Exanthems Flashcards
Streptococcus pyogenes, Group A
Gram pos cocci, catalase negative
Beta Hemolytic, Lancefield group A +
Resistant to dessication
Human throat
Respiratory droplets, direct contact (fomites, exudates), carriage possible in URT/GI
All ages (peaks at 1-15)
Capsule
Grp A specific carbohydrate
M PROTEIN- Adherence, antiphago
F PROTEIN- Fibronectin that binds pharyngeal epithelium
Erythrogenic toxins: SpeA, SpeB , SpeC (SuperAg)
Triggers DTH rxn (Rash)
On lysogenized phage
Streptococcal Toxic Shock Toxin
Streptolysin O & S Streptokinase Streptodornase SCARLET FEVER (Scarlatina) Diffuse maculopapular rash
Upper chest => extremities
Pastia’s lines Sandpaper feel- dark skinned pts Circumoral pallor Strawberry tongue Blanches on Pressure (Schultz-Charleton Phenomenon)
Hallmark- ability to disseminate Clinical expression of Scarlet Fever Lancefield group A positive Rapid Strep Test Culture (often negative) Anti-streptolysin O (agglut. assay)
Penicillin to treat GAS infection
Early diagnosis and treatment; good hygiene to block spread
Rapid Strep test
Lancefield Groupin
Rubeola Virus
Neg sense ss RNA, Enveloped
Buds via plasma membrane
(H and F spikes)
Humans
Respiratory- sneeze or cough produced droplets are inhaled
Highly contagious (90% Attack Rate)
Infectious 5 days before and 4 days after rash appears
Unvaccinated
(more severe in children 2-5 yrs)
Can see in adults
Hemagglutinin(H) GP spike to bind CD46 on our cells
Fusion (F) spike for fusion of virus to cell and syncytia formation.
Hallmark-multinuc giant cells
SSPE: 1-10 years post infx; fatal CNS disease; behavioral- motor control; RF- disease before 2, abn virus in brain
NOTE: virus infected endothelial cells plus immune T cells are what cause the Rash
TYPICAL MEASLES Incubation: 7-18 days (long) High fever (>101) – throughout pres 3C’s = Cough, Coryza ,Conjunctivitis Photophobia KOPLIKS SPOTS - buccal mucosa (100% Pathognomonic), usually disappear at onset of rash Maculopapular rash Confluence of rashes
Face => trunk, incl. palms & soles
Sequelae: SSPE (1-10 yrs later, risk if infected at early age, ass’d w/ defective forms in brain); secondary bacterial infections; giant cell pneumonia
Clinical presentation of Measles
Serology IgM
Supportive = antipyretics/fluids
Antimicrobials for bacterial infections.
Vaccine : MMR (Live attenuated)
Immune serum globulin for immunocompromised
Rash can Coalesce; Not seen in other exanthems
Rubella virus
Pos sense ss RNA linear, Enveloped
Can be translated immediately
(has H but no F peplomer)
Humans
Respiratory w/ nose and throat discharge
Transplacental (teratogenic to fetus /Congenital abnormalities.)
Unvaccinated (especially ages 5-9); unborn fetus
Most contagious when rash is erupting; Virus is shed 7days pre to 4days post rash.
GERMAN MEASLES (3 days) (Mild Rubeola-like) Low fever; No 3C’s (mild coryza and conjunctivitis in some) Rash due to immune complex formation Maculopapular rash; Polyarthralgia
Face => trunk
Congenital Rubella Syndrome
=Heart (PDA, pulmonary A. stenosis), Eyes (cataracts, glaucoma), CNS (microcephaly, deafness)
Doesn’t abort fetus, teratogen (1st trimester), transplacental transmission
Clinical presentation of German Measles
Best = Serology (IgM)
Supportive = antipyretics/fluid
Antimicrobials for bacterial infectns.
Vaccine: MMR (Live attenuated)
HIV & Immunocompromised may be at risk of infections.
Parvovirus B19
Naked ss Linear DNA (- or + sense)
Requires host cell to be replicating
Tropism- Erythroid precursor cells
Binds Globoside /Blood Group P Ag
Humans
Respiratory droplet, (faecal-oral, blood and blood prods.)
