Sources of infection with Crimean hemorrhagic fever. Crimean hemorrhagic fever. Symptoms, prevention, first signs. Treatment, photos, carriers. Anti-epidemic measures, diagnostics. Infection control in health care settings

Crimean-Congo hemorrhagic fever(lat. febris haemorrhagica crimiana, synonym: Crimean hemorrhagic fever, Congo-Crimean hemorrhagic fever, Central Asian hemorrhagic fever) is an acute infectious human disease transmitted through tick bites, characterized by fever, severe intoxication and hemorrhages on the skin and internal organs. It was first identified in 1944 in Crimea. The pathogen was identified in 1945. In 1956, a similar disease was identified in the Congo. Studies of the virus have established its complete identity with the virus discovered in Crimea.

What causes Crimean hemorrhagic fever:

The causative agent of Crimean hemorrhagic fever is a virus from the family Bunyaviridae, genus Nairovirus. Belongs to arboviruses (Arboviridae). Discovered in 1945 by M.P. Chumakov in the Crimea, while studying the blood of sick soldiers and settlers who fell ill while working on hay harvesting. In 1956, a virus with a similar antigenic composition was isolated from the blood of a sick boy in the Congo. The causative agent is called the Congo virus. Virions are spherical, 92-96 nm in diameter, surrounded by a lipid-containing envelope. The most sensitive to the virus are embryonic kidney cell cultures from pigs, Syrian hamsters and monkeys. Poorly stable in environment. When boiled, the virus dies instantly, at 37 `C - after 20 hours, at 45 `C - after 2 hours. When dried, the virus remains viable for over 2 years. In affected cells it is localized mainly in the cytoplasm.

Natural reservoir of the pathogen- rodents, large and small livestock, birds, wild species of mammals, as well as ticks themselves, which are capable of transmitting the virus to offspring through eggs and are virus carriers for life. The source of the pathogen is a sick person or an infected animal. The virus is transmitted through a tick bite or through medical procedures involving injections or blood sampling. The main carriers are ticks Hyalomma marginatus, Dermacentor marginatus, Ixodes ricinus. Outbreaks of the disease in Russia occur annually in the Krasnodar and Stavropol territories, Astrakhan, Volgograd and Rostov regions, in the republics of Dagestan, Kalmykia and Karachay-Cherkessia. The disease also occurs in southern Ukraine and Crimea, Central Asia, China, Bulgaria, Yugoslavia, Pakistan, Central, Eastern and South Africa(Congo, Kenya, Uganda, Nigeria, etc.). In 80% of cases, people aged 20 to 60 years get sick.

Pathogenesis (what happens?) during Crimean hemorrhagic fever:

At the core pathogenesis of hemorrhagic Crimean fever there is an increase in the permeability of the vascular wall. Increasing viremia causes the development of severe toxicosis, up to infectious-toxic shock with disseminated intravascular coagulation, inhibition of hematopoiesis, which aggravates the manifestations of hemorrhagic syndrome.

The gateway to infection is the skin at the site of a tick bite or minor injuries upon contact with the blood of sick people (in case of nosocomial infection). No pronounced changes are observed at the site of the infection gate. The virus enters the blood and accumulates in the cells of the reticuloendothelial system. With secondary, more massive viremia, signs of general intoxication appear, damage to the vascular endothelium and thrombohemorrhagic syndrome develops of varying severity. Pathological changes are characterized by multiple hemorrhages in the mucous membranes of the stomach and intestines, the presence of blood in the lumen, but there are no inflammatory changes. The brain and its membranes are hyperemic, hemorrhages with a diameter of 1-1.5 cm with destruction of the brain matter are found in them. Small hemorrhages are detected throughout the brain. Hemorrhages are also observed in the lungs, kidneys, etc. Many issues of the pathogenesis of Crimean-Congo fever remain unexplored.

At autopsy, multiple hemorrhages are found in the mucous membranes gastrointestinal tract, blood is in its lumen, but there are no inflammatory changes. The brain and its membranes are hyperemic, hemorrhages with a diameter of 1-1.5 cm with destruction of the brain matter are found in them. Small hemorrhages are detected throughout the brain. Hemorrhages are also observed in the lungs, kidneys, liver, etc.

Symptoms of Crimean hemorrhagic fever:

Incubation period from one to 14 days. Most often 3-5 days. There is no prodromal period. The disease develops acutely.

