Relapsing fever - what insects should be afraid of? What is relapsing fever Epidemic relapsing fever.

Relapsing fever(Latin typhus recurrens) is a collective name that combines epidemic (the carrier of the pathogen is a louse) and endemic (the carrier of the pathogen is a tick) spirochetosis, occurring with alternating bouts of fever and periods of normal body temperature.

The causative agents of relapsing fever are spirochetes of the genus Borrelia, in particular, one of the most common pathogens of epidemic typhus is Obermeier's Borrellia Obermeieri, discovered in 1868 by Otto Obermeier.

Tick-borne relapsing fever is a zoonotic vector-borne disease. The causative agents are many types of Borrelia: B. duttonii, B. persica, B. hispanica, B. latyschewii, B. caucasica, common in certain geographical areas. These borrelia are similar to the causative agent of epidemic relapsing fever in morphology, resistance to environmental factors, and biological properties.

A person becomes infected by tick bites. At the site of inoculation of the pathogen, a papule is formed (primary affect). The pathogenesis and clinical manifestations of tick-borne relapsing fever are similar to epidemic. Diseases often occur in the warm season with the activation of the vital activity of ticks.

The population of areas endemic for tick-borne relapsing fever acquires a certain degree of immunity to circulating pathogens - they have antibodies to borrelia common in this region in their blood serum. It is mainly visitors who get sick.

The carriers of epidemic V. typhus are the lice Pediculus humanus capitis (head), P. humanus humanus (clothes) and Phtirius pubis (pubic). The louse, having sucked the patient's blood, becomes capable of infecting a person throughout its life, since borrelia are non-pathogenic for lice, and microorganisms multiply well in the insect's hemolymph. There is no transovarial transmission of Borrelia in lice. A person becomes infected by rubbing lice hemolymph containing Borrelia (when combing a bite, crushing an insect) (contaminative infection). In the environment, Borrelia quickly die. Under the action of a temperature of 45-48 ° C, death occurs after 30 minutes. Epidemic relapsing fever only affects humans.

Pathogenesis (what happens?) during relapsing fever:

Once in the internal environment of the body, Borrelia invade the cells of the lymphoid-macrophage system, where they multiply, and then enter the blood in larger quantities. Under the influence of the bactericidal properties of blood, they are partially destroyed and endotoxin is released, damaging the circulatory and central nervous system. Toxicosis is accompanied by fever, and foci of necrosis appear in the spleen and liver. Due to the aggregates formed under the influence of antibodies from borrelia, which linger in the capillaries of internal organs, local blood supply is disrupted, which leads to the development of hemorrhagic infarcts.

The first febrile period of the disease ends with the formation of antibodies against the first generation Borrelia. Under the influence of these antibodies, microbial aggregates arise with a load of platelets and most of the Borrelia die. Clinically, this is expressed by the onset of remission. But some of the pathogens change their antigenic properties and become resistant to the formed antibodies, they remain in the body. This new generation of borrelias multiplies and, flooding the bloodstream, gives a new attack of fever. The resulting antibodies against the second generation of the pathogen lyse a significant part of them, but not completely. Resistant pathogens that have changed antigenic specificity, multiplying, again give a relapse of the disease. This is repeated several times. Recovery occurs only when a spectrum of antibodies appears in the blood, lysing all antigenic variants of Borrelia.

The transferred disease does not leave strong immunity. The formed antibodies remain for a short time.

Symptoms of relapsing fever:

The first attack begins suddenly: a short chill is replaced by fever and headache; there are pains in the joints and muscles (mainly calf), nausea and vomiting. The temperature rises quickly, the pulse is frequent, the skin is dry. The nervous system is involved in the pathological process, often delirium occurs (see DELIRIOUS). At the height of the attack, various forms of rash appear on the skin, the spleen and liver increase, and jaundice sometimes develops. During a fever, there may be signs of heart damage, as well as bronchitis or pneumonia. The attack lasts from two to six days, after which the temperature drops to normal or subfebrile and the patient's health improves rapidly. However, after 4-8 days, the next attack develops with the same symptoms. Cases without recurrences are rare.

For louse relapsing fever, one or two repeated attacks are characteristic, which end in complete recovery and temporary immunity. Tick-borne relapsing fever is characterized by four or more attacks of fever, they are shorter and milder in clinical manifestations, although the second attack may be more severe than the first.

