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, as it has a very high mortality rate. But besides this, the threat lies in the fact that little is known about him. Ebola fever (symptoms, treatment, causes, symptoms) is being investigated internationally.
The history and geography of the Ebola virus
The most common Ebola virus is 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, Central African Republic, Liberia. Ebola outbreaks occur here in summer and spring.
The disease caused by the Ebola virus was first recorded in the same region of Zaire. Signs of the Ebola virus among local residents arose as far back as 1976. At the same time, the causative agent of this new infection was isolated from the blood of one of the deceased. From 1976 until 1979, many cases of this disease were recorded and described in Zaire and Sudan. Later, in 1994-1995, the virus returned again, and a new wave broke out in the same Zaire, killing hundreds of citizens. Lethal outcome overtook those infected in 53-88 percent of cases.
In 1996, a fever spread to the territory of Gabon. Later, according to retrospective screening among populations of other African countries, researchers concluded that as early as the 1960s, the spread of the Ebola virus was found 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 local residents. As it turned out, the animals were virus carriers. In total, then about 250 people fell ill, 80 percent of whom died.
Epidemic spread
Initially, signs of the Ebola virus occurred in workers at a cotton factory in Nzara. 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 knowledge of the virus at that time. The patients were delivered with an unknown fever; it quickly spread to the staff who came into contact with the blood and secretions of the patients. It was also transferred to other patients through manipulation tools that were not sufficiently disinfected.
Family members of patients became secondary foci of infection. They, leaving the hospital and not realizing that they themselves already carry the virus, living with the carriers for some time, spread it further. Only later it became known about the transmission of the pathogen of Ebola. Infection often occurred even during manipulations with already dead people, for example, during funeral ceremonies.
Last flash
For thirty years, the epidemic periodically arose and again subsided, taking with it a significant number of victims. The Ebola virus has been able to cause damage to thousands of human lives across Central Africa. If past epidemics affected a not so significant territory and population, the last outbreak in the summer of 2014 claimed more than 900 of the 1,700 infected. Of course, if you 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 plague. Despite all the efforts of Nigerian doctors to contain the spread of the virus, more and more cases of infection became known almost every day, and its geography expanded to Cote 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 rodents may serve as its reservoir. Monkeys are also carriers. In the animal world, bats are considered to be carriers of the Ebola virus. They pass it to other inhabitants of the fauna - antelopes and primates. Throughout Central Africa, there is an active trade in wild 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, it becomes dangerous for others, since the spread of the Ebola virus occurs very quickly. In practice, it is known about cases when up to eight consecutive transfers occurred from one person. At the same time, 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 ways
Since the onset of the disease, as soon as the first signs of the Ebola virus appeared, and for 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 were recorded through contact with the patient’s blood, sexually. Even through the use of common household items, dishes, personal hygiene products, the risk of infection is very high.
But in most cases, this occurs through direct contact with infected people. Short-term contact with a sick person leads to infection in 23 percent of cases. With close and prolonged communication, transmission and signs of infection with the Ebola virus are noted 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 contactless being in the same room with patients did not lead to the transmission of the virus to healthy people. Despite these observations, the exact mechanism of transmission is unknown, as are all the primary signs of the Ebola virus.
Risk group
Contaminated blood is the most dangerous, because medical personnel are always at high risk during treatment and patient care. Moreover, it is very important not to have bodily contact with the infected and their physiological materials.
Given that monkeys carry the virus, people who catch and transport them, especially during the quarantine period, are also at risk of being infected. There are known cases of infection with the Ebola virus inside research laboratories where they worked with green monkeys.
Due to the high spread of the virus, as well as the diversity of transmission methods, the great danger is the migration of people from Africa to other countries, as well as the transport of animals that may be carriers of the disease.
Causative agent of Ebola
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, Thai Forest and Bundibuzhio. Its reproduction occurs in the lymph nodes and spleen. After this, the defeat of the cells of the internal organs by the virus itself and the autoimmune reactions of the body to it begins. In the incubation period, the virus does not spread.
The onset of the disease is characterized by impaired microcirculation and rheological properties of blood, capillary toxicosis, hemorrhagic and DIC. Pathological changes in the internal organs, focal tissue necrosis are observed. Ebola virus can have symptoms of the disease as in hepatitis, pancreatitis, pneumonia, orchitis and other diseases. Immune reactions are lowered, while antibodies against the virus in the body begin to appear predominantly after complete recovery.
Ebola virus: signs of the 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 occurs 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, the signs and symptoms of Ebola can resemble a sore throat, during which the tonsils become inflamed and there is a feeling of a painful lump in the throat.
