Smallpox: Virus, Transmission, Pathogenesis, Diagnosis, and Vaccination, Slides of Pediatrics

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Smallpox

SMALLPOX

• 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

SMALLPOX

• 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-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

SMALLPOX

SMALLPOX

• Secondary infection is rare
• Death in second week due to toxemia
• Variola minor-less severe symptoms, rash
• Vaccinated -milder form
• HIV-? (Disseminated vaccina in HIV+ soldier in 1986)

SMALLPOX- Clinical Diagnosis

Smallpox Varicella

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

SMALLPOX

Chickenpox (^) Shingles

SMALLPOX

• 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-Vaccination

SMALLPOX-Vaccine complications

• 70% children with fever > 39C day 4-

SMALLPOX-Autoinoculation