Smallpox natural history
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Natural History
Complications
Common complications of smallpox include:
- Respiratory complications (viral or bacterial):
- Bronchitis
- Fatal pneumonia
- Secondary bacterial skin infection
- Encephalitis - 1 in 500 patients, commonly in adults
- Permanent pitted scars
- Eye problems - 2% of all cases; pustules can form on the eyelid, conjunctiva, and cornea, leading to:
- Conjunctivitis
- Keratitis
- Corneal ulcer
- Iritis
- Iridocylcitis
- Optic atrophy
- Blindness - occurs in 35% to 40% of eyes affected with keratitis and corneal ulcer
- Subconjunctival and retinal hemorrhages.
- Osteomyelitis - lesions are symmetrical, most common in the elbows, tibia, and fibula
- Arthritis may lead to limb deformities
- Ankylosis
Prognosis
The prognosis of smallpox depends on the form of the disease:
Variola major
Ordinary smallpox
- Fatality rate about 10% for patients with discrete lesions and 60% for those with confluent lesions[1]
- In fatal cases, death usually occurs between the tenth and sixteenth days of the illness
- Unclear cause of death, however infection was known to involve multiple organs
- Possible contributors include:
- Circulating immune complexes
- Severe viremia
- Uncontrolled immune response
Flat-type smallpox
- Fatality rate about 90%
- Cause of death commonly included: loss of fluids, electrolytes and protein, as well as severe sepsis
Hemorrhagic-type smallpox
- Fatality rate near 100%, usually between 6th and 7th day after the beginning of fever
- Cause of death was often heart failure, or in late cases intense viremia, with severe platelet loss and weak immune response
Variola minor
- Fatality rate about ≤1%
References
- ↑ Moore, Zack S; Seward, Jane F; Lane, J Michael (2006). "Smallpox". The Lancet. 367 (9508): 425–435. doi:10.1016/S0140-6736(06)68143-9. ISSN 0140-6736.