Infectious disease specialist
Sinitsyn
Olga Valentinovna
33 years of experience
Highest qualification category of infectious disease doctor
Make an appointment
The most dangerous infectious disease, leading to death in 90% of cases of infection, is Ebola fever. This is a viral fever, the course of which is accompanied by severe hemorrhagic syndrome. The causative agent of the disease, the Ebola virus, was discovered in 1976 in Africa and received its name from the river of the same name, in the valley of which an outbreak of infectious fever occurred. The last and most severe epidemic outbreak occurred in 2014, after which the disease was recognized as a threat on a planetary scale.
Brief historical information
The disease was first registered and described in the Ebola region (Zaire) in 1976. At the same time, the pathogen was isolated from the blood of one of the deceased patients. Outbreaks of infection in Zaire and Sudan in 1976-1979, in Zaire in 1994-1995, numbering in the hundreds of cases, were accompanied by high mortality (from 53% to 88%). In 1996, an outbreak of Ebola fever was reported in Gabon. Data from retrospective serological screening of the population suggest that epidemics of the disease were noted in 1960-1965. in Nigeria, Senegal, Ethiopia.
Treatment
There is no specific treatment; symptomatic treatment is used, aimed at alleviating the course of the disease and combating dehydration and toxic shock. At the slightest suspicion of Ebola fever, regardless of the severity of the disease, the patient is urgently hospitalized and isolated in a separate box with exhaust ventilation.
- The patient is prescribed oxygen inhalation through a nasal catheter.
- To control blood clotting, heparin is administered intravenously (since death most often occurs as a result of extensive internal bleeding).
- With this disease, immunological reactivity decreases, so the administration of human immunoglobulin is indicated.
- Maintaining normal blood pressure, treating complications and concomitant diseases.
Vaccine
No Ebola virus vaccine has been approved to date. Many countries are developing a vaccine and conducting tests on animals. Scientists from the United States have been the most successful, producing the experimental vaccine “Brincidofovir”. The drug was tested on 900 patients and no serious side effects were found. But so far the vaccine is in the testing stage and has not received approval from the Ministry of Health.
Epidemiology
The reservoir and source of infection in nature has been little studied; most likely, it is mainly represented by a variety of rodents. The role of monkeys as sources of infection cannot be ruled out. A sick person is very dangerous to others; 5-8 consecutive transmissions of the virus from a patient and the occurrence of nosocomial outbreaks of the disease are known. It was noted that during the first transmissions the mortality rate was the highest (100%), then it decreased. The virus is detected in various organs, tissues and secretions: in the blood (7-10 days), nasopharyngeal mucus, urine, sperm. The patient poses a high risk within 3 weeks from the onset of the disease; During the incubation period, the patient does not secrete the virus.
The mechanism of transmission of Ebola fever is varied. The polytropic nature of the virus and the variety of ways it is released from the body determine the possibility of infection through contact with the blood of patients, through sexual and aerosol routes, through the use of common household items and sharing food. It has been established that infection with Ebola fever is mainly realized through direct contact with infected material. The disease is very contagious and is transmitted when the virus comes into contact with the skin and mucous membranes. Blood is the most dangerous. Medical personnel who care for the sick, as well as personnel who catch, transport and care for monkeys are at greatest risk of infection! quarantine period. The absence of diseases among persons who were in the same room with patients, but did not have close contact with them, allowed us to conclude that airborne transmission is unlikely.
Humans' natural susceptibility to Ebola is high. Post-infectious immunity is persistent. Repeated cases of disease are rare; their frequency does not exceed 5%.
Basic epidemiological signs. Foci of circulation of the Ebola virus are located in the tropical rainforests of Central and Western Africa (Zaire, Sudan, Nigeria, Liberia, Gabon, Senegal, Kenya, Cameroon, Ethiopia, Central African Republic). Outbreaks of Ebola fever in endemic areas occur mainly in spring and summer. In Sudan (Nzara), the primary source of infection arose among workers at a cotton factory, and the disease soon spread to family members and other persons who were in close contact with patients. Nosocomial spread occurred in only 2 cases. The incidence rate was different in the city of Maridi (Sudan) and Zaire, where the hospital played the role of a catalyst for the epidemic process. The patients were taken to the hospital with fever of unknown etiology. Intrahospital spread of infection among personnel occurred when infected material (blood and secretions) came into contact with damaged skin and mucous membranes; patients - during various parenteral manipulations performed with insufficiently treated instruments. A survey of family contacts confirmed the epidemiological significance of contact with patients and the duration of communication with them. Thus, with short-term contact with a patient, 23% fell ill, and with close and long-term contact (caring for a patient) - 81% of people. Families of patients who left hospitals became secondary outbreaks. Infection occurred through close contact with patients (medical care, living together, ritual ceremonies near the bodies of the dead). In December 1994 - June 1995, an outbreak of Ebola fever , associated with the consumption by local residents of the brains of virus-carrying monkeys.
