What is Ebola? How is Ebola contracted?

The 2014 Ebola outbreak across Guinea, northern Liberia, and now eastern Sierra Leone is fuelling concern worldwide. According to the World Health Organization (WHO), with over 1,500 laboratory confirmed cases of Ebola virus this year alone and around 887 deaths from the epidemic, this is the worst outbreak ever. 

This Blognews article examines the effects of Ebola on the human body and the current concerns people may have about the virus.

WHO have launched a new $100 million response plan as part of an intensified international, regional and national campaign, to combat the outbreak of Ebola in West Africa:

The scale of the Ebola outbreak, and the persistent threat it poses, requires WHO and Guinea, Liberia and Sierra Leone to take the response to a new level, and this will require increased resources, in-country medical expertise, regional preparedness and coordination. The countries have identified what they need, and WHO is reaching out to the international community to drive the response plan forward.

Ebola virus disease (EVD), previous known as Ebola hemorrhagic fever (Ebola HF), is a serious, often fatal condition in humans and nonhuman primates such as monkeys, gorillas and chimpanzees. Ebola is one of several viral hemorrhagic fevers (VHF), caused by infection with a virus of the Filoviridae family, genus Ebolavirus.

Ebola has a case fatality rate of up to 90% and is currently one of the world's most infectious diseases. The infection is transmitted by direct contact with the blood, body fluids and tissues of infected animals or people. Severely ill patients require intensive supportive care.

This information page on my Blog will give you the essential details about Ebola, describe what it is, what causes it, who gets the problem and the symptoms they have, the risk factors, how it is diagnosed, and offer an overview of treatment options and prevention measures for Ebola.

You will also see introductions at the end of some sections to any recent developments that have been covered here. Also look out for links to information about related conditions.

Fast facts on Ebola

Here are some key points about Ebola. More detail and supporting information is in the main article.

• Ebola virus disease (EVD) is a serious, often fatal condition in humans and nonhuman primates such as monkeys, gorillas and chimpanzees.
• Ebola has a case fatality rate of up to 90% and is currently one of the world's most infectious diseases.
• Genus Ebolavirus is one of three members of the Filoviridae family (filovirus), along with genus Marburgvirus and genus Cuevavirus.
• Genus Ebolavirus comprises five distinct subspecies: Bundibugyo Ebolavirus (BDBV), Zaire Ebolavirus (EBOV), Reston Ebolavirus (RESTV), Sudan Ebolavirus (SUDV) and Taï Forest Ebolavirus (TAFV).
• It has been hypothesized by researchers that the virus is zoonotic (animal-borne).
• In an outbreak or isolated case among humans, the manner in which the virus is transmitted from the natural reservoir to a human is unclear.
• Ebola tends to spread quickly through families and friends as they are exposed to infectious secretions when caring for an ill individual.
• The time interval from infection with Ebola to the onset of symptoms is 2 to 21 days.
• EVD is often characterized by the abrupt onset of fever, intense weakness, muscle pain, headache and sore throat.
• There is currently no licensed vaccine available for Ebola. Several vaccines are being tested, but at this time none are available for clinical use.

What is Ebola?

The first cases of Ebola were reported simultaneously in 1976 in Yambuku and the surrounding area, near the Ebola River in Zaire, which is now the Democratic Republic of the Congo and in Nzara, Sudan. Since then, eruptions or asymptomatic cases of Ebola viruses in humans and animals have surfaced intermittently in the following locations due to outbreaks or laboratory contamination and accidents:

The first cases of Ebola were reported in 1976 in Yambuku and the surrounding area, near the Ebola River in Zaire, which is now the Democratic Republic of the Congo.

• Zaire (Democratic Republic of the Congo - DRC)
• Sudan (South Sudan)
• England
• US
• Philippines
• Italy
• Gabon
• Ivory Coast
• South Africa
• Russia
• Uganda
• Guinea
• Liberia
• Sierra Leone.

