viral infections Flashcards
what are the 3 main virus groups that cause mucosal diseases
- human herpes virus
- paramyxovirus
- human papilloma virus
what are herpes group viruses?
DNA viruses, all characterised by latency
list the herpes group viruses
> herpes simplex 1 and 2
> varicella - zoster virus
> Epstein - Barr virus
> cytomegalovirus
describe HHV1?
causes primary herpetic gingivostomatitis may become latent and recur as a cold sore
describe HHV2?
also known as HSV-2, causes genital herpes and occasionally causes oral disease that is clinically similar to that of HHV-1 infection
describe HHV-3?
also known as varicella-zoster virus, causes the primary infection chickenpox and the secondary reactivation herpes zoster.
describe HHV-4?
Epstein-Barr virus causes infectious mononucleosis. Implicated in various diseases, such as oral hairy leukoplakia
describe HHV-5?
also known as cytomegalovirus (CMV), causes primary infection of the salivary glands & other tissue, it is believed to have a chronic form
describe HHV-6?
causes roseola infantum, a febrile illness that affects young children. Believed to chronically persist in salivary gland in some hosts
describe HHV-7?
has been isolated from the saliva of healthy adults and has been implicated as one cause of roseola infantum
describe HHV-8?
is associated with Kaposi sarcoma
how is the herpes simplex virus transferred?
> Direct contact with infective lesion
Contact with infected saliva from individual shedding the virus
Transfer via inanimate objects
what is the HPC of primary herpatic gingivo stomatitis?
> onset - sudden onset, incubation period = 2-20 days
> duration - 10-14 days
> number - only 5% clinically severe
> frequency - once only infection
> sites - any mucosal site
> systemic upset - varies with clinical severity
what is the oral clinical features of PHGS?
> Variable, usually ulcers
> Worse in atopics and immunocomp
> May be subclinical
what is the extra oral features of PHGS?
> Cervical lymph adenopathy
> Pyrexia
> Rarely macular skin rashes
how do you diagnose PHGS?
> Virus PCR swab
Clinical diagnosis
Antibody status in acute and convalescent sera
Immunofluorescence
what is the managment of PHGS?
> Maintain fluid intake: lollies
> Analgesic therapy
> Systemic acyclovir: severe cases
> Mouthwash therapy
> Limit spread to other body sites
> Limit spread to other individuals
what happens after the PHGS has cleared?
> the herpes simplex virus may become latent in th snesory ganglia
often the trigeminal ganglion
what are the clinical features of recurrent herpes simplex? (herpes labialis)
> Initial prodrome
> Clusters of tiny blisters, which ulcerate
> Crusting and healing
what is the HPC of herpes labialis?
> onset - spontaneous, trauma, menstration or sunlight
> Duration - 7-10days
> number - single or multiple
> sites - junction vermillion border lip
> systemic upset - uncommon
what is the management of herpes labialis?
> Preventive measures, e.g sunblocks
> Warn patients of infectivity of the lesion
> Topical acyclovir cream in prodromal phase
how does recurrent intraoral herpes simplex present?
> Unilateral linear distribution of ulcers, often in palate
what happens in patients with severe immune defects with herpes labialis?
atypical forms can be seen eg tongue
what dental implications does HSV cause?
> Transmission to dentist (herpetic whitlow or keratitis)
> Transmission to dental equipment and surgery surfaces
> Cross infection control of paramount importance
how is the varicella zoster virus transferred?
> Highly contagious
> direct contact, coughing, sneezing
what is the initial infection of the varicella- zoster virus?
- chickenpox
Where does the varcicella zoster virus lie dormant?
> in the dorsal root, cranial nerve or autonomic ganglion
what is the recurrent infection caused by the varicella zoster virus?
> herper zoster
better known as shingles
what is the clinical appearance of herpes zoster (shingles)
- unilateral
-painful
-vesicular eruption - localised to a single dermatome
> intraoral lesions with obvious unilateral appearance
what is the HPC of herpes zoster ? (shingles)
> reactivation associated with impaired host immunity
> pain preceeds eruption by 2-4 days
> common most CNS viral infection
> usually 40+ age group
what is the management for herpes zoster (shingles) ?
