25. Viral Infections Flashcards
1
Q
What is the most common cause of oral viral infection in humans?
A
human herpesviruses
2
Q
Properties of human herpesviruses
A
- all structurally similar
- enveloped
- icosahedral
- 180-200nm in diameter
- double-stranded DNA - linear DNA
- inactivated by solvents like alcohol and common disinfectants
- neurotropic
- latent - can re-infect host and cause recurrent infection
3
Q
How do human herpesvirus get into human cells?
A
- nucleocapsid transported to host cell nucleus
- viral DNA uncoated
- 3 classes of mRNA are produced - immediate early, delayed early and late
- translation of early and then late proteins
- viral nucleocapsids assembled in nucleus
- viral envelope added during budding through nuclear membrane as exit nucleus
4
Q
Pathogenesis of herpesvirus infections
A
- herpesviruses can remain latent in the body after initial infection
- reactivate under conditions of stress or when immune system is compromised
- herpesviruses can infect neuronal cells and travel to nerve ganglia
- replicate in ganglia or establish a latent infection
- reactivation via certain triggers
- virus travels along neurones and develops secondary infection in relevant dermatomes
5
Q
Types of human herpesviruses
A
- human herpesvirus 1 (HHV-1)
- herpes simplex virus (HSV-1)
- HHV-2
- herpes simplex virus 2 (HSV-2)
- HHV-3
- varicella-zoster virus (VZV)
- HHV-4
- Epstein-Barr Virus (EBV)
- HHV-5
- Human Cytomegalovirus
6
Q
Herpes simplex is caused by …
Primary infections is acquired through …
A
- HSV 1 and 2/human herpes viruses 1 and 2
- direct contact or contaminated secretions
7
Q
Primary Herpes simplex infections
A
- primary gingivostomatitis
- herpetic whitlow
- genital herpes
- conjunctivitis
- encephalitis
8
Q
Explain herpes simplex 1
A
- common
- given through direct contact with infected lesions or saliva
- 3-5 day incubation
- 2-3 week long lesions
- typically infects epithelial cells around mouth
- oral and pharyngeal ulceration
9
Q
Explain herpes simplex 2
A
- one of the most common sexually transmitted diseases
- HSV-2 infections associated with anogenital area
- most likely to be spread if current, active lesions but also transmitted in asymptomatic periods
10
Q
Symptoms in a herpes simplex primary infection
A
- prodomal symptoms like burning, itching, tingling in skin or mucosa for a day or so
- systemic symptoms like fever, malaise, nausea, vomiting, accompanying lymphadenopathy
11
Q
Explain transmission and symptoms of primary herpetic gingivostomatitis
A
- common in young children
- via direct contact with infected lesions or saliva of person with infected lesion
- oral lesions around lip, mouth, less so on tongue, face, palatal/buccal mucosa
- blisters/vesicle erupt as clusters and ooze clear-yellowish fluid that can develop into yellow crust
- ulcers cause intense erythema in gingiva and bleeding
- painful oral ulceration
- pyrexia and increased salivation
12
Q
Treatment of primary herpetic gingivostomatitis
A
- treat symptoms with anti-pyretic medication, rest and maintain fluid intake
- wait for infection to run it’s course (1-2 weeks)
13
Q
Explain herpetic whitlow
A
- herpes simplex infection in fingers
- caused by inoculation from another infected site
- infection of fingers acquired by dentists and nurses due to contamination of hands in viral laced saliva or secretions
14
Q
How can facial herpes infection become recurrent?
