Emerging Vector Borne Diseases

Question 1

Define emerging disease

Answer 1

a disease that has newly appeared in a population, OR that existed previously but is rapidly increasing in incidence or geographic range

Question 2

What is a vector borne disease?

Answer 2

A disease caused by a pathogen spread by an arthropod host (insect, tick, crustacean)
🞑 Not a disease with an intermediate host (eg, snail)
🞑 Not a disease caused by an arthropod itself (eg, scabies, fly strike, myiasis)

Question 3

List tick borne diseases and which ticks are vectors of these?

Answer 3

Vectors of babesiosis, ehrlichiosis and anaplasmosis include
Ixodes ricinus, Dermacentor reticulatus, Rhipicephalus sanguineus

R. sanguineus (brown dog tick) is also a vector of Rickettsia rickettsia (Rocky Mountain spotted fever) which can be fatal in dogs. Use to not be In the UK but seeing more cases

Question 4

name a soft tick

Answer 4

Ornithodorus

Question 5

What causes lyme disease?

Answer 5

Bacterial Spirochaete called Borrelia burgdorferi, spread by Ixodes ricinus

Hence why another name for Lyme disease is Lyme borreliosis

Question 6

Why is Lyme disease significant?

What symptoms/ clinical signs

Answer 6

It is emerging in humans, causing rash, flu, fatigue, joint pain, neuroborreliosis. Can persist long term

Not of major significance in dogs but can cause fever, lameness, joint swelling, swollen lymph nodes, lethargy and inappetence

Question 7

How is the distribution of Ixodes ricinis changing?

Answer 7

Spreading to higher altitude and latitude

Question 8

How do the numbers of deer affect the ticks?

Answer 8

Deer at highest population size in UK since Roman times- emerging Lyme disease

There is a positive association between deer density and questing nymph

Fences put up to keep deer out leads to fewer ticks

Question 9

What is one reason why we are seeing rise in ticks, and their diseases, especially the likes of Rhipicephalus sanguineus

Answer 9

Prior to 2000, pets travelling to mainland Europe were quarantined upon return.

• From 2000, Pete Scheme pets could travel into the UK, upon provision of pet passport with evidence of microchip, rabies vaccination, treatment for tapeworm (Echinococcus) and ticks.
• Compulsory tick treatments stopped in January 2012.

Question 10

Canine babesiosis in the UK?

Answer 10

Seen for the first time in non travelled animals in 2016

Question 11

What is driving the emergence of hard tick borne diseases? (5 marks)

Answer 11

1. Spread of ticks – related to climate: inc latitude and altitude
2. Increased numbers and spread of hosts - deer
3. Increased movements of animals (eg, dogs)
4. Spread of viruses or ticks by migratory birds
5. Changes in international regulations – stopping of tick treatments for imported dogs

Question 12

What is the vector of African swine fever?

Answer 12

Ornithodorus, soft tick

Question 13

What is African swine fever
it causes…
Spread by…

Answer 13

The only known DNA arbovirus
Causes fatal haemorrhage disease of pigs
Spread by aerosol, Omithodorus soft tick bite or in feed (eating animal with disease)

Not in UK

Question 14

Is African swine fever resistant?

How is it dealt with?

Answer 14

Highly stable virus: survives 15 weeks in chilled meats; 6-9 months in cured meats; 15 years in frozen meats

No vaccine, no treatment, animals culled

Question 15

What is the driver of the emergence of African swine fever

Answer 15

🞑 Global movement of goods
Combined with…..
🞑 Poor biosecurity

Question 16

What 2 broad categories of mosquito do we have?

Answer 16

Invasive and Indigenous

Question 17

Talk about Aedes alboplctus mosquito: Asian Tiger Mosquito

Vector of:
How is it transported?

Answer 17

Vector of dengue, chikungunya, zika and Dirofilaria (heart worm)

Eggs laid in water can survive desiccation
🞑 Transported around world in used types and ‘lucky bamboo’ as lays eggs in water

Int the UK

Question 18

What are the drivers of the spread of Aedes albopictus

Answer 18

🞑Global trade (in tyres, plants)
🞑Road transport
🞑Facilitated by climate change

Question 19

Drive of West Nile virus emergence

Answer 19

🞑In USA – introduction of virus into continent with (i) competent vectors, (ii) naïve hosts [susceptible birds]
🞑In Europe – climate change?

Question 20

Culicoides

Answer 20

Pest and disease vector of animals & humans:
Economic damage
🞑	Limit tourism and outdoor activity
🞑	Severe allergic dermatitis (sweet itch) - horses
Transmission of pathogens
🞑	53 viruses
🞑	12 species of protozoa
🞑	18 species of filarial nematode

Question 21

Blue tongue

Answer 21

🞑 Causes severe disease in sheep and mild disease in cattle.
🞑 First discovered in 1904 in South Africa, but subsequently spread to Asia, Americas, Australasia and Europe

Question 22

African horse sickness

Answer 22

Causes severe disease in horses, mild in mules/donkeys.
🞑 First discovered in the 18th C in South Africa. Found throughout Africa, occasional short incursions in Europe/Asia.

Question 23

drivers of emergence of Blue tongue

Answer 23

🞑Climate change
🞑 Causing midges to spread
🞑 Increasing their vector competence
🞑Global movements of animals/goods - bringing the viruses into Europe