Ebola haemorrhagic fever( Ebola fever) - Causes, symptoms and treatment. MF.
The situation of quarantine infections, which includes Ebola fever, on the planet remains tense. The last epidemic of the disease in Africa( 2014) attracted attention once again due to the high infectiousness among the population, the lightning fastness of the development of clinical symptoms and high mortality, reaching on average 70% of the sick.
GL Ebola, transportation of a patient
Ebola haemorrhagic fever( Ebola Haemorrhagic Fever, EHF) is an acute quarantine natural focal disease caused by the Ebola virus, transmitted from rodents and monkeys to humans, and also from person to person, characterized predominantly by a heavy courseand high mortality.
The relevance of the problem is of global scale.
Firstly, it is the possibility of epidemic spreading from natural foci( African countries) to other continents due to migration of the population during the incubation period( the period from the moment of infection until the appearance of symptoms of the disease).
Secondly, GL Ebola refers to quarantine infections, that is, it is highly contagious, and therefore sanitary and epidemiological measures are very important in preventing the spread of infection.
Third, the rapidity of the development of the symptoms of the disease, the severity of its manifestations, as well as high mortality( 50-90%) puts the disease at the leading place among the causes of death from epidemics and requires urgent medical measures in the initial identification of the patient.
Historical and geographical information on the Ebola virus
Ebola virus was discovered recently - just some 38 years ago. The first outbreak of GL Ebola dates back to 1976, then in Zaire( now the Democratic Republic of the Congo) 318 people fell ill, 280 of which( 88%) died. The disease was named after the Ebola River in northern Zaire, near which the first cases of fever were registered. Almost simultaneously there was a flash of GL Ebola and in Sudan - 284 people fell ill, and 151( 53%) died. Subsequently, outbreaks were periodically recorded in Sudan, Kenya, Zaire, Gabon. Scientists have proven the circulation of the virus among the animals and inhabitants of Cameroon, Nigeria, Guinea, Senegal, Sierra Leone, the CAR.Note that all these natural foci of the Ebola virus, in which there is a reservoir of infection( rodents, marmosets), favorable conditions for the existence of the virus, and also recorded with a certain incidence among people. It should not be forgotten that migration of infection to other continents is also possible due to population migration( North and South America, Europe, Asia).
GL Ebola, geographic spread
The last outbreak of GL Ebola was registered in 2013-2014, when cases of disease and deaths occurred in Liberia, Guinea, Sierra Leone from December 2013.Also a number of cases of GL Ebola originated in Nigeria, Congo. During the outbreak several doctors of the humanitarian volunteer mission fell ill, natives of the United States, Great Britain. Official WHO data on 8 September 2014 released data on 3,944 cases, including 2,097 cases( 53%) of deaths. WHO estimates the situation as extreme. Testing of experimental drugs is in full swing, and conditions are being prepared for the clinical testing of the Ebola virus vaccine.
Causes of GL Ebola
Pathogen - GL Ebola - Ebola virus belonging to the family Filoviride( Filoviruses).The genome of the Ebola virus is represented by single-stranded RNA, as part of the virion of 7 structural proteins. Morphologically, the virus is straight strings with rounded ends with a virion diameter of about 100 nm and a length of 650 to 1400 nm.
Ebola virus
The Ebola virus is resistant to high temperatures: at 60 ° C it is inactivated for 30 minutes, under UV radiation - for 2 minutes, disinfectant( formalin, acetone, chloroform) destroys the virus after an hour of exposure. Low temperatures the virus also withstands well: at a temperature of -70 ° it persists long enough( up to 1 year).
