NCCID Disease Debriefs provide Canadian public health practitioners and clinicians with up-to-date reviews of essential information on prominent infectious diseases for Canadian public health practice. While not a formal literature review, information is gathered from key sources including peer reviewed literature, the Public Health Agency of Canada (PHAC), the USA Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO).
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Questions addressed in this Debrief:
What are important characteristics of Ebola virus disease (EVD)?
Infection with Ebola virus, one of the most virulent human pathogens.
Sign and Symptoms
Typically, sudden onset of fever, intense weakness, muscle pain, headache and sore throat, followed by vomiting, diarrhea, rash, impaired kidney and liver function, multiple organ failure, vascular manifestations (conjunctival injection, postural hypotension, edema), neurological signs (headache, confusion, coma) and in some cases, internal and external bleeding. Patients who present with these symptoms and signs should be assessed to determine their risk of exposure to Ebola virus.
Symptoms can begin 2 to 21 days after exposure
Ebola virus can be detected in the blood of an infected person three days after symptom onset by reverse-transcription polymerase chain reaction (RT-PCR)
According to WHO following diagnostic methods are used to confirm Ebola virus infection:
- Antibody-capture enzyme-linked immunosorbent assay (ELISA)
- Antigen-capture detection tests
- Serum neutralization test
- Virus isolation by cell culture
The Government of Canada and the provincial and territorial jurisdictions have case definitions for reporting purposes. In addition, in the context of the current outbreak, federally and some jurisdictions have developed guidelines for the purposes of case management and infection prevention and control.
Case fatality of diagnosed cases has been 30–90%. The average case fatality rate is about 50%.
CDC Outbreak Chronology: Ebola Virus Diseases– 2018
Since 1976 when the first case of Ebola virus was confirmed there have been 22 outbreaks. In 2017, eight cases were reported in the Democratic Republic of the Congo. As of 20 May 2018 the WHO (WHO-External Situation Report 4) reported about 51 cases in DRC with 27 deaths—a case fatality ratio of 52.9%.
During an outbreak, those at higher risk of infection are:
- health workers;
- family members or others in close contact with infected people;
- mourners who have direct contact with bodies during funerary rituals.
Unconfirmed, but considered to be most likely fruit bats (Pteropodidae). Ebola is introduced into the human population through the 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 in the rainforest.
Introduction into the human population: through close contact (handling and/or ingestion) with the blood, secretions, organs or other bodily fluids of infected animals, e.g. chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead in the rainforest. Virus on surfaces may remain infectious from hours to days.
Source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of High-Consequence Pathogens and Pathology (DHCPP), Viral Special Pathogens Branch (VSPB)
Human-to-human transmission: from direct contact (through broken skin or mucous membranes) with the blood, secretions, or other bodily fluids of infected people; or from contact through broken skin or mucous membrane with contaminated environment (e.g. soiled clothing, used needles). Most of these have been associated with care of ill people in health facilities or in the home, and preparation of corpses for burial.
According to the World Health Organization, the most infectious body fluids are blood, feces, and vomit.
2 to 21 days, usually about 10 days
Period of Communicability:
Patients become contagious once they begin to show symptoms; they are not thought to be contagious during the incubation period. The case remains communicable as long as the blood and body fluids (including seminal fluid and breastfeeding) contain the virus. This includes the post-mortem period.
The risks of sexual transmission are not well understood or confirmed. The WHO makes several recommendations for precaution for those in contact with Ebola patients.
Education of the public with respect to reducing exposure to reservoir sources, ill people and corpses in community settings, and implementation by health care workers of infection prevention and control measures in health care settings are the most important current preventive strategies. Health workers should follow specific guidelines for infection control.
According to the WHO, an experimental Ebola vaccine has been shown to be highly protective against the Ebola virus. Several trials involved more than 16,000 volunteers in Europe, Africa and the United States and subsequently the vaccine has been judged safe for use in humans based on available results.
The Ebola rVSV-ZEBOV vaccine works by replacing a gene from a harmless virus known as vesicular stomatitis virus (VSV) with a gene encoding an Ebola virus surface protein. The vaccine does not contain any live Ebola virus.
According to the WHO (May 23, 2018) a team from the Ministry of Health, MSF and WHO will determine who is eligible to be vaccinated, depending on their level of risk and health condition. The following people will be considered for vaccination: (i) contacts and contacts of contacts, (ii) local and international health-care and front-line workers in the affected areas and (iii) health-care and front-line workers in areas at risk of expansion of the outbreak will receive an injection of the candidate vaccine in the arm. Individuals should continue to protect themselves from infection by not touching live or dead infected patients, their body fluids such as blood, vomit, saliva, urine or feces. Even the items for personal use can also transmit the virus.
Similar to smallpox eradication, a ring vaccination strategy has been devised for vaccination.
Adverse effects of vaccination
The vaccine can produce some side effects. People who are vaccinated may have a mild fever or cold like symptoms, headache, muscle pain, fatigue.
Currently, there is no specific licensed treatment for Ebola. Patients are treated for their symptoms. Some people are able to recover without treatment. However, about 90% of Ebola patients die. The sooner the patient get treatment, the better their chances for recovery. Treatment includes:
- Supportive blood pressure and oxygen delivery (reduce vomiting and diarrhea, fever and pain).
