Published on 19/03/2015 by admin

Filed under Dermatology

Last modified 19/03/2015

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Boris D. Lushniak and Cody R. Thornton

Evidence Levels:  A Double-blind study  B Clinical trial ≥ 20 subjects  C Clinical trial < 20 subjects  D Series ≥ 5 subjects  E Anecdotal case reports


Bioterrorism is defined as the use of viruses, bacteria, fungi, or toxins from living organisms to produce death or disease in humans, animals, or plants. The US Centers for Disease Control and Prevention (CDC) has designated several agents/diseases as category A agents that can be easily disseminated or transmitted, result in high mortality rates, have the potential for serious public health impact, and which would require special action for public health preparedness. The diseases that are of greatest concern are smallpox, anthrax, tularemia, plague, the hemorrhagic fevers, and botulism (which have no cutaneous features and will not be further discussed here). Dermatologists should familiarize themselves with these disorders, their recognition and treatment, and the measures that can be undertaken to limit the spread of disease. Several of the conditions discussed, including smallpox, pneumonic plague, and viral hemorrhagic fevers, are contagious to caregivers, so appropriate care must be taken to prevent the further transmission of disease.


The history of smallpox is fascinating, culminating in the public health achievement of worldwide eradication of this double stranded DNA virus. The virus now remains stored in secure laboratory facilities in the US and Russia. Its effect on the world was overwhelming with over 500 million deaths attributed to smallpox in the 20th century. After a worldwide vaccination campaign, the last natural case occurred in Somalia in 1977 and by 1980 the World Health Assembly declared smallpox eradicated.

Smallpox is a highly stable virus, spread by direct contact, short distance (6 feet) aerosol exposure, or, in rare cases, through fomites. The incubation period ranges from 7 to 19 days, followed by a prodrome of 2 to 4 days which includes high fever (101–104°F), prostration, malaise, and myalgias. During this time smallpox becomes communicable after the appearance of an enanthem, including macules, papules, and ulcers on the tongue and mouth, and remains so for about 3 to 4 weeks, until the disappearance of all scabs. After the prodrome, an exanthem appears with a mostly centrifugal distribution. Lesions progress in a synchronous fashion from macule (day 0–1), papule (day 2–3), deep tense umbilicated vesicle (day 3–5), deep round tense pustule (day 6–12), crust formation (day 13–20), crust separation (day 21–28), and resulting depressed scars. Complications of smallpox include sepsis and toxemia, encephalitis, and blindness.

The differential diagnosis for smallpox includes varicella and disseminated herpes simplex or zoster, molluscum contagiosum, erythema multiforme, pustular drug eruption, purpura fulminans, hand, foot, and mouth disease, and monkeypox. Varicella has a relatively benign prodrome, with more superficial lesions in a centripetal distribution with asynchronous evolution and crusting in 4 to 7 days.

Smallpox vaccination with the scarification technique using the live vaccinia virus can cause adverse reactions in those vaccinated as well as their close contacts. Contraindications to non-emergency vaccination include immunodeficiency states, immunomodulating medications, allergic reactions, pregnancy, cardiovascular diseases, and epidermal-disrupting diseases such as atopic dermatitis, pemphigus, or Darier disease in vaccine recipients or family members. Localized skin reactions include a robust primary reaction at the site, autoinoculation or contact transmission of the vaccinia, and ocular vaccinia. Generalized skin reactions with systemic symptoms can also occur, including, generalized vaccinia (distant site viremic spread), erythema multiforme major, progressive vaccinia (progressive necrosis at the site), and eczema vaccinatum (localized or systemic dissemination) as seen in those with atopic dermatitis or other skin diseases. Other adverse reactions of vaccination include post-vaccinial encephalopathy and encephalomyelitis and myopericarditis. New generation vaccines, including non-replicating attenuated modified Vaccinia Ankara, are being investigated to see if adverse reactions can be minimized and for use in atopics.

Management strategy

The management of smallpox includes the recognition, diagnosis, and isolation of index cases, notification of public health authorities, vaccination, treatment, and supportive care of the cases, and vaccination and isolation of those who were in contact with the cases. Although there is no specific treatment for smallpox, there are several investigational antiviral candidates undergoing study for both treatment of disease and for adverse events associated with vaccination. Vaccinia immune globulin is also available from the CDC to treat specific adverse events. In an outbreak scenario a ‘ring vaccination’ strategy, as used in the eradication program, would be used initially whereby the case would be vaccinated, as well as those exposed to the case and those exposed to the exposed, in an expanding ring fashion. Vaccination should be effective in limiting the disease if given within 3 to 4 days of exposure.

Specific investigations

First-line therapies