23 - Viral Causes of Skin lesions/rashes

Rashes: 1st - 6th disease: 6 common exanthems of children

* Enteroviruses

Picornavirus family - table

* current classification of subgroups = HEV-A, -B, -C, -D

Varicella-Zoster

Alphaherpesvirus Primary infection = Varicella (chickenpox) Reactivation of infection = shingles or zoster - Usually only occurs 1x - Risk of zoster increases with age

Exanthema subitum

Also called roseola or 6th Disease *High fever, followed by a rash* - Small, slightly raised pink lesions; starts on the trunk Peak incidence in children 6-15 months old; almost always in children younger than 3 years

Rubella Complications

Arthralgia or arthritis - children rare -adult female up to 70% Thrombocytopenic purpura- 1/3000 cases Encephalitis 1/6,000 cases Neuritis rare Orchitis rare

Eczema herpeticum

Children with eczema Eczema makes it easier for HSV to spread to the skin

Evolution of chicken pox

Clear vesicles on a erythematous base pustules → ulcers → crusted lesions

Hand foot and mouth disease - caused by?

Coxsackie A16, occasionally enterovirus 71

Molluscum contagiosum - what is it? how do you get it?

DNA pox virus Skin-skin contact or exposure to contaminated fomites - Usually in children <5 - Sexually transmitted in adults

8-month-old boy high fever & a widespread blistering eruption on his face Scattered lesions - hands, upper chest, neck & inside his mouth viral culture was positive for HSV-1 his mother had a healing cold sore on her lower lip the eruption improved within 48 hours with parenteral acyclovir discharged on oral valacyclovir to complete a 10 day course of therapy

Eczema herpeticum

Measles - course of infection diagram

Enters respiratory tract, disseminates & returns to respiratory tract Koplik spots - in the mouth

A 9 year old girl developed asymptomatic red cheeks & a symmetric reticulated morbilliform eruption. The rash gradually faded over 6 weeks and brightened with sun exposure and vigorous sports activities

Erythema infectiosum (5th disease) "slap cheek" rash

10-year-old boy multiple flat topped greyish-brown papules Onset ~ 1 year earlier treated with a daily application of treinoin 0.05 % cream.

Flat warts

15-year-old girl asymptomatic eruption on the face, the neck and hands for a year treated with a daily application of treinoin 0.05 % cream

Flat warts

Herpetic whitlow

HSV Infection of the finger Virus enters through breaks in the skin Seen in: - nurses, physicians, dentists who treat patients with HSV - child with HSV who sucks his thumb

Herpetic gladiatorum

Herpes on the skin; again virus enters through breaks in the skin Seen in wrestlers; other contact sports

34 year old man recurrent cluster of itchy vesicles on the neck cleared without treatment within a week

Herpetic gladiatorum

4 year old boy recurrent vesicles & pustules on the left palm every 4-6 months & cleared over 7-10 days bacterial cultures - negative Tzanck smear - multinucleated giant cells oral acyclovir starting at the onset of recurrent infections

Herpetic whitlow

Erythema infectiosum (5th disease) - phases - diagram

Infectious phase - not too many symptoms, nonspecific/flu like; lytic Rash - noninfectious

4-year-old boy multiple 2-3 mm pearly papules, some with central umbilication lesions were generally asymptomatic a few were occasionally itchy

Molluscum contagiosum

Rubella - epidemiology

No longer considered endemic in the US - Most reported rubella in the U.S. since the mid-1990s has occurred among foreign-born Hispanic adults Majority of CRS since 1997 occurred in children of unvaccinated Hispanic women - Mothers mostly born in Latin America

Measles - susceptible population

Non-vaccinated individuals - Religious groups opposed to vaccination - Immigrants - Parents worried about ADRS to the vaccine Some states allow philosophical exemptions to vaccination - ↑# of unvaccinated children in schools School-entry vaccinations are not required for home-schooled children in many states

Measles - Epidemiology

Not endemic in the US - eliminated in the Pan-Am Health Organization Region in 2002 Cases still occur in US: - Importation cases or outbreaks linked to importation case (in communities with unvaccinated individuals)