Complications. Meningitis, iritis, iridocyclitis, uveitis, rupture of the spleen, synovitis. Previously observed icteric typhoid is a layering of salmonella infection.

Diagnosis of relapsing fever:

Recognition is based on epidemiological data, a characteristic clinical picture of the disease (acute onset, a critical drop in temperature with profuse sweating at the end of an attack, an early and significant enlargement of the spleen (splenomegaly), alternating febrile seizures and apyrexia). Diagnostic value are the data of the study of peripheral blood (moderate leukocytosis, especially during an attack, aneosinophilia, thrombocytopenia, increasing anemia, ESR increased).

Laboratory diagnostics
During an attack, at the height of the fever, the pathogen can be relatively easily detected in the patient's blood. To do this, preparations of a thick drop or blood smear are prepared, stained according to Romanovsky - Giemsa or magenta and microscoped. It is possible to microscope blood drops in a dark field, observing the mobility of Borrelia. The method of serological diagnostics consists in the formulation of lysis reactions, RSK.

Differentiation of epidemic from endemic relapsing fever is carried out in a biological experiment: a guinea pig is injected with the patient's blood. Borrelia of epidemic relapsing fever, unlike endemic ones, do not cause disease in the animal. With tick-borne typhus, the mumps falls ill for 5-7 days, and borrelia are found in its blood.

Treatment for relapsing fever:

Antibiotics (penicillin, chloramphenicol, chlortetracycline) and arsenic preparations (novarselon) are used to treat epidemic relapsing fever. In the treatment of tick-borne typhus, tetracycline antibiotics, levomycetin, and ampicillin are used.

Prevention of relapsing fever:

Prevention of epidemic typhus is reduced to the fight against lice, avoiding contact with lice patients. At present, epidemic relapsing fever does not occur in our country and in many others. Prevention of tick-borne relapsing fever is to protect people from tick attacks, the destruction of rodents and insects in natural foci.

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1547 Medline Plus 000760 MeSH 001350

Relapsing fever(lat. typhus recurrents) is a collective name that combines epidemic (the carrier of the pathogen is a louse) and endemic (the carrier of the pathogen is a tick) spirochetosis, occurring with alternating attacks of fever and periods of normal body temperature.

History of the concept

Before the development of microbiology, these diseases were combined with other infectious diseases, accompanied by a "clouding" of consciousness, under the general name typhus. In addition, there are epidemic, carried by lice, typhus and endemic tick-borne.

Epidemiology

Pathogens and vectors

The causative agents of relapsing fever are spirochetes of the genus Borrelia, in particular, one of the most common pathogens of epidemic typhus is Obermeyer's Borrellia recurrentis, discovered in 1868 by Otto Obermeyer.

Tick-borne relapsing fever is a zoonotic vector-borne disease. The causative agents are many types of Borrelia: B. duttonii, B. crocidurae, B. persica, B. hispanica, B. latyschewii, B. caucasica common in certain geographic areas. These borrelia are similar to the causative agent of epidemic relapsing fever in morphology, resistance to environmental factors, and biological properties.

carriers

Carriers of epidemic relapsing fever - lice Pediculus humanus capitis(head), P. humanus humanus(dress). The louse, having sucked the patient's blood, becomes capable of infecting a person throughout its life, since borrelia are non-pathogenic for lice, and microorganisms multiply well in the insect's hemolymph. There is no transovarial transmission of Borrelia in lice. A person becomes infected by rubbing lice hemolymph containing borrelia (when combing a bite, crushing an insect) (contaminative infection). In the environment, Borrelia quickly die. Under the action of a temperature of 45-48 ° C, death occurs after 30 minutes. Epidemic relapsing fever only affects humans.

Course of the disease. Pathogenesis

The first febrile period of the disease ends with the formation of antibodies against the first generation Borrelia. Under the influence of these antibodies, microbial aggregates arise with a load of platelets and most of the Borrelia die. Clinically, this is expressed by the onset of remission. But some pathogens change their antigenic properties and become resistant to the formed antibodies, and subsequently remain in the body. This new generation of borrelias multiplies and, flooding the bloodstream, gives a new attack of fever. The resulting antibodies against the second generation of the pathogen lyse a significant part of them, but not completely. Resistant pathogens that have changed antigenic specificity, multiplying, again give a relapse of the disease. This is repeated several times. Recovery occurs only when a spectrum of antibodies appears in the blood, lysing all antigenic variants of Borrelia.

