CP7 viral and prion pathogens Flashcards
(34 cards)
How many significant herpes viruses are there?
5
How many significant respiratory viruses are there?
4
What is needed for virsuses to replicate?
A host
What are the 3 main components of a virus structure?
A genome (RNA or DNA)
A capsid (a protein coat)
An envelope (sometimes) - formed of a lipid bilayer)
What is the basic virus life cycle?
Absorption
Penetration
Uncoating
Synthesis
Assembly
Release
How are viruses classified?
By their genetic material and the presence of absence of an envelope
What are general properties of herpes viruses?
Double stranded DNA
enveloped
Establish latency and reactivate
What disease is caused by heroes simplex 1?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Cold sores (HSV-1)
Worldwide - 80% of UK population
Spread by direct contact with vesicular fluid from legions. Latency in sensory trigeminal nerve ganglion with periodic reactivation down nerve
Can cause encephalitis (brain inflammation)
What disease is caused by herpes simplex 2?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Genital herpes (HSV-2)
Worldwide and 10-20% of UK population
Direct contact with vesicular fluid from lesions. Latency in sacral ganglia which causes periodic reactivation
Can cause meningitis and neonatal herpes via vertical transmission
What disease is caused by varicella zoster virus?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Chicken pox - reactivatated form called herpes zoster or shingles
95% have chicken pox in UK before age 20, 50% in the tropics
Respiratory droplet from infected individual, direct contact with vesicle fluid.latency established in dorsal root ganglia of whole CNS
Shingles causes unilateral vesicles in a dermatologist distribution unlike widespread rash in chicken pox
What disease is caused by Epstein barr virus?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Glandular fever/mono
90% in UK are affected by age 25, 50% of these infections occur before age 5
Saliva and genital secretions. Establishes latency in B cells
Causes infectious mononucleosis (aka mono) as primary infection - tonsillitis, fever, lymphadenopathy and hepatosplenomegaly). Can also lead to malignant B cell lymphoproliferative disorders in the immunosuppressed.
What disease is caused by CMV?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
CMV (cytomegalovirus)
In UK prevalence = age e.g. 20% of 20 year olds
Saliva and genital secretions, donated blood, stem cells and organs. Latency in myeloid progenitors/monocytes/dendritic cells
Can cause infectious mononucleosis (primary), congenital CMV (infants born to mothers with CMV) and reactivation in immunosupressed patients.
What disease is caused by rhinoviruses?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Common cold
Worldwide distribution more common in autumn winter and spring
Aerosolised respiratory secretions and droplets from the nose and eyes
Most common cause of common cold
What disease is caused by coronaviruses?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Common colds and covid, SARS and MERS
Worldwide distribution infecting both humans and animals
Aerosolised respiratory secretions
Covid 19 causes severe pneumonitis and respiratory failure
What disease is caused by influenza?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Flu
Infects humans and animals and can spread between species. Peaks at winter
Aerosolised respiratory secretions
3 types - A, B, C - with 2 important surface proteins H and N
A mutates regularly.
Can also cause post-influenza secondary bacterial lung infections
What disease is caused by RSV?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Bronchiolitis
Worldwide commonly in winter months. Commonest amongst children
Aerosolised respiratory secretions
Not really
What disease is caused by HIV?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
AIDS (rise in viral load and fall in CD4 count)
38.4 million living globally with HIV- 67% in sub Saharan Africa
Bodily fluids e.g. blood, genital secretions and breast milk and vertically and sexually transmitted
Targets helper t lympocytes. 2-6 weeks after transmission can cause a seroconversion illness and then there is asymptomatic chronic infection.
AIDS defining illnesses (illnesses more common in people with AIDS) include pneumocystis pneumonia, cryptococcal meningitis and kaposi’s sarcoma
What disease is caused by hepatitis A?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Hepatitis A
More common in lower income nations with contaminated water. 10-50% in Europe.
Faeco-orally
Asymptomatic in children and 50% of infected adults are symptomatic.
What disease is caused by hepatitis E?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Hepatitis E
In Western Europe and North America associated with undercooked pork - 95% of cases are asymptomatic
Faeco-oral in contaminated food and water
High mortality in infected pregnant women (25%)
What disease is caused by hepatitis B?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Hepatitis B
248 million people worldwide are chronically infected
Vertical, sexual and needle sharing
Causes acute clinical hepatitis after transmission (often asymptomatic), can then become chronic - younger you are when infected, more likely it is to become chronic infection. Chronic hepatitis leads to cirrhosis which can then cause hepatocellular carcinomas.
What disease is caused by hepatitis C?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Hepatitis c
170 million people are infected globally, in UK 50% of people who inject drugs have hep C
Blood (predominantly), vertical and sexual transmission
After transmission, 25% develop acute clinical hepatitis, 15% clear the virus but 85% will become chronically infected.
What disease is caused by norovirus?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Norwalk virus
90% of adults at some point over their life.
Aerosolised vomit particles
Vomiting is the dominant symptom
What disease is caused by rotavirus?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Rotavirus
80-100% of children in first 3 years of life without vaccination. Seasonally peaks in winter.
Faeco-orally in contaminated food, water and aerosolised faeces and vomit
Large cause of infant mortality in lower income nations. Presents with a fever, vomiting and watery diarrhoea
What are common enteroviruses that cause disease?
What disease is caused by enterovirus?
What is its epidemiology?
How does it spread?
Any distinguishing factors?
Polio, echoviruses, and coxsackie A and B
Hand foot and mouth, 50% of viral meningitis in UK, severe disseminated disease in neonates and poliomyelitis.
Worldwide distribution and peak in summer and autumn in the UK with 75% of cases in under 15 year olds
Faeco-orally by contaminated food and water
Replicates in gut but doesn’t cause GI symptoms. Viruses moves from gut to the lymph nodes and into the blood and sometimes the CNS
