Ebola virus

Background

Microbiology

• Negative-sense single-stranded RNA virus in the Filoviridae family, related to Marburg virus and Cueva virus
• The ebolavirus genus includes five species:
  • Zaire ebolavirus (EBOV), the most common
  • Bundibugyo ebolavirus (BDBV)
  • Reston ebolavirus (RESTV), which does not cause disease in humans
  • Sudan ebolavirus (SUDV)
  • Taï Forest (or Cote d'Ivoire) ebolavirus (TAFV)

Epidemiology

• Essentially located exclusively in west Africa
• Outbreaks occur where there is food insecurity (with resultant hunting for bush meat), increased population density, and insufficient public health infrastructure
• Human-to-human transmission occurs via exposure to contaminated blood or fluids, including providing care to infected family or patient and preparing an infected body for funeral
• Mainly infectious during symptoms, which corresponds to viremia

Clinical Manifestations

• Incubation period 2 to 21 days (generally 3 to 13 days)
• Initially starts as a non-specific influenza-like illness with fever, fatigue, myalgias, weakness, and dizziness
• Followed by multiorgan involvement and hemorrhagic manifestations (30-50%)
• EBOV can persist after resolution of symptoms in privileged sites: the eyes, CNS, male reproductive tract, and mammary glands
• Relapse can occur as uveitis or meningitis
• Death usually within 6 to 16 days of symptom onset

Prognosis and Complications

• 40 to 70% mortality, depending mostly on supportive care
• Hiccups associated with increased mortality

Diagnosis

• Ensure to notify the lab before sending samples, and contact Public Health for instructions
  • Biosafety level 4 agent
• qPCR at the Public Health Laboratory Ontario, but only for Zaire ebolavirus
• Canada's National Microbiology Laboratory does RT-PCR, viral isolation, and serology

Management

• Supportive care alone can decrease mortality to 20-30%
• Monoclonal antibodies
  • REGN-EB3 (6% mortality)
  • mAb-114 (11% mortality)
  • Zmapp (24% mortality)
• Medications
  • Remdesivir (33% mortality)

Prevention

Vaccination

• Vaccination with a recombinant vesicular stomatitis virus that has its glycoprotein replaced by Ebola virus glycoprotein
  • Used in large West African and DRC outbreaks with ring vaccination
  • Efficacy 95-100%
  • >100,000 doses give

Infection Prevention and Control

• Isolate patient
• Droplet precautions and face protection within 1 meter of patient
• Limit hospital staff who have contact