Ebolavirus

Question 1

What is Marburg Haemorrhagic Fever?

Answer 1

1967
= cases of haemorrhagic fever in Marburg, Germany

= Lab workers infected from african green monkeys imported from uganda

= from species: Marburg marburgvirus

= from family: filoviridae
(same family as Ebolavirus)

Question 2

What is Ebola Haemorrhagic Fever?

Answer 2

Zaire + Sudan
= simultaneous outbreaks in 1976 in DRC and Sudan

DRC index case - unknown
Sudan index case - cotton factory workers

= spread by contaminated needles, among family membrs

(named after small river in northwestern DRC)

New species: Bundibugyo ebolavirus
= caused outbreak in western uganda
= 37 deaths, 149 cases

New: Tai Forest
= ethnologist infected while examining dead chimpanzee

New: Reston, USA
= 4 humans seroconverted, no disease
= due to macaques shipped from phillipines
= virus detected in pig in Phillipines, 2009

Question 3

What is the ecology of filovirus?

Answer 3

= marburg virus isolated from cave-dwelling fruit bats
(Rousettus aegyptiacus)

Zaire ebolivurs RNA + antibodies
= found in 3 tree-roosting bats
(BUT not the infectious virus found)

Fruit bats
= don’t show any symptoms (best reservoir)
= make them hard to sample (research needed)

Dead-end hosts
= humans, gorilla, chimpanzees

Bush meat
= common source of food in several african countries

Question 4

What is the correlation of bat population with Ebola prevalence?

Answer 4

= geographical distribution of bats aligned with the disease occurrence
(filovirus positive bat species - genome or antibodies)

= immunisation of hot-spots could avoid recursion

Question 5

What are some examples of Ebolavirus outbreaks involving Chimps?

Answer 5

Gabon, 1996
= Zaire ebolavirus, 37 cases
= chimp found dead in forest was eaten by people hunting for food
= 18 people involved in animal butchering became ill
= 10 other cases in family members

Gabon 1996-97
= Zaire ebolavirus, 60 cases
= hunter who lived in forest camp
= dead chimp found in forest at time was infected with ebolavirus

Question 6

How are humans infected?

Answer 6

= classical zoonosis

= index case: contact with animal carcass (e.g. bushmeat)

= transmitted to other humans by close contact with infected fluids

= chains of human infections are short

= reproductive index = 2

= enters through injuries, skin abrasions

= contact w/ infected blood or body fluids from someone who is sick or has died
(e.g. urine, saliva, sweat, faeces, vomit, breast milk, semen)

= or contact w/ contaminated objects
(e.g. needles, syringes)

(NOT by insects, water, food or aerosol)

NOTE
= also affected by temperature / sample environment

Question 7

What are the clinical features of Ebolavirus?

Answer 7

Incubation period
= 2-21 days
= not contagious

Early symptoms
= fever, headache, muscle pain, diarrhea, vomiting, stomach pain

Peak illness
= rash, haemorrhage, convulsions, severe metabolic disturbance
= diffuse coagulopathy

Question 8

How does the impairment of vascular + coagulation system occur?

Answer 8

= replication in endothelial cells

= tissue factor release from infected macrophages may induce coagulation irregularities

= massive loss of blood

Question 9

What are the multisystem involvement clinical features?

Answer 9

Systemic
= prostation

Gastrointestinal
= anorexia, nausea, vomiting, abdominal pain, diarrhea

Respiratory
= chest pain, shortness of breath, cough

Vascular
= conjunctival infection, postural hypotension, edema

Neurological
= headache, confusion, coma

(up to 90% case fatality ratio in Africa)

Question 10

What are the Environmental and Cultural Factors in Ebolavirus?

Answer 10

= can enhance human-to-human transmission

= seasonal triggers of Ebola outbreaks

e.g.
= decades of civil unrest + human mobility
= background noise from endemic infectious diseases
= damaged public health infrastructures
= high population mobility across porous borders
= severe shortage of health care workers
= cultural beliefs + behavioural practices
= reliance on traditional healers
= spread by international air travel