Ebola

What lineage do hemorrhagic fever viruses belong to?

diverse lineages

How is Ebola transmitted?

• initaially zoonotic, from animals to humans via close contact with secretions/bodily fluids of infected animals

• then, human-to-human transmission via direct contact with blood/fluids/contaminated objects

What are the natural ebola virus hosts?

fruit bats

When is ebola most infectious?

at/after death

In infected people, how can ebola be transmitted?

• via bodily fluids into skin/blood

  • ex. blood, urine, vomit, tears, sweat, saliva, semen, breast milk

• contact with contaminated items

  • ex. clohtes, bedding, medical equipment

• Sexual activity with someone who has recovered from ebola

What are the stages of ebola disease symptoms?

1. infection/exposure

2. incubation period - 4-17 days, can’t transmit virus

3. dry phase - like a bad flu, can transmit, can fight off at this stage

4. wet phase - more fluid release, most contagious

Where did ebola originate from and why?

• Democratic republic of Congo in the 1970s

• found in densely forested areas with more wild animals and hunting of tem

HOw long are people quarantined for potential ebola exposure and why?

• 21 to 45 days

• virus has long potential incubation period

What are the species of Ebola virusses?

• bundibugyo

• zairense

• sudan virus

• Tai Forst

What species of ebola virus most commonly causes outbreaks?

Ebola - Orthoebolavirus zairense

What family do Ebola viruses belong to?

Orthoebolavirues

What species is the current ebola virus outbreak and why does this matter?

• Bundibugyo virus

• less common, fewer helpful medicines

• causing disease to spread faster than previous outbreaks

What is delayed recognition of Ebola virus associated with? Why does delayed recognition occur?

• associated with longer and larger outbreaks

• occurs in areas with high malaria cases, so Ebola often initally assumed to be malaria

What is the primary case in an Ebola virus outbreak?

• first case from zoonotic spillover

• leads to undetected transmission period determined retrospectively

What is the index case?

first recognized case of a virus - official beginngin of an outbreak

What is the final case in terms of an Eboal outbreak?

• last case

• after 42-day observation period

How are ebola case-fatality rates different now than when the virsu officially emerged?

lower death rates

How is the Ebola virus structured?

• enveloped

• non-segment genome - linear

• negative ssRNA

• GP (glycoprotein) on surface

What are GPs on ebola viruses and what do they do?

• glycoprotein

• attachment to host

• entry to host

• counteracts host antiviral and adaptive immune responses by entering WBC

• cause cell death (cytotoxicity)

• decrease endothelial barrier function

Describe how the Ebola virus enters cells once its in the blood

• intially attacks monocytes/macrophages and dendritic cells

• GP protein attaches to host cell membarane

• virus enters WBC and is surronded by a host cell endosome

What causes ebola flu-like symptoms to progress to more severe, full-body symptoms?

virsu can move from WBC to organs and circulatory system (pantropic)

What is a pantropic virus?

virus that can infect a variety of tissue types

What are the different T-cell/immune responses to Ebola viruses and what outcomes do they lead to?

• low T- cell response - Tcell underactivation, low cytokine production → poor, weak immune response (death)

• adequate response - T cell responds adequately, adequate cytokine production → good, robust immune response (recovery)

• massive response - T-cell over response, massive release of cytokines → poor, hyperactivated immune response (death)

Are people immune after recovery from infection with Ebola?

yes

What do T-cells do?

lymphocytes (WBC) that coordinate and destroy virus-infected cells

What inflammatory response does Ebola trigger?

low or excessive cytokine relase

What causes hemorrhagic manifestations/fever in Ebola?

infection of circulatory system

What makes the 2026 DRC outbreak different from previous outbreaks of Ebola disease?

• Bundibugyo strain instead of Zaire strain

• no approved vaccines or specific treatments

• control depends more on early detection, isolation, and safe burials

• faster growth

Are there vaccines or treatments available to fight the current Ebola outbreak?

• testing of a post-exposure antiviral pill

• no approved vaccine or treament

• supportive care ex. fluids, oxygen, blood pressure meds

What clinical testing methods are available to detect Ebola virus infections during the current outbreak?

• PCR testing of blood for RNA

• antigen tests for proteins

• antibody tests for immune response

What else can be done to limit the spread of the Ebola virus during the current outbreak?

• early testing and isolation

• contact training

• safe burials