In the initial (prehemorrhagic) period There are only signs of general intoxication, characteristic of many infectious diseases. The initial period usually lasts 3-4 days (from 1 to 7 days). During this period, against the background of high fever, weakness, fatigue, headache, aches throughout the body, severe headache, pain in muscles and joints.

More rare manifestations of the initial period include dizziness, impaired consciousness, severe pain V calf muscles, signs of inflammation of the upper respiratory tract. Only some patients, even before the development of the hemorrhagic period, develop symptoms characteristic of this disease.
symptoms - repeated vomiting not associated with food intake, lower back pain, abdominal pain, mainly in the epigastric region.

A constant symptom is fever, which lasts on average 7-8 days, the temperature curve is especially typical for Crimean hemorrhagic fever. In particular, when hemorrhagic syndrome appears, there is a decrease in body temperature to subfebrile, after 1-2 days the body temperature rises again, which causes the “double-humped” temperature curve characteristic of this disease.

Hemorrhagic period corresponds to the peak period of the disease. The severity of thrombohemorrhagic syndrome determines the severity and outcome of the disease. In most patients, on the 2-4th day of illness (less often on the 5-7th day), a hemorrhagic rash appears on the skin and mucous membranes, hematomas at the injection sites, and there may be bleeding (stomach, intestinal, etc.). The patient's condition deteriorates sharply. Facial hyperemia gives way to pallor, the face becomes puffy, cyanosis of the lips and acrocyanosis appear. The skin rash is initially petechial, at this time enanthema appears on the mucous membranes of the oropharynx, and there may be larger hemorrhages into the skin. Possible nasal uterine bleeding, hemoptysis, bleeding of the gums, tongue, conjunctiva. The prognosis is unfavorable for the appearance of massive gastric and intestinal bleeding. The condition of the patients becomes even more severe, and disturbances of consciousness are noted. Characterized by abdominal pain, vomiting, diarrhea; the liver is enlarged, painful on palpation, Pasternatsky's sign is positive. Bradycardia gives way to tachycardia, blood pressure is reduced. Some patients experience oliguria and residual nitrogen increases. In peripheral blood - leukopenia, hypochromic anemia, thrombocytopenia, ESR without significant changes. Fever lasts 10-12 days. Normalization of body temperature and cessation of bleeding characterizes the transition to the recovery period. Asthenia persists for a long time (up to 1-2 months). Some patients may have mild forms of the disease that occur without pronounced thrombohemorrhagic syndrome, but they, as a rule, remain undetected.

Sepsis, pulmonary edema, focal pneumonia, acute renal failure, otitis media, thrombophlebitis can be observed as complications. Mortality ranges from 2 to 50%.

Diagnosis of Crimean hemorrhagic fever:

Diagnosis of Crimean hemorrhagic fever based on clinical picture, epidemiological history data (stay in the area of natural foci, tick attacks, contact with patients with Crimean hemorrhagic fever), results laboratory research. There is a reduced number of red blood cells in the blood, leukopenia (up to 1x109-2x109/l), neutropenia, thrombocytopenia. To confirm the diagnosis, virus isolation from the patient’s blood is used; from the 6-10th day of illness, an increase in antibody titer is determined in repeated samples of the patient’s blood serum in the RSC, diffuse precipitation reactions in agar, and passive hemagglutination reactions.

Differential diagnosis is carried out with other viral diseases manifested by hemorrhagic syndrome, especially if the patient is in the last days before the development clinical manifestations The disease was in countries with tropical and subtropical climates, with leptospirosis, hemorrhagic fever with renal syndrome, hemorrhagic vasculitis, sepsis, etc.

Treatment of Crimean hemorrhagic fever:

Patients must be isolated in the infectious diseases department of the hospital. Treatment is symptomatic and etiotropic. Anti-inflammatory drugs and diuretics are prescribed. Avoid the use of drugs that increase kidney damage, such as sulfonamides. Also prescribed antiviral drugs(ribavirin, reaferon). In the first 3 days, heterogeneous specific equine immunoglobulin, immune serum, plasma or specific immunoglobulin obtained from the blood serum of recovered or vaccinated individuals is administered. Specific immunoglobulin is used for emergency prophylaxis in persons in contact with the patient’s blood.

