Ebola: Learn the facts

By Collins Onyango

The Ebola virus disease (EVD) outbreak has plagued three West African states;Sierra Leone, Liberia, and Guinea. As community and health-facility transmissions of infection continue to take place, the epidemic trend remains precarious. This is however not the the first such outbreak to hit Africa

Origin

According to Centre for Disease Control and prevention (CDC), Ebola hemorrhagic fever (Ebola HF) is one of numerous Viral Hemorrhagic Fevers. It is a rare and deadly 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 Ebola virus. When infection occurs, symptoms usually begin abruptly. The first Ebola virus 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.

The disease is native to several African countries and is caused by infection with one of the Ebola viruses (Ebola, Sudan, Bundibugyo, or Taï Forest virus).

It is spread by direct contact with a sick person’s blood or body fluids. It is also spread by contact with contaminated objects or infected animals.

The natural reservoir host of Ebola viruses 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.

Key Facts about -Ebola World Health Organization (WHO)

• Ebola virus disease (EVD), formerly known as Ebola hemorrhagic 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 rain forests.
• 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.

Symptoms

Symptoms include fever, headache, joint and muscle aches, sore throat, and weakness, followed by diarrhoea, vomiting, and stomach pain. Skin rash, red eyes, and internal and external bleeding may be seen in some patients.

Who is at risk?

Outbreaks of Ebola virus disease have been reported in several African countries. Travellers could be infected if they come into contact with blood or body fluids from someone who is sick or has died from Ebola, sick wildlife, or meat from an infected animal. Health care providers caring for Ebola patients without proper protection and family and friends in close contact with an ill person are at highest risk because they may come into contact with blood or body fluids.

What can travelers do to prevent Ebola?

There is no vaccine for Ebola and no specific treatment. It is important to take steps to prevent Ebola.

• Practise careful hygiene. Avoid contact with blood and body fluids of severely ill people. Do not handle items that may have come in contact with an infected person’s blood or body fluids.
• Avoid funeral or burial rituals that require handling the body of someone who has died from Ebola.
• Avoid contact with animals or consumption of raw meat.
• Avoid hospitals where Ebola patients are being treated. Seek medical care if you develop fever, headache, achiness, sore throat, diarrhoea, vomiting, stomach pain, rash, or red eyes.

Transmission

Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals. In Africa, infection has been documented through the handling of infected chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rain forest.

Ebola then spreads in the community through human-to-human transmission, with infection resulting from direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and indirect contact with environments contaminated with such fluids.

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.

When an infection does occur in humans, there are several ways in which the virus can be transmitted to others. These include:

• direct contact with the blood or secretions of an infected person
• exposure to objects (such as needles) that have been contaminated with infected secretions

The viruses that cause Ebola HF are often spread through families and friends because they come in close contact with infectious secretions when caring for ill persons.

During outbreaks of Ebola HF, the disease can spread quickly within health care settings (such as a clinic or hospital). Exposure to Ebola viruses can occur in health care settings where hospital staff is 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 sterilised before being used again. Without adequate sterilisation of the instruments, virus transmission can continue and amplify an

Diagnosis

Diagnosing Ebola HF in an individual who has been infected for only a few days is difficult, because the early symptoms, such as red eyes and a skin rash, are nonspecific to Ebola virus infection and is seen often in patients with more commonly occurring diseases.

However, if a person has the early symptoms of Ebola HF and there is reason to believe that Ebola HF should be considered, the patient should be isolated and public health professionals notified. Samples from the patient can then be collected and tested to confirm infection

Other diseases that should be ruled out before a diagnosis of EVD can be made include: malaria, typhoid fever, shigellosis, cholera, leptospirosis, plague, rickettsiosis, relapsing fever, meningitis, hepatitis and other viral hemorrhagic fevers.

Ebola virus infections can be diagnosed definitively in a laboratory through several types of tests:

• antibody-capture enzyme-linked immunosorbent assay (ELISA)
• antigen detection tests
• serum neutralization test
• reverse transcriptase polymerase chain reaction (RT-PCR) assay
• electron microscopy
• virus isolation by cell culture.

Samples from patients are an extreme biohazard risk; testing should be conducted under maximum biological containment conditions.

Special Recommendation for Health Care Workers

Health care workers who may be exposed to people with the disease should follow these steps:

• Wear protective clothing, including masks, gloves, gowns, and eye protection.
• Practise proper infection control and sterilisation measures. For more information, see “Infection Control for Viral Hemorrhagic Fevers in the African Health Care Setting.”
• Isolate Ebola patients from unprotected people.
• Avoid direct contact with the bodies of people who died from Ebola.
• Notify health officials if you have been exposed to someone with Ebola.

Vaccine and treatment

No licensed vaccine for EVD is available. Several vaccines are being tested, but none are available for clinical use.

Severely ill patients require intensive supportive care. Patients are frequently dehydrated and require oral re hydration with solutions containing electrolytes or intravenous fluids.

No specific treatment is available. New drug therapies are being evaluated.

According to CDC the standard treatment for Ebola HF is still limited to supportive therapy. This consists of:

• balancing the patient’s fluids and electrolytes
• maintaining their oxygen status and blood pressure
• treating them for any complicating infections

Natural host of Ebola virus

In Africa, fruit bats, particularly species of the genera Hypsignathus monstrosus, Epomops franqueti and Myonycteris torquata, are considered possible natural hosts for Ebola virus. As a result, the geographic distribution of Ebola viruses may overlap with the range of the fruit bats.

Ebola virus in animals

Although non-human primates have been a source of infection for humans, they are not thought to be the reservoir but rather an accidental host like human beings. Since 1994, Ebola outbreaks from the EBOV and TAFV species have been observed in chimpanzees and gorillas.

Prevention

The prevention of Ebola HF presents many challenges. Because it is still unknown how exactly people are infected with Ebola HF, there are few established primary prevention measures.

Therefore, health care workers must be able to recognize a case of Ebola HF and be ready to employ practical viral hemorrhagic fever isolation precautions or barrier nursing techniques. They should also have the capability to request diagnostic tests or prepare samples for shipping and testing elsewhere.

MSF (Médecins Sans Frontières) health staff in protective clothing constructing perimeter for isolation ward.

Barrier nursing techniques include:

• wearing of protective clothing (such as masks, gloves, gowns, and goggles)
• the use of infection-control measures (such as complete equipment sterilisation and routine use of disinfectant)
• Isolation of Ebola HF patients from contact with unprotected persons.

CDC, in conjunction with the World Health Organization, has developed a set of guidelines to help prevent and control the spread of Ebola HF. Entitled Infection Control for Viral Hemorrhagic Fevers In the African Health Care Setting, the manual describes how to:

1. recognize cases of viral hemorrhagic fever (such as Ebola HF)
2. Prevent further transmission in health care setting by using locally available materials and minimal financial resources.

 Read more

1. Ebola challenges West African countries as WHO ramps up response
2. Ebola in Guinea
3. Ebola Hemorrhagic Fever
4. Ebola virus disease
5. Ebola virus disease, West Africa –
6. Outbreak of Ebola in Guinea, Liberia, and Sierra Leone