Ebola fever belongs to the group of viral fevers, in which there is a pronounced hemorrhagic syndrome. Today it is one of the most dangerous viral diseases, because it has a very high mortality rate. But other than that, the threat is that little is known about him. Ebola (symptoms, treatment, causes, signs of the disease) is being investigated internationally.
History and geography of the Ebola virus
The Ebola virus is most widespread in the rainforest zone, where there is high humidity. Epidemiological foci are located in Central and West Africa - in Sudan, Zaire, Gabon, Nigeria, Senegal, Cameroon, Kenya, Ethiopia, the Central African Republic, Liberia. Ebola outbreaks occur here in the summer and spring.
The disease caused by the Ebola virus was first recorded in the eponymous region of Zaire. Signs of the Ebola virus in local residents arose as early as 1976. At thatAt the same time, it was possible to isolate the causative agent of this new infection from the blood of one of the dead. From 1976 until 1979, many cases of this disease were registered and described in Zaire and Sudan. Later, in 1994-1995, the virus returned again, and a new wave broke out in the same Zaire, claiming the lives of hundreds of citizens. The lethal outcome overtook those infected in 53-88 percent of cases.
In 1996, the fever spread to the territory of Gabon. Later, according to retrospective screening among the population of other African countries, the researchers came to the conclusion that as early as the 1960s, the spread of the Ebola virus occurred in Nigeria, Ethiopia and Senegal. From December 1994 to June 1995, a new outbreak of Ebola occurred in Zaire. The reason for this was the consumption of monkey brains by the locals. As it turned out, the animals were virus carriers. In total, about 250 people fell ill then, 80 percent of whom died.
Spread of the epidemic
Initially, workers at a cotton factory in the city of Nzara showed signs of the Ebola virus. They extended it to other residents, including members of their families and people who were in contact with them. In the same state, only in the city of Maridi, as well as in Zaire, the spread of the disease occurred directly within the walls of hospitals. Here they played the role of catalysts due to the low level of knowledge of the virus at that time. Patients were brought in with an unknown fever, which quickly spread to staff who came into contact withblood and secretions of patients. It was also transferred to other patients through manipulation instruments that were not sufficiently disinfected.
Members of the families of patients have become secondary foci of infection. They, leaving the hospitals and not realizing that they themselves already carry the virus, living with the carriers for some time, spread it further. Only later did it become known about the ways of transmission of the causative agent of Ebola. Infection often occurred even during manipulations with already dead people, for example, during funeral ceremonies.
Last Flash
The epidemic for thirty years periodically arose and subsided again, taking with it a significant number of victims. The Ebola virus has managed to wreak havoc in thousands of human lives across Central Africa. If the epidemics of past years affected a not so significant territory and population, then the last outbreak in the summer of 2014 claimed more than 900 lives out of 1,700 infected. Of course, if we take into account the population of the entire planet, this number does not look so terrifying. But for small communities and African villages, this has become a real pestilence. Despite all the efforts of Nigerian doctors to contain the spread of the virus, new and new cases of infection became known almost every day, and its geography expanded to Côte d'Ivoire and Sierra Leone.
Sources of infection
The source of infection as such is not fully understood to this day. There are suggestions that its reservoir mayserve as rodents. Monkeys are also carriers. In the animal kingdom, bats are also considered carriers of the Ebola virus. They pass it on to other inhabitants of the fauna - antelopes and primates. Throughout Central Africa, there is an active trade in wild animal meat, which, of course, does not pass any sanitary and epidemiological checks for signs of the Ebola virus. So, a single carcass, which is its carrier, could provoke another outbreak of the disease.
If a person is infected with this virus, he becomes dangerous to others, as the spread of the Ebola virus is very fast. In practice, cases are known when up to eight consecutive transmissions occurred from one person. In this case, the people who become infected first, as a rule, die. Further down the chain, mortality decreases. The virus can develop in completely different organs and tissues. It is detected in the blood 7-10 days after infection. Also, its presence can be determined in the secretions of the human body - urine, nasal mucus, semen.
