Oral Viral Infections Flashcards
What are the general characteristics of a virus?
Small- much smaller than bacteria/human cells
Simple chemical composition- proteins, phospholipids, glycoproteins, nucleic acids (changes depending on family)
No intracellular organelles- obligate intracellular parasites
DNA/RNA- can have either
What are examples of DNA/RNA viruses?
DNA virus- human herpes
RNA virus- mumps
What are the stages of replication of Herpes Simplex?
- Binding
- Entry into cytoplasm
- Release and nuclear transport
- Nuclear entry
- Gene expression- ribosomes translate viral genes into proteins
- DNA replication via viral DNA polymerase
- Packaging
- Egress via endoplasmic reticulum, golgi apparatus and plamsma membrane
What does 1/2 triangles mean?
1- Diagnosis
2- Provisional diagnosis
How is a viral sample taken?
Use viral swab- flocked
Place in molecular sample solution- extracts viral DNA/RNA
After immersion- remove swab
What is used when taking a blood sample to check for viruses?
EDTA- purple topped
-> used in serology and molecular detection of viral DNA/RNA
What information should be included in virology request form?
Pt details & clinician details (inc phone no.)
Clinical details & diagnosis
Date of onset
Patient DOB or CHI number
Specify test (do not request “viral screen”)
What is a maculo-papular rash?
Red flat area on the skin covered with bumps (macules/Papules)
Which viruses can cause a macula-papular rash?
Enterovirus
HHV6
HHV7
Measles
Rubella
*B19, CMV, EBV- require serology for detection using EDTA blood sample
What is a vesicle?
Fluid filled blister
Which viruses are associated with vesicular lesions?
HSV1
HSV2
VZV
Enterovirus
What is an ulcer?
break in bodily membrane
Which viruses are associated with causing ulcers?
HSV
Enterovirus
What specimen/test is required for detecting the cause of macula-papular rashes, vesicular lesions and ulcers?
Specimen- mouth swab
Test- RNA/DNA detection
What is serology used for?
Detect presence of antibodies against a virus?
Which viruses can be diagnosed from presence of IgM antibodies?
CMV
EB
Which viruses can be diagnosed from presence of IgG antibodies?
HSV/Varicella Zoster
Was is meant by laboratory stewardship?
Only using lab as a resource when required
-> Most diagnoses are made via history/clinical investigation
What is characteristic about the appearance of herpes viruses?
Look like a fried egg
What are the types of herpes virus?
Herpes simplex type 1
Herpes simplex type 2
Varicella zoster- chicken pox/shingles
Epstein Barr
Cytomegalovirus
HHV-6
HHV-7
HHV-8 (Kaposi’s Sarcoma Associated virus)
What are the common features of infections with HHVs?
Primary infection
Latency
Recurrent infection
What conditions can HSV1/2 cause?
Gingivo-stomatitis
Herpes labialis- cold sores
Keratoconjuctivitis
Herpetic whitlow
Bell’s palsy
Genital herpes
What are the steps in the pathogenesis of HSV?
Acute infection
Latency
Reactivation
-> Cold sores, viral shedding, cell death
What is the reservoir for HSV?
Saliva
What is the route of transmission for HSV?
Direct by close person to person contact
When does atypical reactivation of HSV occur? What can be used to diagnose this?
In immunocompromised patients
-> take viral swab and do PCR
What is used to treat HSV infections?
ACV to prevent recurrent infection in difficult cases
(200mg x5 daily ACV)
Topical therapy with ACV (aciclovir cream 5%)
IV therapy for severe & immunosuppressed
What is the incubation period for Varicella-zoster?
10-21 days
What are the potential complications of a Varicella infection?
Secondary bacterial infections- group A strep can colonise skin lesions
Pneumonia- vesicles form on epithelial lined surface of lung
Congenital, perinatal/neonatal issues
What are the signs and symptoms of zoster infection?
Vesicles appear in dermatome of cranial or spinal ganglia where the virus has been dormant
-> The affected area may be intensely painful with associated paraesthesia
What are the potential complications of zoster?
Post herpetic neuralgia
Secondary bacterial infections
Ophthalmic zoster
Ramsay Hunt syndrome- paralysis of facial nerve
What are the stages in the pathogenesis of varicella zoster virus?
