MICR5836 L18: Ebola Disease, Transmission and Outbreaks 10/29/36

MICR5836 L18 Ebola

What are viral haemorrhagic fevers?

-Broad clinical grouping of diseases caused by viruses from several classes, orders and families

-Potential for person-to-person transmission

What is the typical reservoir origin category for VHF?

-Zoonotic origin

-High case fatality and severe systemic illness

How do these infections spread among people beyond the initial animal source?

-Potential for human-to-human transmission

-Through close contact

What specific operational risk do these infectious agents pose inside medical facilities?

Significant risk for healthcare-associated transmission to staff and patients

What level of disease severity and lethality can occur during Ebola outbreaks?

-Severe systemic illness with potentially high morbidity and mortality

-Exceeding 80% case fatality rates

True or False: Despite the name implying bleeding, haemorrhage is neither universal nor usually the presenting symptom of VHF

True

What broader taxonomic genus contains the viruses that cause Ebola disease?

Orthoebolavirus

Which specific ebolavirus species was responsible for the large 2014-16 West Africa epidemic?

Ebola (Zaire) virus (EBOV)

What human disease is caused by the Sudan virus (SUDV)?

Sudan virus disease

How frequently does Taï Forest virus (TAFV) cause human disease?

It is a very rare cause of human disease.

What outcome occurs when humans are infected with Reston virus or Bombali virus?

No disease in humans to date

What animal group serves as the most likely natural reservoir for the virus, carrying it asymptomatically?

Fruit bats

How do non-human primates and other mammals typically encounter/contract the virus from natural sources?

-Direct contact with infected bats

-Consuming contaminated fruit.

What specific human activities involving infected wildlife facilitate viral spillover into the human population?

-Hunting, handling, preparing, or consuming infected wildlife

-Commonly referred to as bushmeat

What are the typical early systemic symptoms that mark the onset of Ebola disease?

-Abrupt fever, profound fatigue or malaise

-Headache, myalgia, arthralgia, and sore throat.

How does Ebola disease manifest as it progresses beyond the early stage?

-Nausea, vomiting, diarrhea

-Abdominal pain, dehydration, rash

What critical organ system failures/severe complications characterize the final stages of Ebola disease?

-Shock, multiorgan dysfunction, encephalopathy

-Coagulation defects leading to haemorrhage.

Why is early clinical diagnosis of Ebola disease challenging based on its symptom presentation?

-Clinically non-specific

-Closely resembles many other common infections in returned travelers

A patient presents with acute fever and malaise after returning from an endemic region. What common viral respiratory infection does early Ebola disease frequently resemble?

Influenza or COVID-19

A traveler returning from abroad presents with acute febrile illness. Beyond respiratory viruses, what vector-borne tropical disease must early Ebola be differentiated from?

Malaria, dengue, or yellow fever

When evaluating a returned traveler with early non-specific symptoms, which bacterial gastrointestinal infections can mimic the presentation of Ebola disease?

Typhoid or shigellosis

What is the typical incubation period range for Ebola disease, and what duration is most common?

-Incubation period ranges from 2 to 21 days

-8 to 10 days is the most common

During what timeframe is an Ebola patient considered infectious to others?

-From the exact onset of symptoms

-Until complete symptom resolution or death

How long can the Ebola virus remain viable in post-mortem blood, body fluids, tissues, and body surfaces?

Virus remains viable for at least 7 days after death

What makes deceased Ebola patients remain a significant transmission hazard during funerals?

-Virus remains viable for at least 1 week in post-mortem tissues and fluids

-Deceased patients remain highly infectious

In which anatomical body sites can the Ebola virus persist for many months after recovery?

-Virus can persist in immune-privileged sites

-Semen, eyes, CNS

What primary exposure route involves contact with blood or body fluids from a symptomatic individual?

-Direct contact with blood or body fluids

-Symptomatic or deceased infected person.

How can contaminated environmental surfaces or objects act as a transmission vehicle?

-Contaminated fomites

-Transfer infectious agents upon contact.

What type of professional exposure poses a risk via accidental sharps injuries?

-Healthcare Exposures

-Example: Needlestick injuries.

How common is sexual transmission relative to other routes?

Sexual transmission is Uncommon

Why is casual contact generally insufficient for spreading the pathogen?

It is not transmitted efficiently through casual contact

Under normal conditions, is the pathogen considered airborne?

No, it is not airborne under normal conditions.

True or False: Australia has never had a case of Ebola disease or another quarantinable VHF

True

What constitutes the primary risk factor for Australia concerning viral hemorrhagic fevers?

Main risk: Importation from an outbreak-affected region.

Why is a low statistical probability of a VHF importation not equivalent to a low overall risk?

Because the potential consequences of a single imported case are exceptionally severe.

What clinical and public health characteristics classify viral hemorrhagic fevers as high-consequence infectious diseases?

High morbidity and mortality [along with severe risks] to healthcare workers and close contacts.

What operational demands do viral hemorrhagic fevers require from healthcare infrastructure regarding diagnostics and safety?

1) Specialist laboratory

2) Infection Prevention + Control (IPC) arrangements

What public health tracking measures are necessitated by a suspected or confirmed VHF case?