Transmission routes
From the onset of the disease, as soon as the first signs of the Ebola virus appeared, and within three weeks, the patient is most dangerous to others. The transmission of fever from one patient to another occurs in many ways. So, many cases of infection through contact with the blood of the patient, sexually have been recorded. Even through the use of common household items, dishes, personal hygiene products, the risk of infection is very high.
But in most cases this happens with directcontact with infected people. Short-term contact with a sick person leads to infection in 23 percent of cases. In close and prolonged contact, transmission and signs of Ebola virus infection are observed in more than 80 percent. The virus enters the body, getting on the mucous membrane and even human skin. According to observations, infection by airborne droplets does not occur, since non-contact being in the same room with patients did not lead to the transmission of the virus to he althy people. Despite these observations, the exact mechanism of transmission is unknown, as are all primary signs of the Ebola virus.
Risk group
Contaminated blood poses the greatest danger, because medical personnel are always at high risk during treatment and care of patients. At the same time, it is very important not to have bodily contact with the infected and their physiological materials.
Given that the virus is carried by monkeys, then the people who catch and transport them, especially during the quarantine period, are also at risk of being infected. There are known cases of Ebola infection inside research laboratories where they worked with green monkeys.
Due to the high rate of spread of the virus, as well as the variety of transmission methods, the migration of people from Africa to other countries, as well as the transportation of animals that may be carriers of the disease, is a great danger.
Ebola causative agent
The causative agent of the disease is a virus of the genus Filovirus, which belongs to the family Filoviridae. This is an RNA genomic virus, which today has 5 strains that differ in their antigenic structure - Sudan, Zaire, Renston, Tai Forest and Bundibugyo. Its reproduction occurs in the lymph nodes and spleen. After that, the cells of the internal organs begin to be damaged by the virus itself and the autoimmune reactions of the body to it. During the incubation period, the virus does not spread.
The onset of the disease is characterized by impaired microcirculation and rheological properties of blood, capillarotoxicosis, hemorrhagic and DIC syndromes. There are pathological changes in the internal organs, focal tissue necrosis. The Ebola virus can have signs of the disease as with hepatitis, pancreatitis, pneumonia, orchitis and other diseases. Immune responses are reduced, while antibodies against the virus in the body begin to appear mainly after complete recovery.
Ebola virus: signs of disease
What are the typical signs and symptoms of an Ebola virus infection? The incubation period has a very extended amplitude and is asymptomatic. Cases from several days to 2-3 weeks are described. Its end comes when an acute illness begins. This is evidenced by a sharp increase in body temperature to 38-39 degrees, headache, nausea, malaise, arthralgia and myalgia. In the early days, signs and symptoms of Ebola disease may resemble a sore throat, during which the tonsils become inflamed and there is a feelingpainful lump in throat.
With the development of fever, continuous vomiting, diarrhea that is hemorrhagic in nature, and abdominal pain are added to these symptoms. Soon hemorrhagic syndrome develops, which is accompanied by skin hemorrhages, bleeding inside the organs, vomiting with blood. At the same time, cases of aggressive behavior and extreme excitability of patients are often observed, which persist for a long time and after recovery. Also, in half of the cases, 4-6 days after the onset of the disease, there are manifestations of exanthema, which has a confluent character.
Diagnosis
Since the Ebola virus has no clinical signs as such, it develops very quickly, differential diagnosis is difficult. It can be diagnosed in the laboratory by PCR, ELISA, and immunofluorescent methods. Studies of serological reactions are very effective. But all this is available only in modern laboratories with good equipment and anti-epidemic regime. Of course, there is no way to do this in the field. Without the necessary equipment and professional personnel, laboratory diagnostics is reduced to a complex one using ELISA test systems that detect antigens and antibodies of the Ebola virus.
