Childhood viral exanthems Flashcards

1
Q

What is the difference between a macular and papular rash? What is a morbilliform rash?

A

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

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2
Q

What is an exanthem? A viral exanthem?

A

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.

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3
Q

Name 2 common pediatric viral exanthems

A

1) Varicella zoster virus: chickenpox/shingles (exanthematous pustulosis)
2) Enterovirus: hand foot and mouth disease

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4
Q

Describe the morphology and pathogenicity of measles virus

A

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.

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5
Q

Describe measles

A

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

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6
Q

What are the 4 possible complications of a measles virus infection

A

Bronchitis, encephalitis, pneumonia, subacute schlerosing paraencephalitis.

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7
Q

What is subacute schlerosing paraencephalitis?

A

Rare progressive neurological disorder that may occur years after a fully recovered measles infection usually resulting in death within 3 years

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8
Q

Serology is used for diagnosis and immunity to measles. What antibodies show acute infection and which show immunity?

A

IgM shows an acute infection and IgG shows past exposure to the virus and correlate with immunity

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9
Q

Describe rubella virus and the disease

A

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.

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10
Q

How is congenital rubella syndrome contracted and what are some outcomes of the disease?

A

In utero contraction of rubella virus. Some possible complications include: deafness, cataracts, heart problems, meningoencephalitis

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11
Q

Describe Parvovirus B19 and the disease it causes

A

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

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12
Q

Describe the most common complication of parvovirus infections in infants

A

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

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13
Q

What is the virus that causes roseola infanticum

A

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).

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14
Q

Describe hand foot and mouth disease and the virus that causes it

A

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.

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15
Q

Describe varicella zoster virus and the disease it causes

A

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.

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16
Q

What are some complications that may occur with VZV?

A

Bacterial infections in children (vesicular rash may open and let bacteria in)
Severe pneumonia in adults
CNS infection
Zoster (shingles)

17
Q

What happens during VZV reactivation in adults?

A

Latent virus in dorsal root ganglia may become reactivated in dermatomes (areas of skin supplied by sensory nerves). The reactivation has a dermatomal distribution and is a painful vesicular eruption. May occur as a disseminated zoster where it spans more than one dermatome.

18
Q

How is zoster diagnosed and treated?

A

PCR is highly sensitive and specific. Serology is only used to determine immunity. Can be treated with antivirals and immunoglobulin.

19
Q

How is measles virus detected and where are samples obtained from?

A

RT-PCR, samples from NP, throat, urine