Prevention of Crimean hemorrhagic fever:

To prevent infection, the main efforts are directed towards combating the vector of the disease. Carry out disinfestation of premises for keeping livestock, prevent grazing on pastures located on the territory natural source. Individuals should wear protective clothing. Treat clothing, sleeping bags and tents with repellents. If you are bitten by a tick in your habitat, immediately contact a medical facility for help. For persons who are going to enter the territory of the South of Russia, preventive vaccination is recommended. IN medical institutions the high contagiousness of the virus, as well as its high concentration in the blood of patients, should be taken into account. Therefore, patients must be placed in a separate box, and care must be provided only to specially trained personnel.

Crimean hemorrhagic fever Crimean hemorrhagic fever (CCHF, Crimean-Congo fever, Central Asian fever) is a viral natural focal disease of humans, the causative agent of which, the Crimean-Congo hemorrhagic fever virus, belongs to the RNA-containing viruses of the family Bunyaviridae sort of Nairovirus and is transmitted by ticks. The southern regions of Russia are endemic for CCHF: Astrakhan, Rostov, Volgograd regions, Stavropol and Krasnodar region, the republics of Kalmykia, Dagestan, Ingushetia, the virus also circulates in southern Europe (Greece, Bulgaria, Romania, Yugoslavia), in central Asia (Turkmenistan, Uzbekistan, Tajikistan), in the countries of the Middle East (Turkey, Iran, Iraq, UAE), China and on the African continent.

The disease is characterized by an acute onset, a two-wave rise in body temperature, severe intoxication and hemorrhagic syndrome. From the first days of the disease, hyperemia of the skin of the face, neck and upper half of the body, and a sharp injection of blood vessels in the sclera and conjunctiva are noted. Already in the first two days, nosebleeds, bleeding gums may occur, and a pinpoint petechial rash may appear on the skin of the torso. The second period (the height of the hemorrhagic) of the disease begins with a repeated rise in temperature, which remains at high levels for 3–4 days, then gradually decreases. The duration of the second period is from 3 to 9 days. During this period, the vast majority of patients develop hemorrhagic syndrome - from petechiae on the skin to massive bleeding. Hematomas are often observed at injection sites. Simultaneously with the rash, other manifestations of hemorrhagic syndrome develop: nasal, gastrointestinal and uterine bleeding, hemoptysis, spotting from the eyes and ears, hematuria. The duration of the bleeding period varies, but is usually 3–4 days. The intensity and duration of the hemorrhagic syndrome determine the severity of the disease and often correlate with the concentration of the virus in the blood. During this period, the development of pneumonia is possible due to the occurrence of hemo-aspiration atelectasis.

Anemia, leukopenia with lymphocytosis and severe thrombocytopenia are observed in the blood. Greatest diagnostic value has leukopenia with a predominance of neutrophils. The number of leukocytes drops to 800–1000, which, in combination with the appearance of young forms (myelocytes, myeloblasts), provides grounds for differentiating CHF from blood diseases with hemorrhagic syndrome. The platelet count also drops quickly and sharply, sometimes to zero. A rare exception are cases of transition of leukopenia to moderate leukocytosis, ending in death.

When compared with other hemorrhagic fevers registered in the Russian Federation (Omsk hemorrhagic fever, HFRS), in addition to epidemiological features, CHF is distinguished by a pronounced hemorrhagic syndrome against the background of severe intoxication, as well as the absence of kidney damage with the development of acute renal failure.

Indications for examination

Staying in an area enzootic for CCHF (outings, fishing, etc.) for 14 days preceding the disease;
tick bite or contact with it (removal, crushing, crawling);
the occurrence of the disease during the epidemic season (April–September);
belonging to professional risk groups (agricultural and veterinary workers, persons involved in slaughtering livestock, in field work, individual livestock owners, medical workers);
carrying out instrumental manipulations in patients with suspected CCHF, taking and examining biological material;
caring for patients with suspected CCHF.

Differential diagnosis

Acute infectious diseases (in the first period): influenza, sepsis, typhus and other rickettsioses, meningococcemia;
hemorrhagic fevers (Omsk fever, fever with renal syndrome), thrombocytopenic purpura (Werlhof's disease); hemorrhagic vasculitis (Henoch-Schönlein disease);
malignant blood diseases.

Material for research

Blood plasma – detection of virus RNA;
blood serum – detection of hypertension and specific antibodies;
whole blood – virus isolation.

Etiological laboratory diagnostics includes virus isolation, detection of virus RNA and antigens; detection of specific IgM and IgG antibodies.

Comparative characteristics of laboratory diagnostic methods

Virus isolation can be done in Vero cell culture or using susceptible laboratory animals. Due to the length and complexity of the study, these methods are not used in routine practice.

