The term “hemorrhagic fever” is a group of diseases of viral origin with similar manifestations, in which the leading role is given to vascular lesion with the development of thrombosis or bleeding.
The group of hemorrhagic fevers today includes several diseases – yellow fever, Congo-Crimean, Omsk, fever with renal syndrome, Ebola and many others.
Hemorrhagic fever can be caused by five main types of the virus – Togaviruses, Filoviruses, Flaviviruses, Arenaviruses, Bunyaviruses.
This is a group of infections characterized by natural foci, that is, spread in areas where there are many wild animals, carriers of viruses and carriers from the discharge of ticks or mosquitoes. The main animals that can be sources of these fevers are squirrels, bats, domestic rodents and monkeys.
For some types of hemorrhagic fevers, other pathways are characteristic. Air-dust path, parenteral (through blood and other biological fluids), food, water, through contacts with infected animals are distinguished.
Most often, people are ill, whose work is connected with animals, wildlife and farmland. City dwellers with disease mainly have contact with rodents.
In a simplified form, the mechanisms of damage in hemorrhagic fevers can be represented as follows:
- vascular damage by viruses or their metabolic products,
- violation of the integrity of the walls of blood vessels, their inflammation, the release into the lumen of biologically active substances,
- formation due to bleeding deficiency and the development of the so-called DIC syndrome (massive simultaneous blood clotting in some vessels and parallel bleeding due to low clotting in others).
As a result, tissue hypoxia (lack of oxygen) and abnormalities in the heart, lungs, kidneys and brain are formed, and massive blood loss occurs. The severity of the disease will depend on the type of fever, the degree of immunity activity and the characteristics of the human body. Often, hemorrhagic fevers are difficult and result in high mortality.
Hemorrhagic fever is a classic infectious disease with staged course. The following stages are distinguished:
- incubation – it, depending on the type of virus, can last from several days to three weeks,
- the initial stage or the prodroma period, lasting from a day to a week,
- the period of the illness with the manifestation of all the typical signs of hemorrhagic fever and lasting from one to two weeks,
- a period of recovery or recovery (or in some cases – death).
Recovery can take up to several months, especially in case of severe course and residual effects.
In the initial period, the symptoms of hemorrhagic fever usually non-specific. Usually manifest:
- symptoms of general intoxication,
- disorders of consciousness up to delirium,
- point hemorrhages on the skin in the area of the neck and face, sclera and in the area of the mouth,
- heart rhythm disturbances with an increase or decrease in frequency,
- pressure reduction
- blood tests detect an inflammatory reaction (leukocytosis, maybe with a shift) with slight decrease in platelets .
During the height of the event may be:
- temporary decrease in temperature
- general improvement of condition, after which deterioration occurs again,
- growing toxicosis
- Consciousness progresses,
- small thrombosis and bleeding from the injection sites, from the surfaces of the mucous membranes, the digestive and urinary tracts develop,
- the functions of the lungs, kidneys, heart are violated.
In the recovery period, gradually all the symptoms disappear, the work of the organs is restored.
The danger of hemorrhagic fevers lies in severe and sometimes irreversible lesions of vital organs:
- development of infectious and toxic shock,
- formation acute renal failure and self-poisoning of the body,
- hemorrhage to the internal organs, including the brain,
- the occurrence of coma,
- and in the most severe cases, death from multiple organ failure (failure of all organs).
The basis of the diagnosis is a clinical picture with indications of being in an unfavorable area, insect bites or contact with animals. But to confirm the diagnosis, detection of viruses in the blood or antibodies to them is necessary. Held:
- general blood analysis,
- urinalysis (especially for fevers with renal syndrome),
- biochemical analysis of blood and urine,
- serological tests
- immunochemical and PCR methods for isolating the virus or its antibodies,
- If necessary, carry out the isolation and study of viruses.
Hemorrhagic fevers should be distinguished with severe capillary toxic influenza , rickettsiosis and meningococcal infection – all of them are accompanied by bleeding and are similar in manifestations. In addition, it is necessary to distinguish these infections from blood diseases with bleeding (Shenlein-Henoch or Verlgof disease).
Diagnosis and treatment infectious disease doctors are engaged, and sometimes resuscitation specialists.
All people with suspected hemorrhagic fever should be hospitalized in the boxed ward of an infectious disease hospital.
In the period of acute manifestations parenteral nutrition is shown, in the period of convalescence, a light vegetable-dairy diet with enrichment with vitamins, especially those that strengthen the vascular walls, with vitamins PP, C or K.
In addition, intravenous fluids of glucose solutions, blood transfusions, iron preparations, antihistamines are used. If necessary, enter the platelet mass, coagulation factors.
Bed rest in the isolation ward is observed until complete recovery. In the future, the patient is observed still quite long in an infectious diseases specialist and the therapist.
The main methods of dealing with hemorrhagic fevers include:
- extermination of rodents and insect vectors,
- thorough cleaning of residential areas from grass and shrubs, wetlands,
- when working in the fields and forests, it is necessary to wear protective clothing, the use of repellents,
- Vaccines have been developed for the prevention of some types of hemorrhagic fevers – yellow fever and Omsk hemorrhagic fever.