Genus Ebolavirus is one of three members of the Filoviridae family (filovirus), along with genus Marburgvirus and genus Cuevavirus. Genus Ebolavirus comprises five distinct subspecies:

• Bundibugyo Ebolavirus (BDBV)
• Zaire Ebolavirus (EBOV)
• Reston Ebolavirus (RESTV)
• Sudan Ebolavirus (SUDV)
• Taï Forest Ebolavirus (TAFV).

BDBV, EBOV, and SUDV have been connected with considerable EVD outbreaks in Africa, however RESTV and TAFV have not.

The RESTV subspecies found in Philippines and the People's Republic of China, can infect humans, but no illness or death in humans from this species has been reported to date.² Among workers in contact with monkeys or pigs infected with RESTV, several infections have been documented in people who were clinically asymptomatic. Hence, RESTV appears less able to cause disease in humans than other Ebola species.

What causes Ebola?

Ebola is caused by the five viruses detailed above classified in the genus Ebolavirus, family Filoviridae. The natural reservoir of Ebolavirus has not yet been proven, for that reason, how the virus first appears in a human at the onset of an outbreak is unknown.

It has been hypothesized by researchers that the virus is zoonotic (animal-borne), with the first patient developing the infection through contact with an infected animal.

Ebola is caused by the five viruses above classified in the genus Ebolavirus, family Filoviridae.

The theorized potential natural reservoirs of the Ebola virus are Fruit bats of the Pteropodidae family. In Africa, infection has been documented through the handling of the following infected animals found ill or dead or in the rainforest:

• Chimpanzees
• Gorillas
• Fruit bats
• Monkeys
• Forest antelope
• Porcupines.

In an outbreak or isolated case among humans, the manner in which the virus is transmitted from the natural reservoir to a human is unclear. Person-to-person transmission is a method by which further infections occur after a human is infected.

Transmission of Ebola between humans can occur in several ways, including through:

• Direct contact through broken skin and mucus membranes with the blood, secretions, organs or other bodily fluids of infected people
• Indirect contact with environments contaminated with such fluids
• Exposure to objects (such as needles) that have been contaminated with infected secretions
• Burial ceremonies in which mourners have direct contact with the body of the deceased person can also play a role in the transmission of Ebola
• Men who have recovered from the disease can still transmit the virus through their semen for up to 7 weeks after recovery from illness
• Health care workers have frequently been infected while treating patients with suspected or confirmed EVD.

Ebola tends to spread quickly through families and friends as they are exposed to infectious secretions when caring for an ill individual. The virus can also spread quickly within health care settings for the same reason, highlighting the importance of wearing appropriate protective equipment, such as masks, gowns and gloves.⁷Sterilization and disposal of needles and syringes thoroughly in hospitals is an important factor to prevent virus transmission continuing and amplifying an outbreak.

There is no evidence that Ebola can be spread via insect bites.

Recent developments on Ebola causes 

Scientists discover how deadly Ebola virus 'punches' its way into human cells

Researchers at the University of Virginia School of Medicine have discovered that the deadly Ebola virus uses a "molecular fist" to punch its way out of vesicles - the secure pockets that cells keep captured viruses and other unwanted agents in until they can be disposed of.

Examining the causes of Ebola virus outbreaks

What determines the location and severity of Ebola virus outbreaks? According to Tulane University School of Public Health and Tropical Medicine researcher Daniel Bausch, lead author of "Outbreak of Ebola Virus Disease in Guinea: Where Ecology Meets Economy," a new article in PLOS Neglected Tropical Diseases, the causes are a composite of biological and ecological circumstances superimposed on populations made vulnerable by social and political strife.

Signs and symptoms of Ebola

The time interval from infection with Ebola to the onset of symptoms is 2 to 21 days, although 8 to 10 days is most common. Signs and symptoms may include:⁹

EVD is often characterized by the abrupt onset of fever, intense weakness, muscle pain, headache and sore throat.

• Fever
• Headache
• Joint and muscle aches
• Weakness
• Diarrhea
• Vomiting
• Stomach pain
• Lack of appetite.