In the first week of the disease, studies should be carried out to detect the RNA of the virus (PCR method, diagnostic sensitivity 95–100%). RNA detection is used in combination with the determination of IgM antibodies in the early period of the disease and confirmation of the diagnosis when the titer of IgG antibodies increases in blood samples taken over time (paired sera). IgM antibodies appear on the 3–4th day of illness, IgG antibodies on the 7–10th day. Detection of AT is carried out mainly by ELISA.

Features of interpretation of laboratory results

According to MU3.1.3.2488-09, detection of RNA and/or Ag of the Crimean-Congo hemorrhagic fever virus in the patient’s blood taken at early stages of the disease (before the 5th–7th day), indicates that the patient is infected and, together with the data of the epidemiological history and clinical picture, can be considered the basis for making a diagnosis. If an IgM antibody is detected in a titer of 1:800 or more and an IgG antibody in any titer, the diagnosis of CCHF is considered confirmed.

What is Crimean hemorrhagic fever

What causes Crimean hemorrhagic fever

The causative agent of Crimean hemorrhagic fever is a virus from the family Bunyaviridae, genus Nairovirus. Belongs to arboviruses (Arboviridae). Discovered in 1945 by M.P. Chumakov in the Crimea, while studying the blood of sick soldiers and settlers who fell ill while working on hay harvesting. In 1956, a virus with a similar antigenic composition was isolated from the blood of a sick boy in the Congo. The causative agent is called the Congo virus. Virions are spherical, 92-96 nm in diameter, surrounded by a lipid-containing envelope. The most sensitive to the virus are embryonic kidney cell cultures from pigs, Syrian hamsters and monkeys. Poorly stable in the environment. When boiled, the virus dies instantly, at 37 `C - after 20 hours, at 45 `C - after 2 hours. When dried, the virus remains viable for over 2 years. In affected cells it is localized mainly in the cytoplasm.

Natural reservoir of the pathogen- rodents, large and small livestock, birds, wild species of mammals, as well as ticks themselves, which are capable of transmitting the virus to offspring through eggs and are virus carriers for life. The source of the pathogen is a sick person or an infected animal. The virus is transmitted through a tick bite or through medical procedures involving injections or blood sampling. The main carriers are ticks Hyalomma marginatus, Dermacentor marginatus, Ixodes ricinus. Outbreaks of the disease in Russia occur annually in the Krasnodar and Stavropol territories, Astrakhan, Volgograd and Rostov regions, in the republics of Dagestan, Kalmykia and Karachay-Cherkessia. The disease also occurs in southern Ukraine and Crimea, Central Asia, China, Bulgaria, Yugoslavia, Pakistan, Central, Eastern and Southern Africa (Congo, Kenya, Uganda, Nigeria, etc.). In 80% of cases, people aged 20 to 60 years get sick.

Pathogenesis (what happens?) during Crimean hemorrhagic fever

At autopsy, multiple hemorrhages are found in the mucous membranes of the gastrointestinal tract, blood in its lumen, but there are no inflammatory changes. The brain and its membranes are hyperemic, hemorrhages with a diameter of 1-1.5 cm with destruction of the brain matter are found in them. Small hemorrhages are detected throughout the brain. Hemorrhages are also observed in the lungs, kidneys, liver, etc.

Symptoms of Crimean hemorrhagic fever

Incubation period from one to 14 days. Most often 3-5 days. There is no prodromal period. The disease develops acutely.

In the initial (prehemorrhagic) period There are only signs of general intoxication, characteristic of many infectious diseases. The initial period usually lasts 3-4 days (from 1 to 7 days). During this period, against the background of high fever, weakness, weakness, headache, aches throughout the body, severe headache, pain in muscles and joints are noted.

More rare manifestations of the initial period include dizziness, impaired consciousness, severe pain in the calf muscles, and signs of inflammation of the upper respiratory tract. Only some patients, even before the development of the hemorrhagic period, develop symptoms characteristic of this disease.
symptoms - repeated vomiting not associated with food intake, lower back pain, abdominal pain, mainly in the epigastric region.