The total number of cases exceeded 250 people, the mortality rate was about 80%. Cases of intra-laboratory infection with Ebola fever when working with green monkeys have also been described. Considering the colossal possibilities and speed of international movements, migration of persons in the initial stages of the disease and transportation of infected animals pose a serious danger.
List of sources
- Shchelkanov M.Yu., Magassuba NF, Boiro MY, Maleev V.V. Causes of Ebola fever in West Africa. Attending doctor. 2014; 11:30-6.
- On the epidemiological situation regarding the incidence of Ebola hemorrhagic fever / Letter of the Russian Federation dated August 7, 2014 N 32-024/424.
- Borisevich I.V., Markin V.A., Firsova I.V., Evseev A.A., Khamitov R.A., Maksimov V.A. Epidemiology, prevention, clinical picture and treatment of hemorrhagic fevers (Marburg, Ebola, Lassa and Bolivian). Question virusol. 2006; 5:8–16.
- Petrov A.A., Lebedev V.N., Plekhanova, L.F. Stovba T.M., Borisevich G.V., Sidorova O.N., Chukhralya O.V. Current state of development of means of emergency prevention and treatment of disease caused by the Ebola virus//Central Research Institute" of the Ministry of Defense. Russian Federation, Sergiev Posad.
Pathogenesis
During the incubation period, the Ebola reproduces in regional lymph nodes, the spleen and possibly other organs. The acute onset of the disease with fever coincides with the development of intense viremia with multiorgan dissemination of the pathogen. Damage to cells and tissues of various organs is presumably due to both the direct cytopathic effect of the virus and autoimmune reactions. The development of disturbances in microcirculation and rheological properties of blood is manifested by capillary toxicosis with hemorrhagic syndrome, perivascular edema, and disseminated intravascular coagulation syndrome. Disseminated intravascular coagulation is the leading syndrome detected histologically. Pathological changes in organs in the form of focal necrosis, scattered hemorrhages in the clinical picture are manifested by signs of hepatitis, interstitial pneumonia, pancreatitis, orchitis, etc. The reactions of cellular and humoral immunity are reduced, antiviral antibodies are rarely detected in those who died in the early stages of the disease, in those who recover they appear late .
Consequences and complications
Frequent bleeding with the development of hemorrhagic syndrome, acute cardiovascular and adrenal insufficiency, and cerebral edema . Less commonly, acute liver failure . During pregnancy - spontaneous abortion. The addition of a bacterial infection with the development of bacterial sepsis and infectious-septic shock , multiple organ failure .
Clinical picture
The incubation period varies from several days to 2-3 weeks. The onset of the disease is acute, with an increase in body temperature to 38-39 ° C, headache, myalgia and arthralgia, malaise, and nausea. During the first days, most patients experience symptoms of sore throat; Inflammation of the tonsils causes a painful “ball in the throat” sensation. At the height of the disease, uncontrollable vomiting, abdominal pain and hemorrhagic diarrhea with stool in the form of melena occur. Hemorrhagic syndrome develops rapidly with manifestations of skin hemorrhages, organ bleeding, and hematemesis. Signs of encephalopathy are often observed in the form of agitation and aggressiveness of patients; in cases of recovery, they persist for a long time even during the period of convalescence. On the 4-6th day from the onset of the disease, approximately half of the patients develop a confluent exanthema.
Death with Ebola fever usually occurs at the beginning of the 2nd week of illness. Its main causes are bleeding, intoxication, hypovolemic and infectious-toxic shocks.
In cases of recovery, the acute phase of the disease lasts 2-3 weeks. The period of convalescence lasts up to 2-3 months and is accompanied by asthenia, anorexia, weight loss, hair loss, and sometimes the development of mental disorders.
Diet
Dietary nutrition is prescribed that corresponds to Table No. 4 according to Pevzner, which provides a diet containing the physiological norm of protein with a limitation of fats and carbohydrates. All products that enhance the processes of rotting/fermentation in the intestines and the secretion of the digestive organs are excluded: liquid, semi-liquid and mashed dishes, steamed/boiled in water are indicated. The power mode is fractional. During the recovery period, a diet with a high content of animal protein is indicated.
Epidemiological surveillance
The implementation of the International Epidemiological Surveillance System for Contagious Hemorrhagic Fever is intended to provide the necessary information for the timely and complete implementation of preventive measures. Due to the difficulty in some cases of carrying out full laboratory diagnosis of diseases, clinical manifestations become of utmost importance. Taking into account the WHO concept, all countries are required to immediately notify headquarters of single or group severe diseases characterized by acute hemorrhagic fever syndrome. According to the definition of the WHO Expert Committee, a patient with Lassa, Marburg and Ebola fever is a person with a febrile illness accompanied by one or more of the following signs: virus isolation, a 4-fold increase in antibody titers to the virus 1-2 weeks after collection. With Lassa fever, IgG titers upon admission are at least 1:512 and positive IgM titers; for Marburg and Ebola fevers, the IgM content is 1:8 and higher, IgG - 1:64 in the RIF.