Primary Infection:
Infection with varicella zoster virus
Latency:
Sensory ganglion (Trigeminal)
Recurrent Infection:
Reactivation of latent virus from sensory ganglion (associated with immunosuppression due to age/tx)
What is the route of transmission for Varicella-Zoster?
Direct contact, droplet or airborne spread
In what groups is occurrence of Varicella and Zoster most common in?
V- Children
Z- Immunosuppressed/older
What can be used to test for Varicella-Zoster in atypical cases?
Swab of vesicular/ulcer fluid in MSM
-> PCR
Serum IgG test (not used for diagnosis of zoster) – usually used for chickenpox exposure in HCW’s
How is varicella infection prevented?
Chicken pox vaccine (not routine)- only given to patients who are vulnerable to chickenpox/complications
How is shingles (zoster) treated?
Aciclovir: 800mg Oral x5 daily for 7 days
-> Refer all patients with herpes zoster to a specialist or their general medical practitioner.
What is used to prevent zoster infection?
Zostavax- Live attenuated virus
-> Schedule: All people aged 70 + years
What are the symptoms of an enterovirus infection? (hand, foot and mouth diseases)
Fever, runny nose, sneezing, cough, skin rash, mouth blisters, and body/muscle aches
What are examples of enteroviruses?
Coxsackie- dentally relevant
Polio
How does enterovirus infection spread?
Nose and throat secretions
Fluid from blisters or scabs
Faeces
When are enteroviruses at their most infective?
First week
Which populations tend to suffer from enterovirus infections?
Common in under 5s- nursery/school outbreaks
-> can happen to anyone
What can be used to diagnose enterovirus infection?
Oral swab for detection of enterovirus RNA
-> not usually required
How is hand, foot and mouth disease prevented/treated?
P= Hand washing
Tx= Relieve symptoms and treat dehydration
What are the signs and symptoms of measles?
7-14 days after infection- high fever, runny nose, conjunctivitis, Cough
2-3 days later- Appearance of Koplik spots in the mouth (breakdown of epithelium)
3-5 days later- rash appears on face and spreads downwards
What are the potential complications of measles?
Pneumonia
Brain swelling
Hearing loss
Diarrhoea
Death
-> MMR vaccine reduces risk
How is Measles transmitted?
RNA virus is spread through airborne transmission
or direct contact with infected respiratory secretions
What is mumps?
Epidemic parotitis
How long is the incubation period for mumps?
12-24 days
-> asymptomatic carriage possible
What are the symptoms of mumps?
headache
fever
swelling of the parotid glands (uni or bilateral)
What other conditions can develop as a result of mumps infection?
deafness, encephalitis, pancreatitis, neuritis, arthritis, mastitis, nephritis, thyroiditis, ovaries (oophoritis), swelling of the testes (orchitis) and pericarditis.
What type of virus is mumps?
Paramyxovirus family - RNA
How is mumps spread?
Transmission is by direct contact with saliva/fomites or aerosol
How is mumps diagnosed?
Oral fluid IgM antibody tests or PCR
How are measles and mumps prevented?
MMR vaccine- routine childhood immunisation
What is HPV16 a risk factor for?
Head and neck squamous cell carcinoma
What is aciclovir?
Acyclic purine nucleoside
-> commonly used for intra-oral and perioral viral infection
How does aciclovir work?
Tricks replicating herpes virus into incorporating DOG molecule (defective) into growing DNA chain, blocking further synthesis of viral DNA
Inhibits DNA polymerase (preferential termination- only viral not host DNA)
What is aciclovir’s target viral molecule?
Viral enzyme- thymidine kinase
-> Higher affinity for acyclovir (only active in infected cells)
-> Mutations in this viral can cause resistance as it avoids action of drug
What stage of infection does aciclovir work on?
Active replication stage
-> latency phase is not affected
What is aciclovir used to treat in a dental setting?
Various intra-oral/peri-oral viral infections
-> Herpes simplex (cold sores) and Zoster (shingles) infections
How can aciclovir be administered?
Topically
Systemically
-> orally or intravenously
What is the pro-drug for aciclovir and peniciclovir?
A- valacyclovir
P- Famciclovir