Fatalities
The main cause of death during an outbreak of fever is bleeding, intoxication, and the shock caused by these phenomena. The highest number of deaths occurs insecond week of illness. When the skin is covered with blisters, bleeding from the ears, eyes, mouth opens, the internal organs begin to fail, the worst thing comes - death. Ebola kills quickly but painfully. If the patient has a chance to recover, the acute phase can take up to 2-3 weeks, and convalescence up to 2-3 months. Ebola survivors during this period suffer from dramatic weight loss, anorexia, hair loss and even mental disorders.
Due to the similarity of the first symptoms of Ebola with a number of other diseases, very often the virus can not be diagnosed in the early stages and simply ignored. And this is lost time and, as a result, a fatal outcome. Therefore, doctors are always in a state of readiness. The first days are the most critical, the survival of the patient depends on them, or rather, on whether the body will be able to quickly develop antibodies that will help restore it. If this does not happen within 7-10 days, the person dies.
Treatment
The danger of Ebola is that there is still no effective cure for it. Treatment is carried out exclusively in specialized infectious diseases departments, where patients are in strict isolation. Methods of symptomatic therapy are used, as well as pathogenetic measures. But, as practice shows, in most cases, these methods of treatment do not bring great results and are ineffective. Positive dynamics is shown by the use of convalescent plasma. Etiotropic therapy for the treatment of Ebola does not currently exist.
In case of detectionmanifestations of Ebola hemorrhagic fever, the patient is immediately placed in a box-type hospital, where a strict sanitary regime is observed. Discharge occurs after recovery, but not earlier than on the 21st day after the onset of the acute course of the disease. This occurs when the patient's condition returns to normal, and virological tests show negative results. Everything that the patient uses and with which he comes into contact undergoes thorough disinfection in the box, where it is stored. Patient rooms are equipped with a special exhaust system, which provides only one-way air supply, inside the box.
During the treatment, only disposable instruments are used, which are destroyed after use. The medical staff is in protective anti-plague suits, as are relatives who care for the sick. Examination of blood and secretions of those infected with Ebola, as well as all laboratory work, is carried out with the utmost care and at the highest level of sterility.
Prevention
People who have been in contact with sick people and could become infected are also placed in boxes for up to 21 days for observation. With minimal suspicion of the possibility of a disease, patients are injected with immunoglobulin, which is specially designed from the serum of hyperimmunized horses. This drug works for 7-10 days.
It is also important that even with a clean blood test, the Ebola virus can still be in the body for quite a long time, up to three months. For example, in the chestmilk of women and semen of men. Therefore, even having coped with the disease, they are advised to refuse breastfeeding so as not to infect the child, and practice protected sex. After recovering from Ebola, the body develops a very strong immunity. Re-infection is very rare and does not reach 5 percent.
Control over the spread of hemorrhagic fevers is carried out at the international level. This type of disease includes Ebola, Lassa and Marburg. Therefore, all countries are obliged to report mass and even isolated cases in a timely manner to the WHO headquarters in order to immediately begin preventive measures and prevent an epidemic. Basic research on the Ebola virus made it possible to work on the development of a vaccine against it, as well as protective prophylactic drugs. Also, mass notification of citizens about what Ebola is is constantly carried out. The causes, symptoms of the disease, how to avoid it, what to do in case of infection, everyone should know now. In order to avoid infection with the virus and its spread, tourists are not recommended to visit African countries where its outbreaks are recorded.
Drug development
Since the Ebola virus emerged singly in African villages and soon died out, pharmaceutical companies were not particularly interested in developing a vaccine against it because of the unprofitability of this undertaking. But the governments of many countries have appreciated the seriousness of this virus, therefore they have not regretted the multi-billion dollar investment in its research. Experiments on monkeys have showngood results after application of the developed vaccines. They blocked the virus and even managed to cure a few primates. But the low interest of the pharmaceutical industry is still an obstacle to the large-scale production of an Ebola drug.
Before the development of a vaccine, patients were given painkillers and antibiotics to at least slightly stop the fever, preserve the immune system and prevent the development of complications. Palliative treatment with fluids with electrolytes has also been used. Serum was obtained from the blood of animals. They were infected with the virus and waited for the production of antibodies. This method led to an improvement in the condition of patients. But there is no licensed Ebola vaccine to date.