Hemorrhagic period corresponds to the peak period of the disease. The severity of thrombohemorrhagic syndrome determines the severity and outcome of the disease. In most patients, on the 2-4th day of illness (less often on the 5-7th day), a hemorrhagic rash appears on the skin and mucous membranes, hematomas at the injection sites, and there may be bleeding (stomach, intestinal, etc.). The patient's condition deteriorates sharply. Facial hyperemia gives way to pallor, the face becomes puffy, cyanosis of the lips and acrocyanosis appear. The skin rash is initially petechial, at this time enanthema appears on the mucous membranes of the oropharynx, and there may be larger hemorrhages into the skin. Nasal and uterine bleeding, hemoptysis, bleeding of the gums, tongue, and conjunctiva are possible. The prognosis is unfavorable for the appearance of massive gastric and intestinal bleeding. The condition of the patients becomes even more severe, and disturbances of consciousness are noted. Characterized by abdominal pain, vomiting, diarrhea; the liver is enlarged, painful on palpation, Pasternatsky's sign is positive. Bradycardia gives way to tachycardia, blood pressure is reduced. Some patients experience oliguria and residual nitrogen increases. In peripheral blood - leukopenia, hypochromic anemia, thrombocytopenia, ESR without significant changes. Fever lasts 10-12 days. Normalization of body temperature and cessation of bleeding characterizes the transition to the recovery period. Asthenia persists for a long time (up to 1-2 months). Some patients may have mild forms of the disease that occur without pronounced thrombohemorrhagic syndrome, but they, as a rule, remain undetected.

Sepsis, pulmonary edema, focal pneumonia, acute renal failure, otitis media, thrombophlebitis can be observed as complications. Mortality ranges from 2 to 50%.

Diagnosis of Crimean hemorrhagic fever

Diagnosis of Crimean hemorrhagic fever is based on the clinical picture, epidemiological history data (stay in the area of natural foci, tick attacks, contact with patients with Crimean hemorrhagic fever), and the results of laboratory tests. There is a reduced number of red blood cells in the blood, leukopenia (up to 1x109-2x109/l), neutropenia, thrombocytopenia. To confirm the diagnosis, virus isolation from the patient’s blood is used; from the 6-10th day of illness, an increase in antibody titer is determined in repeated samples of the patient’s blood serum in the RSC, diffuse precipitation reactions in agar, and passive hemagglutination reactions.

Differential diagnosis is carried out with other viral diseases manifested by hemorrhagic syndrome, especially if the patient in the last days before the development of clinical manifestations of the disease was in countries with tropical and subtropical climates, with leptospirosis, hemorrhagic fever with renal syndrome, hemorrhagic vasculitis, sepsis, etc.

Treatment of Crimean hemorrhagic fever

Patients must be isolated in the infectious diseases department of the hospital. Treatment is symptomatic and etiotropic. Anti-inflammatory drugs and diuretics are prescribed. Avoid the use of drugs that increase kidney damage, such as sulfonamides. Antiviral drugs (ribavirin, reaferon) are also prescribed. In the first 3 days, heterogeneous specific equine immunoglobulin, immune serum, plasma or specific immunoglobulin obtained from the blood serum of recovered or vaccinated individuals is administered. Specific immunoglobulin is used for emergency prophylaxis in persons in contact with the patient’s blood.

Prevention of Crimean hemorrhagic fever

To prevent infection, the main efforts are directed towards combating the vector of the disease. They carry out disinfestation of premises for keeping livestock, and prevent grazing on pastures located on the territory of a natural outbreak. Individuals should wear protective clothing. Treat clothing, sleeping bags and tents with repellents. If you are bitten by a tick in your habitat, immediately contact a medical facility for help. For persons who are going to enter the territory of the South of Russia, preventive vaccination is recommended. In medical institutions, the high contagiousness of the virus, as well as its high concentration in the blood of patients, should be taken into account. Therefore, patients must be placed in a separate box, and care must be provided only to specially trained personnel.

Which doctors should you contact if you have Crimean hemorrhagic fever?

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Crimean-Congo hemorrhagic fever virus (CCHFV) causes a number of viral hemorrhagic fever outbreaks.
The case fatality rate during CCHF outbreaks reaches 40%.
The virus is transmitted to people mainly from ticks and livestock. Person-to-person transmission can occur through close contact with the blood, secretions, organs, or other body fluids of infected people.
CCHF is endemic in Africa, the Balkans, the Middle East and Asia, in countries south of the 50th parallel north latitude.
There is no vaccine for humans or animals.

Crimean-Congo hemorrhagic fever (CCHF) is a widespread disease caused by a tick-borne virus (Nairovirus) of the Bunyaviridae family. CCHF virus causes outbreaks of severe viral hemorrhagic fever with a case fatality rate of 10-40%.