There are several subtypes of the Ebola virus:
1) subtype of Zaire( EBOV) - responsible for the largest outbreaks of GL Ebola, causes outbreaks with the highest mortality from 59 to 90%, is characterized by severe course, the first outbreaks are associated with the use of a reusable tool for parenteral interventions without appropriate treatment;
2) subtype Sudan( SUDV) also characterizes the occurrence of a large number of outbreaks of fever, lethality is lower than that of the Zaire virus - 54-68%;
3) subtype of Bundibujo( BDBV) has become pathogenic for humans since 2007, when cases of GL Ebola among humans in Bundibugio,
4) subtype Tae Forest( TAFV) pathogenic for chimpanzees,
5) subtype Reston( RESTV) is considered to be a fairly new virus, it often causes subclinical forms, a fairly easy course of the disease, for humans is poorly pathogenic, but mostly dangerous for green macaques, outbreaks among pigs in China, in the Philippines.
The first three subtypes were the cause of major outbreaks of Ebola fever on the African continent. The Reston type causes the often asymptomatic course of the disease, found in China, in the Philippines.
Source of infection. The primary reservoir of the Ebola virus is unknown in nature( it is in the natural ecosystem that the main cellular host of the Ebola virus exists).The natural biological reservoir of the Ebola virus in Africa is the carnivorous bats - the wing of several genera( Hypsignathus monstrosus, Myonycteris torquata, Epomops franqueti). Accordingly, the range for these species of krylan is also the pathway of the Ebola virus .The ultimate host are primates( African green monkeys - Cerospithecus aethiops, macaques - Macaca fascicularis), swine( Ebola virus subtype Reston) and a person for whom the virus is highly pathogenic. In primates, the disease can occur inapparently( completely without symptoms).
Source of infection Ebola - winged and monkey
A sick person and a sick animal pose a danger to others. Infectious all the discharge of the patient - nasopharyngeal contents, urine, blood, vomit, sperm and others. The patient becomes contagious from the first day of the onset of symptoms of the disease. The virus is released about 3 weeks after the onset of the disease. However, it is described the isolation of the virus with seminal fluid up to 7 weeks after the recovery of the patient. During the incubation period( that is, before the onset of symptoms of the disease), the patient is not infectious. During the outbreak, cases of secondary and tertiary and more infection of a person from a sick patient are recorded, that is, multiple nosocomial infections( the first infected the second, second third, third fourth. ..).
Circulation of the virus is possible in the tropical forest zone in high humidity conditions. These are the countries of Central and West Africa( Congo, Nigeria, Sierra Leone, Liberia, Kenya, Sudan, Gabon, Senegal and many others).
Mechanism of infection with the Ebola virus. In order to talk about possible ways of infection, it should be remembered that the virus has a variety and the ways of isolation - the blood is infectious, nasopharyngeal mucus, urine, vomit, mucus of the genital organs, bronchial secretion, gastrointestinal tract, seminal fluid. The most dangerous material is the patient's blood.
The leading mechanism of infection is contact-household, which implies infection after direct contact with secretions of the patient EHL EHL of an animal or human. This mechanism is implemented with the joint nutrition, general use of household items, direct contact with the discharge of the patient by patient care, disinfection of discharges, conducting laboratory tests, as well as direct contact with animal secretions( chimpanzees, gorillas, carnivorous bats in an endemic region).Infection is possible when the Ebola virus enters the mucous membranes and the human skin when their integrity is compromised, which is why GL Ebola is considered highly contagious.
The aerogenic mechanism of transmission of the Ebola virus( airborne pathway) has not been proven. This is evidenced by the absence of infection in persons who are in the same room with the patient, but who do not have close contact with him.
The index of contagiosity in domestic hearths varies from 20%( with short-term contact) to 80% and more( with prolonged and close contact).
Ebola fever refers to diseases that spread without the participation of bloodsucking insects.
Risk groups for Ebola GL infection:
1) Medical personnel who make direct contact with the patient( patient care, medical manipulations, patient examination).
2) Personnel who identify and catch infected animals( in particular, monkeys).
3) The nearest relatives of the ill GL Ebola( care for patients in the absence of treatment to a doctor, special funeral rites).
The susceptibility of the population to the Ebola GL is quite high.
Immunity after a disease has been sustained, long-lasting. Repeated cases are rare.
Pathogenic effect of the Ebola virus on the human body.