With the development of fever, continuous vomiting, diarrhea of hemorrhagic nature, and abdominal pain are added to these symptoms. Soon hemorrhagic syndrome develops, which is accompanied by skin hemorrhages, bleeding inside the organs, and vomiting with blood. In this case, cases of aggressive behavior and extreme excitability of patients are often observed, which persist for a long time and after recovery. Also, in half the cases, 4-6 days after the onset of the disease, exanthema manifests itself, which has a drainage character.
Diagnostics
Since the Ebola virus does not have clinical signs as such, and it develops very quickly, differential diagnosis has difficulties. It can be laboratory diagnosed by PCR, ELISA, as well as immunofluorescence methods. Studies of serological reactions are very effective . But all this is available only in modern laboratories with good equipment and anti-epidemic conditions. Of course, in the field, this is not possible. Without the necessary equipment and professional staff, laboratory diagnostics is reduced to complex using enzyme-linked immunosorbent assay systems that detect antigens and antibodies of the Ebola virus.
Fatal outcome
The main cause of death during an outbreak of fever is bleeding, intoxication, as well as shock caused by these phenomena. The greatest number of deaths occurs in the second week of the disease. When the skin is covered with blisters, bleeding from the ears, eyes, mouth opens, the internal organs begin to fail, the worst is death. Ebola kills quickly, but painfully. If the patient has a chance to recover, the acute phase may take up to 2-3 weeks, and convalescence up to 2-3 months. Survivors of Ebola during this period suffer from severe 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 in the early stages the virus may not be diagnosed and simply ignored. And this is lost time and, as a result, 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, and more precisely on whether the body can 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 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 are shown by the use of plasma reconvalescents. Etiotropic therapy for the treatment of Ebola does not exist today.
In case of manifestations of Ebola hemorrhagic fever, the patient is immediately placed in a box-type hospital, where a strict sanitary regimen is observed. The discharge occurs after recovery, but not earlier than on the 21st day after the onset of the acute course of the disease. This happens when the patient's condition returns to normal, and virological studies show negative results. All that the patient uses and with which he contacts is thoroughly disinfected in the box, where he is stored. The patient wards are equipped with a special exhaust system, which provides only one-way air supply into the box.
During treatment, only disposable tools are used that are destroyed after use. The medical staff is in protective antiplague suits, as are the relatives who care for the sick. Blood tests and secretions of Ebola-infected people, as well as all laboratory work, are done with the utmost care and at the highest level of sterility.
Prevention
People who were in contact with patients and could become infected are also placed in boxes for up to 21 days for observation. With minimal suspicion of the possibility of disease, patients are given immunoglobulin, which is specially developed from the serum of hyperimmunized horses. This medication is effective 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 breast milk of women and sperm of men. Therefore, even having coped with the disease, they are advised to abandon breastfeeding so as not to infect the baby, and practice protected sex. After curing Ebola, the body develops a very stable immunity. Re-infection occurs very rarely and does not reach 5 percent.
Control over the spread of hemorrhagic fevers is carried out internationally. This type of disease includes Ebola, Lassa, and Marburg. Therefore, all countries are obliged to report mass and even isolated cases to the WHO headquarters in a timely manner in order to immediately begin preventive measures and prevent the epidemic. Basic research on the Ebola virus made it possible to work on a vaccine against it, as well as protective preventive drugs. There is also a constant mass alert to citizens about what Ebola fever is. Everyone should know now the causes, symptoms of the disease, how to avoid it, what to do in case of infection. In order to avoid infection and spread of the virus, tourists are not recommended to visit the countries of Africa where its outbreaks are recorded.
Drug development
Since the Ebola virus single-handedly appeared in African villages and soon faded, pharmaceutical companies were not particularly interested in developing a vaccine for it because of the unprofitability of this venture. But the governments of many countries appreciated the severity of this virus, so they did not spare the multibillion-dollar investment in its research. The experiments on monkeys showed good results after the application of the developed vaccines. They blocked the virus, and even managed to cure several primates. But the low interest of the pharmaceutical industry is still an obstacle to the large-scale production of Ebola virus medicine.
Prior to the development of the vaccine, patients were given painkillers and antibiotics to stop the fever at least a bit, preserve the immune system and prevent the development of complications. Palliative treatment with fluids with electrolytes was also used. We learned how to get serum from the blood of animals. They were infected with a virus and waited for antibody production. This method led to an improvement in the condition of patients. But a licensed vaccine against the Ebola virus to this day does not exist.