History

Fact Explanation
Skin rash The cowpox or catpox virus is a zoonotic member of the family orthopoxviride. It is transferable from animal to human. It is acquired by direct contact with an infected animal (cat in most of cases) to a human during a scratch or bite . Cowpox infection is very rare nowadays. Most cases have been reported in Great Britain and other European countries. In cowpox disease, small number of skin lesions appears on the hands and face. Initially the site of infection appears as an inflamed flat red lesion (macule). Then, the inflamed lesion becomes raised (papular) and develops into a blister-like sore (vesicle). [1,2,3,4,5]
Skin ulcer After 2 weeks of the infection, the vesicular rash becomes filled with blood and pus and eventually ulcerates. Other lesions may develop close by. Within next 2-3 weeks, the ulcerated wound turns into a deep-seated, hard, black crusty sore (eschar) which is surrounded by redness and swelling. By 12 weeks, the eschar begins to flake and slough and the lesion heals, often leaving a scar behind. [1,2,3,4]
Nonspecific symptoms Fever, malaise, vomiting, lethargy, and sore throat, usually lasting 3-10 days,yet get resolved as ulcerative lesion heals. [1,2,6]
At risk population Young population in Great Britain and other surrounding European countries are at higher risk. This is possibly due to the fact that younger people may have closer contact with animals such as cats. [4,5,6]
References
  1. STRENGER V, MüLLER M, RICHTER S, REVILLA-FERNANDEZ S, NITSCHE A, KLEE SR, ELLERBROK H, ZENZ W. A 17-year-old girl with a black eschar. Cowpox virus infection. Clin Infect Dis [online] 2009 Jan 1, 48(1):91-2, 133-4 [viewed 03 August 2014] Available from: doi:10.1086/595004
  2. DURAFFOUR S, MERTENS B, MEYER H, VAN DEN OORD JJ, MITERA T, MATTHYS P, SNOECK R, ANDREI G. Emergence of cowpox: study of the virulence of clinical strains and evaluation of antivirals. PLoS One [online] 2013, 8(2):e55808 [viewed 03 August 2014] Available from: doi:10.1371/journal.pone.0055808
  3. VOGEL S, SáRDY M, GLOS K, KORTING HC, RUZICKA T, WOLLENBERG A. The Munich outbreak of cutaneous cowpox infection: transmission by infected pet rats. Acta Derm Venereol [online] 2012 Mar, 92(2):126-31 [viewed 03 August 2014] Available from: doi:10.2340/00015555-1227
  4. CARDETI G, BROZZI A, ELENI C, POLICI N, D'ALTERIO G, CARLETTI F, SCICLUNA MT, CASTILLETTI C, CAPOBIANCHI MR, DI CARO A, AUTORINO GL, AMADDEO D. Cowpox virus in llama, Italy. Emerg Infect Dis [online] 2011 Aug, 17(8):1513-5 [viewed 03 August 2014] Available from: doi:10.3201/eid1708.101912
  5. HEMMER CJ, LITTMANN M, LöBERMANN M, MEYER H, PETSCHAELIS A, REISINGER EC. Human cowpox virus infection acquired from a circus elephant in Germany. Int J Infect Dis [online] 2010 Sep:e338-40 [viewed 03 August 2014] Available from: doi:10.1016/j.ijid.2010.03.005
  6. CAMPE H, ZIMMERMANN P, GLOS K, BAYER M, BERGEMANN H, DREWECK C, GRAF P, WEBER BK, MEYER H, BüTTNER M, BUSCH U, SING A. Cowpox virus transmission from pet rats to humans, Germany. Emerg Infect Dis [online] 2009 May, 15(5):777-80 [viewed 03 August 2014] Available from: doi:10.3201/eid1505.090159

