Smallpox

SmallpoxSmallpox

D. GOLDBERGD. GOLDBERGPED ID SVCEPED ID SVCE

WRAMCWRAMC

SMALLPOXSMALLPOX• Genus Orthopoxvirus

Smallpox, monkeypox, cowpox,vaccinia

• DNA Virus

• 200 nm brick

shaped

• Smallpox-person to person spread via respiratory secretions/direct contact

• Spread best in low humidity/temperature

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• 2 principle forms-

variola major-Europe/Asia

variola minor-19th century USA

• 2 minor forms-malignant & hemorrhagic

• Spread via respiratory droplets/direct contact at time of rash

• Historically spreads slower than chicken pox, measles

SMALLPOX-PathogenesisSMALLPOX-Pathogenesis

• Incubation period (7-17 days):

Virus infects respiratory/pharyngeal mucosa--> regional lymph nodes--> viremia-->spleen, bone marrow, lymph nodes-->second viremia--> fever,

toxemia--> rash and infectivity

SMALLPOX-PathogenesisSMALLPOX-Pathogenesis

• Clinical Stage-

Onset fever (1030), HA, prostation, bachache, malaise, +/- abd pain, delerium, rash by day 3

Rash-macularpapular on oropharynx, face

forearms-->trunk, legs

-turns vesicular 24-48 hrs

- turns tense round pustules

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• Secondary infection is rareSecondary infection is rare

• Death in second week due to toxemiaDeath in second week due to toxemia

• Variola minor-less severe symptoms, Variola minor-less severe symptoms, rashrash

• Vaccinated -milder formVaccinated -milder form

• HIV-? (Disseminated vaccina in HIV+ HIV-? (Disseminated vaccina in HIV+ soldier in 1986) soldier in 1986)

SMALLPOX- Laboratory DiagnosisSMALLPOX- Laboratory Diagnosis

• Level BL-4 onlyLevel BL-4 only

EM of fluid/scabsEM of fluid/scabs

Culture/PCRCulture/PCR

Oropharyn swabs-day 7/8 of Oropharyn swabs-day 7/8 of infectioninfection

AB titers (day 6 of rash)AB titers (day 6 of rash)

SMALLPOX- Clinical DiagnosisSMALLPOX- Clinical Diagnosis

SmallpoxSmallpox VaricellaVaricella

Prodrome: 2-4 days 1-2 days

Rash: 1-2 days several days

Lesions: deep/tense superficial

Distribution: centrpetal centrifugal

(truncal) (face/extremeties)

Stage: same new crops

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ChickenpoxChickenpox ShinglesShingles

SMALLPOX-TherapySMALLPOX-Therapy

• Cidofovir ?

• ?

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• Postexposure Control-Postexposure Control-

Home care vs hospital care (neg pressure)

Mass “contact” vaccination (up to 4 days post exposure may ameliorate/prevent)

Vaccinated individuals serve as caretakers

Cremation of bodies

Smallpox-VaccinationSmallpox-Vaccination

SMALLPOX

• Vaccination-Vaccination-

limited stock (6 million/ ? dilution)

untrained administrators

Special risk groups immuno- suppressed/ pregnant

women/eczema

limited Vaccina IG (VIG)

side effects

SMALLPOX-Vaccine complicationsSMALLPOX-Vaccine complications

* 70% children with fever > 39C day 4-14

SMALLPOX-AutoinoculationSMALLPOX-Autoinoculation