Viral Exanthams Flashcards
Macule
<1 cm
Circular
Flat
Discolouration (red, brown, blue)
Papule
<0.5 cm Superficial Solid Elevated Color varies
Morbilliform
Erythematous macules and papules
Resembles measles
Vesicle
<1 cm
Circular collection of fluid
Pustule
Vesicle containing pus
Petechiae (petechial)
Pinpoint
Round spots
As a result of bleeding
Exanthem
A rash that appears abruptly and affects several areas of the skin simultaneously
Viral ones are more common in children, nonspecific, and self limiting
Measles virus
enveloped?, nucleic acid, family, genus, causes what, transmission
Enveloped non-segmented ssRNA (-)
Family Paramyxoviridae, genus Morbillivirus
Causes measles (rubeola): infection of the respiratory tract, spreads and presents as a morbilliform rash
Highly contagious
Spread by aerosol and contact
R naught
Average number of people that one sick person will infect
Measles has a very high R0 (18)
Symptoms of Measles (rubeola)
Fever
The 3 C’s: cough, coryza, conjunctivitis
Koplik spots in the mouth
Morbilliform rash: generalized, maculopapular, erythematous
Complications of measles
Bronchitis Pneumonia Encephalitis Death SSPE (Subacute sclerosing panencephalitis)
Subacute sclerosing panencephalitis
Rare progressive neurological disorder
Can occur years after measles infection
Even if the person is fully recovered from the illness
Death usually within 3 years
Molecular detection of measles
Respiratory illness but spreads to areas including the bladder
RT-PCR from nasopharyngeal swabs, throat, and urine
RT-PCR more sensitive than IgM
Viremia before rash appears
Rubella Virus
enveloped?, nucleic acid, family, genus, transmission, causes what, detection
Enveloped, ssRNA (+) Family: Togaviridae, genus: Rubivirus Tranmission droplet and vertical Adult disease is a self limiting rash Concern is infection during pregnancy: congenital rubella syndrome, miscarriage or severe birth defects MMR vaccination! Serology is useful, also PCR
Congenital Rubella Syndrome
Child contracted rubella from the mother in utero
Outcomes: deafness, cataracts in the eyes, heart problems, meningoencephalitis, mental or growth retardation, enlarged liver and spleen, skin lesions, bleeding problems
Parovirus B19
enveloped?, nucleic acid, family, genus, transmission, causes what
Non-enveloped ssDNA Parvoviridae family, Erythrovirus genus Transmission droplet and vertical Infectious period before the onset of rash Causes erythema infectiosum
Erythema infectiosum
Prodrome: low-grade fever, malaise, headache, coryza, myalgias, joint pain (more common in adults)
Exanthem: begins with bright red ceeks, then get a symmertric, erythematous, reticular eruption on trunk and extremities
Usually mild for children and adults
Can lead to aplastic crisis
Treat with blood transfusion
Hydrops fetalis
Fetal anemia can lead tot his
Intrauterine growth retardation, pleural/pericardial effusions, and death
Roseola infanticum (exanthema subitum) (enveloped?, nucleic acid, transmission, symptoms)
Human herpesvirus 6 or 7
Enveloped, dsDNA
Transmission unknown, but likely droplet and contact
No vaccine, infection leads to immunity
Immunocompromised have significant mortality
Rash: papular purpuric gloves and socks syndrome, purple or brownish red spots, usually in adolescents
Enterovirus
family, enveloped?, nucleic acid, transmission, causes what
Picornaviridae family
Non-enveloped, ssRNA (+)
Transmission: droplet, contact
Respiratory, CNS and exanthems
Hand foot and mouth disease (skin and oral lesions resembling canker sores)
Seasonal: common in late summer and early fall
Hand foot and mouth disease
From enteroviruses, echoviruses, and coxsackie viruses
Rash starts in the mouth and resembles canker sores
Later presents on hands and feet (bring pink macules and papules, then painful vesicles and erosions with erythema, usually self limiting and resolves within days)
Varicella zoster virus
enveloped?, nucleic acid, family, transmission, symptoms
Enveloped dsDNA Family: herpesviridae Human herpes virus 3 Transmission: aerosols Vaccines available Contagious for a couple days before rash Rapid progression from macules to papules to vesicles with crusting
Complications of varicella
Bacterial infections in children (skin and soft tissue) Severe pneumonia (adults) Septicemia Necrotizing faciitis Septic arthritis Hemorrhagic conditions CNS infection/encephalitis Zoster in children
Herpes Zoster
Painful vesicular eruption in a dermatomal distribution
From VZV reactivation
Disseminated zoster spans more than one dermatome, in immunocompromised people
Diagnosis for herpes zoster
PCR is highly sensitive and specific
Serology (only for immunity)
Herpes zoster treatment
Antivirals: acyclovir, cidofovir, foscarnet
VZIG (immunoglobulin): exposed neonate or susceptible adult
2 VZV vaccines
Varivax (chickenpox vaccine): childhood vaccination programs
Zostavax (shingles vaccine): reduces severitiy and occurances of PHN
