Presentation 7: Tick Borne Encephalitis

Question 1

How is TBEV classified?

Answer 1

Family: Flaviviridae
Genus: Flavivirus
Positive single stranded RNA

Question 2

What are the 3 subtypes of TBEV?

Answer 2

European TBEV
Siberian TBEV
Far eastern TBEV

Question 3

What is attributed to a rise in TBEV?

Answer 3

Biotic factors and climate change

Question 4

What was the question of this paper?

Answer 4

How can the virus be maintained in a small focus geographically despite such low infection prevalence in I. ricinus?

Question 5

What is the importance of a tick?

Answer 5

Carry many different viruses

Ixodes Ricinus is the most common tick vector for pathogens of human diseases in Europe

Question 6

How were the ticks collected in this study?

Answer 6

29 locations in southern and central Sweeden
2074 nymphs
906 adult ticks

Question 7

What were the other methods in this study?

Answer 7

RT-PCR was used to screen for TBEV in ticks
Extracted in pools: 20 nymphs or one adult tick
Primers targeted 3’ end region of TBEV genome

Question 8

What results were found in Sweden?

Answer 8

Nymphs: MIR = 0.10%, 2/108 TBEV positive
Adults: MIR = 0.55%, 5/906 TBEV positive
Toro: Nymph MIR = 0.51%, Adult MIR = 4.48%
Overall data: MIR = 0.23%

Question 9

What results were found in Northern Europe?

Answer 9

Denmark, Sweden, Norway, Finland
Overall mean MIR = 0.28%
Based on nymphs and adult

Question 10

What were the overall results?

Answer 10

Mean prevalence = 0.28%
TBEV is transmitted 5 ways:
–> Ticks feed on virally infected hosts
–> Transovarial transmission
–> Transstadial transmission
–> Sexual transmission (male to female)
–> Non-viraemic transmission (most common)