oral viral infections Flashcards
What are the characteristics of viruses
Small size
Simple chemical composition
No intracellular organelles
Genetic info as DNA or RNA
obligate intracellular parasite
What are the stages of viral replication DNA virus
- binding
- Entry
- Release and nuclear transport
- Nuclear entry
- Gene expresssion
- DNA replication
- Packaging
- Egress
What is the symbol for provisional diagnosis
2 triangles next to each other
What is the symbol for diagnosis
1 triangle
What is required for a viral swab
Use of a flocked swab
Palced in molecular sample solution
After the immersion the swab is removed
What must you fill out in a virology request form
Pt details & clinician details (inc phone no.)
Clinical details & diagnosis
Date of onset
Patient DOB or CHI number
Specify test wanted
What human herpes virus infections are there
Herpes simplex type 1
Herpes simplex type 2
Varicella zoster
Epstein Barr
Cytomegalovirus
HHV-6
HHV-7
HHV-8 (Kaposi’s Sarcoma Associated virus)
What are common features of human herpes virus
Initial primar infection then a period of latency and then a recurrent infection
What are clinical fatures of herpes simplex types 1&2
Gingivo stomatitis
Herpes labialis
Keratoconjuctivitis
Herpetic whitlow
Bell’s palsy
Genital herpes
What is the pathogenesis of herpes simplex
- Acute infection to periphery epithelial cells
- Its taken up by sensory neurons and undergoes retrograde transport to the sensory ganglia where latency is esstablished
- Reactivation of the virus and is transported in a anterograde fashion back and infects epithelial cells again
- Cold sores form again etc
How would you diagnose HSV 1&2
most diagnosis can be made based on history & clinical appearance
in aytipcal cases a Vesicle/ulcer fluid swab &
molecular sample media for PCR
What is the prevention and treatment of HSV 1&2
Chemoprophylaxis
-ACV to prevent recurrent infection in difficult cases
(200mg x5 daily ACV)
Antiviral therapy
-topical therapy with ACV
(aciclovir cream 5%)
-IV therapy for severe & immunosuppressed
What are clinical features of Varicella (chickenpox)
Red dots innit
What complications can arrise from Varicella (chickenpox)
Secondary bacterial infections
Pneumonia
What are clinical features of Zoster (shingles)
Vesicles appear in dermatome, representing cranial or spinal ganglia where the virus has been dormant.
The affected area may be intensely painful with associated paraesthesia
What complications can arrise from Zoster (shingles)
Post herpetic neuralgia
Secondary bacterial infections
Ophthalmic zoster
Ramsay Hunt syndrome
What is the pathogenesis of Varicella
Same as HSV with primary infection from varicella zoster virus (chicken pox)
How to diagnose Varicella
most diagnosis can be made based on history & clinical appearance
in aytipcal cases a Vesicle/ulcer fluid swab &
molecular sample media for PCR
What is the treatment for varicella zoster
Important to diagnosis and treat early because
Early treatment reduces severity & duration of pain & complications Pain may mimic toothache
Antiviral therapy
-Aciclovir: 800mg Oral x5 daily for 7 days
What are the clinical features of enterovirus infection (hand, foot & mouth)
Fever, runny nose, sneezing, cough,
With skin rash, mouth blisters, and body and muscle aches
What are clinical features of measles
2-3 days, Tiny white spots in mouth (kopliks spots)
3-5 days, Rash on face that spreads down
7-14 days, High fever cough runny nose conjunctivitis
What is the pathogenesis of measles
An RNA virus spread through airborne transmission
or direct contact with infected respiratory secretions
What is aciclovir
An acyclic purine nucleoside
How does aciclovir work
- Viral enzymes, thymidine kinase which has a high affinity for aciclovir, add a phosphate group to acyclovir
- Human enzymes add 2 more phosphate groups producing aciclovir triphosphate
- During viral DNA replication acyclovir is added to the growing strand halting further elongation of DNA molecule and stops viral replication
How does aciclovir triphosphate work
better substrate for viral than for host cell DNA polymerase and hereby causes preferential termination of viral DNA synthesis
Does aciclovir affect the latency stage
no
