Viruses & The Skin Flashcards
What are exanthems
widespread rash & systemic symptoms
What erythematous exanthems tend to start on the face
• MEASLES
• Rubella
• Erythema infectiosum
What erythematous exanthems tend to start on the trunk
• ROSEOLA
• Scarlet fever
• Unilateral laterothoracic exanthem
Name 2 Papulo-vesicular exanthems
• Chickenpox (syn. varicella)
• Gianotti-Crosti syndrome
What erythematous exanthems tend to effect the extremities
Hand, foot & mouth disease
What is an enanthem
Rash on the mucosal membrane
What is the incubation period of an infection
Incubation period is the time from being infected & showing symptoms
When is the infectious period of an infection
Depends on the infectious agent
What causes measles & how is it transmitted
Measles virus (part of paramyxovirus family)
Respiratory droplets
What is the incubation period of measles
8-12 days
Measles clinical features
- High fever (above 40 degrees)
- Cough
- Coryza
- Conjunctivitis
- Koplik spots
- Maculopapular rash, beginning on head before spreading
Describe koplik spots & the measles rash
Koplik spots - small grey discolourations of the mucosal membranes in the mouth, appearing 1-3 days after symptoms begin during the prodrome phase of infection
Measles rash - Maculopapular rash, beginning on head, spreading to trunk & extremities
Measles treatment
Preventative vaccination
Supportive treatment
Measles investigations
1st: measles-specific IgM and IgG serology (ELISA), most sensitive 3-14 days after onset of the rash
2nd: measles RNA detection by PCR, best for swabs taken 1-3 days after rash onset
Measles complications
Conditions caused by disruption of epithelial surfaces & immunosuppression e.g. otitis media, febrile seizures etc
What type of vaccine is measles & what does this mean clinically
Live vaccine
& so avoided in immunodeficient/suppressed individuals
What causes erythema infectiosum & what is it aka
Aka Slapped cheek disease/ fifth disease
Is caused by human parvovirus B19 (HPV B19)
Describe the rash of erythema infectiosum & state associated symptoms
Reticular lacy pattern sparing palms & soles
Red ‘slapped’ cheeks
Malaise & fever
What indicates that a child’s chicken pox is infectious
Chicken pox is infectious until ALL lesions have crusted over
What infectious agent causes chicken pox
Varicella zoster
What happens when varicella zoster is reactivated
Virus reactivates in the dermatome it was dormant & causes shingles
What is herpes zoster opticus
occurs when a shingles outbreak affects the facial nerve near one of your ears
Varicella zoster virus investigations
PCR of vesicle fluid/pus
Varicella zoster virus treatment (chicken pox & shingles)
Anti viral e.g. acyclovir may be prescribed depending on severity, patient age & complications
How is rubella similar but different to measles in clinical presentation
Similarity
- Erythema exanthem/ maculopapular rash
- Rash starts at head & spreads to trunk/ extremities
Differences
- Rash is typically less red & lasts a shorter durations
- Different systemic symptoms,
- Rubella typically associated with cervical lymphadenopathy
What live vaccines are currently available in the UK
Live influenza vaccine
MMR vaccine
Rotavirus vaccine
Shingles vaccine
BCG vaccine
Oral typhoid vaccine
Varicella vaccine
Yellow fever vaccine
What is the clinical relevance of the human papilloma virus
It has a vaccine
It can cause a range of cancers
What are the two strains of herpes simplex virus
HSV1 & HSV2
Herpes simplex virus clinical features
- Severe gingivostomatitis
- Cold sores
- Painful genital ulceration
Herpes simplex virus treatment
- Gingivostomatitis: oral aciclovir, chlorhexidine mouthwash
- Cold sores: topical aciclovir
- Genital herpes: oral aciclovir
How does acyclovir work in HSV
Acyclovir reacts with multiple cellular kinases
This forms acyclovir triphosphate
This gets incorporated into HSV DNA & causes DNA chain termination
What type of skin rash occurs in HSV
Localised vesicular rash
What other family of viruses can present with a rash similar to measles & rubella
Echovirus
What causes infectious mononucleosis
EBV
What is infectious mononucleosis aka
Glandular fever
Infectious mononucleosis clinical features
Diffused maculopapular eruption & urticaria
Lymphocytosis & lymphadenopathy
Splenomegaly etc
Palatal petechial, periorbital oedema
