Emerging viruses

Question 1

Emerging vs re-emerging vs deliberately emerging infections

Answer 1

Emerging: new (for human population), eg SARS-CoV2
Re-emerging: known pathogens > increased incidence/occurence in new geographic regions, eg Zika
Deliberatelyemerging: generated in lab (bioterrorism), eg Anthrax

Question 2

Factors that promote occurrence of emerging diseases

Answer 2

Microbial factors (eg mutations). 
Social determinants (eg increasing population size, poverty, war international travel/trade).
Environmental factors (eg climate change, exploitation of natural resources, nnatural disasters).

Question 3

Def zoonoses

Answer 3

Infectious diseases that are transmittable between animals and humans (both directions).

Major part of emerging infectious diseases.

Question 4

Def natural reservoir

Answer 4

(Animal) species that carries/amplifies a zoonotic pathogen, usually does not develop (severe) disease, secretes/disseminates the zoonotic pathogen.

Can but does not have to be source of human infection.

Question 5

Transmission routes from natural reservoir to humans

Answer 5

1. Direct (via air/aerosol or biting/bodily fluids)

2. Indirect (via contaminated food/water or vectors or intermediate hosts)

Question 6

Influenza A transmission, reservoir

Answer 6

Direct: air/aerosols.

Natural reservoir: aquatic birds. Bird-to-human transmission of Avian influenza A, but no/inefficient human-to-human transmission.

Question 7

Lymphocytic choriomengitis virus transmission

Answer 7

Direct transmission (air/aerosols).

Reservoir: rodents. Infection of humans via aerosolized feces (dust) or contaminated food.

Risk only for immunocompromised/fetus.

Question 8

Rabies virus - transmission, reservoir

Answer 8

Direct (biting/saliva).

Resrevoir: bats/terrestrial carnivores.

Humans: fatal encephalitis.

Question 9

HepE transmission

Answer 9

Indirect: water/food.

Reservoir: pigs.
Humans: hepatitis

Transmission: fecal oral (water), raw meat products

Risk for pregnant women.

Question 10

Nipah virus transmission

Answer 10

Indirect (water/food).
Reservoir: bats.
Humans: encephalitis.
High mortality.

Source: contaminated palm juice in Bangladesh/India.

Question 11

Arbovirus transmission

Answer 11

Indirect (insects).

Insects can either act as an exclusive hsot (Vector > no transmission to offspring) or as
Vector and host (> transmission of virus to offspring)

Dengue, Zika

Question 12

Indirect transmission via intermediate host (2 ways)

Answer 12

1. the intermediate host bridges a ecological gap between the natural reservoir and humans (virus is already capable of infecting humans), eg Hendra virus
2. the virus mutates/apapts (genetic gap) within the natural reservoir and thereby gains the ability to efficiently infect humans, eg SARS-CoV

Question 13

Hendra virus transmission

Answer 13

Indirect (intermediate host).
Reservoir: bats.
Infection of horses via food/water.
Horse-human transmission via secretions. No human-human.

Respiratory, neurological diseases.

Question 14

SARS-CoV transmission

Answer 14

Indirect (intermediate host).
Reservoir: horseshoe bats. Virus mutated in intermediate host (civet cat). Severe atypical pneumonia in humans.

Receptor: ACE2

Question 15

Most common cause of food-ass. zoonoses

Answer 15

Bacteria

But: HepE!

Question 16

Ebola virus transmission

Answer 16

Contact to bodily fluids (blood, feces, urine, sweat).
Enters body thourgh microlesions in skin/mucosa.
Needle-stick infections are lethal.
Not transmitted via air.

Question 17

Ebola clinical picture

Answer 17

Phase 1: fever, fatigue, headache etc.
Phase 2: vomiting, diarrhea, rash etc., sometimes hemorrhages
Phase 3: cardiopulmonary shock, death

Question 18

Ebola zoonosis

Answer 18

Reservoir: flying foxes.

Transmission chains: bats > other animals > humans

Question 19

Reston virus

Answer 19

Closely related to Ebola, but apathogenic in humans.

Question 20

Ebola glycoprotein

Answer 20

Glycosylations reduce efficency of neutralizing ab.
Use unspecific, interchangeable attachment factors on cell surface.
Find receptor (NPC1) in cell.
Activated by endosomal cysteine proteases cathepsin at low pH.

Question 21

Coronoviruses - origin

Answer 21

All human CoV originate from animals.
Ancient introduction (animal background: bats, rodents) > human-associated common cold viruses
Recent introduction (from bats, via intermediate hosts): zoonotic viruses causing severe disease in humans

Question 22

Coronavirus spike glycoprotein

Answer 22

Key for cell entry. Binds to ACE2.

Defines host range.

Question 23

New coronaviruses

Answer 23

Bats carry diverse coronaviruses.

Coronavirus genomes can recombine, resulting in “new” viruses with possibly new properties (host range, infectivity, transmissibility, pathogenesis, …) Future spillover events by bat coronaviruses are likely, as some of them can already infect human cells without prior adaptation

Question 24

Coronaviruses that infect humans

Answer 24

Common cold: HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU1

Severe pneumonia: SARS-CoV, SARS-2-CoV, MERS-CoV