History

Fact Explanation
Skin rash Orf is an infection caused by a parapox virus known by the same name. It is a common among sheep and goats. Direct contact with an infected animal or contaminated fomites results in transmission of the virus to human body. Therefore, Orf is frequently seen in farmers and meat handlers. Orf lesions are generally solitary or few in number. Though the classical site is the dorsum of the index finger, it can be seen on other fingers, hands, forearms or on face. [1,2,3,4,5]
Fever A low-grade fever may result. It usually subsides within 3-4 days. [2,3,4]
Larger lesions Though orf is a benign self-limiting illness, it can be very progressive and even life-threatening in the immune-compromised host. They may develop larger or unusual orf lesions. [1,3,4,5]
At risk population Orf is very common among shepherds, veterinary surgeons, farmers who bottle-feed young lambs, butchers and meat handlers. Trivial injury such as pricks from thistle or substantial trauma such as bites can facilitate the transmission of orf virus. [2,4,6]
References
  1. GRAY EH. Contagious ecthyma in man. Calif Med [online] 1949 May, 70(5):417 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/18120863
  2. KITCHEN M, MüLLER H, ZOBL A, WINDISCH A, ROMANI N, HUEMER H. ORF virus infection in a hunter in Western Austria, presumably transmitted by game. Acta Derm Venereol [online] 2014 Mar, 94(2):212-4 [viewed 02 August 2014] Available from: doi:10.2340/00015555-1643
  3. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Human Orf virus infection from household exposures - United States, 2009-2011. MMWR Morb Mortal Wkly Rep [online] 2012 Apr 13, 61(14):245-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22495228
  4. FRANDSEN J, ENSLOW M, BOWEN AR. Orf parapoxvirus infection from a cat scratch. Dermatol Online J [online] 2011 Apr 15, 17(4):9 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/21549084
  5. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Orf virus infection in humans--New York, Illinois, California, and Tennessee, 2004-2005. MMWR Morb Mortal Wkly Rep [online] 2006 Jan 27, 55(3):65-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/16437055
  6. SIMMONS JF, HAFERNICK AC. Painless, red nodule on the finger of a veterinary student. Am Fam Physician [online] 2012 Jul 1, 86(1):77-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22962916

Examination

Fact Explanation
Orf lesion Rash starts as small raised bumps (Papules). It is firm, red or reddish-blue lump and enlarges to form a flat-topped, blood-tinged pustule or blister. The average diameter is around 2-5cm. Though it seems to be full of pus, incision may reveal the actual red, firm tissue underneath the flat top. There is an umbilicated center. In the center of the blister/ pustule. It is covered with a crust. Sometimes the orf lesion is irritable and rarely tender. The lesion may be secondarily infected by bacteria. [1,2,3,4]
Lymphadenitis and lymphadenopathy Red streaks up the lymph channels with enlargement of the lymph glands on the inner side of the elbow and/or under the arm are not uncommon. [2,3,4]
Erythema multiforme A secondary allergy rash to the presence of the orf virus is developed in some patients. Erythema multiforme are the allergic target lesions. Few to hundreds of skin lesions erupt within a 24-hour period. The lesions are first seen on the backs of hands and/or tops of feet, then spread along the limbs towards the trunk. [1,3,4]
References
  1. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Human Orf virus infection from household exposures - United States, 2009-2011. MMWR Morb Mortal Wkly Rep [online] 2012 Apr 13, 61(14):245-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22495228
  2. SIMMONS JF, HAFERNICK AC. Painless, red nodule on the finger of a veterinary student. Am Fam Physician [online] 2012 Jul 1, 86(1):77-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22962916
  3. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Orf virus infection in humans--New York, Illinois, California, and Tennessee, 2004-2005. MMWR Morb Mortal Wkly Rep [online] 2006 Jan 27, 55(3):65-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/16437055
  4. SIMMONS JF, HAFERNICK AC. Painless, red nodule on the finger of a veterinary student. Am Fam Physician [online] 2012 Jul 1, 86(1):77-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22962916

Differential Diagnoses

Fact Explanation
Acute Febrile Neutrophilic Dermatosis Sweet's syndrome or acute febrile neutrophilic dermatosis is a skin disease characterized by the sudden onset of fever, leukocytosis, and tender, erythematous, well-demarcated papules and plaques that show dense infiltrates by neutrophil granulocytes on histologic examination. Acute, tender, erythematous plaques, nodes, pseudovesicles and, occasionally, blisters with an annular or arciform pattern occur on the head, neck, legs, and arms, particularly the back of the hands and fingers. [1]
Erysipeloid Erysipeloid is an acute bacterial infection of the skin and other organs caused by the microorganism Erysipelothrix rhusiopathiae. The transmission occurs when the infected animals or meat contacts with traumatized (abrasion or cut) human skin. It may present with localized or generalized skin lesions.[2]
Milker's Nodules Milker's nodule is an infection of the skin caused by a virus that infects the teats of cows. Milker's nodule is caused by a parapoxvirus. After an incubation period of 5-14 days small, red, raised, flat-topped spots develop. Within a week they appear as red-blue, firm, slightly tender blisters or nodules (lumps), usually between 2 and 5 in number although they may be solitary or more numerous. The nodules are usually on the hands, particularly the fingers, but occasionally the face. The top of the nodules often develops a greyish skin and a small crust. [3]
References
  1. KUMAR P, DAS A, MONDAL A. Acute febrile neutrophilic dermatosis (sweet syndrome). Indian Pediatr [online] 2014 May 8, 51(5):420 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/24953595
  2. PRICE JE, BENNETT WE. The erysipeloid of Rosenbach. Br Med J [online] 1951 Nov 3, 2(4739):1060-2 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/14869813
  3. SIMMONS JF, HAFERNICK AC. Painless, red nodule on the finger of a veterinary student. Am Fam Physician [online] 2012 Jul 1, 86(1):77-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22962916

