infectious diseases Flashcards
pathogens
• Organism that is capable of causing disease
levels of virulence
–High - causes disease in a healthy population
–Low - causes disease only in susceptible populations
Opportunistic Infections
example?
• Non-pathogenic organism with Low virulence
• Immunocompromised host
C. albicans
Mutualism
• Interaction between two organisms
• Both organism benefits
Commensalism, example
Commensalism
• Interaction between two organisms
• One organism benefits
• Other is neither harmed nor helped
• C. albicans
How do pathogens injure cells and cause tissue damage?
• Bind to or enter host cells
• Release endotoxins or exotoxins
• Release enzymes that degrade tissue components
• Damage blood vessels and cause ischemic injury
• Induce host inflammatory and immune responses
general types of pathogens
• Prions
• Viruses
• Bacteria
• Chlamydia
• Rickettsia
• Mycoplasma
• Fungi
• Protozoa
• Helminths
• Ectoparasites
General Principles of Viral Infections
intracell?
tropism?
latent?
• Intracellular parasites, cannot replicate on their own
• Cell type specific
• Viral latency
A virus is a nucleic acid looking for a home
Viral Infection and Replication process
• Attach
• Penetrate
• Reproduce
• Assemble virions
• Release, usually kills
types of Viral Infections
• Transient infections
• Chronic latent infections
• Chronic productive infections
• Transforming infections/oncogenic
transient infection example
HepA
Chronic latent infection example
HSV
chronic productive infection example
HepB
oncogenic viruses examples
EBV, HPV
HHV
reservoir?
states?
• Humans are the natural reservoir
• Latency
• Reactivation
Human Herpes Virus types and names
• HHV-1= Herpes Simplex Virus Type 1
• HHV-2= Herpes Simplex Virus Type 2
• HHV-3= Varicella Zoster Virus
• HHV-4= Epstein Barr Virus
• HHV-5= Cytomegalovirus
• HHV-8= Kaposi Sarcoma associated virus
Transmission HSV
symptomatic?
Asymptomatic
• Contact with affected individual shedding virus can be done with:
–Symptomatic active lesions
–Asymptomatic viral shredding
HSV1 mostly causes infections where?
presents as?
oral infections, vesicles form and rupture with ulcerative transudate
Herpes Simplex Virus Type 2 mostly effects?
• Mostly genital infections, still ulcerations and ruptured vesicles
Primary Infection With. Herpes Simplex Virus
when does this usually occur?
symptoms?
• Initial exposure to virus in an individual without immunity
• Generally occurs at young age after physical contact with infected individual
• Mostly subclinical disease–80% of US population has antibodies to HSV, asymptomatic
Primary Herpetic Gingivostomatitis
S/S?
systemic and symptomatic
• Flu-like illness with fever, malaise, arthralgia, headache
• Cervical lymphadenopathy
erythematous marginal gingiva
primary herpetic gingivostomatitis
what oral tissues can be affected in primary gingivostomatits?
both bound and unboud tissues (keratinized and non-kertinized)
is primary gingivostomatitis acute or chronic? duration?
acute process with rapid onset and duration of 2-3 weeks
Recurrent Herpes Labialis
only affects?
only affects the lips
clustered vesicles that will rupture
recurrent herpes labialis
Recurrent Intra-Oral Herpes
usually on?
what can lesions do?
usually on the hard palate/ keratinzed and bound tissue
lesions can coalesce to form larger ulcers
recurrent intraoral herpes
Where is HSV dormant in affected indidivuals
trigeminal ganglion, can reactivate to cause S/S
HSV histology
form blisters with thin epithelium filled with transudate/ Tzanck cells= dying cells
HSV cytopathic effect
creates multinucleated cells
herpes whitlow
dentists without gloves, infection by HSV
herpes gladiatorium
usually close contact sports, can affect extra-oral tissues
HSV autoinoculation
usually affects the eye, infected indivivduals touch lesions then the eye
can result in herpes simplex keratitis
herpes simplex keratitis
What Is Recurrent Aphthous Stomatitis?
presentation?
cells involved?
viral?