The entrance gate of the infection is the damaged skin and mucous membranes( mouth, mucous eyes), on which the Ebola virus enters. The whole nature of the disease is largely determined by the trophicity of the virus - that is, the favorite "target cells", which are the endothelium of the blood vessels, the stem cells of the bone marrow.
When infected with Ebola virus, the following processes occur:
1) there is no change at the site of introduction of the virus, the virus enters the regional lymph nodes from the entry gate of the infection, where it multiplies( the period is called incubation, there are no clinical symptoms in this period);
2) the virus penetrates the blood( viremia, toxemia), the symptom of which the patient is fever and intoxication, at this stage a person becomes contagious to others;
3) damage to the endothelium of blood vessels in various organs and systems, characterized by the development of multi-organ pathology( liver, kidney, myocardium, spleen, lungs and others);in the organs there are necrosis, hemorrhages, inflammatory changes;
4) development of thrombohemorrhagic syndrome or DIC syndrome( hemorrhage and bleeding).
Symptoms of GL Ebola
The incubation period( the period from the moment of infection to the onset of symptoms of the disease) can last from 3 to 21 days. The precursor period is absent.
• Acute onset: patients are worried about high febrile temperature( up to 39-40 ° C), chills, severe headache, back pain, muscle aches, joint pain. In the first 3-4 days, the disease resembles the flu.
• On the 3-4th day there may be vomiting, sometimes repeated, diarrhea, abdominal pain without a specific place of localization, admixture of blood in the feces.
• Somewhat later, a dry cough and stitching pains appear in the chest, signs of dehydration develop.
• Within 4-5 days from the onset of the disease, the patient's condition becomes critical, with extreme drowsiness and changes in the psyche. Dryness in the mouth and throat, sores on the back of the pharynx, characteristic pain in the throat.
• On the 5th-7th day of the disease, a patchy-papular rash appears, after the disappearance of which there is peeling of the skin.
GL Ebola, rash
• Hemorrhagic syndrome manifests itself as a rash of hemorrhagic nature( from point to major hemorrhages), nosebleeds, bloody vomiting, gastrointestinal bleeding, uterine bleeding, pregnant women have a miscarriage.
GL Ebola DIC-
syndrome In a general blood test: neutrophilic leukocytosis, anemia, a decrease in platelets.
In case of a favorable course of the disease, recovery occurs on average during 2-3x weeks. During rehabilitation( up to 3 months after recovery), patients can feel weakness, fatigue, nervousness, hair loss.
Death usually occurs at week 2 of the disease with bleeding and shock( intoxication and
dehydration).
Complications of Ebola GL are quite severe and lead to the majority of death of the patient: DIC-syndrome with the development of massive bleeding( gastrointestinal, uterine) and hemorrhages in vital organs( brain, adrenal glands), hypovolemic shock( extreme dehydration), infectious-toxic shock( at the height of the fever develops neurotoxicosis or infectious-toxic encephalopathy, which is manifested by cerebral edema, loss of consciousness, stopping the functions of vital brain centers).
The prognosis is unfavorable - lethality with GL Ebola up to 90%( varies from 50 to 90%).
Diagnosis of GL Ebola
Primary diagnosis is clinico-epidemiological:
1) A leading information point is a carefully collected epidemiological history( living in an endemic region, staying in or coming from a region where GL Ebola cases are recorded, contact with a fever patient in an endemic area, contact with animals in African countries).
2) Clinical data( acute onset, rapid development of symptoms, presence of fever, severe intoxication, hemorrhagic syndrome, signs of damage to many organs and systems - liver, kidneys, lungs, myocardium, etc.).
3) The differential diagnosis should be carried out with other hemorrhagic fevers( Marburg, Lassa, yellow hemorrhagic fever and others), typhoid fever, malaria, typhus, cholera, meningitis, hepatitis.
The final diagnosis is carried out using laboratory tests( all specific studies are carried out in specially equipped laboratories for working with especially dangerous infections, since all materials from the patient represent a high biological hazard):
1) Laboratory tests for the detection of the Ebola virus antigen.
