eMedicine Specialties > Infectious Diseases > Viral Infections

Parapoxviruses: Differential Diagnoses & Workup

Author: Larry I Lutwick, MD, Professor of Medicine, State University of New York, Downstate Medical School; Director, Infectious Diseases, Veterans Affairs New York Harbor Health Care System, Brooklyn Campus
Coauthor(s): Adam M Rotunda, MD, Fellow, Department of Dermatology, David Geffen School of Medicine at University of California at Los Angeles
Contributor Information and Disclosures

Updated: May 15, 2009

Differential Diagnoses

Staphylococcal Infections

Other Problems to Be Considered

Cutaneous anthrax
Herpetic whitlow
Cutaneous leishmaniasis
Cutaneous fungal infections

Workup

Laboratory Studies

  • Electron microscopy of skin tissue3
    • This study allows direct visualization of the Parapoxvirus, and its characteristic appearance is considered the criterion for diagnosis.
    • Nevertheless, given the lack of availability of electron microscopy in the areas endemic for infection, light microscopy and traditional histopathologic techniques afford accurate identification of the characteristic cutaneous changes observed in a parapox infection.

Histologic Findings

Histologically, orf and milker's nodule appear identical.4 With orf and milker's nodule, an impressive epidermal proliferation, mild acanthosis, parakeratosis, spongiform keratinocytic degeneration, and viral cytopathic changes occur, including cytoplasmic inclusion bodies and nuclear and cytoplasmic vacuolization. In the dermis, a dense inflammatory infiltrate develops, consisting of mast cells, lymphocytes, polymorphs, eosinophils, and prominent upper-dermal edema. Most notably, capillary dilatation and proliferation give the impression of an angiomatous dermal lesion.

The histological appearance of bovine papular stomatitis shares many features with orf and milker's nodule infections. These include epidermal acanthosis, hyperkeratosis, parakeratosis, intercellular edema, abundant lymphocytic and polymorphonuclear leukocytic infiltrate, and intracellular inclusions (generally not noted).

More on Parapoxviruses

Overview: Parapoxviruses
Differential Diagnoses & Workup: Parapoxviruses
Treatment & Medication: Parapoxviruses
Follow-up: Parapoxviruses
References
Further Reading
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References

  1. Abrahao JS, Campos RK, Trindade GS, Guedes MI, Lobato ZI, Mazur C, et al. Detection and phylogenetic analysis of Orf virus from sheep in Brazil: Case Report. Virol J. May 4 2009;6(1):47. [Medline].

  2. Radtke MA, Günzl HJ, Siemann-Harms U, Augustin M, Coors EA. [Expanding papillomatous nodule on forearm with acute lymphangitis : Case of diagnosis.]. Hautarzt. Apr 24 2009;[Medline].

  3. Mast J, Demeestere L. Electron tomography of negatively stained complex viruses: application in their diagnosis. Diagn Pathol. Feb 10 2009;4:5. [Medline].

  4. Ceovic R, Pasic A, Lipozencic J, Marinovic-Kulisic S, Budimcic D, Sviben M, et al. Milker's nodule--case report. Acta Dermatovenerol Croat. 2007;15(2):88-91. [Medline].

  5. Baxby D, Bennett M. Poxvirus zoonoses. J Med Microbiol. Jan 1997;46(1):17-20, 28-33. [Medline].

  6. Bowman KF, Barbery RT, Swango LJ, Schnurrenberger PR. Cutaneous form of bovine papular stomatitis in man. JAMA. Dec 18 1981;246(24):2813-8. [Medline].

  7. Centers for Disease Control and Prevention. Orf virus infection in humans--New York, Illinois, California, and Tennessee, 2004-2005. MMWR Morb Mortal Wkly Rep. Jan 27 2006;55(3):65-8. [Medline].

  8. Davis CM, Musil G. Milker''s nodule. A clinical and electron microscopic report. Arch Dermatol. Mar 1970;101(3):305-11. [Medline].

  9. de la Torre C. Gianotti-Crosti syndrome following milkers'' nodules. Cutis. Nov 2004;74(5):316-8. [Medline].

  10. Groves RW, Wilson-Jones E, MacDonald DM. Human orf and milkers'' nodule: a clinicopathologic study. J Am Acad Dermatol. Oct 1991;25(4):706-11. [Medline].

  11. Leavell UW Jr, McNamara MJ, Muelling R, et al. Orf. Report of 19 human cases with clinical and pathological observations. JAMA. May 20 1968;203(8):657-64. [Medline].

  12. Muller G, Groters S, Siebert U, et al. Parapoxvirus infection in harbor seals (Phoca vitulina) from the German North Sea. Vet Pathol. Jul 2003;40(4):445-54. [Medline].

  13. Robinson AJ, Petersen GV. Orf virus infection of workers in the meat industry. N Z Med J. Feb 9 1983;96(725):81-5. [Medline].

  14. Schmidt E, Weissbrich B, Brocker EB. Orf followed by erythema multiforme. Eur Acad Dermatol Venereol. 2006;20:612-3.

  15. Schuler G, Honigsmann H, Wolff K. The syndrome of milker's nodules in burn injury: evidence for indirect viral transmission. J Am Acad Dermatol. Mar 1982;6(3):334-9. [Medline].

  16. Shelley WB, Shelley ED. Farmyard pox: parapox virus infection in man. Br J Dermatol. Jun 1983;108(6):725-7. [Medline].

  17. Slattery WR, Juckett M, Agger WA. Milkers' nodules complicated by erythema multiforme and graft-versus-host after allogenic hematopoietic stem cell transplantation for multiple myeloma. Clin Infect Dis. 2005;40:e63-6.

  18. Smith KJ, Skelton HG 3d, James WD, Lupton GP. Parapoxvirus infections acquired after exposure to wildlife. Arch Dermatol. Jan 1991;127(1):79-82. [Medline].

  19. Tompkins DM, Sainsbury AW, Nettleton P. Parapoxvirus causes a deleterious disease in red squirrels associated with UK population declines. Proc Biol Sci. 2002;269:529-33.

  20. Wilkinson JD. Orf: a family with unusual complications. Br J Dermatol. Oct 1977;97(4):447-50. [Medline].

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Further Reading

Related eMedicine topics

Poxviruses

Orf

Milker's Nodules

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Keywords

viral infection, virus, poxviruses, Parapoxvirus, Poxviridae, Poxvirus, orf, ecthyma contagiosum, bovine papular stomatitis, pseudocowpox, milker's nodule, paravaccinia, farmyard pox

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Contributor Information and Disclosures

Author

Larry I Lutwick, MD, Professor of Medicine, State University of New York, Downstate Medical School; Director, Infectious Diseases, Veterans Affairs New York Harbor Health Care System, Brooklyn Campus
Larry I Lutwick, MD is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Coauthor(s)

Adam M Rotunda, MD, Fellow, Department of Dermatology, David Geffen School of Medicine at University of California at Los Angeles
Disclosure: Nothing to disclose.

Medical Editor

Pranatharthi Haran Chandrasekar, MD, Director of Infectious Disease Fellowship, Professor, Department of Internal Medicine, Harper Hospital, Wayne State University School of Medicine
Pranatharthi Haran Chandrasekar, MD is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Thomas M Kerkering, MD, Chief of Infectious Diseases, Virginia Tech, Carilion School of Medicine, Roanoke, Virginia
Thomas M Kerkering, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Public Health Association, American Society for Microbiology, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, Medical Society of Virginia, and Wilderness Medical Society
Disclosure: Nothing to disclose.

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

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