CCHF is endemic in Africa, the Balkans, the Middle East and Asian countries south of the 50th parallel north latitude, the geographic limit of the tick's primary vector.

Crimean-Congo hemorrhagic fever virus in animals and ticks

CCHF virus vectors include a wide range of wild and domestic animals such as cattle, sheep and goats. Many birds are resistant to the infection, but ostriches are susceptible and may have high infection rates in endemic areas where they are a source of infection in human cases. For example, one past outbreak of the disease occurred at an ostrich slaughterhouse in South Africa. There are no obvious signs of disease in these animals.

Animals become infected by the bite of an infected tick, and the virus remains in their bloodstream for approximately one week after infection, allowing subsequent tick bites to continue the tick-animal-tick cycle. Although several species of ticks can be infected with the CCHF virus, the main carriers are ticks of the Hyalomma species.

Transmission of infection

CCHF virus is transmitted to humans either through tick bites or through contact with infected blood or tissues of animals during and immediately after slaughter. Most cases of infection occur in people involved in factory farming, such as farm workers, slaughterhouse workers and veterinarians.

Person-to-person transmission can occur through close contact with the blood, secretions, organs, or other body fluids of infected people. Hospital-acquired infections may also occur as a result of improper sterilization of medical equipment, reuse of needles, and contamination of medical supplies.

Signs and symptoms

Duration incubation period depends on the method of infection by the virus. After infection through a tick bite, the incubation period usually lasts one to three days, with a maximum duration of nine days. The incubation period after exposure to infected blood or tissue typically lasts five to six days, with a documented maximum period of 13 days.

Symptoms appear suddenly with elevated temperature, myalgia ( muscle pain), dizziness, neck pain and stiffness, back or lower back pain, headache, eye inflammation and photophobia (sensitivity to light). Nausea, vomiting, diarrhea, abdominal pain and sore throat may occur, followed by mood swings and confusion. After two to four days, agitation may give way to drowsiness, depression and fatigue, and abdominal pain may be localized to the upper right with detectable hepatomegaly (enlarged liver).

Other clinical signs include tachycardia (rapid heartbeat), lymphadenopathy (increased lymph nodes) and petechial rash (a rash caused by bleeding into the skin) on the inner surface of mucous membranes, such as the mouth and throat, and on the skin. Petechial rashes can develop into larger rashes called ecchymoses and other hemorrhagic phenomena. Signs of hepatitis are common, and after the fifth day of illness, severely ill patients may experience rapid deterioration of kidney function and sudden liver or pulmonary failure.

The mortality rate for CCHF is approximately 30%, with death occurring in the second week of illness. In recovering patients, improvement usually begins on the ninth or tenth day after the onset of the disease.

Diagnostics

CCHF virus infection can be diagnosed by several different laboratory tests:

enzyme immunoassay (ELISA);
identification of antigens;
serum neutralization;
reverse transcriptase polymerase chain reaction (RT-PCR);
virus isolation in cell cultures.

Terminally ill patients and those in the first few days of illness usually do not produce measurable antibodies, so diagnosis in these patients is made by detecting virus or RNA in blood or tissue samples.

Testing of patient samples poses an extremely high biological risk and should only be carried out under maximum biosafety conditions. However, if samples are inactivated (e.g. by virucides, gamma radiation, formaldehyde, exposure to high temperatures etc.), they can be handled under basic biosafety conditions.

Treatment

The main approach to the management of CCHF in humans is usual supportive care with symptomatic treatment.

The antiviral drug ribavirin leads to obvious positive results in the treatment of CCHF infection. Both oral and intravenous dosage forms are effective.

Disease prevention and control

Control of CCHF in animals and ticks

Robert Swanepoel/NICD South Africa

Prevention and control of CCHF infection in animals and ticks is difficult because the tick-animal-tick cycle is usually silent and infection in domestic animals usually occurs without obvious signs. In addition, ticks that transmit the disease are numerous and widespread, so the only practical option for properly managed enterprises livestock production is the fight against ticks using acaricides (chemicals intended to kill ticks). For example, following an outbreak of this disease at an ostrich slaughterhouse in South Africa (mentioned above), measures were taken to ensure that ostriches remained tick-free in the quarantine facility for 14 days before slaughter. This measure helped reduce the risk that the animal was infected at the time of slaughter and prevented infection of people who had contact with the animals.