A
- reactivation of latent virus at trigeminal ganglion
15
Q
Explain herpes labialis
A
- cold sores
- most common manifestation of recurrent herpes simplex virus infection
- lesions appear at mucocutaneous junction of lip
- fluid-filled semi-translucent blisters which enlarge and coalesce to form large blister that weeps exudate
- typically after 2-3 days lesions rupture and crust over
- can last up to 12 days
- infectious virus shed from lesion until healed
16
Q
Triggering factors that cause reactivation of herpes labialis include …
A
- other illness like common cold
- emotional stress
- exposure to cold/sunlight/UV
- menstruation
- dental treatment
- immunosuppresion
17
Q
Symptoms of herpes labialis
A
- lesions in mucocutaneous junction of lip
- prodomal paraesthesia/burning/tingling at site of future blisters
18
Q
Management of herpes labialis
A
- adequate hydration, pain, fever management
- with analgesics and antipyretics and topical anesthetics such as lidocaine gel
- antiviral medication (acyclovir)
- reduce symptoms if started within 24-48 hrs of vesicle eruption, recurrent infections treated symptomatically, severe cases need systemic antiviral medication
19
Q
What is human herpes virus 3 - VZV?
A
- causes chicken pox and shingles
- pox is the primary and shinges the reactivation
20
Q
Explain chicken pox
A
- highly contagious
- benign infection in childhood and self limiting
- transmission by direct contact with infected or by droplets/nasopharyngeal secretions
- incubation of 10-21 days
21
Q
How does chickenpox infect the body?
A
- enters epidermal cells
- and via retrogade axonal transport to neuronal cell bodies in sensory doral root ganglia
- becomes latent there
22
Q
Symptoms of chickenpox
A
- fever, malasie, sore throat
- intense, uncomfortable, itchy rash on trunk and face
- rash becomes vesicles before scabbing over
- worse in adulthood/pregnancy
- can be oral lesions on palate, buccal mucosa and uvulu
23
Q
How to manage chickenpox?
A
- symptomatic relief
- adequate hydration, rest, fever control by paracetamol, lotion for rash
- severe infections may require antiviral therapy
24
Q
Herpes zoster is what?
How does it cocur?
A
- reactivation of Varicella-zoster virus infection/chicken pox
- more common in elderly
- predisposed with age, immunosuppression, stress/trauma
25
Q
Initial clinical signs of Herpes Zoster
A
- unilateral pain in dermatome supplied by nerve in which virus has become latent
- headache, photophobia and malaise
26
Q
Clinical symptoms of Herpes Zoster
A
- severe neuralgic burning pain
- development of rash in dermatome
- clusters of clear vesicles
- these rupture, ulcerate and crust over in 7-10 days
- fever and malaise
- pain continues until legions heal
- can have long term neuralgic pain/numbness
27
Q
Herpes zoster of the trigeminal area
A
- pain precedes rash
- lesions localised to one side - within distribution of any divisions of trigeminal nerve
- malaise and pain are severe, life-threatening in immunosuppression
- patients may require treatment with systemic antiviral drugs like acyclovir
- antibiotics may be required if rash/vesicles become infected
28
Q
Dental considerations of herpes zoster
A
- oral manifestations like intra-oral vesiclesm ulceration, localised/unilateral
- unilateral pain and ulcers in trigeminal herpes zoster
29
Q
Management of herpes zoster
A
- analgesia
- antiviral medication (acyclovir)
30
Q
Human herpes virus 4/EBV causes what?
A
- infectious mononucleosis (glandular fever)
- Burkitt’s lymphoma
- oral hairy leukoplakia
31
Q
What percentage of the world report to be infected with EBV?
Where’s the highest prevalence?
A
- 90-95%
- in adolescents and young adults
32
Q
Explain infectious mononucleosis
A
- caused by EBV in 90% of cases or cytomegalovirus
- from kissing infected individuals, infected parents or siblings
- sudden onset sore throat, sloe development of malaise, myalgia, posterior cervical lymphadenopathy, palatal petechiae
33
Q
Explain human herpes virus 5 - human cytomegalovirus
A
- almost ubiquitous virus causes acute primary disease and remain latent for recurrent infection
- almost all infections are asymptomatic
- can cause infectious mononucleosis-like symptoms
