Human Cowpox Infection Clinical Presentation

Updated: Jun 19, 2018
  • Author: Nikki A Levin, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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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. [14, 15, 16, 17, 18] One case was reported in an animal keeper who was exposed to an infected circus elephant. [19]

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 Examination

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. [20, 21]

  • 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. [22]



Most patients will have scarring at the sites of the healed pox lesions.

Patients with underlying skin disorders, such as atopic dermatitis, are at risk for generalized skin infection, resembling eczema herpeticum. One case of facial cellulitis with necrotizing lymphadenitis requiring surgical lymph node removal has been reported. [22]  One case of necrotizing cellulitis of the nose has been reported. [23]

One death from generalized cowpox has been reported in a patient with atopic dermatitis and asthma, and another death has been reported in an immunosuppressed renal transplant patient. [13]