Investigations - for Diagnosis

Fact Explanation
Serology Immunoglobulin G and M are raised during the illness. But serology does not permit to distinguish the virus from other parapoxviruses (paravaccinia/pseudocowpox). [1,2,3,4]
Electron microscopy Electron microscopy also does not help in a definitive diagnosis beyond the Parapoxvirus genera. [2,4,5]
Polymerase chain reaction (PCR) Only PCR can definitively identify a parapoxvirus as orf virus. [3,4]
Skin biopsy A punch biopsy specimen may help significantly in the diagnosis. Epidermal pseudoepitheliomatous hyperplasia, necrosis of the epidermis with central ulceration can be seen. Intranuclear and intracytoplasmic inclusion bodies, pyknosis of individual keratinocytes and dense inflammatory cell infiltration are some microscopic findings. [3,4,5]
References
  1. FRANDSEN J, ENSLOW M, BOWEN AR. Orf parapoxvirus infection from a cat scratch. Dermatol Online J [online] 2011 Apr 15, 17(4):9 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/21549084
  2. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Human Orf virus infection from household exposures - United States, 2009-2011. MMWR Morb Mortal Wkly Rep [online] 2012 Apr 13, 61(14):245-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22495228
  3. SIMMONS JF, HAFERNICK AC. Painless, red nodule on the finger of a veterinary student. Am Fam Physician [online] 2012 Jul 1, 86(1):77-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22962916
  4. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Orf virus infection in humans--New York, Illinois, California, and Tennessee, 2004-2005. MMWR Morb Mortal Wkly Rep [online] 2006 Jan 27, 55(3):65-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/16437055
  5. KITCHEN M, MüLLER H, ZOBL A, WINDISCH A, ROMANI N, HUEMER H. ORF virus infection in a hunter in Western Austria, presumably transmitted by game. Acta Derm Venereol [online] 2014 Mar, 94(2):212-4 [viewed 02 August 2014] Available from: doi:10.2340/00015555-1643

Management - General Measures

Fact Explanation
Son steroidal anti inflammatory drugs (NSAIDs) Ibuprofen is used to relieve the pain and inflammation along with other supportive therapies such as moist dressings and immobilization. Most of the time these will be sufficient because the lesions resolve spontaneously after about six weeks. [1,2,3]
Prevention The best preventive measure is orf vaccination every 6-8 months in animals. Barrier protection (e.g., nonporous gloves) and hand washing during the care of sheep and goats is recommended whenever feasible. Patients who are immunosuppressed or those who with compromised skin barriersmust avoid contact with infected animals. [1,2,3]
References
  1. SIMMONS JF, HAFERNICK AC. Painless, red nodule on the finger of a veterinary student. Am Fam Physician [online] 2012 Jul 1, 86(1):77-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22962916
  2. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Orf virus infection in humans--New York, Illinois, California, and Tennessee, 2004-2005. MMWR Morb Mortal Wkly Rep [online] 2006 Jan 27, 55(3):65-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/16437055
  3. GRAY EH. Contagious ecthyma in man. Calif Med [online] 1949 May, 70(5):417 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/18120863

Management - Specific Treatments

Fact Explanation
Antibiotics Topical or systemic antibiotics are used to treat any secondary bacterial infections of the orf lesion. [1,2,3]
Imiquimod It is an immune response modifier that has proven benefit in rapid regression of the lesions. [2,4,5,6]
Surgery Surgical options such as dissection, curettage and electrodesiccation, shave excision or cryotherapy Is used when the orf lesion is large and for those which does not spontaneously recover or unresponsive to medical treatment. [1,2,5,6]
References
  1. KITCHEN M, MüLLER H, ZOBL A, WINDISCH A, ROMANI N, HUEMER H. ORF virus infection in a hunter in Western Austria, presumably transmitted by game. Acta Derm Venereol [online] 2014 Mar, 94(2):212-4 [viewed 02 August 2014] Available from: doi:10.2340/00015555-1643
  2. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Human Orf virus infection from household exposures - United States, 2009-2011. MMWR Morb Mortal Wkly Rep [online] 2012 Apr 13, 61(14):245-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22495228
  3. FRANDSEN J, ENSLOW M, BOWEN AR. Orf parapoxvirus infection from a cat scratch. Dermatol Online J [online] 2011 Apr 15, 17(4):9 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/21549084
  4. CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Orf virus infection in humans--New York, Illinois, California, and Tennessee, 2004-2005. MMWR Morb Mortal Wkly Rep [online] 2006 Jan 27, 55(3):65-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/16437055
  5. GRAY EH. Contagious ecthyma in man. Calif Med [online] 1949 May, 70(5):417 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/18120863
  6. SIMMONS JF, HAFERNICK AC. Painless, red nodule on the finger of a veterinary student. Am Fam Physician [online] 2012 Jul 1, 86(1):77-8 [viewed 02 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22962916