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Human Cowpox Infection Clinical Presentation

  • Author: Nikki A Levin, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
Updated: Sep 08, 2015


Generally, patients are young; 50% of patients are younger than 18 years. Most cases occur in late summer to fall. Cases present in endemic areas of Europe.

Contact with rodents, cats, or cows is reported in 50% of cases.[10, 11, 12, 13, 14] One case was reported in an animal keeper who was exposed to an infected circus elephant.[15]

Usually, only 1 or a small number of lesions occur on the hands (48%) and face (33%). Patients may report having a flat red lesion that became raised and then blistered over a period of 2 weeks. The blister subsequently became crusted, with the surrounding skin becoming red and swollen. The lesions are characteristically described as quite painful.

Patients may have eye complaints. Patients may report fever, malaise, lethargy, vomiting, and sore throat, which usually lasts 3-10 days but resolves during the eschar stage of cutaneous lesions.



Physical findings generally are limited to the skin, eyes, and lymph nodes. Cutaneous findings develop as follows:

  • Days 1-6 (after inoculation): An inflamed macule appears at the site of contact with the infected animal and at any secondary sites of accidental transfer.
  • Days 7-12: The inflamed lesion becomes papular, then vesicular.
  • Days 13-20: The vesicle becomes hemorrhagic, then pustular, and has a tendency to ulcerate, with surrounding edema and induration. Secondary lesions may form nearby.
  • Weeks 3-6: The vesicopustule progresses to a deep-seated, hard, black eschar, often surrounded by edema, induration, and erythema. Most patients present at this stage, which may appear similar to cutaneous anthrax. [16, 17]
  • Weeks 6-12: The eschar sloughs, and the lesion heals, usually with scarring.
    A 16-year-old boy with generalized cowpox. Courtes A 16-year-old boy with generalized cowpox. Courtesy of Dr. Reinhard Hoepfl, Innsbruck, Austria.

Rarely, the cutaneous lesions may become generalized before resolving. Ocular findings include conjunctivitis, periorbital edema, and corneal involvement. Enlarged painful local lymph nodes often are observed. Necrotizing lymphadenitis has been reported.[18]



The natural reservoir of cowpox virus is believed to be small woodland mammals, such as bank voles and wood mice, with humans, cows, and cats being only accidental hosts.

Risk factors for infection with cowpox include exposure to potentially infected animals (eg, cats, cows, rodents) in an endemic area. Risk factors for dissemination of infection include atopic dermatitis and use of systemic corticosteroids.

Contributor Information and Disclosures

Nikki A Levin, MD, PhD Associate Professor of Medicine, Division of Dermatology, University of Massachusetts Medical School

Nikki A Levin, MD, PhD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, Phi Beta Kappa, Sigma Xi

Disclosure: Nothing to disclose.

Specialty Editor Board

Richard P Vinson, MD Assistant Clinical Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine; Consulting Staff, Mountain View Dermatology, PA

Richard P Vinson, MD is a member of the following medical societies: American Academy of Dermatology, Texas Medical Association, Association of Military Dermatologists, Texas Dermatological Society

Disclosure: Nothing to disclose.

Jeffrey Meffert, MD Associate Clinical Professor of Dermatology, University of Texas School of Medicine at San Antonio

Jeffrey Meffert, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, Association of Military Dermatologists, Texas Dermatological Society

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

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A 16-year-old boy with generalized cowpox. Courtesy of Dr. Reinhard Hoepfl, Innsbruck, Austria.
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