Examination

Fact Explanation
Skin lesion The inoculated site (usually the skin of the hands and face) initially become inflamed and manifest as macular rash. The surrounding area is also erythematous. Within weeks, it becomes a vesiculopapular rash. Vesicle is usually filled with blood. With time, the vesicles are filled with pus. Some of them may ulcerate. The surrounding area may remain erythematous and indurated. A deep-seated, hard, black eschar follows the ulcers. During the final stage, the eschar heals and a scar is left. Lesions may be single or multiple and usually does not itch. Rarely the localized lesions may spread into the rest of the body to form a generalized skin lesions. [1,2,3,4]
Eye examination This may rarely reveals conjunctivitis, periorbital edema, and corneal involvement. [2,3,4]
Lymphadenopathy Rarely localized tender lymph node enlargement can be observed. [2,4]
References
  1. TRENGER V, MüLLER M, RICHTER S, REVILLA-FERNANDEZ S, NITSCHE A, KLEE SR, ELLERBROK H, ZENZ W. A 17-year-old girl with a black eschar. Cowpox virus infection. Clin Infect Dis [online] 2009 Jan 1, 48(1):91-2, 133-4 [viewed 03 August 2014] Available from: doi:10.1086/595004
  2. HEMMER CJ, LITTMANN M, LöBERMANN M, MEYER H, PETSCHAELIS A, REISINGER EC. Human cowpox virus infection acquired from a circus elephant in Germany. Int J Infect Dis [online] 2010 Sep:e338-40 [viewed 03 August 2014] Available from: doi:10.1016/j.ijid.2010.03.005
  3. CAMPE H, ZIMMERMANN P, GLOS K, BAYER M, BERGEMANN H, DREWECK C, GRAF P, WEBER BK, MEYER H, BüTTNER M, BUSCH U, SING A. Cowpox virus transmission from pet rats to humans, Germany. Emerg Infect Dis [online] 2009 May, 15(5):777-80 [viewed 03 August 2014] Available from: doi:10.3201/eid1505.090159
  4. CARDETI G, BROZZI A, ELENI C, POLICI N, D'ALTERIO G, CARLETTI F, SCICLUNA MT, CASTILLETTI C, CAPOBIANCHI MR, DI CARO A, AUTORINO GL, AMADDEO D. Cowpox virus in llama, Italy. Emerg Infect Dis [online] 2011 Aug, 17(8):1513-5 [viewed 03 August 2014] Available from: doi:10.3201/eid1708.101912

Differential Diagnoses

Fact Explanation
Orf Orf is an infection caused by a parapox virus called 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]
Anthrax Anthrax is a bacterial infection caused by Bacillus anthracis. Untreated, up to one-fifth of infected individuals die of the disease. Prompt treatment with antibiotics is curative and most recover fully. Most often anthrax starts as a localised infection on exposed skin (usually face, hands or arms). It looks like an insect bite and is known as a "malignant pustule". Usually painless, an itchy bump appears with surrounding redness. Apart from the cutaneous form, pulmonary and gastrointestinal tract anthrax are also not uncommon.[2]
Herpes Simplex Herpes simplex is a common viral infection that presents with localised blistering. It affects most people on one or more occasions during their lives, and is caused by the Herpes Simplex Virus (HSV). HSV infection causes several distinct medical disorders. Common infection of the skin or mucosa may affect the face and mouth (orofacial herpes), genitalia (genital herpes), or hands (herpetic whitlow). More serious disorders occur when the virus infects and damages the eye (herpes keratitis), or invades the central nervous system, damaging the brain (herpes encephalitis). [3]
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. [4]
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. INSTITUTE OF MEDICINE (US) COMMITTEE ON HEALTH EFFECTS ASSOCIATED WITH EXPOSURES DURING THE GULF WAR. [online] 2000 [viewed 03 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/25077264
  3. MIRANDA CA, LIMA EG, DE LIMA DB, COBUCCI RN, CORNETTA MDA C, FERNANDES TA, DE AZEVEDO PR, DE AZEVEDO JC, DE ARAúJO JM, FERNANDES JV. Genital infection with herpes simplex virus types 1 and 2 in women from natal, Brazil. ISRN Obstet Gynecol [online] 2014:323657 [viewed 03 August 2014] Available from: doi:10.1155/2014/323657
  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

