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Flaviviruses Flashcards

1
Q

What is the family and genus of Japanese encephalitis virus?

A

Flaviviridae family, flavivirus genus

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2
Q

What is the vector of JEV?

What is the main amplifying host?

Which two animals get clinical symptoms?

A

Culex tritaeniorhynchus

Pigs are important amplifying hosts (herons are maintenance hosts!)

Pigs and horses get clinical symptoms

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3
Q

What are the transmission routes of JEV?

A

Mosquito bite

Occasional reports of lab associated, organ and NSI transmissions

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4
Q

Where is JEV endemic?

A

Most of Asia (as of 2022 Australia) - esp risk in rural areas of China with rice and pig farming

Vaccination has eliminated JEV from Japan, South Korea, Singapore, Taiwan

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5
Q

What % of JEV infections are asymptomatic?

A

> 99%

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6
Q

What is the fatality rate of JEV in severe cases?

A

30%

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7
Q

What are the symptoms of JEV?

A

Initial ILI followed by encephalitis

(also aseptic meningitis, AFP, coma, seizures)

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8
Q

Treatment for JEV

A

Supportive only

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9
Q

Risk of primary JEV in pregnancy

A

Miscarriage

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10
Q

What is the name of the UK licensed JEV vaccine?

What type of vaccine?

What age is it licensed in?

What is the schedule?

Are boosters required?

A

Ixiaro

Inactivated vaccine

> 2 months

Two doses 28 d apart (can have rapid course 7 d apart)

Booster required 1-2 y post primary course and this provides protection for 10 y

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11
Q

What is the family, genus and complex of WNV?

A

Flaviviridae family, flavivirus genus, JEV serogroup

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12
Q

What are the reservoir hosts of WNV?

A

Birds

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13
Q

What animal is most severely affected by WNV?

A

Horses have severe illness and are dead end hosts

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14
Q

Where does WNV circulate?

A

Mostly in Africa, post 1999 it was found in America and is now also seen in Europe and Australia

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15
Q

What is the vector of WNV?

A

Culex (esp C. pipiens) is the most important vector but other mosquitos and ticks can be infected

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16
Q

Do humans transmit WNV to mosquitos?

A

No, humans are dead end hosts

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17
Q

How is WNV transmitted to humans?

A

Mosquito bite

Rarely infected by handling infected tissues

Transplacental transmission is possible as is infection via breast milk

Possible sexual transmission

Transfusion and organ transmission have occurred

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18
Q

Where is WNV found in Europe?

What is the risk in the UK?

A

Outbreaks in Romania since 1996

Cases identified in France, Italy, Portugal, Spain

No locally acquired cases in UK

However, Culex modestus has been found around the Thames estuary so autochthonous transmission risk

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19
Q

What is the incubation of WNV?

Which patient groups are most at risk of severe disease?

A

2-14 d (average 2-6 d) can be up to 21 in immunocompromised

> 50 years and immunocompromised

Children rarely get WV encephalitis

Mortality highest in >70 y

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20
Q

Clinical presentations of WNV

A

1) Mostly asymptomatic

2) <20% get West Nile fever - ILI, rash, conjunctivitis

3) <1% Neuroinvasive disease - meningitis, encephalitis (10% mortality and high sequelae), AFP (known as WN polio) appears rapidly with no preceding signs of illness

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21
Q

What are some of the rarer manifestations of WNV?

A

Most commonly ocular complications

Myocarditis, pancreatitis, orchitis, fulminant hepatitis, kidney disease and haemorrhagic symptoms (rare)

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22
Q

Diagnosis of WNV?

A

IgM and rising IgG (serology complicated by cross reactivity with other flavis)

RNA in blood (early) and urine

In CNS infection, RNA or IgM in CSF

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23
Q

When to consider diagnosis of WNV?

A

In patients with travel to Southern/Eastern Europe, Africa/North America

With febrile or acute neurological illness

Also consider in patients living near the North Kent and Essex coastlines

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24
Q

Are there vaccines from WNV?

