Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide







  • Last modified
  • 14 July 2018
  • Datasheet Type(s)
  • Animal Disease
  • Preferred Scientific Name
  • cowpox
  • Pathogens
  • cowpox virus
  • Overview
  • Cowpox virus is a member of the genus Orthopoxvirus, and therefore is closely related to smallpox virus (now eradicated) and vaccinia virus (the smallpox vaccine). Cowpox virus, despite its name (and the claims of older...

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Preferred Scientific Name

  • cowpox


Top of page cowpox virus


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Cowpox virus is a member of the genus Orthopoxvirus, and therefore is closely related to smallpox virus (now eradicated) and vaccinia virus (the smallpox vaccine). Cowpox virus, despite its name (and the claims of older texts), is endemic in wild rodents (Baxby and Bennett, 1999). Occasionally other hosts can become infected, most commonly cats but also cattle, various zoo animals, dogs and humans, either directly from rodents or from cattle or cats. Different strains of cowpox virus, possibly with different host ranges, are found in different areas. Infection of cattle is now rarely reported, perhaps because of the hygienic precautions taken in most modern dairy herds (Baxby, 1977). Indeed, it probably never was common in cattle; even Edward Jenner had difficulty finding cases for use as the source of his smallpox vaccine. Despite its name, the principal poxvirus infection of cattle is pseudocowpox virus, a member of the Parapoxvirus genus.

Host Animals

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Animal nameContextLife stageSystem
Bos indicus (zebu)Domesticated hostCattle & Buffaloes: All Stages
Bos taurus (cattle)Domesticated hostCattle & Buffaloes: All Stages

Hosts/Species Affected

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In addition to wild rodents (in which infection is endemic), cowpox has been reported in a wide range of domestic mammalian hosts. These include: cattle (Gibbs et al., 1973), domestic cats (Gaskell et al., 1983; Bennett et al., 1986, 1990; Mahnel et al., 1989; Maenhout et al., 1991; Bomhard et al., 1992; Nowotny, 1996), domestic dogs (Bomhard et al., 1992; Smith et al., 1999), horses (Pfeffer et al., 1999) and various zoo animals such as big cats (Marennikova et al., 1977b, 1984; Baxby et al., 1982), beavers (Hentschke et al., 1999), anteaters (Marennikova et al., 1977b), alpacas (Schüppel et al., 1997), okapi (Zwart et al., 1971), elephants and rhinoceroses (Pilaski et al., 1988).

Systems Affected

Top of page mammary gland diseases of large ruminants
multisystemic diseases of large ruminants
respiratory diseases of large ruminants
skin and ocular diseases of large ruminants


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Published accounts of the distribution of cowpox suffer from both under- and over-reporting. Unless clinically obvious disease is seen and recognized in domestic animals or humans, it is unlikely to be reported, while pseudocowpox is often incorrectly reported as cowpox and, particularly in the older literature, vaccinia (including buffalopox viruses) and cowpox viruses were often not distinguished. Reliable reports of characterized virus suggest that cowpox virus is found throughout much of Europe (although not Ireland, the Iberian Peninsula or, possibly, the Balkans), possibly in parts of the Middle East and eastwards to the Urals in the North and Turkmenistan in the South. It does appear to be widespread in Africa, the Americas, Australasia or the Far East.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.


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Vesicular and ulcerative lesions of cowpox are often limited to the skin in non-reservoir hosts, although systemic lesions, particularly in the lungs and abdominal cavity, are sometimes encountered. The microscopic changes include epithelial hyperplasia and hypertrophy, lysis of the prickle cell layer in the epidermis and microscopic vesicle formation, and characteristic intracytoplasmic, eosinophilic inclusion bodies.


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A presumptive diagnosis can often be made on clinical signs alone, particularly in cats. However, confirmation requires isolation of the virus and its characterization. Histology, especially if immunostaining is used, can confirm an orthopoxvirus infection, as can serology. Serology has the advantage of being available retrospectively. Electron microscopy can provide a rapid result, but only to the level of confirming a non-parapoxvirus, poxvirus infection.

