provokes spontaneous abortions, premature birth, uterine bleeding. Among other complications of recurrent typhus, there are iridocyclitis, purulent otitis, neuritis of the auditory nerve, diffuse bronchitis, focal pneumonia, etc. Immunity is unstable, repeated infections with lice recurrent typhus are possible.
The pathognomonic sign of tick-borne recurrent typhus is the occurrence of a primary affect at the site of the tick bite, which is a small papule surrounded by a hemorrhagic rim. The incubation period lasts 5-15 days. The disease also manifests with acute fever and severe intoxication syndrome, which persist for 1-4 days. At the end of the fever period, the temperature drops critically, and a period of apyrexia begins. The total number of seizures can reach 10 or more; the duration of non–sporadic periods varies from several days to 3-4 weeks.
In general, despite a long course (2-3 months), the disease is more easily tolerated than lice recurrent typhus: seizures are shorter, periods of apyrexia are longer, hepatosplenomegaly is less pronounced. After the tick-borne recurrent typhus, the local population develops a long and lasting immunity; if natural immunization (repeated tick bites) stops, a repeat disease may develop. Complications after recurrent typhus occur less frequently and almost never lead to fatal outcomes. Among them, iridocyclitis, keratitis, and uveitis usually prevail; in some cases, meningitis and encephalitis develop.
Diagnosis and treatment
Primary clinical diagnosis is based on epidemiological data and characteristic symptoms. When recognizing tick-borne recurrent typhus, the detection of the primary affect at the site of the tick bite is of paramount importance. To confirm the diagnosis, laboratory diagnostics is carried out: detection of spirochetes in the patient’s blood at the height of the attack (with lice typhus), in the febrile and non-sporadic period (with tick-borne typhus).
The method of thick droplet or blood smear microscopy is used as the main one, in addition – complement binding reaction, precipitation reaction, platelet loading reaction, etc. To diagnose tick-borne recurrent typhus, a biological test is sometimes used – infection with the patient’s blood of guinea pigs. Recurrent typhus must be differentiated from malaria, brucellosis, leptospirosis, influenza, Lyme disease, typhus, sepsis, dengue fever.
Antibacterial drugs are used as etiotropic therapy of recurrent typhus: penicillin, erythromycin, tetracycline, chloramphenicol or ampicillin for 5-7 days. Antimicrobial therapy allows you to quickly stop a febrile attack and prevent relapses of the disease. Additionally, pathogenetic and symptomatic treatment, detoxification therapy are carried out.
Immunization against recurrent typhus has not been developed. In preventing outbreaks of lice fever, it is of great importance to combat pediculosis, improve the sanitary and hygienic living conditions of the population, identify and hospitalize patients, carry out disinfection and disinfection measures in the hearth. Non-specific prevention of tick-borne recurrent typhus requires the destruction of ornithodor mites and rodents, protection from tick bites in endemic foci with the help of special clothing and repellents.