Viral Exanthems Flashcards
What is a macule/macular rash?
<1cm, circular, flat, with red, brown, or blue discolouration
What is a papule/papular rash?
<0.5 cm, superficial, solid, elevated with varied colours
What is a morbilliform rash?
erythematous macules and papules that resemble measels
what is a vesicle?
<1cm circular collection of free fluid
What is a pustule?
Vesicle containing pus
What is a petechiae or petechial rash?
Pinpoint round sports that form as the result of bleeding
What in an exanthem?
A rash that appears abruptly and affects several areas of the skin simultaneously
most viral exanthems affect… and are.. (2 things)
Affect mainly children and are non-specific and self limiting
Measles virus (MeV) presents with what kind of rash?
Morbilliform rash
What is another name for measles
rubeola
What is measles an infection of?
the respiratory tract
How is measles spread? Is it very contagious or not?
Spread by aerosol and contact and is highly contagious
What is the R naught value?
Average number of people that one sick person will infect
What is the infectious period for Measles?
4 days before the onset of the rash and the 14 days after the rash has cleared
What are 4 symptoms of Measles?
- Fever
- The 3 C’s
- Koplik spots in the mouth
- Morbilliforme rash
What are the 3 C’s of measles?
cough, coryza, and conjunctivitis
What is the morbilliforme rash of measles like? where does it first appear? does it spread?
generalized, maculopapular, and erythematous
First appears on the face and neck
- spreads quickly to entire body
What are 5 potential complications resulting from an infection with measles?
- Bronchitis
- Pneumonia
- Encephalitis
- Death
- Subacute sclerosing panencephalitis (SSPE)
What is Subacute sclerosing panencephalitis (SSPE)?
a rare and progressive neurological disorder that can appear years after measles infections
people die usually within 3 years
What % of the population needs to be vaccinated in order to benefit from heard immunity?
at least 90%
How is serology useful in differentiating between acute disease and previous exposure?
high IgM levels correlate to acute disease where IgG levels correlate to immunity
How is molecular detection useful in the diagnosis of measles?
MeV is a resp. virus but will spread to other areas including the bladder
What kind of molecular method is used to test for measles? using what sample?
RT-PCR from nasopharyngeal swab, throat swab, and urine sample
Which is more sensitive? RT-PCR or IgM serology?
RT-PCR
Why is molecular detection more useful for measles?
can detect viremia before the rash appears
How is rubella virus (RuV) transmitted?
droplet and vertical transmission from nasal or throat secretions
Why is rubella a concern for pregnant women?
can result in birth defects and miscarriage as well as congenital rubella syndrome (CRS)
What is the usual result of a rubella infection in adults?
self limiting rash
What is another name for rubella?
german measles
What is the rash presentation for rubella?
another maculopapular, mobilliform rash on the skin
also petechial rash presentation on the uvula
What is the infectious period like for rubella?
7 days before to 14 days after the rash
What is the incubation period for rubella?
14 to 21 days
When are children most contagious with rubella?
when the rash is erupting
Where does the rash usually present for rubella?
on the torso, arms and face (as well as the uvula)
What is congenital rubella syndrome?
child contracting rubella from the mother in utero
What are the outcomes of CRS?
Deafness Cataracts in the eyes Heart problems - patent ductus arteriosus Meningoencephalitis Microcephaly Mental or growth retardation Enlarged liver and spleen (hepatosplenomegaly) Skin lesions (exanthem) Bleeding problems
What is the viral cause of erythema infectiosum?
parvovirus b19
how is parvovirus b19 transmitted?
droplet and vertical transmission
When is the infectious period for parvovirus B19
before the onset of the rash
What is the prodrome of symptoms for erythema infectiosum? who is the most common in?
low grade fever, malaise, headache, coryza, myalgias, joint pain
more common in adults
What is the exanthem progression for erythema infectiosum?
Begins with bright red “slapped” cheeks
- fades over 1-4 days
Symmetric, reticular (lace like), erythematous eruption appears on trunk and extremities
- lasts 5-9 days
What is a potential complication for parvovirus B19 infections?
Aplastic crisis
- infection of RBC progenitors leads to reticulocytopenia
What is the treatment for aplastic crisis? who is most susceptible?
immunosuppressed are particularly at risk
treatment is blood transfusion
What is a result of aplastic crisis in a fetus?
Anemia which can cause Hydrops fetalis
- Intrauterine growth retardation, pleural/pericardial effusions, and death
What is the main way to test for parvovirus infection/immunity?
serology
What do HHV-6 and HHV-7 cause?
Roseola infanticum
also called exanthema subitum
What is the transmission for HHV 6 and 7?
unknown, likely droplet and contact
When are HHV 6 and 7 an issue?
when someone is immunocompromised - leads to significant morbidity
What is the difference in presentation for Roseola infanticum between children and adolescents?
Children: maculopapular mobilliform rash
Adolescents: Papular purpuric gloves and socks syndrome. Purple or brownish-red spots
What viruses causes hand foot and mouth disease?
Enteroviruses, echoviruses and coxsackie viruses
What kind of distribution do enteroviruses have?
Seasonal - common in late summer and early fall
What are the exanthem vs enanthem of HFM disease?
Exanthem (blister like macules and papules) and enanthem (oral lesions) resembling aphthae (“canker sores”)
What comes first for HFM disease? the exanthem or the enanthem?
the enanthem (canker sore like lesions in the mouth) appears first
later presents with macules and papules on the hands and feet
- painful erythemic vesicles and erosions on
What is done to treat HFM disease?
nothing, self limiting and usually resolves in a few days
another name for HHV-3 is….
Varicella zoster virus (VZV)
What is the transmission like for VZV?
aerosol/airborne (like measles)
What is the infectious period for VZV?
1-2 days before the onset of the rash until the lesions have crusted over
Is there a vaccine for VZV?
yes
what treatments are available for VZV?
acyclovir or VZIG (immunoglobulin)
What is the rash like for VZV? progression?
Generalized and pruritic (itchy)
Rapid progression from macules to papules to vesicules with crusting
What is a/are some severe complication(s) of VZV in children? in adults?
Children:
- Bacterial infections (skin and soft tissue)
- CNS infections and encephalitis
- zoster
Severe pneumonia (adults)
What is herpes zoster?
Reactivation of HHV-3 later in life occurring in specific dermatomes
- very painful vesicular eruptions
What are dermatomes?
areas on skin supplied by sensory nerves
What is disseminated zoster? When does that occur?
zoster spanning more than more dermatome
usually if someone is immunosuppressed/compromised
What is the most sensitive and specific method for testing of HZV?
PCR
When do you use serology as a means for testing for HZV?
only to test for immunity
- prenatal screening
What treatments are available for VZV? When do you give either one?
Antivirals (ex: acyclovir, cidofovir, foscarnet)
VZIG (immunoglobulin) - exposed neonate or susceptible adult
What are the two vaccines for VZV? when are either of them given?
Varivax (“chickenpox vaccine”)
-Childhood vaccination programs
Zostavax (“shingles vaccine”)
-Reduces severity and occurrences of PHN
