Contents

Search

smallpox & alastrim

Etiology: - viral infection with Variola major (smallpox) & Variola minor (alastrim) Epidemiology: 1) last case of endemic smallpox in 1977 (Somalia) - last case of smallpox reported in U.S. in 1949 2) World Health Organization has declared smallpox has been eliminated world-wide as a result of global vaccination & eradication program 3) humans are the sole reservoir for infection 4) no carrier state 5) only 2 known remaining respositories worldwide, USA & Russia 6) relatively non-contagious disease, requiring close contact for several hours for transmission 7) infection spread through aerosolized droplets 8) immunity from vaccination prior to 1972 is 'iffy' at best 9) consider smallpox through occupational exposure to an act of bioterrorism as a likely diagnosis if clinical manifestations are consistent with smallpox [4] - absence of any case reports Clinical manifestations: 1) incubation period of 7-17 days, average 12 days 2) initial presentation of fever (> 38.3 C, 101.3 F) prior to rash onset 3) fatigue, headache, vomiting, back pain, abdominal pain 4) macular rash beginning 2-3 days after onset of fever, with progression to vesicular & pustular lesions over 1-2 weeks - lesions may become umbilicated or confluent 5) rash begins on buccal & pharyngeal mucosa, face, proximal arms & legs, then spreads to chest & distal extremities - lesions on the palms &/or soles 6) rash is in the same stage in all locations at any one time, i.e. all papules -> all vesicles -> all pustules -> all scabs [4] - each stage lasts 1-2 days 7) lesions scab in about 2 weeks 8) may leave permanent scarring 9) patient become infectious with onset of rash 10) conjunctivitis [4] 11) alstrim is a clinically milder form of smallpox * images [8] Laboratory: - skin biopsy a) characteristic histology b) antigen detection Differential diagnosis: - chickenpox: rash is in different stages at different locations i.e. a mix of vesicles papules, pustules & scabs Management: 1) patient isolation a) notify health department b) airbone precautions c) mass public vaccination if epidemic [4] 2) tecovirimat FDA-approved July 2018 [9,10] 3) cidofovir may be helpful 4) prognosis: a) smallpox mortality 20-50% b) mortality of alastrim is 1% 5) prevention: - vaccinia vaccine (live virus vaccine) - possible exposure, even if on immunosuppressive agent [4] - vaccinate if within 7 days of exposure [4] - provides protection if given within 3 days of exposure [4] - immunity retained for > 30 years [3] - smallpox antiviral Arestvyr effective even if given 3 days after exposure Notes: - potential agent of bioterrorism [6]

Related

chickenpox smallpox vaccine; vaccinia vaccine (Dryvax, Arestvyr, Jynneos, Ankara-Bavarian Nordic vaccine, MVA-BN vaccine) Variola major (smallpox virus)

General

viral infection

References

  1. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 1095
  2. Prescriber's Letter 9(12):72 2002
  3. Internal Medicine News, Jyly 2005, pg 63
  4. Medical Knowledge Self Assessment Program (MKSAP) 14, 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 2006, 2009, 2012, 2015, 2018, 2021.
  5. Physician's First Watch, March 14, 2013 David G. Fairchild, MD, MPH, Editor-in-Chief Massachusetts Medical Society http://www.jwatch.org - McNeil DG Wary of Attack With Smallpox, U.S. Buys Up a Costly Drug http://www.nytimes.com/2013/03/13/health/us-stockpiles-smallpox-drug-in-case-of-bioterror-attack.html
  6. Guharoy R, Panzik R, Noviasky JA, Krenzelok EP, Blair DC. Smallpox: clinical features, prevention, and management. Ann Pharmacother. 2004 Mar;38(3):440-7. Epub 2004 Jan 30 PMID: 14755066
  7. Breman JG, Henderson DA. Diagnosis and management of smallpox. N Engl J Med. 2002 Apr 25;346(17):1300-8. PMID: 11923491
  8. Brady MP (images) Cutaneous and Mucosal Manifestations of Viral Diseases. Medscape. March 2017 http://reference.medscape.com/features/slideshow/viral-skin
  9. Grosenbach DW, Honeychurch K, Rose EA Oral Tecovirimat for the Treatment of Smallpox. N Engl J Med 2018; 379:44-53. July 5, 2018 PMID: 29972742 https://www.nejm.org/doi/full/10.1056/NEJMoa1705688
  10. FDA News Release. July 13, 2018 FDA approves the first drug with an indication for treatment of smallpox. https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm613496.htm
  11. Petersen BW, Damon IK, Pertowski CA et al Clinical guidance for smallpox vaccine use in a postevent vaccination program. MMWR Recomm Rep. 2015 Feb 20;64(RR-02):1-26. PMID: 25695372 Free Article
  12. National Institute of Allergy and Infectious Diseases (NIAID) Smallpox https://www.niaid.nih.gov/diseases-conditions/smallpo