Emergency Preparedness

Kern Medical Bioterrorism Response Guide Section 2-C-1 – Smallpox vesicles on the skin. Any unprotected (ungloved) contact with an infected person’s skin, clothing, bed linens, or other contaminated surfaces or articles may result in transmission. Clinical Presentation Three clinical forms of smallpox: ordinary, flat or hemorrhagic, may occur in unvaccinated individuals. An additional, modified type, is seen most frequently in individuals with previous vaccination. Although the case fatality rate varied with the different clinical forms of smallpox, it was approximately 30% in unvaccinated An asymptomatic viremia occurs within 2-4 days following the first exposure date. During this phase, the virus multiplies and spreads to the bone marrow, lymph nodes, and spleen. The person is asymptomatic and not infectious at this time. About 5 - 8 (up to 13) days following the first exposure date, a secondary viremiaoccurs which carries the virus to the basal layer of the oropharynx and the epidermis of the skin. The prodromal symptoms include high fever (38.5 - 40.5 degrees C), fatigue, headache, backache, abdominal pain, vomiting, and possibly deliri um, and lasts for about 4 days. In pale-skinned persons there may be an erythematous rash, or rarely a petechial rash during the prodromal stage. As the fever pattern begins to decline from its peak, the eruptive phase begins with the development of lesions in the oropharynx followed by the development of skin lesions that spread to the face, forearms andhands including the palms. The lesions then spread to the legs and feet, including the soles, and to the truck. The rash is centrifugal in distribution, i.e., more dense on the face and extremities than on the trunk. On any given part of the body, the lesions are generally at the same stage of development. Within 1 - 2 days, the rash becomes vesicular and, later, pustular. The pustules are round and tense, and deeply embedded in the dermis. Crusts begin to form about the 8 th or 9 th day after the appearance of the rash. At least 90% of all cases are clinically characteristic. Flat-type or Malignant Smallpox A deficient cellular immune response to the variola virus may be responsible for this manifestation that occurs in about 2 - 5% of smallpox cases. It is characterized by intense toxemia and occurs more frequently in children. The skin lesions develop slowly, become confluent, and remain flat and soft, almost velvety, never progressing to the pustular stage. Most cases are fatal but if the patient survives, the lesions gradually disappear without forming scabs. Hemorrhagic Smallpox In patients with severe compromised immune systems, there is e xtensive multiplication of the virus in the spleen and bone marrow. Megakaryocyte destruction in the bone individuals during the smallpox era. Ordinary Presentation (Variola major)

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