• Focal mucosal destruction, “kanker sore”, exudate surrounded red halo forming an ulcer
• T lymphocyte mediated cytotoxic reaction, NOT VIRAL
Evolution Of An Aphthous Ulcer
Precipitating Factors for Recurrent Aphthous Stomatitis
• Sodium lauryl sulfate (SLS), toothpaste component
• Stress
• Trauma
• Allergies
• Acidic foods / juices
• Gluten
• Endocrine alterations
duration of Recurrent Aphthous Stomatitis
2-3 weeks
what tissues are affected by Recurrent Aphthous Stomatitis
non-keratinzed tissue, moveable and non-bound
Clinical Forms of Recurrent Aphthous Stomatitis
minor, major, and herpetic Aphthae
Minor Aphthae
occurance?
presentation?
healing time?
• Recurrent disease
• Shallow, painful ulcerations on non-keratinized mucosa
• Solitary or multiple lesions
• Heal in two weeks
minor aphthae
Major Aphthae
size?
depth?
healing?
• Larger (> 0.5cm)
• Deeper - may heal with scarring
• Heal slowly - weeks to months
major aphthae
scarring of major aphthae
Herpetiform Aphthae presentation?
healing time?
remission?
• Crops of small, shallow, painful ulcers (mimics herpes clusters)
• Heal in two weeks
• Short remissions
Herpetiform aphthae Resembles Recurrent Intra-oral Herpes Simplex
BUT
Located on non-keratinized mucosa and Does not begin as vesicles
Clinical Differential Diagnosis of recurrent herpes and recurrent aphthae
vesicular stage?
number of lesions?
location?
Aphthous-like Lesions May Be Associated With _________? examples?
systemic dx
• Behcet’s Syndrome
• Reiter’s Syndrome
• Inflammatory Bowel Disease
– Ulcerative colitis
– Crohn’s Disease
• Malabsorption Syndromes
– Gluten Sensitive Enteropathy
• Cyclic Neutropenia
• HIV / AIDS
Primary And Recurrent Infections With Varicella Zoster Virus
• Primary Infection -Varicella (Chicken Pox)
• Recurrent Infection -Zoster (Shingles)
Varicella (Chicken Pox)
transmission?
clinical or nonclinical?
symptoms?
lesions where?
waves?
scarring?
Varicella (Chicken Pox)
• Transmission by inspirationof infected droplets
• Clinical disease in mostindividuals
• Constitutional symptoms
• Skin lesions begin on face/trunk
• Vesicles in repeated waves
• Heal without scarring
can varicella have oral lesions
yes
how does varicella resolve
immunity created, virus becomes dormant in doral root ganglia
how does zoster occur
reactivation of the virus in doral root ganglia, leads to unilateral signs in associated dermatome
prodrome of zoster
pain and parathesia
can zoster present facially and orally?
yes, vesicles can form in mouth and on face and rupture.
does zoster have scarring
yes, lesion on skin may scar with healing
zoster and bone, dental correlation?
can lead to bone necrosis, seen on hard palate
zoster on the palate difference from herpes?
will have similar appearance but have a longer duration and intense pain
chronic pain of zoster
post-herpetic neuralgia (lasting pain in affected area) can occur after the prodromal and acute pain of zoster
Epstein Barr Virus
HHV?
most adults?
latent?
tropism?
infects epithelial cells where?
• Herpesvirus (HHV-4)
• Most adults EBV+
• Latency
• Tropism for B lymphocytes
• Infects epithelial cells of oral mucosa, oropharynx and nasopharynx
Dx’s associated with EBV
- Infectious Mononucleosis
- Lymphomas –NHL and HL (Burkitt lymphoma (NHL))
- Nasopharyngeal Carcinoma
- Oral Hairy Leukoplakia
Clinical Features of Infectious Mononucleosis
limiting?
usually occurs in what demographic? why?
signs and symptoms?
• Debilitating EBV infection
• Self-limiting
• Young adults- Salivary transmission
• Fatigue
• Malaise
• Lymphadenopathy
• Fever
• Sore throat
infectious mononucleosis infects what cells?
results in?
• Peripheral blood lymphocytosis
• Lymphocytes, not monocytes
• Atypical lymphocytes (Downey Cells)
infectious mononucleosis effects on the palate
petechia hemmorhages common
Infectious Mononucleosis effect on gingiva
Necrotizing Ulcerative Gingivitis