There are no vaccines for use in animals.

Reducing the risk of human infection

Although an inactivated vaccine derived from mouse brain tissue has been developed against CCHF and has been used on a small scale in Eastern Europe, there is currently no safe and effective vaccine for widespread use in humans.

In the absence of a vaccine, the only way to reduce the number of infections among people is to increase awareness of risk factors and educate people about measures they can take to limit exposure to the virus.

Reducing the risk of virus transmission from ticks to humans:

wear protective clothing (long sleeves, long trousers);
wear light-colored clothing that makes it easy to spot ticks on clothing;
use approved acaricides ( chemicals intended for the destruction of ticks) for clothing;
use approved repellents for skin and clothing;
regularly inspect clothing and skin to detect ticks; if found, delete them safe methods;
strive to prevent animals from being affected by ticks or carry out tick control in animal housing;
avoid staying in areas where there is large number ticks, and in those seasons when they are most active.

Reducing the risk of virus transmission from animals to humans:

Wear gloves and other protective clothing when handling animals or their tissues in endemic areas, especially during slaughter, dressing and culling in slaughterhouses or at home;
Quarantining animals before entering slaughterhouses or routinely treating animals with pesticides two weeks before slaughter.

Reducing the risk of person-to-person transmission in selected communities:

avoid close physical contact with people infected with CCHF;
wear gloves and protective clothing when caring for sick people;
Wash your hands regularly after caring for or visiting sick people.

Infection control in health care settings

Health care workers caring for patients with suspected or confirmed CCHF or handling specimens collected from them should follow standard infection control precautions. These include basic hand hygiene, use of personal protective equipment, safe injection practices and safe disposal practices.

As a precaution, healthcare workers caring for patients directly outside the CCHF outbreak area should also follow standard infection control measures.

Specimens from people with suspected CCHF should be handled by trained staff working in appropriately equipped laboratories.

Recommendations for infection control during the care of patients with suspected or confirmed Crimean-Congo hemorrhagic fever should be consistent with WHO recommendations developed for Ebola and Marburg hemorrhagic fevers.

WHO activities

WHO is working with partners to support CCHF surveillance, diagnostic capacity and outbreak response in Europe, the Middle East, Asia and Africa.

WHO also provides documentation to support research and control of the disease and has developed an advisory note on standard precautions in health care settings, which is intended to reduce the risk of transmission of bloodborne and other pathogens.

Among experts you can hear other names for this dangerous disease- infectious capillary toxicosis, Crimean-Congo hemorrhagic fever or Central Asian hemorrhagic fever.

The disease got its name after in 1945, after a detailed study of the blood of sick migrants and military personnel engaged in haymaking in the Crimea, its causative agent was identified. 11 years later, cases of a similar disease were recorded in the Congo. Laboratory tests showed that their pathogens are identical.

Susceptibility to the disease is high regardless of a person’s age. Crimean hemorrhagic fever is more often detected in men aged 20 to 60 years. Seasonal outbreaks of the disease are recorded in summer time. People are predisposed to the disease professional activity associated with livestock farming, as well as hunters and caregivers of patients with this infection.

REASONS FOR THE DISEASE DEVELOPMENT

The causative agent of Crimean hemorrhagic fever is an arbovirus belonging to the buniavirus family. Its ability to replicate in two temperature ranges (22-25°C and 36-38°C) allows the pathogen to multiply both in the body of insects and in the body of humans and warm-blooded animals.

The Crimean hemorrhagic fever virus is inactivated by solutions of disinfectants and fat solvents. When boiled, it quickly dies; heating to 45°C leads to its death within two hours, while when frozen, the virus persists for a long time.

The development of Crimean hemorrhagic fever is poorly understood. The gateway for the entry of an infectious agent is the site of a tick bite or skin lesions, as well as direct contact with infected blood. The tissue at the site of entry of the virus is not changed.

SYMPTOMS

The incubation period of Crimean hemorrhagic fever is relatively short, usually a latent course is observed for 3-7 days, but the duration of the latent period can range from 1-14 days. Yes, when tick bite it lasts up to three days, and with contact transmission it lasts about 5-9 days.

The pathological process manifests itself rapidly. The first symptoms of Crimean hemorrhagic fever make themselves felt by an increase in temperature to critically high levels, which is accompanied by intoxication.

