KEY FACTS;
.Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a severe, often fatal illness in humans.
.EVD outbreaks have a case fatality rate of up to 90%.
.EVD outbreaks occur primarily in remote villages in Central and West Africa, near tropical rainforests.
.The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission.
.Fruit bats of the Pteropodidae family are considered to be the natural host of the Ebola virus.
.Severely ill patients require intensive supportive care. No licensed specific treatment or vaccine is available for use in people or animals.
Ebola hemorrhagic fever (Ebola HF) is one of numerous Viral Hemorrhagic Fevers. It is a severe, often fatal disease in humans and nonhuman primates (such as monkeys, gorillas, and chimpanzees).
Ebola HF is caused by infection with a virus of the family Filoviridae, genus Ebolavirus. When infection occurs, symptoms usually begin abruptly. The first Ebolavirus species was discovered in 1976 in what is now the Democratic Republic of the Congo near the Ebola River. Since then, outbreaks have appeared sporadically.
There are five identified subspecies of Ebolavirus. Four of the five have caused disease in humans: Ebola virus (Zaire ebolavirus); Sudan virus (Sudan ebolavirus); Taï Forest virus (Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus); and Bundibugyo virus (Bundibugyo ebolavirus). The fifth, Reston virus (Reston ebolavirus), has caused disease in nonhuman primates, but not in humans.
The natural reservoir host of ebolaviruses remains unknown. However, on the basis of available evidence and the nature of similar viruses, researchers believe that the virus is zoonotic (animal-borne) with bats being the most likely reservoir. Four of the five subtypes occur in an animal host native to Africa.
A host of similar species is probably associated with Reston virus, which was isolated from infected cynomolgous monkeys imported to the United States and Italy from the Philippines. Several workers in the Philippines and in US holding facility outbreaks became infected with the virus, but did not become ill
SIGNS AND SYMPTOMS OF EBOLA
Signs and symptoms of Ebola usually begin suddenly with an influenza-like stage characterized by fatigue, fever (greater than 38.6°C or 101.5°F), headaches, joint, muscle and abdominal pain. Vomiting, diarrhea and loss of appetite are also common. Less common symptoms include the following: sore throat, chest pain, hiccups, shortness of breath and trouble swallowing.
The average time between contracting the infection and the start of symptoms (incubation period) is 8 to 10 days, but it can vary between 2 and 21 days. Skin manifestations may include a maculopapular rash (in about 50% of cases). Early symptoms of EVD may be similar to those of malaria, dengue fever or other tropical fevers, before the disease progresses to the bleeding phase.
In 40–50% of cases, bleeding from puncture sites and mucous membranes (e.g. gastrointestinal tract, nose, vagina and gums) has been reported.In the bleeding phase, which typically starts 5 to 7 days after first symptoms internal and subcutaneous bleeding may present itself through reddening of the eyes and bloody vomit.Bleeding into the skin may create petechiae, purpura, ecchymoses and hematomas (especially around needle injection sites). Types of bleeding known to occur with Ebola virus disease include vomiting blood, coughing it up or blood in the stool. Heavy bleeding is rare and is usually confined to the gastrointestinal tract.In general, the development of bleeding symptoms often indicates a worse prognosis and this blood loss can result in death.All people infected show some symptoms of circulatory system involvement, including impaired blood clotting.If the infected person does not recover, death due to multiple organ dysfunction syndrome occurs within 7 to 16 days (usually between days 8 and 9) after first symptoms.
TRANSMISSION
Because the natural reservoir of ebolaviruses has not yet been proven, the manner in which the virus first appears in a human at the start of an outbreak is unknown. However, researchers have hypothesized that the first patient becomes infected through contact with an infected animal.
When an infection does occur in humans, the virus can be spread in several ways to others. The virus is spread through direct contact (through broken skin or mucous membranes) with;
a sick person's blood or body fluids (urine, saliva, feces, vomit, and semen)
objects (such as needles) that have been contaminated with infected body fluids
infected animals
Healthcare workers and the family and friends in close contact with Ebola patients are at the highest risk of getting sick because they may come in contact with infected blood or body fluids.
During outbreaks of Ebola HF, the disease can spread quickly within healthcare settings (such as a clinic or hospital). Exposure to ebolaviruses can occur in healthcare settings where hospital staff are not wearing appropriate protective equipment, such as masks, gowns, and gloves.
Proper cleaning and disposal of instruments, such as needles and syringes, is also important. If instruments are not disposable, they must be sterilized before being used again. Without adequate sterilization of the instruments, virus transmission can continue and amplify an outbreak.