The transferred disease does not leave strong immunity. The formed antibodies remain for a short time.

Clinical picture

The first attack begins suddenly: a short chill is replaced by fever and headache; there are pains in the joints and muscles (mainly calf), nausea and vomiting. The temperature rises quickly, the pulse is frequent, the skin is dry. The nervous system is involved in the pathological process, delirium often occurs. At the height of the attack, various forms of rash appear on the skin, the spleen and liver increase, and jaundice sometimes develops. During a fever, there may be signs of heart damage, as well as bronchitis or pneumonia. The attack lasts from two to six days, after which the temperature drops to normal or subfebrile and the patient's health improves rapidly. However, after 4-8 days, the next attack develops with the same symptoms. Cases without recurrences are rare.

Laboratory diagnostics

During an attack, at the height of the fever, the pathogen can be relatively easily detected in the patient's blood. To do this, preparations of a thick drop or blood smear are prepared, stained according to Romanovsky - Giemsa or magenta and microscoped. It is possible to microscope blood drops in a dark field, observing the mobility of Borrelia. The method of serological diagnostics consists in the formulation of lysis reactions, RSK.

Prevention

Treatment

Antibiotics (penicillin, levomycetin, chlortetracycline) and arsenic preparations (novarsenol) are used to treat epidemic relapsing fever. In the treatment of tick-borne typhus, tetracycline antibiotics, levomycetin, and ampicillin are used.

Forecast

In most parts of the world, with the exception of some countries in Central Africa, relapsing fever is rarely fatal, especially in healthy, well-nourished people. Epidemics of relapsing fever among weakened groups of the population in conditions of poor medical care can be accompanied by high mortality among the sick - up to 60-80%. Complications of relapsing fever include myocarditis and inflammatory eye lesions, heart attacks and abscesses of the spleen, dermatitis, pneumonia, temporary paralysis and paresis, a variety of mental disorders from twilight consciousness to manic states.

Sources

epidemic relapsing fever

Relapsing fever (Latin typhus recurrens) is a collective name that combines epidemic (the carrier of the pathogen is a louse) and endemic (the carrier of the pathogen is a tick) spirochetosis, occurring with alternating attacks of fever and periods of normal body temperature.

Morphology and ultrastructure of Borrelia. B.recurrents the causative agent of epidemic typhus. Spiral prokaryotic cells 0.3-0.6 by 8-18 microns in size, have 3-8 large uneven curls, have active mobility due to the presence of a motor apparatus located intracellularly. Borrelia are strict anaerobes. Gram (-).

Staining methods and laboratory diagnostics. When stained according to Romanovsky, it is stained purple. They stain well with aniline dyes, especially when using phenol as a mordant. Microbiological diagnostics. Bacterioscopic method - detection of a pathogen in blood stained according to Romanovsky - Giemsa. Microscopic method - take the patient's blood at the height of the febrile period. They study either native preparations of a “hanging drop” in a dark field of vision and a blood smear. As an auxiliary, a serological method with the setting of RSK is used.

Cultivation of Borrelia, features of metabolism. It grows on nutrient media and on developing chicken embryos, the optimum growth temperature is 28-30C. Pathogenic for monkeys, white mice and rats. Sensitive to penicillin, antibiotics of the tetracycline group, chloramphenicol, erythromycin.

Antigenic properties of Borrelia. The proteins of the fibrillar apparatus and the outer membrane are variable, which is clearly manifested in the development of the disease, causing the formation of agglutinating, complement-fixing and lysing antibodies in the body.

Ecology and epidemiology. Relapsing fever occurs throughout the world, with the exception of Australia, as a sporadic, epidemic or endemic disease. The greatest incidence and the most severe forms of relapsing fever are noted in Africa. The only source and reservoir of infection is a sick person. A person becomes infected with relapsing fever by rubbing the hemolymph of crushed lice into the skin while scratching the bite site. Carriers are body lice, which can transmit the infection 5 days after infection. Head and pubic lice have no great epidemiological significance. Infection of lice from typhoid patients occurs only during the feverish period of the disease. There is currently no relapsing fever in Russia.