-Intensive Contact Identification + Monitoring

-Required to prevent onward transmission

Beyond clinical patient management, what broader systemic impacts do VHFs cause within a healthcare system?

Major Workforce + Service Disruption

What external socio-political pressures typically accompany the threat of an imported VHF case?

Significant Community Concern + Intense Media Attention.

Why do the repercussions of a single imported VHF case extend beyond the individual patient?

-Widespread impacts

-Healthcare strain, workforce disruption, intense public scrutiny

When was Ebola disease first recognized?

1976 in DR Congo and South Sudan

Across which regions have Ebola outbreaks predominantly occurred?

-Sub-Saharan Africa

-Especially Central and East Africa.

What was the major geographical exception to the typical outbreak locations?

West African epidemic from 2014-2016

What is the typical case scale for most Ebola outbreaks?

Most Ebola outbreaks are smaller, involving 10s to 100s of cases

How many historical Ebola outbreaks have surpassed 1,000 total cases?

Only 3 outbreaks have surpassed 1,000 cases.

What was the case count, death count, and case fatality rate of the West Africa 2014-16 Ebola outbreak?

It had 28,600 cases and 11,300 deaths, resulting in a case fatality rate of approximately 40%.

What are the case and death totals as of 5 October 2026 for the ongoing DRC/Uganda Ebola outbreak?

It has recorded 8,700 cases and 4,200 deaths, with a case fatality rate around 48%.

What was the case fatality rate during the 2018-20 DRC/Uganda Ebola outbreak?

Outbreak had 3,500 cases, 2,300 deaths, and a higher case fatality rate of approximately 66%.

Which specific viral strain caused the 2013-2016 Ebola epidemic?

Ebola Zaire virus strain

Where did the 2013-2016 Ebola outbreak officially begin?

Guinea in late 2013

What were the three primary nations that experienced major transmission during the 2013-2016 Ebola epidemic?

1) Guinea

2) Liberia

3) Sierra Leone.

How did the viral geographic spread change as the 2013-2016 Ebola epidemic progressed within the affected countries?

Spread rapidly into dense urban populations and capital cities

How far did the 2013-2016 Ebola outbreak reach beyond the three primary West African nations?

-Spread internationally to 7 additional countries

-Including nations in North America and Europe.

Why was containing the 2013-2016 Ebola epidemic so difficult globally and regionally?

-Transmission was augmented

-Control efforts were hampered by a combination of compounding factors

What key factors drove the West Africa 2014-2016 Epidemic?

• Fragile clinical and public health infrastructure

• Urban and slum transmission

• Porous borders and high mobility

• Traditional burial and cultural practices

• Healthcare worker vulnerability

• Delayed response and mistrust in institutions

Describe the massive, coordinated international public health effort to end the West Africa 2014-2016 epidemic:

-Community Efforts

• Rapid case isolation in purpose-built Ebola Treatment Units

• Contact tracing, community engagement

• Safe/dignified burial protocols with religious clerics

Describe the massive, coordinated international public health effort to control the West Africa 2014-2016 epidemic:

-International Efforts

• Accelerated development of licensed vaccines and therapeutics

• Enhanced infection prevention + control measures in healthcare settings → PPE, decontamination

• International mobilisation → WHO, US CDC, USAID, UN taskforce, military/medical personnel

True or False: West Africa's 2014-2016 Ebola epidemic remains the largest Ebola epidemic ever recorded and appeared unique for a decade

True

What is the Case Fatality Rate (CFR) for the 2026 Bundibugyo epidemic?

-Approximately 48%

-About half of all cases have died.

How does the 2026 Bundibugyo epidemic rank historically among all Ebola outbreaks recorded?

Second-largest Ebola outbreak ever recorded

What distinguishes the 2026 Bundibugyo epidemic among Bundibugyo virus outbreaks specifically?

Largest Bundibugyo outbreak ever recorded and only the third on record.

What distinguishes the transmission velocity of this outbreak compared to others?

Fastest-growing Ebola outbreak ever recorded.

What region remains the primary epicentre of transmission for 2026 Bundibugyo within the DRC?

Ituri region

How widespread is Bundibugyo across the DRC 2026 in terms of health zones and provinces?

Affects 63 health zones across 7 provinces

What characterizes the 2026 Bundibugyo transmission trends across the affected areas in the DRC?

-Trends are not homogeneous

-Transmission is declining in some areas and increasing in others

Describe the international spread of 2026 Bundibugyo

-Uganda: 20 confirmed [15 imported, 5 local]

-France: 1 imported

-Kenya: 1 imported

Which country received medical evacuations for two cases diagnosed in the DRC?

Germany received 2 medically evacuated cases diagnosed in the DRC

What distinguishes the case accumulation speed of the 2026 Bundibugyo epidemic compared to the 2018-20 DRC Ebola epidemic?

2026 Bundibugyo epidemic surpassed the total case count of the 2018-20 epidemic (3,748 cases) in just 11 weeks

How does the duration of the 2018-20 DRC Ebola epidemic contrast with the rapid timeline of the 2026 Bundibugyo outbreak?

