week 11 - viral infections Flashcards
What is varicella zoster virus?
Presents as chicken pox in children (primary children) and presents as shingles in adults (secondary infection)
What are the routes of transmission for varicella zoster virus?
Inhalation of aerosols
Direct contact
Very contagious
What is the pathogenesis of varicella zoster virus?
It is a virus that infects the epithelial cells of the upper respiratory tract, it replicates in the tonsils/lymph nodes, internal organs and skin causing the chickenpox vesicles present on the skin.
Can infect the bloodstream (viraemia) and most commonly affects children 2-6 years old.
What are the symptoms of varicella zoster virus?
Rash on head that spread over the body
Itchy blisters surrounded by red inflamed skin
Fever
Fatigue
Headache
Flu lime symptoms
How does the rash start for varicella zoster virus?
Rash starts as a macule (flat spot)
Then changes to clear blister (vesicle) which are infectious
Then forms pustule which then scabs and crusts over
Scabs fall off after 2 weeks.
How is varicella zoster virus diagnosed?
Clinical observation
qPCR
Serology
What are the complications of varicella zoster virus?
Staph and strep infections of the vesicles (blisters that appear on the skin)
Infection of eye or ear
For pregnancy risk of deformities for the baby
The virus stays latent in the dorsal root ganglia which can reactivate as shingles as an adult
What is the vaccine for Varicella Zoster virus?
Varivax - it is a live vaccine offered ti people in close contact to give long term immunity.
What are shingles?
Shingles occur when varicella zoster virus is reactivated in late adulthood.
A few days before the shingles rash appears, there is a painful burning sensation along nerve routes
Vesicles appear in clusters along nerve routes and fill with fluid after a few days.
CANNOT GIVE TO ANOTHER ADULT, can cause chicken pox in children and adults not previously exposed
What are the risk factors for varicella zoster virus?
host immune status
Diabetes
Hypertension
Dyslipidaemia
COPD
Hypothyroidism
What is the polio virus>?
Is an enterovirus called pico-RNA-virus
Non enveloped, single stranded.
Has a capsid
Is positive sense - its genome can be used as mRNA as it can be translated into protein by host cell.
What are the transmission routes of polio virus?
Faecal oral route, respiratory route
What is the pathogenesis of polio virus?
It spreads along neurone and destroys nerve cells that activate muscle movement.
Causes acute flaccid paralysis - affected ,muscle can’t function and limb is floppy
What is bulbar polio?
It is severe cases of polio where the virus attacks nerve cells of brain stem causing breathing difficulties and swallowing/speaking difficulties.
What is the hepatitis C virus?
Hepacivirus genus
Is a positive sense single stranded RNA virus, has a cell membrane derived envelope.
Out replicates in the hepatocyte cells of the liver
Can range from mild illness to a serious lifelong condition causing liver cirrhosis.
How is hepatitis C transmitted?
It is transmitted through exposure to infected blood.
What is the pathogenesis of hepatitis C virus?
Chronic infection of hepatitis C causes liver disease, causing cirrhosis causes liver cancer.
What are the symptoms of hepatitis virus?
Most people don’t have any symptoms.
Acute symptoms: fever,. nausea, jaundice, abdominal/joint pain, fatigue, decreased appetite
How is hepatitis c virus diagnosed>?
For people who have been infected before -detect antibodies against hep C
For those which chronic infection; Detect hep C RNA via a PCR and nucleic acid test.
‘Can also detect antibodies for against hep C.
What is the treatment for hep C chronic virus infections?
Interferon and ribavirin
What does the treatment for hep C depend on?
Strain of virus
degree of liver damage
Duration of infection.
