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Zoonotic Diseases

By

James G. H. Dinulos

, MD, Geisel School of Medicine at Dartmouth

Last full review/revision May 2021| Content last modified May 2021
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Topic Resources

Contagious ecthyma and milker's nodules are two viral skin diseases that are rarely transmitted from animals to humans.

Contagious ecthyma

Contagious ecthyma (contagious pustular dermatitis) is caused by orf virus, a poxvirus that infects ruminants (most often sheep and goats). Farmers, veterinarians, zoo caretakers, and others with direct animal contact are at risk. The cutaneous findings pass through 6 stages that together last about 1 week:

  • Stage 1 (papular): A single red edematous papule on a finger (most commonly right index finder)

  • Stage 2 (target): A larger nodule with a red center surrounded by a white ring with a red periphery

  • Stage 3 (acute): A rapidly growing infected-looking tumor

  • Stage 4 (regenerative): A nodule with black dots covered with a thin transparent crust

  • Stage 5 (papillomatous): A nodule with a surface studded with small projections

  • Stage 6 (regressive): A flattened nodule with a thick crust

Patients can develop regional adenopathy, lymphangitis, and fever.

Lesions spontaneously heal; no treatment is necessary.

Milker’s nodules

These nodules are caused by paravaccinia virus, a parapoxvirus that causes udder lesions in cows. Infection requires direct contact and causes macules that progress to papules, vesicles, and nodules. This infection has 6 stages, which are similar to those of contagious ecthyma Contagious ecthyma Contagious ecthyma and milker's nodules are two viral skin diseases that are rarely transmitted from animals to humans. Contagious ecthyma (contagious pustular dermatitis) is caused by orf virus... read more Contagious ecthyma . Fever and lymphadenopathy are uncommon.

Lesions heal spontaneously; no treatment is necessary.

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