Some patients may experience:

• A rash
• Red eyes
• Hiccups
• Cough
• Sore throat
• Chest pain
• Difficulty breathing
• Difficulty swallowing
• Bleeding inside and outside of the body.

EVD is often characterized by the abrupt onset of fever, intense weakness, muscle pain, headache and sore throat. These signs are usually followed by vomiting, diarrhea, rash, impaired kidney and liver function, and in some severe cases, both internal and external bleeding.

Laboratory outcomes include low white blood cell and platelet counts and elevated liver enzymes.

As long as the patient's blood and secretions contain the virus, they are infectious. Ebola virus was isolated from semen 61 days after onset of illness in a man who was infected in a laboratory.

Risk factors

Risk of contracting Ebola is low. There is a higher risk of becoming infected when:

• Traveling to Africa - where most confirmed cases of Ebola have been reported
• Conducting animal research with monkeys imported from Africa or the Philippines
• Providing medical or personal care - protective gear such as surgical masks and gloves should be worn
• Preparing people for burial.

Tests and diagnosis of Ebola

Before Ebola can be diagnosed, other diseases should be ruled out such as:

• Malaria
• Typhoid fever
• Shigellosis
• Cholera
• Leptospirosis
• Plague
• Rickettsiosis
• Relapsing fever
• Meningitis
• Hepatitis
• Other viral hemorrhagic fevers.

If Ebola is suspected, the patient should be isolated, and public health professionals notified. Ebola virus infections can be diagnosed definitively in a laboratory through several types of tests.

Within a few days after symptoms begin, the virus can be diagnosed with:

• Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing
• IgM ELISA
• Polymerase chain reaction (PCR)
• Virus isolation.

In the more advanced stages of the disease or after recovery, the diagnostic test available is:

• IgM and IgG antibodies.

Retrospectively Ebola can be diagnosed in deceased patients by:

• Immunohistochemistry testing
• PCR
• Virus isolation.

According to the World Health Organization, samples from patients with Ebola are an extreme biohazard risk. Testing should be conducted under maximum biological containment conditions.

Recent developments on Ebola diagnosis

Ebola outbreak in West Africa shows no sign of slowing down

The spread of deadly Ebola in West Africa appears to be increasing and getting out of control, as a leading medical charity warns of over-stretched resources, and concerns are raised that it may spread to other continents.

Sierra Leone researchers call for health surveillance improvements to tackle Ebola crisis

The Lancet publish a statement from researchers working in Sierra Leone calling for improvements to health care resources, disease surveillance and diagnostic technologies to tackle the ongoing Ebola crisis in West Africa.

How is Ebola treated?

There is currently no licensed vaccine available for Ebola. Several vaccines are being tested, but at this time none are available for clinical use.

Treatment for Ebola is limited to intensive supportive care and often includes:

• Balancing the patient's fluids and electrolytes
• Maintaining their oxygen status and blood pressure
• Treating a patient for any complicating infections.

Experimental treatments have been tested and proven effective in animal models but as yet have not been used in humans.

Recent developments on Ebola treatment from MNT news

Natural antiviral protein stops HIV, deadly viruses entering cells

Researchers in the US have identified a natural antiviral protein that stops HIV and certain other deadly viruses like Ebola, Rift Valley Fever and Nipah, from entering host cells.

How is Ebola prevented?

As it is still unknown how individuals are infected with Ebola, the prevention of the infection presents a challenge. However, there are primary prevention measures that can assist with the challenge, such as:

• Wearing of protective clothing (such as masks, gloves, gowns and goggles) for health care professionals
• The use of infection-control measures (such as complete equipment sterilization and routine use of disinfectant)
• Isolation of Ebola patients from contact with unprotected persons.

Together with the World Health Organization, CDC has developed a set of guidelines to help prevent and control the spread of Ebola - Infection Control for Viral Hemorrhagic Fevers In the African Health Care Setting.

Source and Reference: World Health Organization (WHO)