Viral Infections of Skin

Question 1

exogenous source of skin infections

Answer 1

from without. infection at site of lesion. breaks in skin integrity, cuts, pimples, insect bites. mucous membranes

Question 2

endogenous source of skin infections

Answer 2

from within, disseminated infection. viremia: spread throguh blood and lymph. reactivation from latency

Question 3

herpesvirus infections

Answer 3

large, enveloped DNA virus. 8 species. secretions and mucous membranes contain infectious herpesvirus when an infected individual has a primary infection or recurrence of a latent infection. Establish latency in neurons or lymphocytes during primary infection. Asymptomatic shedding can occur at any time, and can transmit to naive people.

Question 4

HSV Type 1

Answer 4

childhood. spread by close contact with active lesions or asymptomatic shedding. lesions on mouth, face, nose, eyes etc. latency in dorsal root ganglia neurons. usually above the waist. treat with acyclovir.

Question 5

recurrent HSV-1: herpes labialis

Answer 5

cold sores. 20% of seropositive people have recurrent lesions. triggered by fever, UV exposure, stress, hormones, etc. Contagious lesions. treat with acyclovir, zovirax, valtrex, famvir.

Question 6

HSV Keratitis and corneal scarring

Answer 6

primary infection in eye often from vaginal mucosa at birth. caused by recurrence of HSV 1 or 2. chronic keratitis can lead to corneal scarrring and lost vision. mediated by infiltration of T cells that destroy cornea. may need cornea transplant

Question 7

Herpetic whitlow

Answer 7

primary HSV-1 or 2 of non-mucosal sites. acquired by direct contact. recurrences at unusual sites: hands, legs, back. treat with acyclovir and derivatives. prevent with gloves

Question 8

HSV-2: primary genital herpes

Answer 8

extensive vesicular, pustular, or erythematous lesions on penis, labua, anus. Pain itching, fever, malaise, headache. usually below waist. antiviral treatment prevents spread, especially to brain. HSV-1 and 2 double infections are common.

Question 9

HSV-2: recurrent genital herpes

Answer 9

prodrome: itching, tingling at lesion site a day before outbreak. vesicular lesions appear on penis, labia, anus. contagious lesions, but shedding can be asymptomatic. prophylactic antiviral treatment can reduce recurrences.

Question 10

varicella-zoster virus

Answer 10

primary infection as chicken pox (varicella). latency in neurons of dorsal root ganglia and remains quiescent for decades. later in life can cause shingles (herpes zoster)

Question 11

Primary VZV: varicella

Answer 11

aerosol transmission, highly contagious. 1-2 week incubation. fever, malaise precede and accompany rash. latency in dorsal root ganglia neurons. distinctive rash: drops on rose petals. lesions are itchy, vesicular, form scabs that may scar. treat with vaccine (varivax), acyclovir, foscarnet. visceral infections, dissemination to brain, pneumonitis, bacterial infection of lesions. severity increases with age

Question 12

VZV recurrence: herpes zoster

Answer 12

prodrome: itching, tingling, burning. outbreak along single dermatome. vesicular lesions are extremely painful and puritic. more common in elderly and immunocompromised. treat with acyclovir. complications include keratitis, retinitis, bell’s palsy, posterpetic neuralgia

Question 13

HZO: herpes zoster opthalmicus

Answer 13

30% of zoster outbreaks affect the face. zoster in eye can destroy retina leading to blindness. all tissues of the eye can be infected and damaged during HZO. long lasting pain common. treat aggressively

Question 14

VZV vaccines

Answer 14

live, attenuated virus. varivax to prevent varicella. zostavax to prevent zoster. zostavax is 14 times higher dose than varivax. both are recommended

Question 15

epstein barr virus: primary infectious mononucleosis

Answer 15

B cells and epithelia of oropharynx infection. restricted to humans. childhood infections are often asymptomatic. older teens have Mono.

