Exotic Viruses

Question 1

What are the four exotic viruses?

Answer 1

West Nile virus
Zika virus
Lassa
Dengue

Question 2

How was West Nile virus uncovered?

Answer 2

People were getting ill at the same time as birds and animals were dying
Vets found quicker than clinicians through PCR that it was West Nile virus which hadn’t really been seen in America before

Question 3

What did the America variant most closely resemble?

Answer 3

The Israel sequencing

Question 4

What are the top main clinical features of West Nile virus?

Answer 4

Encephalitis
Fever
Weakness
Meningitis

Question 5

Where did Zika virus travel?

Answer 5

From Africa, Asia, pacific islands to South America

Question 6

What was Zika virus first isolated from?

Answer 6

Rhesus monkey in 1947 in zika forest in Uganda

Question 7

What is Zika virus transmitted by?

Answer 7

Aedes mosquitoes

Question 8

What may have caused the 2014/2015 zika outbreaks?

Answer 8

World Cup or olympics

Question 9

What are clinical features of Zika virus?

Answer 9

Incubation period 2-12 days
Only ~20% of adults symptomatic
- fever
- myalgia
- headache

Question 10

What are complications of Zika virus?

Answer 10

Uveitis
Guillain-Barré syndrome
Meningoencephalitis
Coagulopathy

Question 11

What group does Zika virus mainly affect?

Answer 11

Pregnant women, children had low birth weights, people were losing babies

Question 12

Where was Zika virus found in babies?

Answer 12

Placental trophoblasts and foetal endothelial cells
Amniotic fluid
CNS of babies with microcephalic

Question 13

How does Zika virus travel?

Answer 13

Through sexual contacts , can stain sperm for Zika virus and it on the spermatozoa

Question 14

What is the guidance for pregnancy and Zika?

Answer 14

If you have been to a zika endemic area, even if the male is asymptomatic, you shouldn’t try to conceive for 6 months after just in case there is an issue

Question 15

What are viral haemorrhagic fevers?

Answer 15

Ebola
Marburg
Crimean-Congo
Lassa
These have high mortality rate

Question 16

What was the last case of lassa in this country?

Answer 16

Mother that was unwell, went to Luton, transferred to Cambridge
Person that had travelled was her partner, he had travelled to Africa, past it onto her and she died

Question 17

What was Lassa fever named after?

Answer 17

After the place where 3 nurses were first found to have it

Question 18

What is the reservoir for Lassa fever

Answer 18

Mastomys rodents
Can pass onto offspring or through urine and saliva

Question 19

When are the most human infections of lassa

Answer 19

In dry season, when fields are burnt

Question 20

What are clinical features of lassa?

Answer 20

Conjunctivitis
Sore throat
Retrosternal chest pain
Vomiting
Back pain
Cough

Question 21

What can help treat people with lassa?

Answer 21

Ribavirin

Question 22

What type of virus is dengue?

Answer 22

Flavivirus

Question 23

What is dengue virus transmitted by?

Answer 23

Mosquitoes mainly aedes aegypti

Question 24

What percent of the worlds population live in endemic areas for dengue?

Answer 24

40%

Question 25

What are the phases of dengue virus?

Answer 25

Febrile
Critical
Convalescent

Question 26

What was the previous clinical classification?

Answer 26

Asymptomatic
Dengue fever
Dengue haemorrhagic fever
Dengue shock syndrome

Question 27

What is the incubation period for dengue fever?

Answer 27

3-14 days

Question 28

What are clinical features of dengue fever?

Answer 28

Acute febrile illness
Frontal headache
Myalgia
Nausea and vomiting
Thrombocytopaenia

Question 29

What are clinical features of dengue haemorrhagic fever?

Answer 29

Haemorrhagic manifestations e.g. bruising, mucosal bleeding
Platelets <100
Evidence of plasma leakage
Often preceded by abdominal pain, vomiting

Question 30

What are clinical features of dengue shock syndrome?

Answer 30

DHF plus
Narrow pulse pressure
SBP <80mmHg
Sustained abdominal pain
Persistent vomiting
Mortality 12-44%

Question 31

How many sterotypes of dengue fever are there?

Answer 31

DENV-1, 2, 3, 4

Question 32

With dengue fever, what can you get antigenic cross reaction with?

Answer 32

Zika virus

Question 33

What type of immunity does infection with one DENV serotype lead to?

Answer 33

Lifelong immunity to that serotype
Heterologous immunity to other sterotypes for 3 months to 2 years

Question 34

What does NS1 protein do in dengue?

Answer 34

Pro-inflammatory
Activates complement C3a and C5a
Increases vascular permeability

Question 35

What was the antibody complication hypothesis?

Answer 35

Non-neutralising in antibody from first infection aids opsonisation via Fc receptors in infection by another serotype

Question 36

Why does DHS more often occur in patients who have had previous infection?

Answer 36

ADE ( antibody dependent enhancement)

Question 37

Why is DHS commoner in second infections in Asia and not in S. America?

Answer 37

Viral diversity and ADE

Question 38

Why is severe dengue disease rare in third and fourth infections?

Answer 38

Improved homologous immunity

Question 39

Why do children under 6 months not get DHF, and then alter get severe disease?

Answer 39

Waning maternal antibody titres
Also greater baseline vascular permeability in children

Question 40

Why do Brazilians of African descent get less DHF than non-African descent?

Answer 40

DENV-2 replicates to higher levels in PBMCs from white people than black people
Polymorphisms in OSBPL10 and RXRA
Cross genetic resistance to yellow fever?

Question 41

What are dengue vaccines?

Answer 41

Dengvaxia - only given to people that have had first infection
Qdenga - given to those that have or have not been infected
Butantan - DV