Mechanisms and ways of transmission. Infection occurs when lice are crushed, from where they penetrate into the hemolymph, where they multiply and accumulate. The spread of lousy relapsing fever is facilitated by unfavorable sanitary and hygienic conditions and a large crowding of people. It is also possible to infect a person through the mucous membrane of the eye when rubbing the hemolymph and directly with the patient's blood. There is no transovarial transmission of Borrelia in lice. In the environment, Borrelia quickly die. Under the action of a temperature of 45-48 ° C, death occurs after 30 minutes.

Pathogenic properties of Borrelia.

Endotoxin - LPS of the cell wall (causes general intoxication of the body, hypermia, increases the permeability of blood vessels, which leads to dysfunction of vital organs and systems)

active mobility

Tropism of Borrelia to nervous tissue

Pronounced antigenic variability

The pathogenesis of borreliosis. After penetration into the body (by getting the hemolymph of crushed infected lice into small skin lesions), spirochetes multiply in the vascular endothelium and in the cells of the reticuloendothelial system. The appearance of a large number of spirochetes in the blood coincides with the onset of an attack of the disease. The severity of the febrile state and damage to organs and tissues depends on the number of circulating spirochetes, the number of which in severe forms can reach more than 100 102 liters. Thrombohemorrhagic syndrome may develop. Local blood supply disturbances occur, and hemorrhagic infarcts or granuloma-type lesions appear. Endotoxin acts on the central and peripheral nervous system, which is manifested by neurological and meningeal symptoms. Under the influence of antibodies formed in the body, the bulk of spirochetes die, a period of apyrexia sets in. However, a small number of spirochetes of the new antigenic variant persist in the blood or tissues. A new antigenic variant is formed spontaneously by genetic mutations with a frequency of one individual per 103-105 spirochetes and carries surface proteins that are different from those that caused the infection or previous relapse. Spirochetes of the new antigenic variant multiply and after about 7 days their number reaches a level sufficient for the development of a new attack. As a result, immunity against several races of spirochetes is formed and clinical recovery occurs.

Features of immunity. After suffering epidemic relapsing fever, short, humoral.

Relapsing fever is a group of rare infections carried by arthropods that are characterized by repeated episodes of fever. The causative agent belongs to the genus Borrelia, is demanding on nutrient media, is ubiquitous and is carried by lice and ticks.

Epidemic relapsing fever (lice relapsing fever) is caused by B. recurrentis, which is transmitted from person to person by Pediculus humanus, the body louse. After the patient's blood enters the intestines of the louse, Borrelia spp. penetrate its wall, migrate with hemolymph and multiply in it. Borreim spp. remain viable until the end of the life of the louse (several weeks). A person becomes infected by scratching the bite, while the lice are crushed, and their hemolymph is rubbed into the damaged skin.

Endemic relapsing fever (tick-borne) is caused by several types of Borrelia; Infection vectors are ticks of the genus Omithodoros. In the western states of the United States, the main causative agent of relapsing fever is B. hermsii, and in Mexico and Central America, B. dugesi. After the tick sucks on the patient's blood, borrelia penetrate into all his organs and tissues, including the salivary glands and genitals. The latter explains the transovarial transmission of the pathogen to the next generation of ticks. Borrelia enter the human body with saliva or excrement of ticks during bloodsucking.

Epidemiology

Relapsing fever tends to cause epidemics, fueled by war, poverty, famine, and poor personal hygiene. This variety is more common in the cold season. The main natural focus of epidemic relapsing fever is the highlands in Ethiopia.

Ticks of the genus Omithodoros, carriers of endemic relapsing fever, are distributed throughout the world, including in the western states of the United States. These mites prefer warm and humid climates, as well as highlands; settle in caves, rodent burrows. Rodents serve as the main reservoir of Borrelia. From rodents living in a human dwelling, ticks can pass to people. Often the tick bite goes unnoticed, since they feed mainly at night, and their bites are painless; in addition, having sucked blood (which takes a short time), the tick immediately leaves the person.