2018-20 epidemic lasted nearly 23 months to reach its total case count.

Besides the 2018-20 DRC outbreak, what other major historical Ebola epidemic experienced a slower growth rate than the 2026 Bundibugyo event?

2014-16 West African epidemic

What is this?

1) Delayed Recognition

2) No licensed vaccines or therapeutics

3) Population Mobility

4) Conflict and displacement

5) Collapsed Public Health Infrastructure

6) Congolese Burial Practices

7) Community Mistrust

Drivers of the 2026 Bundibugyo epidemic

Why was there a delay in recognising 2026 Bundibugyo epidemic initially?

Outbreak was already well established before it was officially confirmed

What contributed to early cases failing to be identified correctly?

Healthcare personnel did not initially recognise them as possible Ebola infections.

Why did early diagnostic kits fail during the outbreak?

They were designed exclusively to detect the more common Ebola Zaire virus strain instead of the Bundibugyo virus.

What availability status do vaccines and therapeutics have for the Bundibugyo virus?

There are currently no licensed vaccines, antiviral drugs, or registered therapeutics, though clinical trials are ongoing.

Name this driver of the 2026 Bundibugyo Epidemic:

• Outbreak was established before confirmation.

• Early cases were not recognised as possible Ebola.

• Early diagnostic kits failed because they were designed only to detect the more common Ebola (Zaire) virus strain rather than Bundibugyo virus

(1) Delayed Recognition

Name this driver of the 2026 Bundibugyo Epidemic:

• Unlike Ebola (Zaire) virus, there are no licensed vaccines, antiviral drugs, or registered therapeutics for Bundibugyo → trials are ongoing.

(2) No licensed vaccines or therapeutics

Name this driver of the 2026 Bundibugyo epidemic:

• There is substantial internal population movement in Ituri and surrounding provinces, cross-border trade, mining-related movement and road and river transport.

• International borders are highly porous.

(3) Population Mobility

Name this driver of the 2026 Bundibugyo epidemic:

• Decades of regional insecurity and conflict.

• Large displaced populations and

encampments.

• Difficult physical access to some communities

(4) Conflict and Displacement

Name this driver of the 2026 Bundibugyo Epidemic:

• Heavily under-resourced health system.

• Compounded by healthcare worker strikes due to non- payment.

• Limited operational public health capacity → contact tracing gaps.

• Geopolitical environment → severe aid funding contractions.

(5) Collapsed Public Health Infrastructure

Name this driver of the 2026 Bundibugyo epidemic:

• High degree of contact with the deceased

• Large, prolonged vigils and gatherings.

(6) Congolese burial practices

Name this driver of the 2026 Bundibugyo epidemic:

• Deep-seated distrust of government authorities.

• Reluctance to engage with healthcare and response teams.

• Spread of misinformation.

• Mistrust has resulted in violent attacks on response teams.

(7) Community Mistrust

List all drivers of the 2026 Bundibugyo Epidemic

1) Delayed Recognition

2) No licensed vaccines or therapeutics

3) Population Mobility

4) Conflict and displacement

5) Collapsed Public Health Infrastructure

6) Congolese Burial Practices

7) Community Mistrust

According to the WHO's August 2026 rapid risk assessment, what is the risk level for further spread to additional health zones within the DRC?

Very high

Based on the August 2026 WHO assessment, what risk level is assigned to countries sharing land borders with the DRC?

High

What risk level did the WHO rapid risk assessment assign to the rest of the African Region outside of the DRC and its bordering nations?

Low

In the WHO August 2026 assessment, how is the risk of spread to the rest of the world categorized?

Low

What is the current risk assessment level given by the Australian Centre for Disease Control regarding the affected region?

Low

How do geographic distance and travel routes help keep Australia's risk assessment low?

Long + indirect travel routes from affected region

What characterizes the annual traveller volumes from the affected region to Australia?

Comparatively small

What type of exposure is required for transmission to occur, as opposed to casual contact?

Direct exposure to infectious body fluids

Are infected individuals infectious during the incubation period?

No, infected people are not infectious during incubation

What established systems in Australia contribute to the low risk assessment alongside geographic and transmission factors?

Surveillance, border, and public health systems

What are the implications if Bundibugyo (Ebola) is imported to Australia?

-Public

• Potential household, community and healthcare exposures

• Intense public + media concern

• Discrimination

What are the implications if Bundibugyo (Ebola) is imported to Australia?

-Healthcare Infrastructure

• Interruption to normal hospital services/workforce impacts

• Specialised transport, laboratory requirements, waste management

• Substantial resources required for response

Which level of government holds the primary responsibility for preparedness and response to viral haemorrhagic fevers (VHFs) in Australia?

-States and territories take the principal leadership role

-Support from federal legislative frameworks and guidance

What legislative mechanism classifies viral haemorrhagic fevers as listed human diseases to enable enhanced border control and screening powers in Australia?

-Biosecurity Act 2015 provides the national biosecurity legislation

-Classifies VHFs accordingly

What organization produces consistent national public health guidelines detailing case definitions as well as case and contact management for public health authorities?

Communicable Diseases Network Australi