Question 16

EBV recurrences

Answer 16

latent in a small fraction of B cells. immune surveillance suppresses EBV. recurrences are linked to B cell cancers, especially in the immunocompromised

Question 17

oral hairy leukoplakia

Answer 17

epithelial overgrowth caused by EBV. nonpainful hairy or feathery lesions on the tongue or buccal mucosa. associated with HIV infection, transplantation, chemo, etc

Question 18

cytomegalovirus: primary infection

Answer 18

usually asymptomatic and acquired in childhood. similar to mono caused by EBV. lack of sore throat and presence of petechial rash and jaundice differentiate from EBV.

Question 19

roseola: exanthem subitum

Answer 19

caused by HHV6b and HHV7. infect CD4+ T cells, site of latency. transmitted in saliva. 3 day illness of high fever, followed by faint rash on the trunk. many infants are mistakenly given antibiotics for a suspected infection, and the rash is attributed to a drug allergy

Question 20

kaposi’s sarcoma herpesvirus: KSHV, HHV8

Answer 20

KSHV prevalent in african, mediterranean, homo populations. evidence for sexual transmission. found in B cells and endothelial cells. Recurrences linked to cancers associated with KSHV. kaposi’s sarcoma, body cavity based lymphomas, castleman’s disease, hyperplastic lympadenopathy

Question 21

coxsackie virus

Answer 21

large family of small, naked ssRNA viruses (Enteroviridae)

includes poliovirus and many others that cause GI infections, neuromuscular diseases, and encephalitis and meningitis

Question 22

skin manifestations of coxsackie virus

Answer 22

herpangina: throat infection causes red ringed blisters and ulcers on tonsils and soft palate. Hemorrhagic conjunctivitis: begins as eye pain, then red, watery eyes with swelling, light sensitivity, and blurred vision.

Question 23

hand foot and mouth disease

Answer 23

painful red blisters in the throat, tongue, gums, hard palate, inside of the cheeks, and the palms of the hands and soles of the feet. common in preschool aged children and their parents. transmission: highly contagious, spread on hands and surfaces contaminated with saliva and feces. aerosol spread. no treatment

Question 24

human papilloma virus HPV

Answer 24

small, naked DNA virus. HPV infects skin, genitals, cervix, anus, and mucosa. spread by direct contact. treat with chemical or surgical removal. gardasil: vaccine for young women and men. differentiate from lesions caused by molluscum contagiosum virus

Question 25

molluscum contagiosum virus

Answer 25

lack of inflamation, pearly vesicles. large, enveloped DNA virus. lesions are umbilicated. occur anywhere on body, and genitals in adults. single giant molluscum may occur. lesions rarely on palms, soles, mucosa, face, eyes. skin-skin contact or fomite transmission. treat with surgery, crytotherapy, or chemicals. topical treatment with cidofovir is promising

Question 26

monkey pox

Answer 26

indistinguishable from smallpox. 10-15% fatality. endemic to west and central africa. squirrels are the natural host, disease occurs in humans and monkeys. transmission via direct contact, aerosol, ingestion, needles, person to person

Question 27

variola virus (smallpox)

Answer 27

fever, severe aching pains and prostration, 2-3 days later an umbilicated papular rash over face and extremities. papular, vesicular then pustular rash. scabs leave pitted scars.

Question 28

variolation evolved into vaccination

Answer 28

variola virus and other poxviruses were blended to create the modern vaccine strain: vaccinia virus

Question 29

vaccinia adverse vaccine reactions

Answer 29

live vaccine. auto-innoculuation from arm to eyes, generalized vaccinia, virus disseminates through the body, excema vaccinatum: contraindicated with anyone with eczeema. progressive vaccinia: vaccinia necrosum or gangrenosum. in immunocompromised. treat with VIG or cidofovir

Question 30

measles virus

Answer 30

paramyxovirus. enveloped, negative strand RNA. contagious during incubation. cough, conjunctivitis, fever, rash. Koplik’s spots: small red spots with bluish centers.

Question 31

rubella virus

Answer 31

togavirus, enveloped positive strand RNA. respiratory virus, aersosol spread. macuopapular rash, lymphadenopathy, arthralgia. congenital infections are severe. prevent with MMR vaccine