Pathogenesis

The paroxysmal nature of the fever is explained by the ability of Borrelia spp. constantly changing antigens. During the first attack of fever, many antigenic varieties appear simultaneously, but only one becomes dominant. Borrelia spp. isolated during the first attack of fever are antigenically distinct from those isolated during subsequent attacks. During an attack of fever, Borrelia spp. enter the bloodstream, induce the synthesis of specific IgM and IgG antibodies, and then undergo agglutination, immobilization, lysis and phagocytosis. During the interictal period, Borrelia spp. may remain in the bloodstream, but bacteremia is not sufficient to cause clinical manifestations. The number of fever attacks depends on the number of antigenic variants of the strain that caused the disease.

Symptoms of relapsing fever

The disease is characterized by bouts of fever lasting from 2 to 9 days with periods of normal temperature lasting from 2 to 7 days. With epidemic relapsing fever, the incubation period, the duration of fever attacks, periods of normal temperature are longer, and the number of fever attacks is less than with endemic relapsing fever. The incubation period for endemic relapsing fever is usually 8 days (5 to 15). All types of the disease are characterized by a sudden increase in body temperature to high numbers, confusion, photophobia, nausea, vomiting, myalgia, arthralgia. Later, these symptoms may be joined in the abdomen, coughing up sputum, and mild respiratory distress. Increased bleeding is often observed: nosebleeds, hemoptysis, hematuria and hematemesis. A diffuse rash may appear on the trunk and shoulders in the form of hyperemic spots or petechiae. Rash almost always occurs towards the end of the first attack of fever, more common in epidemic relapsing fever (25%), there are 1-2 days. Perhaps the development of lymphadenopathy, pneumonia and splenomegaly. A common symptom is right upper quadrant pain caused by hepatomegaly. Approximately 50% of affected children have jaundice. With late relapses, CNS damage in the form of confusion, stupor, symptoms of irritation of the meninges, convulsions, peripheral neuritis, focal neurological symptoms, and damage to cranial nerves may come to the fore. In severe cases, myocarditis, liver failure and DIC are observed. The critical end of the first attack of fever after 2-9 days is characteristic, which is accompanied by profuse sweating, hypothermia, arterial hypotension, bradycardia, severe muscle weakness and exhaustion. In untreated patients, a second attack of fever occurs within a week, usually followed by three more (up to 10). At the same time, each subsequent attack is shorter and less severe, and the intervals between attacks are lengthened.

Diagnostics

The diagnosis is made after microscopic examination of a thick drop, blood smears stained according to Giemsa or Wright. In this case, blood is taken at the height of fever, since in the interictal period Borrelia spp. are not detected by this method. Serological studies (ELISA, immunoblotting) are not standardized and are usually not available. The causative agents of endemic relapsing fever cross-react with other spirochetes, including Borrelia burgdorferi, the causative agent of Lyme disease.

Treatment of relapsing fever

Tetracycline is the drug of choice for all types of typhoid. Older children and adults are prescribed 500 mg of tetracycline orally every 6 hours 10 days. In adults, even a single dose of 500 mg of tetracycline or erythromycin may be effective, but there are few data on this regimen in children. In children under 12 years of age, erythromycin should be used (50 mg / kg / day - 4 doses, treatment duration 10 days). Penicillin and chloramphenicol are also effective.

Against the background of a decrease in body temperature (naturally or under the influence of treatment), with each attack of fever, the Jarisch-Herxheimer reaction usually occurs within 2 hours, indicating a weakening of bacteremia. Attempts to attenuate this reaction by prior administration of glucocorticoids or NSAIDs have had little success.

Forecast

With adequate treatment, mortality is less than 5%. Most patients (both treated and untreated) recover after the appearance of antibodies to Borrelia spp., which agglutinate, kill or opsonize the latter.

Prevention

There is no vaccine, so prevention consists of killing insect vectors or preventing contact with them. During outbreaks of typhus, it is necessary to maintain personal hygiene and sanitize people, their clothes and homes with insecticides. The risk of contracting typhoid is minimal if there are no rodents in the home.

