Ebola virus disease (EVD) or Ebola hemorrhagic fever (EHF) is a severe viral hemorrhagic disease caused by ebola viruses.
After an incubation period ranging from 3 to 12 days, patients present with sudden onset of the non specific symptoms of fever, malaise, arthralgia, myalgia, and chest pain followed by gastrointestinal symptoms like abdominal pain, vomiting and diarrhea. The viremia also affects other systems.
In the respiratory system it causes pharyngitis, sore throat, dyspnoea and occasionally hiccups. Late in the disease, one may see myocarditis and pulmonary oedema due to cardiovascular complications. It causes central nervous system symptoms like headaches, confusion, depression, fatigue and may even lead to coma.
In the skin, one may notice a maculopapular rash, petechial haemorrhages, ecchymosis and haematomas which make the prognosis very poor. Due to the disseminated intravascular coagulation, there is bleeding from various sites producing hematemesis, hemoptysis, gastro intestinal bleeds and malena. Bleeding from punctures sites is seen in 50% of patients.
Ebola virus disease is indistinguishable from other viral diseases with similar manifestations like malaria, typhoid, Marburg hemorrhagic fever, acute surgical abdomen and other hemorrhagic fevers like dengue, etc.
However, the most important indicator to distinguish it is the patient’s history of travel to an endemic area and occupational history of working with infected patients.
Basic laboratory tests include blood tests like complete blood counts with differential counts which show thrombocytopenia, leucopenia while lymphopenia, neutrophilia develop after several days of infection. Liver enzymes are elevated. Bilirubin may or may not be elevated. In extreme cases, Blood Urea Nitrogen and Creatinine may increase.
Studies for isolating the Ebola virus include tissue culture which is performed only in specialized class 4 laboratories and reverse transcription polymerase chain reaction assays (RT-PCR).
Other serological test includes ELISA for antigens or IgM and IgG antibodies. Electron microscopy was used to detect filoviruses in tissues but obvious limitations of this diagnostic modality prevent it from being used in the areas of human outbreaks .
The basic treatment for Ebola virus disease is supportive care with special attention being paid to barrier isolation. All body fluids contain infected virions and thus should be handled with care and disinfected with 0.5% sodium hypochlorite solution.
General medical support like replacement of coagulation factor and administration of heparin is to be done if disseminated intravascular coagulation (DIC) occurs. Checking the intravascular volume and electrolytes imbalance and correcting them are essential.
A drug containing activated C protein is under study and trials against the Ebola virus . Another drug under study is a recombinant inhibitor for the tissue factor VIIa . Although this study is still being undertaken only in the rhesus monkeys and human trials are yet to begin. Studies on pharmacological drugs against Ebola virus disease are under process.
S-Adenosylhomocystein Hydrolase (SAH) inhibits transmethylation reaction required for replication of Zaire virus. It was tried on mice and 90% survived . Administration of interferon beta early after exposure with the virus may be a promising adjunct in the treatment of Ebola virus disease. The study on rhesus monkeys with the interferon significantly improved survival time but did not reduce mortality .
Work on a vaccine is under progress. A recombinant human monoclonal antibodies vaccine directed against the envelope glycoprotein (GP) of the virus has a neutralizing effect. It may be useful in vaccine development as a passive prophylactic agent.
A vaccine containing naked DNA was reported by Sullivan et al that could encode the Ebola proteins and be followed up with a booster dose having recombinant adenoviral vector expressing the glycoprotein of Ebola virus . Geisbert et al analyzed multiple vaccines which protected rodents against the Ebola virus infection but failed to protect rhesus or cynologus macaques .
Nutrition post infection is altered due to gastro intestinal symptoms. Weight gain and strength comes slowly during recovery. Ebola virus continues to be present in the body fluids even after the clinical illness is over. Care should be take to closely watch the recovering patients as the recovery is slow and may take months to recover.
Ebola virus disease is caused by four out of the five viruses in the genus Ebola virus of the family Filoviridae, order Mononegavirus. Those are Bundibugyo Ebola virus, Zaire Ebola virus, Sudan Ebola virus and Tai Forest Ebola virus. The fifth one, Reston Ebola virus, is non-pathogenic in humans.
