Crimea-Congo hemorrhagic fever

Crimea-Congo hemorrhagic fever is an acute zoonotic natural-focal viral infection with a transmissible transmission mechanism characterized by pronounced hemorrhagic syndrome and a two-wave fever.

Crimea-Congo hemorrhagic fever was first described on the basis of flash materials in the Crimea (Chumakov MP, 1944-1947), therefore it was called Crimean hemorrhagic fever (CGL). Later, cases of a similar disease were recorded in the Congo (1956), where in 1969 a virus was identified that was similar in antigenic properties to the Crimean hemorrhagic fever virus. To date, the disease has been registered in countries of Europe, Central Asia and Kazakhstan, Iran, Iraq, the United Arab Emirates, India, Pakistan, Africa (Zaire, Nigeria, Uganda, Kenya, Senegal, South Africa, etc.).

[1], [2], [3], [4], [5], [6], [7],

Epidemiology of the Crimea-Congo hemorrhagic fever

The reservoir and sources of infection - domestic and wild animals (cows, sheep, goats, rabbits, etc.), as well as more than 20 species of ixodid and argasid mites, primarily pasture mites of the genus Hyalomma. The main reservoir of infection in nature is small vertebrates, from which livestock is infected through ticks. The contagiousness of the animals is determined by the duration of the viremia, which lasts about a week. Ticks are a more resistant reservoir of infection due to the possibility of sexual and transovarial transmission of the virus. High contagiousness of sick people was noted. In animals and humans, the virus is found in the blood with intestinal, nasal and uterine bleeding, as well as in secretions containing blood (vomit masses, feces).

Mechanisms of transmission - transmissible (with bites of ixodid ticks), as well as contact and aerogenic. In case of infection from a person or animals, the contact mechanism of transmission is the main one due to direct contact with blood and tissues of infected animals and people (intravenous infusion, stopping of bleeding, artificial respiration by mouth-to-mouth, taking blood for examination, etc.). The aerogenic mechanism of transmission of infection is described when personnel are infected internally during abnormal situations during the centrifugation of a virus-containing material, as well as in other circumstances, if the virus was kept in the air.

The natural susceptibility of people is high. Postinfectious immunity persists for 1-2 years after the disease.

The main epidemiological signs. Crimean-Congo disease hemorrhagic fever is distinguished by a pronounced natural focality. In countries with a warm climate, foci of infection in the form of outbreaks and sporadic cases are confined mainly to steppe, forest-steppe and semi-desert landscapes. The incidence rate is associated with a period of active attack of adult ticks (in the tropics - all year round). Men are more often ill 20-40 years. Cases of infection prevail among persons of certain professional groups - livestock breeders, agricultural workers, veterinary and medical workers. Nosocomial outbreaks of infection and intra-laboratory infections are described.

[8], [9],

Pathogenesis of the Crimea-Congo hemorrhagic fever

The pathogenesis of the Crimea-Congo hemorrhagic fever is similar to other viral haemorrhagic fevers. Characteristic of the development of intensive viremia, thrombocytopenia, lymphopenia in the acute stage of the disease, as well as an increase in ACT, as with most viral haemorrhagic fevers, a less pronounced increase in ALT. In the terminal stage, hepatic and renal insufficiency, acute cardiovascular failure are observed. With autopsy in the liver, eosinophilic infiltration is revealed without a marked inflammatory reaction, necrotic changes in the spleen, lymph nodes. Perhaps the development of massive bleeding. DIC-syndrome is recorded in the terminal phase, its genesis is not clear. As with other viral hemorrhagic fevers, there are dystrophic processes in the muscle tissue, weight loss.

Symptoms of Crimea-Congo hemorrhagic fever

The incubation period of the Crimean-Congo hemorrhagic fever after a bite of an infected tick lasts 1-3 days, after contact with blood or infected tissues it can be delayed up to a maximum of 9-13 days. Symptoms of the Crimea-Congo hemorrhagic fever range from erased forms to severe ones.

The initial period of the disease lasts 3-6 days. It is characterized by an acute onset of the disease, a high fever with chills. The following symptoms of the Crimean-Congo hemorrhagic fever appear: headache, pain in the muscles and joints, in the abdomen and in the lower back, dry mouth, dizziness. Sometimes there are pains in the throat, nausea, vomiting, diarrhea. Often there is excitation, and sometimes the aggressiveness of patients, photophobia, rigidity and soreness of the occipital muscles.

