Ebola Virus Disease (EVD); transmission, diagnosis, management and prevention

Introduction

Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a rare but deadly virus that causes bleeding inside and outside the body often affecting humans. It is an acute, serious illness which is often fatal if untreated. Ebola virus disease (EVD) first appeared in 1976 near the Ebola River in what is now the Democratic Republic of Congo. The virus thus surfaces from time to time causing outbreaks in several African Countries.

As to where the virus comes from is currently unknown to scientists but it is believed to be zoonotic (in this case, transmitted from bats and other animals).

The average EVD case fatality rate is around 50%. Case fatality rates have varied from 25% to 90% in past outbreaks.

Creator: Hilliard, Aaron; USC's MPH Online Program - University of Southern California

Incubation period: 2-21 days after exposure.

Mode of Transmission

Direct contact with

  • Body fluids of persons infected by the virus or has died from Ebola (blood, vomitus, urine, stool, semen, sweats etc.)
  • Contaminated instruments such as needle, syringes and other medical equipment.
  • Infected animals (fruit bats, monkeys, chimpanzees etc.)

It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts, Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals such as chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rainforest.

Ebola then spreads through human-to-human transmission via direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.

Health-care workers have frequently been infected while treating patients with suspected or confirmed EVD. This has occurred through close contact with patients when infection control precautions are not strictly practiced.

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. People remain infectious as long as their blood contains the virus.

Note: All Ebola survivors and their sexual partners should receive counselling to ensure safe sexual practices until their semen has twice tested negative. Survivors should be provided with condoms.

Signs and symptoms

  1. High fever
  2. Headache
  3. Joint and muscle aches
  4. Sore throat
  5. Weakness
  6. Stomach pain
  7. Lack of appetite
  8. Bleeding; as the disease gets worse, it causes bleeding inside the body, as well as from the eyes, ears, and nose. Some people vomit blood (hematemesis) or cough up blood (hemoptysis), have bloody diarrhea, and get a rash.

Diagnosis

  • Blood and tissue test.
  • Clinical features; it’s difficult sometimes to tell if a person has Ebola from the symptoms alone. Doctors may test to rule out other diseases. There is also no licensed vaccines available yet, but 2 potential vaccines are undergoing human safety testing.

Management

There is no cure for Ebola, though researchers are working on it. Treatment includes an experimental serum that destroys infected cells.

Doctors/Nurses manage the symptoms of Ebola with:

  • Immediate isolation of suspected and confirmed cases to prevent spread.
  • Fluids and electrolytes
  • Oxygen
  • Blood pressure medication
  • Blood transfusions
  • Treatment for other infections

Prevention and control

Good outbreak control relies on applying a package of interventions namely;

  • Case management
  • Surveillance and contact tracing
  • A good laboratory service
  • Safe burials and social mobilization.

Community engagement is key to successfully controlling outbreaks. Raising awareness of risk factors for Ebola infection and protective measures that individuals can take is key.

  • Reducing the risk of wildlife-to-human transmission from contact with infected fruit bats or monkeys/apes and the consumption of their raw meat. Animal products (blood and meat) should be thoroughly cooked before consumption. 
  • Reducing the risk of human-to-human transmission from direct or close contact with people with Ebola symptoms, particularly with their bodily fluids. Gloves and appropriate personal protective equipment should be worn when taking care of ill patients at home. Regular hand washing is required after visiting patients in hospital, as well as after taking care of patients at home. 
  • Reducing the risk of possible sexual transmission, based on further analysis of ongoing research and consideration by the WHO Advisory Group on the Ebola Virus Disease Response. W.H.O recommends that male survivors of Ebola virus disease practice safe sex and hygiene for 12 months from onset of symptoms or until their semen tests negative twice for Ebola Virus.
  • Outbreak containment measures, including prompt and safe burial of the dead, identifying people who many have been in contact with someone infected with Ebola and monitoring their health for 21 days, prioritize separating the healthy from the sick to prevent further spread and practice good hygiene.

Controlling infection in health care setting

Health-care workers should always take standard precautions when caring for patients, regardless of their presumed diagnosis. These include basic hand hygiene, respiratory hygiene, use of personal protective equipment (to block splashes or other contact with infected materials), safe injection practice - and safe burial practices.

Health-care workers caring for patients with suspected or confirmed Ebola virus should apply extra infection control measures to prevent contact with the patient’s blood and body fluids and contaminated surfaces or materials such as clothing and bedding. When in close contact (within metre) of patients with EBV, health-care workers should wear face protection (a face shield or medical mask and goggles), a clean, non-sterile long-sleeved gown, and gloves (sterile gloves for some procedures).

Laboratory workers are also at risk. Samples taken from humans and animals for investigation of Ebola infection should be handled by trained staff and processed in suitably equipped laboratories.

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