Varicella Zoster / Polio / Hepatitis C

Question 1

what is varicella?

Answer 1

chicken pox

Question 2

what is herpes zoster?

Answer 2

shingles

Question 3

who does chicken pox infect?

Answer 3

• primary infection in children & young adults

Question 4

who does shingles infect?

Answer 4

secondary infection in adults

Question 5

what is the viral structure of varicella zoster?

Answer 5

Linear DNA genome

Icosahedral nucleocapsid

Question 6

how is varicella zoster transmitted?

Answer 6

Respiratory route of infection
Inhalation of aerosols
Direct contact with virus infected vesicles
Very contagious virus

Question 7

what is the pathogenesis of varicella zoster virus?

Answer 7

Affects children 2-6 years old (2 week incubation)
Virus infection of upper respiratory tract
Replication in regional lymph nodes
Infection of bloodstream (viraemia)
Replication in internal organs (liver and spleen)
Replication in capillary endothelial cells and skin (chickenpox vesicles)
Latency in dorsal root ganglia

Question 8

what is the symptoms of varicella zoster virus?

Answer 8

Appearance of rash on head that quickly spreads throughout body
Rash is composed ofgroups of small, itchy blisters surrounded by inflamed skin
Mild fever
Fatigue
Headache
Flu like symptoms

Question 9

what are the characteristics of a varicella zoster virus rash?

Answer 9

Rash starts as flat spot (macule)

Changes into clear blister (vesicle) - these are infectious - contain live virus

Then to pustule, which drys out and forms a scab

Scab falls off after about 2 weeks

Question 10

typical case study:

Eight year old child developed generalised itchy rash that appeared 2 days ago on face as discrete red spots
Spots developed into small vesicles and spread over body
Fever (37.9 0C), tiredness and headache

On examination patient is febrile with itchy rash and flu like symptoms

what is it?

Answer 10

varicella zoster virus

Question 11

what are the complications of varicella zoster virus?

Answer 11

Staphylococcus and Streptococcus infections of vesicles - especially if scratched

Immunocompromised patients more extensive eruptions, haemorrhagic blisters, skin necrosis, secondary bacterial infections

Virus can persist in dorsal nerve ganglia in body for many years
May lead to re-occurrence as shingles in adult

Question 12

what are the characteristics of shingles?

Answer 12

Reactivation of varicella zoster virus during adulthood
4-5 days before shingles rash, get pain & burning or itching along the nerve routes
Vesicles appear in clusters or lines along the nerve routes
Vesicles fill with fluid after 3-4 days
Then become pustules – when vesicles crust over

Question 13

what are the characteristics of shingles rash?

Answer 13

Vesicles are infectious

Cause chicken pox in children or adults not previously exposed

CAN NOT give shingles to another adult

Question 14

what is the name of the organism that causes polio?

Answer 14

Enterovirus genus

Question 15

what is the genome characteristics of polio?

Answer 15

Non-enveloped

Single stranded, positive sense,RNA genome

Icosahedralcapsid

“Positive sense”

Question 16

how is polio transmitted?

Answer 16

Transmission faecal-oral route

respiratory route

Question 17

how prevalent are the symptoms of polio?

Answer 17

90% people have no symptoms or very mild symptoms

1 in 200 irreversible paralysis (legs) when virus spreads to central nervous system

Question 18

what is the pathogenesis of polio?

Answer 18

Virus spreads along neurons and destroys nerve cells that activate muscles

Causes acute flaccid paralysis - affected muscles do not function & limb becomes floppy

Most severe cases - bulbar polio - virus attacks nerve cells of brain stem reducing breathing capacity and causing difficulty in swallowing and speaking

5 - 10% death rate - breathing muscles are immobilized

Question 19

what are the 4 types of polio vaccination?

Answer 19

Oral polio vaccine (OPV)
Monovalent oral polio vaccines (mOPV1 & mOPV3)
Bivalent oral polio vaccine (bOPV)
Inactivated polio vaccine (IPV)

Question 20

what are the genome characteristics of hep c?

Answer 20

Positive sensesingle strandedRNA virus
Cell membrane derived envelope
Icosahedral nucleocapsid

Question 21

what is the genus of hepatitis c?

Answer 21

Hepacivirus Genus

Question 22

what are the characteristics of hep c?

Answer 22

Replicates mainly inhepatocyte cells of liver
Range of severity - mild illness for few weeks - serious lifelong condition that can lead liver cirrhosis or cancer
> 350 000 people / year die from hepatitis C-related liver disease
No vaccine

Question 23

what is the viral structure of hep c?

Answer 23

single-stranded RNA
nucleocapsid
envelope
envelope proteins

Question 24

how is hepatitis transmitted?

Answer 24

Transmitted through exposure to infectious blood

Contaminated blood transfusions, blood products & organ transplants
Injection with contaminated syringes & needle-stick injuries in health-care setting
Injection drug use
Babies born to hepatitis C-infected mother

Less common transmission - sex with infected person or sharing personal items contaminated with infectious blood

Question 25

how do you diagnose hep c?

Answer 25

Person is or has been infected:

- Antibodies against hepatitis C virus 
- Recombinant immunoblot assay and / or hepatitis C virus RNA testing confirm diagnosis

Chronic infection:

- Hepatitis C virus RNA (nucleic acid testing) 
- Person also has antibodies against hepatitis C virus

Specialized tests evaluate liver disease (cirrhosis & cancer)

Question 26

what are the symptoms of hep c?

Answer 26

Incubation period of 2 weeks to 6 months
Approximately 80% of people do not exhibit any symptoms

Acute symptoms:
fever, fatigue, decreased appetite, nausea, vomiting, abdominal pain, joint pain & jaundice (yellowing of skin and the whites of the eyes)

Question 27

what is the pathogenesis of hep c?

Answer 27

75 - 85 % new infection cases develop chronic infections
60 - 70% chronic infection cases develop chronic liver disease
5 - 20% chronic liver disease cases develop cirrhosis
1–5% of people die from cirrhosis or liver cancer

25% of liver cancers - underlying cause hepatitis C