The virus affects human and non-human primates through transmission from unknown hosts, mostly fruit and insectivorous bats, via direct contact through body fluids like blood, saliva and other body tissues.
Evidence shows that the Sudan and Zaire species of the Ebola virus family can be transmitted via contact with mucous membrane, breaks in skin, pharyngeal and conjunctival surface, gastrointestinally and lastly, by aerosolization .
Individuals who come into direct contact with the infected person without proper barrier protection are at high risk of becoming infected with the disease. A study observing 24 contacts that remained close to infected symptomatic persons found that the contacts had an active Ebola virus infection .
Ebola virus disease first occurred in Zaire and Sudan in 1976. It is mainly restricted to Africa. Individuals at risk are those with travel history to Sub Saharan Africa, medical workers who care for infected patients, animal workers who have worked with primates infected with the disease.
It has no sexual or racial predilection. Children are less likely to come into direct contact with infected patients.
Ebola virus mainly affects the endothelial cells, phagocytes and hepatocytes. It has two glycoproteins; a smaller one which is secreted early in the disease, a surface glycoprotein (sGP) which inhibits the early neutrophil activation, thus preventing the effective host immune response. It thereby causes lymphopenia.
Second somewhat larger protein is a transmembrane glycoprotein which invades, replicates and destroys the endothelial cells of the host resulting in the disseminated intravascular coagulation (DIC), leading to the hemorrhagic manifestations of the Ebola virus disease.
The virus replicates in all tissues leading to focal necrosis most commonly seen in liver, known as Councilman-like bodies, which are also seen in yellow fever. In most fatal cases, the host’s tissues and blood contain large virions making them highly infectious.
Currently, no specific therapy or vaccine is available, as a consequence, raising awareness of the risk factors and the protective measures individuals can take is the only way to reduce human infection and death.
Ebola virus disease (EVD) or Ebola hemorrhagic disease is caused by Ebola virus first found in the Ebola river in the Democratic Republic of Congo.
The genus Ebola virus is from the Filoviridae family and five different species of Ebola virus have been identified till date of which only four are pathogenic to human. It is a RNA virus with lipid envelope mainly affecting the microvascular system.
The exposure to virus is either primary i.e. presence in Ebola virus endemic area or secondary i.e. human to human or primates to human transmission.
The disease is initially recognized by fever and malaise followed by gastrointestinal symptoms, bleeding, shock and finally multi-organ failure. Currently no specific treatment or vaccine is available for the disease and care should be administered with strict attention to barrier isolation.
Ebola virus disease is one of the least known hemorrhagic fever disease and is caused by the Ebola virus first isolated in the Ebola river in Africa. It is mainly found in sub Saharan region and remote parts of Africa.
There are 5 species of the Ebola virus of which 4 are pathogenic to humans. The mammal bat is believed to be a primary reservoir of Ebola virus affecting the primates like gorilla, chimpanzees through saliva or other body fluids. Dogs have shown to get infected asymptomatically with the virus .
Disease spreads to humans by coming in contact with those affected with disease, either primates or humans, residing in the endemic area of Ebola virus. Source of infection includes body fluids like saliva, blood and semen of the infected person. Thus special attention should be paid towards barrier isolation of the infected person.
Ebola virus disease is easily confused with other hemorrhagic fevers due to atypical manifestation like fever with or without chills, malaise, body pain, headache, chest pain followed by gastric symptoms like nausea, vomiting, diarrhea. It mainly affects liver causing localized cell death. There is bleeding at the site of puncture and also from various orifices of the body.
Treatment includes differentiating the disease with simple blood tests, liver test, isolation of virus through tissue culture in specialized laboratories.
Pharmacological treatment is still under research, however the supportive treatment includes managing the basic life support of patient i.e. airway, breathing and circulation, fluid and electrolyte balance.
Vaccines for ebola virus disease are being researched. The mainstay of treatment is isolation of patients suffering from Ebola virus disease and proper disposal of materials used for their treatment.