PREVENTION AND CONTROL
Ebola viruses are contagious, with prevention predominantly involving behavior changes, proper full-body personal protective equipment, and disinfection. Techniques to avoid infection involve not contacting infected blood or secretions, including from those who are dead.
.This involves suspecting and diagnosing the disease early and using standard precautions for all patients in the healthcare setting.Recommended measures when caring for those who are infected include isolating them, sterilizing equipment, and wearing protective clothing including masks, gloves, gowns, and goggles. Hand washing is important but can be difficult in areas where there is not even enough water for drinking.Other supplies are also in critical shortage in the 2014 outbreak - even soap When soap is hard to find during emergencies, WHO promote using substitutes like clean ash (or sand)
The Ebola virus can be eliminated with heat (heating for 30 to 60 minutes at 60 °C or boiling for 5 minutes), some alcohol-based products on surfaces,lipid solvents, detergents, sodium hypochlorite (bleach) or calcium hypochlorite (bleaching powder) at appropriate concentrations and other suitable disinfectants.
Due to lack of proper equipment and hygienic practices, large-scale epidemics have occurred mostly in poor, isolated areas without modern hospitals or well-educated medical staff. Traditional burial rituals, especially those requiring washing or embalming of bodies, should be discouraged or modified. Airline crews are instructed to isolate anyone who has symptoms resembling Ebola virus.
Quarantine
Quarantine, also known as enforced isolation, is usually effective in decreasing spread.Governments often quarantine areas where the disease is occurring or individuals who may be infected. In the United States, the law allows quarantine of those infected with Ebola. The lack of roads and transportation may help slow the disease in Africa. During the 2014 outbreak, Liberia closed schools.
Vaccine
No vaccine is currently available for humans. The most promising candidates are DNA vaccines or vaccines derived from adenoviruses, vesicular stomatitis Indiana virus or filovirus-like particles (VLPs)because these candidates could protect nonhuman primates from ebolavirus-induced disease. DNA vaccines, adenovirus-based vaccines, and VSIV-based vaccines have entered clinical trials.
Vaccines have protected nonhuman primates. Immunization takes six months, which impedes the counter-epidemic use of the vaccines. Searching for a quicker onset of effectiveness, in 2003, a vaccine using an adenoviral (ADV) vector carrying the Ebola spike protein was tested on crab-eating macaques. Twenty-eight days later, they were challenged with the virus and remained resistant. A vaccine based on attenuated recombinant vesicular stomatitis virus (VSV) vector carrying either the Ebola glycoprotein or the Marburg glycoprotein in 2005 protected nonhuman primates, opening clinical trials in humans. The study by October completed the first human trial, over three months giving three vaccinations safely inducing an immune response. Individuals for a year were followed, and, in 2006, a study testing a faster-acting, single-shot vaccine began; this new study was completed in 2008. Trying the vaccine on a strain of Ebola that more resembles one that infects humans is the next step. On 6 December 2011, the development of a successful vaccine against Ebola for mice was reported. Unlike the predecessors, it can be freeze-dried and thus stored for long periods in wait for an outbreak. An experimental vaccine made by researchers at Canada's national laboratory in Winnipeg was used, in 2009, to pre-emptively treat a German scientist who might have been infected during a lab accident. However, actual EBOV infection could never be demonstrated without a doubt. Experimentally, recombinant vesicular stomatitis Indiana virus (VSIV) expressing the glycoprotein of EBOV or SUDV has been used successfully in nonhuman primate models as post-exposure prophylaxis. The CDC's recommendations are currently under review.
Laboratory
Ebola viruses are World Health Organization Risk Group 4 pathogens, requiring biosafety level 4-equivalent containment. Laboratory researchers must be properly trained in BSL-4 practices and wear proper personal protective equipment.
TREATMENT
A hospital isolation ward in Gulu, Uganda, during the October 2000 outbreak
No ebolavirus-specific treatment exists. Treatment is primarily supportive in nature and includes minimizing invasive procedures, balancing fluids and electrolytes to counter dehydration, administration of anticoagulants early in infection to prevent or control disseminated intravascular coagulation, administration of procoagulants late in infection to control bleeding, maintaining oxygen levels, pain management, and the use of medications to treat bacterial or fungal secondary infections. Early treatment may increase the chance of survival. A number of experimental treatments are being studied.
In the United States, in the setting of a phase I clinical trial, the FDA's animal efficacy rule can be used to demonstrate reasonable safety to obtain permission to treat people who are infected with Ebola. The animal efficacy rule exists, because the normal path for testing the safety and efficacy of drugs is not possible for diseases caused by dangerous pathogens or toxins. The FDA has allowed two drugs, ZMapp and an RNA interference drug called TKM-Ebola, to be used in people infected with Ebola under these programs during the 2014 outbreak.
.Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a severe, often fatal illness in humans.
.EVD outbreaks have a case fatality rate of up to 90%.
.EVD outbreaks occur primarily in remote villages in Central and West Africa, near tropical rainforests.
.The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission.
.Fruit bats of the Pteropodidae family are considered to be the natural host of the Ebola virus.
Ebola hemorrhagic fever (Ebola HF) is one of numerous Viral Hemorrhagic Fevers. It is a severe, often fatal disease in humans and nonhuman primates (such as monkeys, gorillas, and chimpanzees).
Ebola HF is caused by infection with a virus of the family Filoviridae, genus Ebolavirus. When infection occurs, symptoms usually begin abruptly. The first Ebolavirus species was discovered in 1976 in what is now the Democratic Republic of the Congo near the Ebola River. Since then, outbreaks have appeared sporadically.
There are five identified subspecies of Ebolavirus. Four of the five have caused disease in humans: Ebola virus (Zaire ebolavirus); Sudan virus (Sudan ebolavirus); Taï Forest virus (Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus); and Bundibugyo virus (Bundibugyo ebolavirus). The fifth, Reston virus (Reston ebolavirus), has caused disease in nonhuman primates, but not in humans.
The natural reservoir host of ebolaviruses remains unknown. However, on the basis of available evidence and the nature of similar viruses, researchers believe that the virus is zoonotic (animal-borne) with bats being the most likely reservoir. Four of the five subtypes occur in an animal host native to Africa.
A host of similar species is probably associated with Reston virus, which was isolated from infected cynomolgous monkeys imported to the United States and Italy from the Philippines. Several workers in the Philippines and in US holding facility outbreaks became infected with the virus, but did not become ill
SIGNS AND SYMPTOMS OF EBOLA
Signs and symptoms of Ebola usually begin suddenly with an influenza-like stage characterized by fatigue, fever (greater than 38.6°C or 101.5°F), headaches, joint, muscle and abdominal pain. Vomiting, diarrhea and loss of appetite are also common. Less common symptoms include the following: sore throat, chest pain, hiccups, shortness of breath and trouble swallowing.
The average time between contracting the infection and the start of symptoms (incubation period) is 8 to 10 days, but it can vary between 2 and 21 days. Skin manifestations may include a maculopapular rash (in about 50% of cases). Early symptoms of EVD may be similar to those of malaria, dengue fever or other tropical fevers, before the disease progresses to the bleeding phase.
In 40–50% of cases, bleeding from puncture sites and mucous membranes (e.g. gastrointestinal tract, nose, vagina and gums) has been reported.In the bleeding phase, which typically starts 5 to 7 days after first symptoms internal and subcutaneous bleeding may present itself through reddening of the eyes and bloody vomit.Bleeding into the skin may create petechiae, purpura, ecchymoses and hematomas (especially around needle injection sites). Types of bleeding known to occur with Ebola virus disease include vomiting blood, coughing it up or blood in the stool. Heavy bleeding is rare and is usually confined to the gastrointestinal tract.In general, the development of bleeding symptoms often indicates a worse prognosis and this blood loss can result in death.All people infected show some symptoms of circulatory system involvement, including impaired blood clotting.If the infected person does not recover, death due to multiple organ dysfunction syndrome occurs within 7 to 16 days (usually between days 8 and 9) after first symptoms.
TRANSMISSION
Because the natural reservoir of ebolaviruses has not yet been proven, the manner in which the virus first appears in a human at the start of an outbreak is unknown. However, researchers have hypothesized that the first patient becomes infected through contact with an infected animal.
When an infection does occur in humans, the virus can be spread in several ways to others. The virus is spread through direct contact (through broken skin or mucous membranes) with;
a sick person's blood or body fluids (urine, saliva, feces, vomit, and semen)
objects (such as needles) that have been contaminated with infected body fluids
infected animals
Healthcare workers and the family and friends in close contact with Ebola patients are at the highest risk of getting sick because they may come in contact with infected blood or body fluids.
During outbreaks of Ebola HF, the disease can spread quickly within healthcare settings (such as a clinic or hospital). Exposure to ebolaviruses can occur in healthcare settings where hospital staff are not wearing appropriate protective equipment, such as masks, gowns, and gloves.
Proper cleaning and disposal of instruments, such as needles and syringes, is also important. If instruments are not disposable, they must be sterilized before being used again. Without adequate sterilization of the instruments, virus transmission can continue and amplify an outbreak.
PREVENTION AND CONTROL
Ebola viruses are contagious, with prevention predominantly involving behavior changes, proper full-body personal protective equipment, and disinfection. Techniques to avoid infection involve not contacting infected blood or secretions, including from those who are dead.