Signs of the first stage of Crimean hemorrhagic fever:

increased body temperature;
chills;
nausea, vomiting;
slow heart rate (bradycardia);
weakness;
migraines;
myalgia and arthralgia;
fear of bright light;
epigastric pain;
redness of the face and mucous membranes.

Before the disease manifests itself, body temperature drops to 37°C and then rises again. On days 3-6 after the onset of the disease, the condition worsens significantly, and the next stage of the disease develops - hemorrhagic syndrome.

Signs of the hemorrhagic stage:

bruising on the skin and mucous membranes, reminiscent of bruises, rashes or spots;
bleeding where the syringe punctures;
nosebleeds;
bleeding gums;
pain in the liver;
yellowing of the skin;
hepatomegaly;
vomiting and diarrhea;
enlarged lymph nodes;
pallor and swelling of the face;
tachycardia.

The fever continues for 10-12 days. Stopping bleeding and stabilizing body temperature to normal indicators indicate a transition to the recovery stage. As a rule, after suffering from Crimean fever, patients remain in an exhausted state for another 1-2 months.

The outcome of the disease depends on the severity of the symptoms. Hemorrhagic manifestations of Crimean hemorrhagic fever can have varying severity - from skin rashes to abdominal bleeding from the digestive, respiratory and internal genital systems (uterine bleeding).

At this stage of Crimean fever, severe conditions may develop, which are accompanied by convulsions, confusion and coma.

Complications of Crimean hemorrhagic fever:

sepsis;
pulmonary edema;
otitis;
secondary bacterial infections;
focal type pneumonia;
renal dysfunction;
thrombophlebitis;
infectious toxic shock.

Autopsies of patients who died from this infection reveal multiple bruises on the mucosal surface digestive tract, in the lungs, kidneys, liver, hyperemia of the brain, its membranes and hemorrhages with damage to the medulla.

Sometimes hemorrhagic syndrome and repeated rise in body temperature are absent. Often, with such symptoms, Crimean hemorrhagic fever is not detected, since signs of intoxication have common features with other common infections.

TREATMENT

If Crimean hemorrhagic fever is detected, the sick person is urgently hospitalized in an infectious diseases hospital. Such patients are isolated in special boxes to prevent contact with others. They are recommended bed rest and avoidance of physical activity.

Complexity early diagnosis is that during the incubation period of fever there are no prodromal phenomena.

Principles of treatment of Crimean fever:

Symptomatic treatment using antipyretics based on ibuprofen and paracetamol. If there is a significant increase in body temperature to critical levels, intravenous infusion of more effective drugs is performed.
Infusions to correct water and electrolyte balance and remove toxins.
Hemostatic agents to prevent bleeding or stop it.
Antiviral drugs as etiological treatment.
Immunocorrective therapy involves the administration of heterogeneous specific serum obtained from the blood of sick or vaccinated people. In addition, such immunoglobulin-based drugs are used as prophylaxis among close contacts.
Hyposensitizing therapy.
The diet involves the consumption of easily digestible foods, preference is given to such simple dishes, like soups and cereals.
Antibiotics wide range actions, antishock and cardiovascular drugs are prescribed according to indications.
Transfusion of donor blood elements to restore normal blood clotting of the patient.
Intensive therapy and resuscitation measures for extremely severe development of the disease.

When treating Crimean hemorrhagic fever, the use of drugs based on sulfonamides, which can have a traumatic effect on the kidneys, is excluded.

PREVENTION

After treatment of hemorrhagic fever, immunity to the pathogen persists for 1-2 years. To create sustainable artificial immunity, it is recommended to administer a vaccine made from the brains of infected rats and mice. Preventive vaccination is recommended for everyone who plans to travel to the southern regions of Russia and Ukraine.

To prevent Crimean fever, ticks are controlled.

Primary prevention measures:

regular disinfection of livestock premises with special chemicals against ticks - acaricides;
a ban on grazing animals in natural areas where the disease spreads;
treating animals with pesticides and quarantining them before sending them to the slaughterhouse;
use of protective equipment in the form of closed clothing and repellents when visiting forests or pastures;
regular self-examination to identify attached ticks.

The destruction of ticks in their natural habitat does not show high efficiency.

To prevent Crimean hemorrhagic fever, patients are sent to an isolated hospital. From such patients, blood is drawn using a special technique, their secretions are disposed of, and instruments are disinfected.

Outbreaks in recent years are explained by non-compliance with anti-epidemic measures and lack of proper treatment of livestock against disease-carrying ticks.

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