The article was prepared and edited by: surgeon

Typhus recurrent fever (Typhus recurrens) is an infectious disease caused by Borrelia recurrentis, characterized by bouts of fever with muscle and headaches, followed by fever-free intervals. anthroponotic disease. Spirochete was discovered in 1868 by the German physician O. Obermeyer. Borrelia are large spirochetes with large irregular curls; Gram-negative, mobile. The carrier of pathogens is body louse. When bloodsucking, borrelia from the patient enter the intestines of the louse and can remain there throughout its life. Infection occurs as a result of crushing the louse, rubbing the pathogens contained in the hemolymph into scratches. Borrelia that have penetrated into the body are captured by macrophages and lymphoid cells and, as they multiply, enter the bloodstream. Being destroyed, they release endotoxins, which are the cause of clinical manifestations - chills, fever, headaches and muscle pain and other symptoms. The incubation period averages 7-8 days. Post-infection immunity is unstable and short-lived.

Treatment is with antibiotics.

Specific prophylaxis has not been developed. The main control measures are reduced to the destruction of lice, the identification of patients, the sanitization of persons who were in the outbreak.

Microbiological diagnostics is based on the detection of Borrelia in smears from the patient's blood, stained according to Romanovsky-Giemsa. Serological reactions are of auxiliary importance.

For differentiation with endemic typhus, infection of guinea pigs with the blood of the patient is used.

12.1.4. The causative agent of epidemic typhus

Typhus (Typhus exanthematicus) is an infectious disease caused by Rickettsia prowazekii, accompanied by fever, a specific rash, damage to the central nervous system and blood vessels. Anthroponosis.

Taxonomy. The causative agent of typhus is named after the American scientist N. T. Ricketts and the Czech scientist S. Provacek, who died while studying typhus. Prowaceca rickettsiae belong to the Gracilicutes division of the Rickettsiaceae family.

Epidemiology. The source of infection is a sick person. The carrier of pathogens is the body louse, which becomes infected by bloodsucking on the patient. Rickettsia multiply in the intestinal epithelium of the louse and are released into the lumen of its intestines. Rickettsia are not contained in the salivary glands, sucking apparatus of lice, therefore they are not transmitted with a bite. The lice bite is accompanied by itching. A person, combing the bite site, rubs lice feces containing rickettsia into it, and thus becomes infected. Consequently, the occurrence and spread of typhus are associated with lice (pediculosis). Typhus has been known since ancient times, but as an independent disease it was isolated at the end of the 19th century. Distributed everywhere. Typhus epidemics accompany wars, famines, social upheavals, i.e. associated with a decrease in the sanitary and hygienic level and living conditions of people. Mortality reached 80%. Sporadic cases are currently being reported, mostly in the form of Brill's disease.

Pathogenesis. Rickettsia Provacec enter the bloodstream, penetrate into the endothelial cells lining the blood vessels, multiply in them, releasing endotoxin. Under the action of the toxin, the destruction of endothelial cells occurs, rickettsiae again enter the bloodstream. Predominantly small vessels, capillaries are affected, which leads to disruption of microcirculation in the brain, myocardium, kidneys and other organs and the occurrence of meningoencephalitis, myocarditis, glomerulonephritis. In the body of patients, rickettsia can persist for a long time after recovery, which causes the appearance of recurrent forms of typhus.

Clinical picture. The incubation period averages 12-14 days. There are mild and varying degrees of severity of the disease. The disease begins with fever, excruciating headache, insomnia, agitation; after 4-5 days, a characteristic rash appears due to the expansion of skin capillaries and their damage. In severe forms, complications can develop in the form of damage to the heart and brain. Currently, cases of recurrent typhus are more common, characterized by a milder course and called Brill's disease.

Microbiological diagnostics. Isolation of rickettsia from the patient's body is difficult. The main diagnostic method is serological. RNGA, RA, RSK, RIF, ELISA are used to detect rickettsial antigen or antibodies in various materials taken from patients. Differential diagnosis of typhus and Brill's disease is based on the phenomenon of immunological memory: in typhus, first IgM is formed, and then IgG; in Brill's disease - the rapid formation of IgG.

Treatment. The most effective antirickettsial agents are tetracyclines, levomycetin, rifampicin.

Prevention. Elimination and prevention of lice are necessary. Specific prophylaxis is of secondary importance. Currently, a dry chemical typhus vaccine is being prepared in the Russian Federation, which is a purified concentrated substance of the surface antigen of Rickettsia Provacec. Vaccination is carried out according to epidemic indications. Vaccinations are shown to medical personnel working in epidemic conditions or in research laboratories.