Smallpox
Smallpox has been eliminated by vaccination. The last case was reported in 1978. The illness began with malaise, fever, vomiting, backache, and headache. A rash appeared two to four days later with rapid progression from macules to papules to deep pustular vesicles.
CASES/YEAR
0 (US); 0 (Global)
OTHER NAMES
Variola virus infection;
INCUBATION
7-19 days; [CCDM]
INITIAL SYMPTOMS
High fever, prostration, headache, & backache; Rash appears on day 3; Rash is maculopapular, then vesicular, then pustular; Rash begins on face/forearms & spreads to trunk & legs; [Cecil, 24th Ed, p. 86] Chickenpox rash 1st on trunk; [Wallach, p. 1190]
PRECAUTIONS
Contact + Airborne for duration of illness; "Until all scabs have crusted and separated (3-4 weeks). Non-vaccinated HCWs should not provide care when immune HCWs are available; N95 or higher respiratory protection for susceptible and successfully vaccinated individuals; postexposure vaccine within 4 days of exposure protective." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
The last case of smallpox was reported in 1978. The illness began with malaise, fever, vomiting, backache, and headache. A rash appeared two to four days later with rapid progression from macules to papules to deep pustular vesicles. Lesions were more abundant on the extremities and face and appeared in the same stage of maturity in a given area (unlike chickenpox in which the lesions are superficial vesicles in various stages of maturity more abundant on the covered parts of the body). The fatality rate for variola major was about 30% in unvaccinated populations. Transmission was by inhalation of droplets or inoculation of skin or conjunctiva. Less than 3% of variola major cases followed a hemorrhagic, rapidly fatal course. [CCDM, p. 561-4] Patients are not contagious until the rash appears, and at that stage, most patients are bedridden. Therefore, most secondary cases would occur in households and hospitals. Laundry and waste from patients are potential sources of infection. Encephalitis, similar to that observed in cases of measles and varicella, may occur. Petechiae and bleeding from the skin and mucous membranes may occur in the 10% of smallpox cases that are termed "malignant" or "hemorrhagic." Smallpox can be rapidly confirmed in the laboratory by electron microscopy of fluid from vesicles or pustules. "Vaccination administered within 4 days of first exposure has been shown to offer some protection against acquiring infection and significant protection against a fatal outcome." [Henderson DA, et al. Smallpox as a biological weapon.JAMA.1999;281:1735-45.] Hemorrhagic shock is one of the causes of death. [PPID 7th Ed., p. 3955] Cough and bronchitis were occasionally reported, but pneumonia was an unusual complication. Orchitis in 0.1% of cases; [Guerrant, p. 371, 372]
DIAGNOSTIC
Clinical; Culture; Electron microscopy (EM); PCR; [CCDM] EM cannot distinguish smallpox from monkeypox, vaccinia, or cowpox; [Guerrant, p. 373]
SIGNS & SYMPTOMS
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>fatigue, weakness
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>fever
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>fever, biphasic or relapsing
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>myalgia
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E stomatitis
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G abdominal pain
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G nausea, vomiting
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H leukopenia
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H thrombocytopenia
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N confusion, delirium
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N headache
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N seizure
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O conjunctivitis, acute
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R cough
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S papules or plaques
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S petechiae and ecchymoses
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S pustule
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S rash (exanthem)
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S rash on palms
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S skin blister or vesicles
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U hematuria
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*arthritis
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*bleeding tendency
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*blindness
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*encephalitis
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*epididymo-orchitis
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*osteomyelitis
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*pneumonia
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*sepsis
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*shock
ENTRY
Inhalation, Skin or Mucous Membranes (Includes Conjunctiva)
RISK FACTORS
- Care for patients (droplet/airborne)
- Victim--air release of infectious agents
- Work in a medical or research lab
REFERENCES FOR CASES/YEAR
1. (US) 0
2. (Global) 0