Investigations - for Diagnosis

Fact Explanation
Electron microscopy Electron microscopic evaluation of vesicle fluid, scab extracts or biopsy specimens may reveal characteristic "mulberry" and "capsule" forms which may diagnostic of Orthopoxviruses. Still the definitive diagnosis of cowpox virus can not be made by this means. [1,2,3]
Polymerase chain reaction (PCR) PCR may be performed on biopsy material or cell culture. This is diagnostic of cowpox virus. [1,3]
Skin biopsy for histology Immunohistochemistry detects cowpox antigens in infections in cats. Using electron microscopy, biopsy material may reveal viral particles which rarely helps in a differential diagnosis. [2,3]
References
  1. HEMMER CJ, LITTMANN M, LöBERMANN M, MEYER H, PETSCHAELIS A, REISINGER EC. Human cowpox virus infection acquired from a circus elephant in Germany. Int J Infect Dis [online] 2010 Sep:e338-40 [viewed 03 August 2014] Available from: doi:10.1016/j.ijid.2010.03.005
  2. STRENGER V, MüLLER M, RICHTER S, REVILLA-FERNANDEZ S, NITSCHE A, KLEE SR, ELLERBROK H, ZENZ W. A 17-year-old girl with a black eschar. Cowpox virus infection. Clin Infect Dis [online] 2009 Jan 1, 48(1):91-2, 133-4 [viewed 03 August 2014] Available from: doi:10.1086/595004
  3. CAMPE H, ZIMMERMANN P, GLOS K, BAYER M, BERGEMANN H, DREWECK C, GRAF P, WEBER BK, MEYER H, BüTTNER M, BUSCH U, SING A. Cowpox virus transmission from pet rats to humans, Germany. Emerg Infect Dis [online] 2009 May, 15(5):777-80 [viewed 03 August 2014] Available from: doi:10.3201/eid1505.090159

Management - General Measures

Fact Explanation
Bed rest Patients may feel unwell and require bed rest and supportive therapy. [1,2,3]
Occlusive bandages Wound dressings or bandages may be applied to lesions to prevent spread to other sites and potentially to other people. [2,3,4]
Antiviral medications Antiviral medications are not routinely indicated. Cidofovir, an injectable antiviral medication, can be considered in disseminated cases of cowpox. [2,4,5]
Antibiotics Topical or systemic antibiotics are only used in case of secondary bacterial infection. [1,2,4]
Antivaccinia gammaglobulin As most cases are mild and self-limited, usually no treatment is required. However, for severe cases with widespread involvement antivaccinia gammaglobulin may be considered. [1,3,4,5]
Surgical options Surgical treatments other than standard wound dressings are not recommended as they can prolong the infection or spread it to other body sites. [1,4,5,6]
Prevention Avoiding exposure to sick cats or other sick animals may prevent the infection from the virus. Recombinant vaccines studied in mice against cowpox may be available for human use in the future. [1,3,4,5,6]
References
  1. DURAFFOUR S, MERTENS B, MEYER H, VAN DEN OORD JJ, MITERA T, MATTHYS P, SNOECK R, ANDREI G. Emergence of cowpox: study of the virulence of clinical strains and evaluation of antivirals. PLoS One [online] 2013, 8(2):e55808 [viewed 03 August 2014] Available from: doi:10.1371/journal.pone.0055808
  2. STRENGER V, MüLLER M, RICHTER S, REVILLA-FERNANDEZ S, NITSCHE A, KLEE SR, ELLERBROK H, ZENZ W. A 17-year-old girl with a black eschar. Cowpox virus infection. Clin Infect Dis [online] 2009 Jan 1, 48(1):91-2, 133-4 [viewed 03 August 2014] Available from: doi:10.1086/595004
  3. CAMPE H, ZIMMERMANN P, GLOS K, BAYER M, BERGEMANN H, DREWECK C, GRAF P, WEBER BK, MEYER H, BüTTNER M, BUSCH U, SING A. Cowpox virus transmission from pet rats to humans, Germany. Emerg Infect Dis [online] 2009 May, 15(5):777-80 [viewed 03 August 2014] Available from: doi:10.3201/eid1505.090159
  4. HEMMER CJ, LITTMANN M, LöBERMANN M, MEYER H, PETSCHAELIS A, REISINGER EC. Human cowpox virus infection acquired from a circus elephant in Germany. Int J Infect Dis [online] 2010 Sep:e338-40 [viewed 03 August 2014] Available from: doi:10.1016/j.ijid.2010.03.005
  5. CARDETI G, BROZZI A, ELENI C, POLICI N, D'ALTERIO G, CARLETTI F, SCICLUNA MT, CASTILLETTI C, CAPOBIANCHI MR, DI CARO A, AUTORINO GL, AMADDEO D. Cowpox virus in llama, Italy. Emerg Infect Dis [online] 2011 Aug, 17(8):1513-5 [viewed 03 August 2014] Available from: doi:10.3201/eid1708.101912
  6. VOGEL S, SáRDY M, GLOS K, KORTING HC, RUZICKA T, WOLLENBERG A. The Munich outbreak of cutaneous cowpox infection: transmission by infected pet rats. Acta Derm Venereol [online] 2012 Mar, 92(2):126-31 [viewed 03 August 2014] Available from: doi:10.2340/00015555-1227