- Ensuring proper fluid and care and electrolytes levels (necessary minerals for the body) by orally or intravenously.
- Strictly isolation in an intensive care unit to prevent the disease from spreading to others.
- A range of potential treatments including blood products, immune therapies and drug therapies are currently being evaluated.
Prognosis and when to discharge from hospital
According to the World Health Organization, individuals who no longer have signs and symptoms of Ebola virus disease can be discharged if they have two negative PCR tests on whole blood, separated by at least 48 hours.Back to top
What is happening in the 2018 EVD outbreak?
On 8 May 2018, an outbreak of Ebola virus disease (EVD) was announced by the Ministry of Health of the Democratic Republic of the Congo in Bikoro Health Zone, Equateur Province. As of May 27, 2018, a total of 54 EVD cases including 25 deaths (case fatality rate = 52.9%) have been reported from three health zones in Equateur Province. The total includes 14 confirmed, 21 probable and 10 suspected cases in Bikoro (n=29), Iboko (n=16) and Wangata (6) health zones. Bikoro health zone remains the epidemic center of the outbreak, reporting 56.9% of the total cases and 81.5% of all deaths. About 51% of the cases in Bikoro health zone were reported from Ikoko-Impenge health area – the area from where the first cases were reported. As one confirmed case was reported in Mbandaka (population of 1.2 million), there is a risk of spread to larger urban centres and neighbouring countries.Back to top
What is the current risk for Canadians from EVD?
Although it is quite possible that a person could arrive in Canada during the incubation period or after the onset of symptoms, the risk for Canadians is considered very low at this time. No case has been reported in Canada.
The Government of Canada provides relevant information to the Canadian public and travelers. Canada has protocols and resources to detect, investigate, and manage Ebola cases. As of May 18, 2018, Ebola virus disease in DRG is at level 1 risk which means travelers should practice usual precautions, routine vaccinations, handwashing and protective measures to avoid mosquito bites
WHO StatementsBack to top
What measures should be taken for a suspected EVD case or contact?
The government of Canada provides a guidance document for public health authorities in the event a human case of EVD or a close contact of an EVD case is identified in their jurisdiction.
Patients under investigation for Ebola virus disease must be immediately reported as per jurisdictional protocols. Provinces and territories are requested to notify and provide a clinical history of the patient’s illness to the Public Health Agency of Canada Health Portfolio Operations Centre (HPOC) at 1-800-545-7661. They should also fill out the Ebola Virus Disease Care Report Form at the time of the initial report.
NCCID’s Notifiable Diseases Database contains a summary of the reporting requirements for each jurisdiction across Canada for all viral hemorrhagic fevers, including Ebola.
Laboratory testing for a patient under investigation for Ebola virus disease must be done only with ongoing risk assessment and corresponding biosafety procedures, for which PHAC provides interim biosafety guidelines for laboratories handling specimens from patients under investigation for Ebola virus disease. Ebola viral cultures can only be done in a Containment Level 4 laboratory. The National Microbiology Laboratory (NML) is the only such facility in Canada. If a sample requires diagnostic testing for EVD, health professionals and laboratories should liaise with their provincial public health laboratory to coordinate with the NML. The number to coordinate with the NML Operations Centre Director (OCD) is 1-866-262-8433. The NML OCD will work with the requesting provincial or territorial jurisdiction to activate the Emergency Response Assistance Plan and will connect the individual with the subject matter expert if require assistance with the shipping process, sample requirements and sample shipping conditions.
Along with laboratory service requests for Ebola or other VHFs, provinces and territories should report a patient’s clinical history of illness to the HPOC. Contact the HPOC at 1-800-545-7661. Clarification or further information may be requested from the patient’s clinician to optimize delivery of requested laboratory services.
Infection prevention and control (IPC) measures
The Government of Canada, the WHO and the CDC have issued guidelines on IPC measures to be undertaken in a health care setting, including measures for environmental cleaning and linen and waste management (see PHAC Expert Working Group guidelines below). The Government of Canada also provides guidelines on IPC measures for passenger conveyances and terminals and interim guidance for airline cabin crews. Some provincial/territorial jurisdictions have developed their own guidelines for IPC measures in the context of the current outbreak.
Treatment is supportive, and is directed at maintaining renal function and electrolyte balance, and at combatting hemorrhage and shock.
The Government of Canada has created guidelines for the management of close contacts of EVD cases.
A close contact is defined as an individual:
- Including, but not limited to, a health care worker, family member, funeral worker, or volunteer, who has provided care to a confirmed or probable case or who has had other close physical contact with the case or deceased body, that may have resulted in unprotected exposure to blood or other body fluids from the case;
- Who has had contact with surfaces or equipment contaminated with blood or body fluids of a confirmed or probable case;
- Who has worked in a laboratory handling specimens from confirmed or probable cases and may have had unprotected exposure to these specimens through the course of their work.
The CDC and WHO recommends that contacts be followed for 21 days following exposure.
Some provincial/territorial jurisdictions have developed their guidelines for contact definition and management.