1 - Oral viral infections Flashcards
What are the characteristics of a virus?
- simple chemical composition
- no intracellular organelles
- they are obligate intracellular parasites
- genetic information carried as DNA or RNA
Give an example of a DNA virus.
Human herpes viruses
Give an example of a RNA virus.
Paramyxovirus (mumps)
What are the key stages of viral replication?
- binding
- entry
- release and nuclear transport
- nuclear entry
- gene expression
- DNA replication
- packaging
- egress
What is shorthand for provisional diagnosis?
Two triangles
What is shorthand for diagnosis?
One triangle
What is used for a viral swab?
- flocked swab
- placed in molecular sample solution (MSS)
- after immersion remove swab
What is used for a blood sample?
- placed in purple topped tube
- EDTA solution
What information is required on a virology request form?
- patient details and clinician details
- provisional diagnosis
- date of onset
- specify test required
What viruses typically present with a maculopapular/erythematous appearance?
- enterovirus
- HHV6/7
- measles
- rubella
What viruses typically present with a vesicular appearance?
- HSV1/2
- HZV
- enterovirus
What viruses typically present with ulcers?
- HSV
- enterovirus
Define maculopapular.
A mix of macules (flat discolored areas of skin) and papules (small raised bumps)
What is used for detection of viral nucleic acid?
Nucleic acid amplification
What antibody indicates a primary response?
IgM
What antibody indicates a secondary response?
IgG
What viruses are part of the HHV group?
- HSV1
- HSV2
- varicella zoster
- epstein barr
- cytomegalovirus
- HHV6
- HHV7
- HHV8 (Kaposi’s Sarcoma)
Describe the clinical features of HSV1 and HSV2 infection.
- gingivo stomatitis
- herpes labialis
- keratoconjunctivitis
- herpetic whitlow
- bell’s palsy
- genital herpes
Define herpetic whitlow.
A lesion (whitlow), typically on a finger or thumb, caused by the herpes simplex virus (HSV)
What are the key stages of HSV pathogenesis?
- acute infection in periphery epithelial cells
- latency within nerves (retrograde transport)
- reactivation within nerves (anterograde transport)
- presents with cold sores, viral shedding, epithelial cell death
What percentage of the population have HSV?
> 90%
What is the reservoir for HSV?
Saliva
What is the route of transmission of HSV?
Direct by close contact
How can an immunocompromised patient present with reactivation of HSV?
Painful ulceration on the tongue
What is used for chemoprophylaxis for recurrent HSV?
200mg x5 daily acyclovir
What antiviral therapy is available for an acute episode?
Topical acyclovir 5%
What complications are associated with varicella viral infections?
- secondary bacterial infections
- pneumonia
- congenital perinatal/neonatal
What complications are assorted with zoster viral infections (shingles)?
- post herpetic neuralgia
- secondary bacterial infections
- ophthalmic zoster
- Ramsay Hunt syndrome
What is Ramsay Hunt syndrome?
Paralysis of facial nerve
How does shingles present?
- vesicles present in a dermatome related to the ganglia that the virus has been dormant
- area is intensely painful and may experience paraesthesia
What antiviral therapy is available for shingles?
Acyclovir 800mg x5 daily for 7 days
How does hand, foot and mouth disease present?
- fever, runny nose, sneezing, cough
- maculopapular rash, mouth blisters, body and muscle aches
What causes hand, foot and mouth disease?
Enterovirus (Coxsackie)
How does hand, foot and mouth disease spread?
- nose/throat secretions
- fluid from blisters/scabs
- faeces
Who typically presents with hand, foot and mouth disease?
<5 years
What is the management of hand, foot and mouth disease?
- symptomatic relief
- prevent dehydration
- hand hygiene essential to prevent spread
What are Koplicks spots?
Tiny white spots on buccal mucosa caused by measles infection
What is utilised to get a lab diagnosis of measles?
Mouth swab and PCR
What is utilised to get a lab diagnosis of monkeypox?
Mouth swab and PCR
How does mumps present?
- uni or bilateral swelling of parotid glands
- headache and fever
What causes mumps?
Paramyxovirus family
Which HPV is a high risk for head and neck cancer?
HPV-16
How does monkeypox present?
- self limiting disease
- rash 1-5 days post fever
- blistering rash or skin lesions in mouth, on skin and genitals
What is acyclovir?
- antiviral drug
- acyclic purine nucleoside
How does acyclovir work?
- inhibits DNA polymerase in viral DNA
- mimics guanine (DNA nucleotide) and binds to the substrate, this faulty molecule can no longer replicate
What viral enzyme interacts with acyclovir?
Thymidine kinase
When is acyclovir effective?
- only when there is an acute infection/reactivation
- acyclovir only targets virus when there is active replication
- latent infections are not affected