After 2-4 days from the onset of the disease, excitement is replaced by fatigue, depression, drowsiness. There are pains in the right hypochondrium, the liver is enlarged. When examining patients, there is hyperemia of the face, neck, shoulder girdle and mucous membranes of the oral cavity, a decrease in blood pressure, a tendency to bradycardia. On the 3-5th day of the disease, a "cut in" on the temperature curve is possible, which usually coincides with the appearance of bleeding and hemorrhage. In the future, a second wave of fever develops.

The peak period corresponds to the next 2-6 days. Hemorrhagic reactions develop in different combinations, the degree of expression of which varies widely from the petechial exanthema to profuse cavitary bleeding and determines the severity and outcome of the disease. The condition of patients deteriorates sharply. When they are examined, attention is drawn to pallor, acrocyanosis, progressive tachycardia and arterial hypotension, depression of mood of patients. Lymphadenopathy may appear. Often find an increase in the liver, sometimes jaundice of a mixed nature (both hemolytic and parenchymatous). In 10-25% of cases, convulsions, nonsense, coma develop, meningeal symptoms appear.

Reconvalescence begins after 9-10 days of illness and takes a long time, up to 1-2 months; Asthenia can persist up to 1-2 years.

Complications of the Crimea-Congo hemorrhagic fever are diverse: thrombophlebitis, pneumonia, pulmonary edema, severe gastrointestinal bleeding, acute hepatic and / or renal insufficiency, infectious-toxic shock. Lethality varies from 4% to 15-30% and usually occurs in the second week of the disease.

Diagnosis of the Crimean-Congo hemorrhagic fever

Differential diagnosis of the Crimean-Congo hemorrhagic fever in the initial period presents great difficulties. In the midst of the Crimean-Congo disease, hemorrhagic fever is differentiated from other infections that occur with hemorrhagic syndrome. The most revealing clinical signs of the disease are fever (often two waves) and severe hemorrhagic manifestations.

[10], [11], [12], [13]

Laboratory diagnostics of the Crimea-Congo hemorrhagic fever

Laboratory diagnosis of the Crimean-Congo hemorrhagic fever is conducted in specialized laboratories with an increased level of biological protection. Characteristic changes in the hemogram are pronounced leukopenia with a shift to the left, thrombocytopenia, an increase in ESR. In the analysis of urine hypoisostenuria, microhematuria are determined. It is possible to isolate the virus from the blood or tissues, however in practice the diagnosis is more often confirmed by the results of the conducted serological reactions (ELISA, RSA, RNGA, NERIF). Antibodies of IgM class in ELISA are determined within 4 months after the disease, IgG-antibodies - within 5 years. It is possible to determine the antigens of the virus in ELISA. In recent years, a polymerase chain reaction (PCR) has been developed to determine the genome of the virus.

Treatment of Crimea-Congo hemorrhagic fever

Hospitalization and isolation of patients are mandatory. Treatment of the Crimean-Congo hemorrhagic fever is carried out in accordance with the general principles of therapy of viral hemorrhagic fevers. In a number of cases, the positive effect of the administration of 100-300 ml of the immune serum of convalescents or 5-7 ml of hyperimmune equine immunoglobulin was noted. In some cases, a good effect can be obtained from the use of ribavirin intravenously and orally (see Lassa fever).

Prevention of Crimea-Congo hemorrhagic fever

When hospitalization of patients should strictly comply with the requirements for the prevention of nosocomial infections and personal prophylaxis of employees, use caution when performing invasive procedures. Persons who come in contact with the blood and discharge of the patient, as well as with the sectional material as an emergency prophylaxis, are administered a specific immunoglobulin. Deratization and acaricidal measures in natural foci are not very effective, as carriers are numerous and widespread. Particular attention is paid to protecting people from ticks. Personal protective measures - wearing protective clothing, impregnating clothes, tents and sleeping bags with repellents. According to epidemics, it is recommended to use formalin-inactivated vaccine from the brain of infected white mice or suckling suckers, but there is still no reliable and effective vaccine against the Crimean-Congo fever.

Medical workers who have been in contact with patients or suspicious persons for this disease, as well as biomaterial from them, should be monitored for three weeks with daily thermometry and careful registration of possible symptoms of Crimea-Congo hemorrhagic fever. In the hearth, disinfection is carried out, contact persons are not disconnected.