Smallpox

Generalities
Agent	Variola virus of Orthopoxvirus species
Incubation period	7-19 days (10-14 days for illness, 2-4 days more for rash)
Period of transmissibility	3 weeks from onset of skin lesions
Reservoir	Humans
Modes of transmission	- Person-to-person: direct contact with droplets or skin lesions - Conjunctiva or placenta may be points of entry
Clinical presentation	- Prodomic phase with fever and flu-like illness - Classical form: fever with characteristic centrifugal deep-seated skin eruption: succession of macules, papules, vesicles, and pustules then crusted scabs. The lesions appear first at on the face, extremities, including the palms and soles, sand subsequently on the trunk. Skin lesions are at same stage in same area. - Two forms: minor with a case fatality < 1% and major with case fatality 20-50%. In less than 3%, the major form shows bleeding into the skin and mucous membranes (hemorrhagic smallpox).
Resources
Case definition	MOPH circular no. 37 (2012)
Forms	- General reporting form - Smallpox investigation form
Data	- Smallpox was declared eradicated in 1979 - Last minor case: 1977 in Somalia - Last major case: 1976 in Bangladesh