EMERGING AND RE-EMERGING ZOONOSES

Question 1

Definition of emergening zoonotic disease

Answer 1

= zoonotic disease either by
i) New agents
ii) Micro-organisms previously known but now occurring in new places or species

Question 2

How does deforestation/changing farming practices lead to emergency of infectious disease

Answer 2

Bring farmed animals into proximity of insect vectors and new species

Question 3

Main 3 factors involved in emerging diseases

Answer 3

> Biodiversity loss
POverty
War/farmine

Question 4

Which type of virus can specifially adapt rapidly

Answer 4

RNA viruses
Error prone polymerase proof reading

Question 5

Stages of diseases adapting to infect humans 1-5

Answer 5

1 = just animals
2 = primary infection from animals to humans
3 = limited outbreak; some transmission b/w humans
4 = long outbreak; transmission from animals to humans and b/w humans
5 = exclusively human agent so just catch from other people

Question 6

What is vesicular exanthema of swine and how was it controlled

Answer 6

Disease in pigs characterised by vesicles and erosions in mouth/feet/teats
Indistinguishable from FMD

INtroduced requirement to cook pig swill before feeding

Question 7

Cause of SARS early 2000s outbreak and why was it easier to control that SARS-CoV-2

Answer 7

Coronavirus; from palm civets sold live; then spread via human travel

Controlled via banning sale of this species, closing markets and putting quarantine into place

Easy to contro because transmission only occurred when people were very ill (so not out)

Question 8

What is West Nile Fever virus and how is it controlled

Answer 8

= flavivirus occuring in low mortality in bird populations
Spread via mosquitos and ticks to humans and horses where it can cause encephalitits

Can’t eradicate due to wild bird prevalence; do surveillane, mosquito control, vaccination

Question 9

What issues does hepatitis E virus cause

Answer 9

High mortality in pregnant women (20%)

Endemic in pigs; may be assocaited with raw pig liger consumption, working with pigs

Mixed human and pig strains suggests transmission between the two species

Question 10

What is monkeypox

Answer 10

= virus of arboreal squirrels in central Africa
In humans causes fever and generalised rash

Shows signs of adaptations to humans; now lower mortality and more human to human transmission

Question 11

Where did COVID-19 come from and which species did it affect

Answer 11

From horseshoe bats

Endemic transmission in humans
INfection of cats and dogs (seem to be dead ends)
Amongst farmed mink and back to humans
+ transmission to/from hamsters and white tailed deer

Question 12

What demographic of people die from rabies

Answer 12

Developing world
Mostly children <15

Question 13

What type of virus is rabies and what serotype

Answer 13

= lyssavirus (enveloped RNA virus)
Serotype I (same as EBLV in bats etc)

Question 14

Why is the incubation period of rabies long and why so variable

Answer 14

Because spread is via nervous system not blood

Variation due to where the bite was and the virus entered nerves

Question 15

Pathogenesis of rabies

Answer 15

Enters muscle tissue via bite wound; then enters PNS via an NMJ
Travels up nerves to the spinal cord and brain

replicates in brain esp in purkinje cells of the cerebellum

Leaves via parasympathetic nerves to the salivary glands where it replicates and can infect new hosts

+ virus enters peripheral nerves of skin and hair follciles

And spreads from brain to other orcans

Question 16

Symptoms of rabies in humans + incubation period

Answer 16

Incubation = 20-60 days
Get actue fatal encephalitis with death in 1-5 days of signs

Non-specific febrile illness
Hyperexcitability, fever, fluctuating consciousness, anxiety, confusion, hallucinations, automonic dysfunction, dysphagia, insomnia, seizures, hydrophobia

Question 17

What is considered a category III exposure to rabies i.e highest risk

and what to do

Answer 17

Transdermal bite
Lick of broken skin
Contamination of mucous membranes with saliva

Give vaccine and rabies immunoglobulin (as distant sites to each other)

Question 18

What is a category II exposre to rabites and what to do

Answer 18

Nibbling of uncovered skin, minor scratches or abrasions without bleeding

Give vaccine asap

Question 19

Is dumb or furious rabies more common in dogs

Answer 19

80% get dumb rabies as endstage

Question 20

Rabies incubation period in dogs and first signs

Answer 20

7 days to several motnhs

First enter the prodromal stage: behavioural change, pyrexia, dilated pupils, nictitating membrane across eye, salivation

Question 21

Signs of rabies in cats

Answer 21

Non specific encephalitis/fever
80% show aggression
Dead end hosts with death in days

[In prodromal stage, just subtle behavioural change]

Question 22

What sign do horses with rabies often first present with

Answer 22

Choke

Question 23

How do cattle and sheep with rabies present

Answer 23

High % go to furious form
Mostly dead edn

Question 24

What proportion of human cases of rabies come from dogs

Answer 24

99%

Question 25

What type of vaccine is the dog rabies vaccine

Answer 25

Inactivated tissue culture
Do first one at 3 months and then boost at 2-3 years

Question 26

What wildlife species is important in rabies cycles in europe

Answer 26

foxes

Question 27

How was oral baited vaccine monitored e.g in foxes

Answer 27

Looking for oxytetracycline in teeth as this was added to vaccine