WK 6- Viral and Parasitic infections of Skin and Soft Tissue Flashcards
What tests are needed to confirm a measles diagnosis
blood for Measles Ig, urine & nasopharyngeal swab for Measles PCR
What symptoms are associated with measles
Blotchy, dark red rash appears starting on face, then spreads over entire body (24 to 48 hours)
- Rash lasts ~6 days then fades but skin retains brownish colour for longer then →desquamation
- rash is non as a morbilliform rash
What virus causes measles
paramyxovirus
What virus causes rubella
rubella virus (Togavirus, ssRNA genome- single stranded RNA)
What symptoms are associated with rubella
- Clinical features generally mild & up to 50% cases asymptomatic→Transient, generalized, erythematous, maculopapular rash, lymphadenopathy+/- mild fever, mild polyarthritis
- maculopapular rash begins on the face and spreads outwards- fading after 2-3 days
What is the pathogenesis of the rubella virus
virus enters via inhalation and infects cells of the respiratory trace→ will then spread to lymph nodes and into the blood→ will then spread to target organs
How can the rubella virus cause foetal abnormalities
infect foetus via maternal viraemia→ invasion of placenta→ foetal infection→ slowed growth rate of foetal cells and apoptosis induced by viral protein→ can cause issues such as deafness
What is required for a rubella diagnosis to be formed
serology (rubella IgM), Rubella PCR via throat swab
What virus causes Human Parvovirus B19
Parvoviridae, ssDNA genome
What are the symptoms associated with parvovirus
- flushed red cheeks contrasting with pallor around mouth followed by lacelike rash on limbs→ the rash and arthropathy are mediated by immune complexes
- can cause aplastic anaemia
What is the pathogenesis of parvovirus
- primary infection of the upper resp tract→ has a high lytic activity in rapidly dividing cells (adult haemopoetic cells and foetal cells) → high viraemia for around 1 week
- can cause foetal abnormalities/miscarriage
What is needed to confirm parvo
serologocial detection of specific IgM and parvovirus PCR
What are the symptoms of roseola infantum/exanthum subitum
Fever ~3-5 days, then rash may appear on body & spread to arms & legs, +/- Rash ~1-2 days
What virus causes roseola
human herpesvirus 6 (HHV-6)
What happens to immunocompromised patients who contract roseola
seizures, encephalitis, pneumonia
What is required for a lab diagnosis of roseola to be made
Serology detection for HHV6 IgM
and PCR for HHV6 through CSF, serum, tissue, BM, eye specimens
What type of herpes does HSV1 cause
Oral herpes
What type of herpes does HSV2 cause
Genital herpes
Where do HSV2 vesicles present
- Males: usually vesicles on penis
- Females: vesicles on labia, vulva &/or perineum→ can cause cervicitis
Where do HSV1 vesicles appear
oropharyngeal (gingivostomatis on the mouth and gums),
What is required for a lab diagnosis of herpes simplex to be made
characteristic presentation, or lab diagnsosis may be required if vesicles aren’t visible
- Vesicle/lesion swab for HSV PCR (need a dry swab)→ serology is not useful due to it being present in mucous membranes, not blood
- can test CSF
What is shingles
(shingles)
- reactivation of varicella that has been residing in ganglia→ lesions usually confined to the dermatome they were residing in
- common in immunocompromised individuals
What is required to test for varicella
: lesion swab for VZV PCR, blood for VZV IgM
What is the tx for varicella
antivirals→ good for shingles to prevent post-herpetic neuralgia
-used to shorten the span of the infection
