Flashcards in L13: Viral Skin Rashes Deck (12):
Name some of the symptoms of Measles virus.
- Runny nose
- Red/watery eyes
- Koplik's spots (white spots on the inside of the cheeks)
- Maculopapular rash (raised, red spots) usually on face and upper neck which tracks downward over a few days
What kind of IR is initiated upon MV infection?
Strong MV-specific humoural and cell-mediated immune response --> induces life-long immunity
Descirbe MV pathogenesis.
- MV enters host via infection of alveolar macrophages and/or DCs
- replicates in lungs/lymph nodes
- spreads to other tissues (viraemia here too)
- Come back to epithelial cells and do a bunch of damage to facilitate transmission via coughing/sneezing
What causes the characteristic rash of a MV infection?
Is MV a good candidate for eradication? Why/why not?
- no non-human reservoirs
- sensitive AND specific diagnostic tests available
- effective vaccine is available
What are some limitations to MV eradication?
- Attenuated vaccines inactivated by light and heat
- Needs to be stored within a very specific and narrow temperature range
- Must be administered intramuscularly or subcutaneously (requires training and proper sharps disposal)
- Maternal Abs hinder protective efficacy of vaccines if given too early
- Can still lead to complications in severely immunocompromised individuals
Describe the pathogenesis of poxviruses.
- Incubation period of 7-10 days --> individual is asymptomatic
- Prodrome phase --> fever, malaise, head/body aches (**sometimes contagious)
- Early rash --> Emerges in nose/mouth/throat, sores break open too for inc transmission, moves to extremeties not as much on torso like in MV infections (MOST CONTAGIOUS)
- Pustular rash --> bumps become pustules, feel a bit like BB pellets (contagious)
- Pustules & scabs --> pustules start to scab (still contagious)
- Resolving scabs --> Scabs fall off, leave sexy pitted scars (contagious)
- Resolved scabs --> All your scabs are gone and you are no longer contagious
What are some general characteristics of viral skin rashes?
- Infection occurs in the upper respiratory tract and moves to the skin via the blood
- Usually accompanied by fever/malaise/headache
- Rash is usually due to the IR rather than the virus itself
What is the importance of vaccinia virus?
It is the vaccine virus for smallpox --> contributed significantly to eradication
Why was smallpox able to be eradicated? (3)
- No animal reservoir
- Vaccinia virus was an effective immunogen
- Patients either died or recovered with lifelong immunity
Describe the pathogenesis of VZV.
- Gains entry to the body via the repiratory epithelial cells
- Virus gains access to permissive T cells and replicateds in lymphoid tissues
- Also moves through the body (primary viraemia) and replicates in the skin, liver and spleen
- Replication in epidermal cells causes rash
- During secondary viraemia, virus can reach neurons in sensory ganglia where it can establish latency