Transplacental (rare, Spontaneous Abortions)
Elementary age, Unborn fetus
Individuals w/ preexisting anemias –Sickle cell anemia
Extra Note: in pregnancy, it’s important to distinguish from Rubella: congenital anomalies from Parvovirus B19= Miscarriage
Immune complex hypersensitivity causes rash; sudden arthritis in all of the joints
ERYTHEMA INFECTIOSUM (5TH DISEASE)
Fever, coryza, headache, and mild GI distress
Slapped Cheek Syndrome – 2 to 5 days later
Lacy Reticulate Maculopapular Rash; pruritic; Drop in Hb/Hct
Rash starts from face => trunk & limbs
Aplastic Crisis; Hydrops Fetalis; Fatal Haemolytic Anaemia
Clinical presentation of 5th disease-slapped cheeks
PCR; Serology—IgM and IgG for confirmation; drop in Hct may be seen; Giant pronormoblast
Supportive (healthy)
Blood transfusion (aplastic anemia)
Passive immunization (immunocompromised)
Droplet isolation precautions to protect susceptible populations; No vaccine; Long lasting immunity
Giant Pronormoblast in biopsy of Parvo B19 infection
Human Herpes Virus 6 (HHV-6)
ds Linear DNA, Enveloped
Replicates in T cells, B cells and oropharyngeal epithelium
Packages all of its enzymes
Humans (Lifelong infections)
Respiratory droplets;
Possible Transplacental and perinatal
Children 6-12 months- Most common childhood exanthem
Immunocompromised (usually due to reactivation)
No rash during febrile period
EXANTHEM SUBITUM (ROSEOLA)
3-5 days High Fever
Fever ends and Rose colored macular to maculopapular rash erupts
Rash is due to Immune complex hypersensitivity
May have URT signs/ symptoms
Rash starts on face and trunk
Can have fever w/out rash=Infantile Fever; may cause seizures in kids
Clinical presentation
Confirmed via serology (IgG paired sera)
Symptomatic relief
No vaccine; Long lasting immunity
Varicella-Zoster virus
ds Linear DNA, Enveloped Humans Lifelong latent infection Reactivates as Shingles Droplet; Direct and Indirect exposure of mucosa to exudate from skin lesions Unvaccinated populations
Begins as macular maculopapularVesicle
VARICELLA (Chickenpox)
Incubation 12-21 days
Infective 4-8days prior lesions & 4-5days after crust
Bad rash = high fever Rash = itchy, vesicular Dew drops on a rose petal Hallmark: Mixed lesions Face /trunk => extremeties (moves outwards) Sequelae: Reye’s syndrome (children<12) aspirin use
ZOSTER (Shingles)
Reactivation; Painful vesicular lesions in dermatomes; can get
Post Herpetic Neuralgia
PERINATAL VARICELLA SYNDROME
Infection occurs in mother
5days prior to birth or 2days post-partum
Ramsay-Hunt Syndrome: facial palsy; CN VII-VIII
Clinical; pos culture from lesions and detect specific Ag; also Tzanck smear: multinucleate giant cells
Topical for pruritus, Acycloir
No aspirin in Peds = Reyes
Pain control, Varicella Ig (passive immunization)
Live attenuated vaccine, passive post exposure. Booster in elderly for zoster.
ZOSTAVAX – for Shingles. (SubQ)
Variola virus
ds Linear DNA, double envelope: Replicates in cytoplasm
Unique inclusion bodies:
Gurarnieri’s Bodies
Humans
Respiratory Droplets Aerosolization from skin lesions Unvaccinated populations Bioterrorism DNA dependent RNA pol; exocytosis via golgi apparatus
SMALL POX Mild prodrome: flu-like Sx Fever falls, abrupt onset of rash Macular=>Vesicular=>Pustular All lesions are at the same stage No mixed lesions Mouth =>Face/extremeties => trunk (moves inward)
Several different expressions of disease including a hemorrhagic form
Virus released from blood vessels begins to grow in epidermis
25% mortality rate
Clinical presentation / History of exposure/No vaccination, inclusion bodies
DFA & PCR
Symptomatic relief
Passive immunization
Live Genetically related Vaccinia vaccine
Cocksackie A16
MOST COMMON
Pos sense ss RNA; Naked
Replicates in cytoplasm
Humans
Fecal-Oral- generally water
Person-person
Summer/Fall sessions
Infants and Young children
(2 wks to 3 yrs old)
HAND, FOOT AND MOUTH DISEASE
Fever vesicular eruptions on hand, palate (mouth) and feet.
Children younger than 10
Sore mouth, sore throat & anorexia
Meningitis can occur
Difficult based on clinical presentation alone, use epidemiology
Self Limiting
Pleconaril recently
No vaccine
Boil anything that touches mouth/saliva of infected person
Monkey Pox
ds linear DNA; double envelope
Primarily animals from Africa, exotic pets
Resp/aerosolized fluid from lesions; bites, blood expos
Unvaccinated; expose to infected animals
MONKEY POX
Not as severe as smallpox, more random distribution; Profound Lymphadenopathy involving submandibular, cervical and sublingual regions; acute febrile exanthem;
IgM and clinical presentation; History of Exposure!
Self limiting
Smallpox vaccination appears to protect or previous exposure