Barriers to the virus
With doctors, nurses, journalists, priests, travelers returning from Africa, the virus also reaches Europe and America. Cases of Ebola fever were recorded in 2014 in the USA (6, as of October 23, 1 dead), Spain (2 cases, 1 dead), France, Great Britain, Germany, Norway (one case each, no deaths so far).
It can be noted that in developed countries, the mortality rate from this disease is lower than in Africa - the level of health care, the general sanitary situation, behavioral aspects, and the effectiveness of government actions have an impact. In addition, there is research evidence that shows that Ebola is more lethal in those who are malnourished and deficient in folate because the virus uses a molecule that masquerades as this vitamin when it enters cells.
Therefore, one of the directions in the search for cures for the disease is the development of agents that block folate receptors, and consequently, the development of the pathological process at the cellular level. At the same time, there is no sufficient basis for the conclusion that taking folic acid supplements can have a therapeutic or preventive effect in the case of Ebola fever.
The fight to prevent the spread of the virus to other countries and continents includes sanitary and epidemiological control measures at arrival airports, that is, attention to those passengers arriving from countries where cases of the disease have been recorded, especially if they experience the symptoms listed above. These actions, which are also used in our country at the initiative of the Ministry of Health, are aimed at promptly applying quarantine to the sick, infected, and people who have come into contact with them.
Specialists, in particular virologists, are on duty at airport terminals. In an interview with the Vesti on Saturday program with Sergei Brilev, Russian Health Minister Veronika Skvortsova said that seven and a half thousand flights are inspected monthly - that’s about one and a half million people. Hospital reception departments are equipped with special protective suits, and boxes are equipped for sick people. Medical staff are instructed to record all cases of respiratory diseases with severe complications. In order to objectively assess the epidemiological situation in the countries of the African continent, a visit of virologists was organized. Doctors from Russia, like specialists from other countries, provide assistance to colleagues from West Africa.
Activities in the epidemic outbreak
Patients with Lassa, Marburg and Ebola hemorrhagic fevers are subject to immediate hospitalization in ward units, subject to the strict regime recommended in cases of particularly dangerous infections such as plague and smallpox. Those who have recovered are discharged no earlier than the 21st day from the onset of the disease if the condition of the patients is normalized and virological tests are 3 times negative. All patient household items must be strictly individual and labeled. They are stored and disinfected in a box. Disposable instruments are used for treatment; After consumption, they are autoclaved or burned. During the current disinfection period, a 2% phenol solution [with the addition of 0.5% sodium bicarbonate (1:500)], iodoform (450 g per 1 ml of active iodine with the addition of 0.2% sodium nitrate) is used. Discharges from patients are also treated accordingly. Maintenance personnel must work in type 1 anti-plague suit. Special plastic boxes have been developed in which, using an exhaust system equipped with a decontamination unit, air flow is ensured in one direction - into the box. Such boxes are equipped with a conventional system to ensure complete safety of personnel during medical procedures. Particular care should be taken when examining blood and other biological materials from patients with hemorrhagic fevers and those suspected of having the disease.
Persons who have been in direct contact with an Ebola (or a person suspected of developing the disease) are isolated in a box and observed for 21 days. In all cases of suspected infection with the Ebola virus, specific immunoglobulin is administered from the serum of hyperimmunized horses. The validity period of immunoglobulin is 7-10 days.
Source: “Infectious diseases and epidemiology” V.I. Pokrovsky, 2007
Diagnostic methods
For our country, Ebola fever remains an extremely rare disease, so diagnostic tests are performed in specialized virology laboratories that adhere to the highest biosafety standards. The virus is isolated from any biological fluids of the patient, after which it is transferred to cell cultures, PCR tests are performed, and biopsies of the skin and internal organs are examined using an electron microscope. In addition, a general analysis and blood coagulogram are performed to identify characteristic changes.
What a tourist needs to know
It is better to avoid traveling to countries where there have been outbreaks of fever. But if this is necessary, you should carefully listen to the recommendations of infectious disease doctors from WHO:
- It is necessary to study information about the disease: symptoms, routes of infection, methods of prevention and protection;
- Do not contact with wild animals;
- Refrain from eating meat;
- Do not touch infected people and their personal items;
- Do not approach the corpses of people who have died of fever;
- The most vulnerable places for infection are the eyes, damaged skin and mucous membranes of the nose and mouth. Just one drop of mucus or saliva released when sneezing can lead to infection.
Author:
Selezneva Valentina Anatolyevna physician-therapist
