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Epidemiology - MIDTERM 2 > Topic 45 - Louping ill and tick-borne encephalitis > Flashcards

Topic 45 - Louping ill and tick-borne encephalitis Flashcards

1
Q

Causative agent of Louping ill diease

A

Flaviviridae family

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2
Q

are flavivirus enveloped or non-enveloped?

A

envelopd = low resistance

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3
Q

Are flavivirus RNA or DNA viruses?

A

RNA

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4
Q

Name genuses under flaviviridae family:

A
  1. Orthoflavivirus
  2. Pestivirus
  3. Hepacivirus
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5
Q

Pestivirus genus resistance:

A

Bit better than orthoflavivirus. They can retain their infectivity in the stomach and can therefore cause oral infections

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6
Q

Hepacivirus genus resistance:

A

Causes only human disease, no important to us

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7
Q

Orthoflavivirus genus resistance:

A

VERY weak. Can not survive in the stomach pH and can therefore NOT cause oral infections and need vectors for transmission

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8
Q

Why are enveloped viruses in general, sensitive to detergents and disinfectants?

A

Because enveloped viruses contain a lot of liquid

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9
Q

Is orthoflavivirus a arbovirus?

A

yes, due to weak resistance

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10
Q

Vectors for flaviviruses:

A

Mosquitos and ticks

Few are non-arboviruses

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11
Q

Are the mosquitos biological vectors, what does it mean?

A

yes
The virus replicates in the body of the mosquito

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12
Q

Host range of flavivirus:

A

Euryxen - Wide

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13
Q

Are flaviviruses season dependent?

A

yes.
The virus need optimal temperature in the body of the mosquito, so warmer weather.

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14
Q

First signs of flaviviruses and why:

A

The mosquito injects the virus into the blood (by feeding on it), and the first cells to multiply from the virus are the endothel cells, which cover the inner wall of the blood vessels. We have an instant reaction of the damged endothel cells, which are RASH, HEAMORRHAEGES and OEDEMAS

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15
Q

Target organ of the flaviviruses:

A

The brain, the neuron cells.

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16
Q

Why do we in some cases see CNS problems in case of flaviviruses, and in some not?

A

Normally the virus is NOT able to cross the blood-brain-barrier, but if there is an underlying disease (diabetes feks), it will make the barrier more diffusible and the virus will cross it and we see CNS signs.

Due to the Blood-brain-barrier, 80-90% of west-nile fever infections are subclinical

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17
Q

Antigenicity of flaviviruses:

A
  1. Good antigens - induce a strong immune response
  2. serological cross-reactions
  3. Sometimes cross-protections - never reliable as this is not 100%
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18
Q

Why is louping ill disease called what it is?

A

Because the animal lifts their legs in a way that it looks like they want to jump over a fence, it is a very characteristic sign

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19
Q

Occurence of louping ill disease:

A
  1. British isles
  2. Scandinavia
  3. Spain
  4. Greece
  5. Turkey
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20
Q

Vector of louping ill disease

A

Ixodes ricinus

Therefore seasonal outbreaks: late spring, summer and late autumn

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21
Q

Susceptible species of louping ill disease:

A
  1. sheep
  2. Domesticated and wild mammals
  3. red grouse = rype
  4. humans
22
Q

Which of the susceptible species of louping ill disease, are also maintaining hosts?

A

Sheep and red grouse

23
Q

incubation time of louping ill disease:

24
Q

Clinical signs of louping ill disease:

A
  1. Biphasic fever = 2 stage fever
  2. depression
  3. Ataxia
  4. trembling
  5. salivation
  6. convulsions
  7. tics

Often permanent damage after recovery

25
Q

how is louping ill disease shed?

A

through milk

Therefore young animals can be infected, through oral infection in this case

26
Q

histopathological lesions in case of louping ill disease:

A
  1. brain inflammation and neuron cell damages
  2. lymphocytic encephalitis
  3. neuron necrosis
  4. glia-proliferation
27
Q

How can we diagnose louping ill disease?