.This involves suspecting and diagnosing the disease early and using standard precautions for all patients in the healthcare setting.Recommended measures when caring for those who are infected include isolating them, sterilizing equipment, and wearing protective clothing including masks, gloves, gowns, and goggles. Hand washing is important but can be difficult in areas where there is not even enough water for drinking.Other supplies are also in critical shortage in the 2014 outbreak - even soap When soap is hard to find during emergencies, WHO promote using substitutes like clean ash (or sand)The Ebola virus can be eliminated with heat (heating for 30 to 60 minutes at 60 °C or boiling for 5 minutes), some alcohol-based products on surfaces,lipid solvents, detergents, sodium hypochlorite (bleach) or calcium hypochlorite (bleaching powder) at appropriate concentrations and other suitable disinfectants.
Due to lack of proper equipment and hygienic practices, large-scale epidemics have occurred mostly in poor, isolated areas without modern hospitals or well-educated medical staff. Traditional burial rituals, especially those requiring washing or embalming of bodies, should be discouraged or modified. Airline crews are instructed to isolate anyone who has symptoms resembling Ebola virus.
Quarantine
Quarantine, also known as enforced isolation, is usually effective in decreasing spread.Governments often quarantine areas where the disease is occurring or individuals who may be infected. In the United States, the law allows quarantine of those infected with Ebola. The lack of roads and transportation may help slow the disease in Africa. During the 2014 outbreak, Liberia closed schools.
Vaccine
No vaccine is currently available for humans. The most promising candidates are DNA vaccines or vaccines derived from adenoviruses, vesicular stomatitis Indiana virus or filovirus-like particles (VLPs)because these candidates could protect nonhuman primates from ebolavirus-induced disease. DNA vaccines, adenovirus-based vaccines, and VSIV-based vaccines have entered clinical trials.
Vaccines have protected nonhuman primates. Immunization takes six months, which impedes the counter-epidemic use of the vaccines. Searching for a quicker onset of effectiveness, in 2003, a vaccine using an adenoviral (ADV) vector carrying the Ebola spike protein was tested on crab-eating macaques. Twenty-eight days later, they were challenged with the virus and remained resistant. A vaccine based on attenuated recombinant vesicular stomatitis virus (VSV) vector carrying either the Ebola glycoprotein or the Marburg glycoprotein in 2005 protected nonhuman primates, opening clinical trials in humans. The study by October completed the first human trial, over three months giving three vaccinations safely inducing an immune response. Individuals for a year were followed, and, in 2006, a study testing a faster-acting, single-shot vaccine began; this new study was completed in 2008. Trying the vaccine on a strain of Ebola that more resembles one that infects humans is the next step. On 6 December 2011, the development of a successful vaccine against Ebola for mice was reported. Unlike the predecessors, it can be freeze-dried and thus stored for long periods in wait for an outbreak. An experimental vaccine made by researchers at Canada's national laboratory in Winnipeg was used, in 2009, to pre-emptively treat a German scientist who might have been infected during a lab accident. However, actual EBOV infection could never be demonstrated without a doubt. Experimentally, recombinant vesicular stomatitis Indiana virus (VSIV) expressing the glycoprotein of EBOV or SUDV has been used successfully in nonhuman primate models as post-exposure prophylaxis. The CDC's recommendations are currently under review.
Laboratory
Ebola viruses are World Health Organization Risk Group 4 pathogens, requiring biosafety level 4-equivalent containment. Laboratory researchers must be properly trained in BSL-4 practices and wear proper personal protective equipment.
TREATMENT
A hospital isolation ward in Gulu, Uganda, during the October 2000 outbreak
No ebolavirus-specific treatment exists. Treatment is primarily supportive in nature and includes minimizing invasive procedures, balancing fluids and electrolytes to counter dehydration, administration of anticoagulants early in infection to prevent or control disseminated intravascular coagulation, administration of procoagulants late in infection to control bleeding, maintaining oxygen levels, pain management, and the use of medications to treat bacterial or fungal secondary infections. Early treatment may increase the chance of survival. A number of experimental treatments are being studied.
In the United States, in the setting of a phase I clinical trial, the FDA's animal efficacy rule can be used to demonstrate reasonable safety to obtain permission to treat people who are infected with Ebola. The animal efficacy rule exists, because the normal path for testing the safety and efficacy of drugs is not possible for diseases caused by dangerous pathogens or toxins. The FDA has allowed two drugs, ZMapp and an RNA interference drug called TKM-Ebola, to be used in people infected with Ebola under these programs during the 2014 outbreak.
){kind=link}