A

Only for animals

No human vaccine in phase III trials, development hindered by risk of ADE

25
How is the UK blood supply protected from WNV?
Donations deferred from patients for 28 days following WNV risk area
26
When was the recent Zika outbreak in Brazil and what were the symptoms?
2015 - causing microcephaly and GBS
27
Which lineage of Zika causes congenital disease?
Only the Asian lineage, the African lineage does not Suggested that a SNP arose around 2013 linked to congenital infection
28
Where does Zika circulate?
Africa, Asia, the Pacific Islands, Central and South America and the Caribbean
29
What is the main vector of Zika?
Aedes aegyptii
30
What is the reservoir host of Zika?
Unknown
31
What are the transmission routes of Zika?
Mosquito bite or sexual transmission
32
How long is sexual transmission of Zika a risk?
3 months from males 2 months from females
33
What is the advice to couples trying to conceive after visiting a Zika risk country?
Barrier contraception for 3 months for males, or 2 months for females if trying to conceive. If male has been to at risk country then they should use barrier contraception for the duration of pregnancy
34
How long after Zika risk can negative serology be used to determine there has been no infection?
Negative serology 4 weeks after last risk indicates patients highly unlikely to have been infected
35
As per RCOG how should an asymptomatic pregnant traveller with Zika be managed?
Serum should be stored Baseline foetal ultrasound repeated at 18-20 w Consider a follow up at 28-30 w Baby will need review
36
As per RCOG how should a symptomatic pregnant traveller with ?Zika be managed?
If current symptoms - serum and urine to RIPL and baseline foetal ultrasound if negative consider repeat serology and return to normal care If history of compatible symptoms - serum to RIPL and baseline foetal ultrasound if negative consider repeat serology and return to normal care If serology positive or inconclusive send further samples and refer to foetal medicine. MRI and amniocentesis may be required. If serology positive neonate will need review and follow up at birth
37
Incubation and clinical features of Zika infection
Incubation 3-12 d Mostly asymptomatic Febrile illness with (itchy) rash Conjunctivitis may be present Severe disease unusual, GBS and congenital infection is a risk
38
Differential diagnosis of Zika?
Chikungunya Dengue Measles Rubella Parvovirus Enterovirus Malaria
39
What are the risk dates for congenital Zika syndrome? When is the highest risk? What are the symptoms?
8 weeks PRIOR to conception throughout pregnancy Highest risk is in first trimester (8%), second (6%), third (4%) Symptoms: Microcephaly Intracranial calcifications Ventriculomegaly Cell migration abnormalities Congenital contractures
40
What tests should be performed on a baby with ?congenital Zika, or born to a mother with confirmed Zika during pregnancy (or pre-conception)? When would baby receive follow up?
PCR and histology of placenta and umbilical cord at birth Cranial ultrasound or MRI of brain Ophthalmic and hearing review Follow up at 3 months, then every 3 months until 12 months
41
What samples are useful for diagnosis of Zika infection?
Short viraemia so PCR in serum often not useful Sheds for 2-3 weeks in urine so urine good sample IgM can cross react with other flavis and can be neg in patients with previous dengue
42
Which groups are eligible for testing for Zika at RIPL?
1) Symptomatic travellers within 2 weeks of returning from risk countries 2) Symptomatic patient in contact with male sexual partner who has had Zika risk in the previous 3 months
43
What are the sample requirements for patients being tested for Zika at RIPL?
Serum sample and urine if within 21 days of symptom onset
44
Regarding organ donors, what two scenarios should Zika be considered in potential organ donors?
1) Return from a risk country within 28 days 2) Sexual partners of those who have return from a risk country
45
Is Zika virus infection a contraindication to a) organ b) tissue donation?
a) Yes unless in exceptional circumstances b) Absolute contraindication
46
Name some flaviviruses other than: Dengue, JEV, TBEV, WNV, Yellow fever, Zika
Spondweni Wesselsbron St Louis Encephalitis Usutu Murray valley virus Rocio virus Louping Ill virus Kyasanur Forest disease virus Omsk haemorrhagic fever Powassan virus
47
What virus other than Yellow fever is part of the Yellow fever complex?
Wesselsbron virus
48
Where does Wesselsbron circulate? What are the symptoms? What does it cause in ruminants and what is the main vector?
Africa Mild disease but has caused encephalitis Causes miscarriages in ruminants Aedes sp.
49
What virus is Spondeweni virus phylogenetically and antigenically related to?
Zika
50
Name 6 viruses in the Japanese encephalitis complex. Which are HG3?
JEV WNV St Louis encephalitis Murray Valley encephalitis Usutu Rocio virus All are HG3, except Usutu which is HG2
51
Where does St Louis encephalitis virus circulate? What are the symptoms? What are the amplifying host? And what is the main vector?
Eastern and Central USA Mild ILI but encephalitis can occur in older adults (case fatality 5-15%) Wild birds Culex sp.
52
Where does Usutu virus circulate? What virus is its close relate? What are the symptoms? What is the reservoir and spill over host? And what is the main vector?
Europe (France, Germany, Italy, Austria, Netherlands) West Nile virus Mostly asymptomatic but neuroinvasive cases in elderly and immunocompromised (like WNV) Birds are reservoir, horses are spill over host Culex sp.
53
Where does Murray Valley encephalitis virus circulate? What are the symptoms? What is the reservoir? And what is the main vector?
Australia and Papua New Guinea Mostly asymptomatic but encephalitis and meningoencephalitis can occur Water birds (herons and cormorants) Culex annulirostris
54
Name 5 viruses in the Tick Borne encephalitis complex. What hazard group are they?
TBEV Louping Ill Powassan Omsk haemorrhagic fever Kyasanur Forest disease virus All HG3 *PLOK*
55
Where does Louping Ill virus circulate? What are the symptoms? Which animals get severe illness? And what is the vector?
UK particularly Scotland Rarely reported in humans, mostly ILI but can cause meningoencephalitis Sheep and red grouse Ixodes ricinus
56
Where does Kyasanur Forrest disease virus circulate? What is it otherwise known as? What are the symptoms? And what is the vector?
South India Monkey fever Febrile illness with haemorrhagic fever in 5-10% (high fatality rate) Hemaphysalis spinigera (hard ticks)
57
Where does Omsk haemorrhagic fever virus circulate? What are the symptoms? And what are the vectors?
Siberia and Russia Febrile illness with haemorrhage, can cause neurological disease Spread by ticks and small mammals
58
Where does Powassan virus circulate? What are the symptoms? What are the maintenance hosts? And what is the vector? What is the incubation?
North America Mostly asymptomatic or mild, if symptoms occur then febrile prodrome followed by headache and rash, neuroinvasive disease follows in the majority Maintained in squirrels, groundhog, mice and deer. Spread by Ixodes spp. Incubation of 1-5 weeks

Part 2 Revision (57 decks)

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