A
  1. Epizootiology
  2. Case history: seen tick in wool, geographical area
  3. Clinical signs
  4. histopathology
    By this we will have a good suspicion, but we have to detect the virus present
28
Q

Method done for detecting virus in case of louping ill disease

A

RT-PCR and dead animals brain are sendt for testing

ELISA is mostly done if we want to know if a geographical area or a farm have the presence of the virus, psotive result in active cases

29
Q

Is louping ill disease a notifiable disease?

A

no

BUT, clinical signs are similar to other notifiable disease (west nile fever), so we have to do samples to rule this out

30
Q

Prevention of louping ill disease:

A
  1. Tick control, prevent tick bites
  2. vaccine
31
Q

Vaccine type for louping ill disease

A

Inactivated vaccine in endemic areas, advised to immunise the sheep

32
Q

Public health considerations regarding louping ill disease:

A
  1. Human infections are rare
  2. humans ca be infected by: drinking milk, tick bite
  3. In rare cases, human show clinical signs: fever and meningoencephalitis
33
Q

Occurence of Tick-borne encephalitis

A

Tick-borne encephalitis have two types:

  1. Central-European (endemic)
  2. Far-Eastern lineages
34
Q

Vector of Tick-borne encephalitis:

A

Europe: Ixodes ricinus

Asia: ixodes persulcatus!!

35
Q

Transmission route of Tick-borne encephalitis:

A
  1. Vectors are biological vectors
  2. Vectors have transovarial transmisson
36
Q

What is a transovarial transmission, in this case - Tick-borne encephalitis?

A

The tick is hatched already contaminated with the virus

37
Q

Susceptibility of Tick-borne encephalitis:

A
  1. human
  2. domesticated and wild mammals
  3. birds
38
Q

Natural cycle of Tick-borne encephalitis:

A

Rodents + small mammals are maintaining host, then the tick feeds on them and transfers the virus

39
Q

How can Tick-borne encephalitis infection of humans and domesticated animals happen?

A
  1. Tick-bite (but seasonal)
  2. Consumption of raw milk (from goat)
40
Q

Pathogenesis of Tick-borne encephalitis:

A

The tick injects the virus into the blood vessels, the endothel cells multiply the virus and we get the viraemia which spreads the virus to the visceral organs and also gets to the CNS

41
Q

Incubation time for Tick-borne encephalitis:

42
Q

When can we see clinical signs in case of Tick-borne encephalitis?

A

If the blood-brain-barrier is weakened by other disease or a weak immune system

43
Q

How many days after Tick-borne encephalitis infection can we see the second fever?

44
Q

Which CNS signs are seen in case of Tick-borne encephalitis?

A
  1. Headache
  2. Restlessness
  3. Neck stiffness
  4. Weak limbs
  5. Paralysis
45
Q

mortality rate of Tick-borne encephalitis:

A

usually complete recovery, but permanent lesions may also remain if CNS symptoms where present

46
Q

Virus detection method of Tick-borne encephalitis:

A

RT-PCR

We use ELISA to see if the geographical area has the disease

47
Q

Differential diagnosis of Tick-borne encephalitis:

A

Everything which causes CNS problems

  1. Entero
  2. Toga
  3. Flavivirus (west nile virus)
  4. herpesvirus
  5. bacterial meningitis
48
Q

Prevention of Tick-borne encephalitis

A
  1. Prevent tick bite
  2. Vaccination
49
Q

Vaccination type for Tick-borne encephalitis

A

Only in humans!!

We use inactivate vaccine

50
Q

How often do we vaccinate in case of Tick-borne encephalitis:

A

We vaccinate 2 times a basic vaccination, then 1 shot in another year and then repeated every 3-4 years

Epidemiology - MIDTERM 2 (35 decks)

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