Erythema infectiosum (5th disease) - description of virus

Parvovirus B19 DNA, icosahedral, naked Erythrovirus genus - may be called Erythrovirus B19 transcription, replication and assembly occur in the nucleus requires host cell enzymes and functions present in *mitotically active cells* tropism for *erythroid progenitor cells*

19 year old woman extensive confluent rough papules & plaques sides & bottoms of both feet 10 years duration

Plantar warts

Viral exanthems in children - general characteristics of infection

Respiratory pathogens which cause systemic infection - Measles, rubella, erythema infectiosum, exanthema subitum Localized infection that disseminates via lymphatics &/or blood - secondary viremia may occur - replication at secondary site Rash is the result of an immune response to the virus Incubation period during dissemination Symptoms, including rash, occurs after dissemination Viral shedding occurs before symptoms are obvious

10-month-old 3 day hisory of fever to 103 ºF axillary less active than usual but not ill otherwise fever resolved on day 4 developed a pink papular rash over his trunk & proximal extremities

Roseola

General characteristics of Enteroviruses

Spread fecal-orally & through respiratory secretions Most common in summer & fall Tend to be more common in children than adults - Constant exposure to multiple serotypes may induce cross-reactive antibodies Often asymptomatic; otherwise cold or flu-like illness, sometimes a rash

Zoster (shingles) - symptoms & duration

Symptoms - severe pain in the area of skin supplied by infected sensory nerves - vesicles on skin supplied by the affected nerves (trunk, head, neck) Duration = ~ 1 wk

Rubella - characteristics

Togavirus (RNA, icosahedral, enveloped) 30-60% of infections result in clinical disease

Human herpesvirus type 6 (HHV-6) - spread

Ubiquitous - Almost 100% seropositivity by age 2 years Replicates in salivary glands - spread via oral secretions Latent infection in T cells & monocytes - Can reactivate in immunosuppressed individuals

Rubella & CRS - worldwide

WHO - encouraging developing countries to include rubella vaccine in childhood vaccination schedule - Until 1990's - used mostly in developed countries - Countries need to maintain high vaccination coverage - Low coverage → ↓ virus circulation - Could ↑ age of exposure from childhood to childbearing years

Common warts

Wart is being treated with topical salicylic acid Results in irritation and erosion The black dots represent necrosis of blood vessels.

Molluscum contagiosum - lesion

White, pink or flesh colored dome-shaped papules; develops a central depression (umbilicated) - Painless; occurs in crops - Usually on chest, arms, legs & face - Self-resolving (months to years) except lesions can persist in individuals who are immunocompromised

Measles - rash

also - watery eye, runny nose

Erythema infectiosum (5th disease) - course of infection - diagram

arthralgia - more common in women

HPV - types of warts - chart

don't need to memorize subtypes

Rubella - course of infection - diagram

enters through respiratory tract disseminates fever, rash, lymphadenopathy (less severe than measles)

Viral pathogens of paramyxoviridae family

enveloped RNA

Tzanck smear

for herpes

Chicken pox - incubation period, symptoms, rash

incubation period = 14-21 days symptoms - fever, headache rash - pustules, vesicles, crusts - trunk, face, limbs, buccal & pharyngeal mucosa - crops of pocks over 2-4 days contagious during the incubation period, until pocks crust over

Erythema infectiosum (5th disease) - complications

persistent or recurring arthralgia, more often in females fetal infection - miscarriages - anemia in the fetus - fetal death due to congestive heart failure associated with severe anemia aplastic crisis in patients with chronic RBC disorders (sickle cell anemia)

Zoster (shingles) - complications

postherpetic neuralgia (persistent pain) disseminated infection (immunocompromised)

Complications of varicella

varicella pneumonia (adults) encephalitis (1:1,000 cases) disseminated varicella - neonates, immunocompromised individuals - lungs, liver, CNS, bone marrow invasive group A streptococci - necrotizing fasciitis

Erythema infectiosum (5th disease) - epidemiology

winter & spring most often seen in the 5-14 year age group about 25% of infections are asymptomatic ~65% of adults have antibodies to B19