Childhood viral exanthems Flashcards
What is the difference between a macular and papular rash? What is a morbilliform rash?
Macular rashes are less than 1 cm wide, flat with discoloration
Papular rashes are less than 0.5 cm wide, solid, elevated and discolored
Morbilliform rashes are erythematous macules and papules
What is an exanthem? A viral exanthem?
An exanthem is a rash that appears abruptly and affects several areas of the skin simultaneously. Viral exanthems are more common in children and are mostly nonspecific and self limiting.
Name 2 common pediatric viral exanthems
1) Varicella zoster virus: chickenpox/shingles (exanthematous pustulosis)
2) Enterovirus: hand foot and mouth disease
Describe the morphology and pathogenicity of measles virus
Enveloped, non-segmented ssRNA virus of the paramyxoviridae family. Causes measles, a respiratory tract infection that spreads to form a MORBILLIFORM rash. It is highly contagious and spread via aerosol and contact.
Describe measles
AKA rubeola. Fever, 3 C’s (cough coryza and conjunctivitis), Koplik spots in mouth, morbilliform rash.
Rash first appears on face and neck and quickly spreads across entire body
What are the 4 possible complications of a measles virus infection
Bronchitis, encephalitis, pneumonia, subacute schlerosing paraencephalitis.
What is subacute schlerosing paraencephalitis?
Rare progressive neurological disorder that may occur years after a fully recovered measles infection usually resulting in death within 3 years
Serology is used for diagnosis and immunity to measles. What antibodies show acute infection and which show immunity?
IgM shows an acute infection and IgG shows past exposure to the virus and correlate with immunity
Describe rubella virus and the disease
Rubella virus is an enveloped ssRNA virus of the togaviridae family. Transmission occurs through droplets. In adults the disease is only a self-limiting morbilliform rash rash but infection during pregnancy is a cause for concern due to Congenital Rubella syndrome or miscarriage or birth defects.
How is congenital rubella syndrome contracted and what are some outcomes of the disease?
In utero contraction of rubella virus. Some possible complications include: deafness, cataracts, heart problems, meningoencephalitis
Describe Parvovirus B19 and the disease it causes
Parvovirus is a non-enveloped dsDNA virus of the parvoviridae family. It is spread vertically or through droplets. It is infectious only before the onset of the rash. It causes erythema infectiosum. The prodrome is low grade fever, malaise, headaches etc. The exanthem begins with bright red cheeks which fades after a few days followed by a rash eruption on the trunk and extremities
Describe the most common complication of parvovirus infections in infants
Parvovirus infects red blood cell progenitors which can lead to an aplastic crisis - fetal anemia. Fetal anemia can lead to hydrops fetalis which is intrauterine growth retardation, pleural/pericardial effusions and death
What is the virus that causes roseola infanticum
Human herpesvirus 6 or 7. It is an enveloped, dsDNA virus. There is no vaccine but infection leads to immunity. There is significant morbidity in immunocompromised individuals. Roseola infancticum is a morbilliform rash of purple or red-brown spots on the feet and hands (gloves and socks syndrome).
Describe hand foot and mouth disease and the virus that causes it
Caused by enterovirus (or echoviruses, coxsackie viruses) of the picornaviridae family, a non-enveloped ssRNA virus. HFM disease is characterized by exanthems and enanthems that begin in the mouth and move to the feet and hands.
Describe varicella zoster virus and the disease it causes
VZV is an enveloped dsDNA virus of the herpesviridae family. It is transmitted through aerosols. The virus is contagious before the rash appears and after until the lesions have crusted over. Varicella is the rash caused by the virus and is generalized and itchy. The rash rapidly progresses from macules to papules to vesicles with crusting.