> high dose systemic acyclovir for 7-10 days
800mg x5/day
what is the dental significance of herpes zoster (shingles) ?
> infectivity of lesions
> pain may mimic toothache
> post herpetic neuralgia
what is the pathology behind the varicella zoster virus?
> Degeneration of epithelial cells leads to vesicle formation and ulcer formation
> Chronic inflammatory cell infiltrate in the connective tissues
what is the Epstein Barr virus associated with?
> associated with glandular fever
> associated with hairy leukoplakia
> EBV related to oral ulceration - mimics SCC in immunocompromised
> associated with mumps like disease
what is cytomegalovirus associated with ?
> oral ulceration in immunocompromised host
what can cytomegalovirus affect?
> salivary glands in infants and immunocompromised
what is the action of acyclovir (anti viral drug_
- antiviral drugs should affect the virus but not host cells
- Analogue of purine nucleotide
- Viral enzymes phosphorylate drug to Acyclo-AMP
- Cellular enzymes phosphorylate Acyclo-AMP to Acyclo-GTP
- Acyclo-GTP inhibits viral DNA synthesis
what is the uses of acyclovir?
> Herpes labialis
Primary herpetic gingivostomatitis
Herpes Zoster Infection
what is the pharmacokinetics of acyclovir?
what is the pharmacokinetics of acyclovir?
- Oral absorption moderate
- Half life 2.5 hours
- Crosses blood brain barrier
- Eliminated by the kidney
what is the acyclovir treatment for primary gingivostomatis?
> only in severe cases
- Systemic therapy 200mg five times a day
- Begin treatment at onset of infection
- Children over 2 years old – full adult dose
what is the acyclovir treatment for herpes labialis?
- Topical (5%) cream in prodromal phase
- Aborts lesion in prodromal phase in 40% cases
- Reduces duration of lesions which develop
what is the paramyxovirus better known as?
> large family - measles virus and mumps virus
what is the paramyxovirus better known as?
> large family - measles virus and mumps virus
what is the transmission pathway for measles?
> Primarily air borne
Highly contagious
Effective vaccination programme
what is the clinical features of measles ?
> Respiratory symptoms
- Cough, runny nose
> Inflamed eyes
Pyrexia
Rash
Koplik spots
- intra-oral may form before skin rash
> Usually self limiting
Potentially serious / life threatening complications eg encephalitis, pneumonia, blindness
what is the transmission pathway of mumps?
> Airborne
Inanimate objects
Highly contagious
Effective vaccination programmes
what is the clinical features of mumps?
> Enlarged salivary glands
- Usually parotids
- Bi or unilateral
> Flu like symptoms
- Joint pain, headache, pyrexia, general malaise
> Usually self limiting
Potentially serious complications
- Meningitis, orchitis, oophoritis, pancreatitis, deafness,
how do you diagnose measles and mumps?
> Clinical – both mumps & measles have distinct clinical picture
PCR
Acute and convalescing serum
what is the treatments for measles and mumps?
> Supportive therapies
- Fluids, bed rest, analgesia
> Notify Public Health Agency
what is the symptoms of hand foot and mouth disease?
- General malaise
- fever
- flat red rash on hands, feet & around mouth.
- Rarely complications eg meningitis
what causes HFM disease?
- variety of viruses
what age is HFM disease most common?
< 5 years
what is the diagnosis and treatment of HFM disease?
> diagnosis - clinical
> treatment - supportive
what type of virus is the human papilloma virus?
- DNA virus
- over 100 types discovered
how is the human papilloma virus transferred?
- skin to skin contact
- infectivity not fully understood, there are links with tobacco and sun exposure
what is the the clinical appearance of a squamous papilloma?
- pedunculated
- finger like projections
- benign mucosal mass
what HPVs cause a squamous papilloma?
6 and 11
what is the treatment if the squamous papilloma?
- excisional biopsy
how does the HPV become malignant in a host?
> HPV can integrate into host’s genome
interfere with function of regulatory proteins eg p53, p16, and pRb
loss of control over cell proliferation
Most types are considered “low-risk” for development of malignancy, but about 13 types are considered “high-risk”.