2) Reactions to identify antibodies to the Ebola virus.
To solve these problems, the neutralization reaction( pH), the enzyme-linked immunosorbent assay
( ELISA), the polymerase chain reaction with reverse transcriptase( RT-PCR), electron microscopy, the immunosorbent assay-binding antibody capture( ELISA), isolation of the Ebola virus in cellcultures.
GL Ebola work in the laboratory
Treatment of GL Ebola
Treatment activities include a number of basic principles:
1) Organizational and Regime Activities - immediate hospitalization of patients in
infectious disease hospital, rapid isolation of the patient, compliance with epidemiological safety requirements - all personnel should be instructedon the mechanism of transmission, work in special suits with maximum protection of skin and mucous membranes( type I anti-plague suit, now there are Sovreennye modification) chemically and physically light diet for a patient, sufficient water-drinking mode.
GL Ebola costume
GL Ebola nursing
2) Treatment measures .Until( 2014), a specific treatment for GL Ebola is not made public,
there are experimental drugs that are being clinically tested during the last outbreak in Africa( 2014), and there are positive results.
All medical measures are reduced to pathogenetic and symptomatic treatment:
maintenance of the vital functions of the patient's body by carrying out detoxification( reducing fever and intoxication with intravenous detoxification of cocktails, preventing the development of shock), rehydration( replenishment of lost fluid volumes), correction of thrombotic hemorrhagicsyndrome, hormone therapy, immunotherapy and much more.
Patient discharge is performed with complete clinical recovery and 3x the results of a virological examination, but not earlier than 21 days after the onset of the disease.
Prevention of GL Ebola
1) Carrying out antiepidemic measures to prevent the spread of infection in the
within the endemic foci and beyond its borders, as well as preventing the spread of GL Ebola to other continents. They include:
• for the suspicion of the outbreak of GL Ebola, the closure of this territory to quarantine( the entry and exit of the population within the territory of quarantine, export and import of animals is prohibited),
• the work of all medical personnel in special suits for especially dangerous highly contagious infectious diseases( mandatory mask or facialshield, glasses, gowns with long sleeves, gloves),
• active identification of patients,
• isolation of patients in compliance with all epidemiological safety rules, all utensils for the patient dMust be individualized,
• identification of contact with sick persons,
• establishment of quarantine measures - monitoring of contact for 21 days( temperature measurement, objective status survey),
• all contact inserts specific immunoglobulin, which should be entered as early as possible,
• work with the local population( informing about the causes of the disease, the mechanisms of infection, the need to seek medical help, preventing the shelter of patients in family foci, precautionsto prevent further spread of the infection, all products of animal origin - meat, blood, milk - subjected to thorough heat treatment),
• current disinfection in the outbreaks is carried out with a 2% solution of phenol with the addition of 0.5% sodium hydrogen carbonate 1: 500, iodoform450 g per 1 ml of active iodine with addition of 0.2% sodium nitrate.
GL Ebola disinfection of
• immediate burial of the deceased from GL Ebola by cremation of the deceased( according to WHO recommendation).
2) Actions are also being taken to prevent the import of infection from Africa to other continents( control of visitors from Central and South Africa, identification of the risk of infection, if there is a risk of infection with the Ebola virus, the establishment of a 21-day quarantine).
3) The work of veterinary surveillance in endemic regions( control of pig and monkey farms - cleaning and disinfection using disinfectants, slaughtering infected and sick animals).
4) Prevention of laboratory contamination - work with the material from patients should be specially trained personnel in specially equipped laboratories and with personal protective equipment.
5) Specific prevention. At the moment( 2014) vaccines against GL Ebola( including in Russia) have been developed, which have successfully passed preclinical approbation, that is, they are ready for testing in humans. These optimistic data allow us to talk about an early solution of the issue of specific immunization against GL Ebola.
Doctor infectious diseases Bykova N.I.