List of Symptoms/Signs

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SignLife StagesType
Respiratory Signs / Nasal mucosal ulcers, vesicles, erosions, cuts, tears, papules, pustules Cattle & Buffaloes:All Stages Sign
Skin / Integumentary Signs / Scarred skin Cattle & Buffaloes:All Stages Sign
Skin / Integumentary Signs / Skin papules Cattle & Buffaloes:All Stages Sign
Skin / Integumentary Signs / Skin pustules Cattle & Buffaloes:All Stages Sign
Skin / Integumentary Signs / Skin ulcer, erosion, excoriation Cattle & Buffaloes:All Stages Sign
Skin / Integumentary Signs / Skin vesicles, bullae, blisters Cattle & Buffaloes:All Stages Sign

Disease Course

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No clinical disease is seen in most wild rodent hosts (Bennett et al., 1997; Feore et al., 1997). The pathogenesis of feline cowpox follows the typical pattern of a systemic poxvirus infection (Bennett et al., 1989). A single primary skin lesion develops at the site of infection, usually the head or a forelimb, within a few days. A white cell-mediated viraemia follows, with virus replication in lymphoid tissue, the lungs and turbinates. This lasts approximately 5 days, and secondary, widespread skin lesions appear just over a week after the primary lesion. Small erythematous nodules increase in size over 2-3 days to become scabbed ulcers approximately 0.5-1 cm across. These gradually heal, so that by 4-6 weeks the dried scabs separate leaving small bald patches. More severe disease, such as pneumonia or large or non-healing lesions, is often associated with immunosuppression, and may result from co-infection with feline leukaemia or feline immunodeficiency viruses (FeLV or FIV), or some other concurrent illness (Bennett et al., 1986, 1990; Brown et al., 1989).

In cattle and humans, only primary lesions at sites of inoculation are usually seen. The lesions of natural bovine cowpox are usually found only on the teats of dairy cows (Gibbs et al., 1973). This may reflect areas of skin most likely to be both damaged and to come into contact with rodent-contaminated material. The usual route of infection in humans is also through a break in the skin, most often the hands or face, including eyes. Human lesions can vary in size and severity, and are often very painful (Baxby et al., 1994). Local lymphadenopathy and systemic signs such as pyrexia and nausea are common, and many cases require hospitalization. More severe cowpox, with multiple lesions and (rarely) death, has been reported, usually associated with immunosuppression (Czerny et al., 1997).


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Cowpox virus is endemic in wild rodents, particularly voles of the genera Microtus and Clethrionomys, and mice of the genus Apodemus (Lvov et al., 1988; Crouch et al., 1995; Boulanger et al., 1996; Tryland et al., 1998b; Begon et al., 1998, 1999; Chantrey et al., 1999). In some areas, for example at the eastern extreme of its range, other rodent hosts such as gerbils (Meriones and Rhombomys) and suslicks (Spermophilus) (Marennikova et al., 1977a, 1978, 1984; Tsanava et al., 1989a, b). In Georgia and Russia, infection of rats (Rattus rattus) has been reported, but there is no serological evidence of infection of rats or mice (Mus musculus) in the UK.

Infection of other hosts presumably results from contact with rodents. The most commonly reported accidental host is the domestic cat, at least in Western Europe, which appears to become infected through hunting wild rodents, and is also an important liaison host; more than 50% of human cases can be traced to contact with a domestic cat (Willemse and Egberink, 1985; Czerny et al., 1991; Baxby et al., 1994). Antibody thought to be due to cowpox has also been reported in foxes (Mayr et al., 1995; Henning et al., 1995; Müller et al., 1996), although experimentally they have proved difficult to infect with a strain of virus from the UK (Boulanger et al., 1995).

None of the details of transmission amongst and from rodents are known, although infection rates in wild populations clearly depend on population size and, apparently, specific behaviours (Begon et al., 1999). Indeed, cowpox is most studied currently as a model endemic infection for testing theoretical concepts of disease ecology.

Disease in other hosts is sporadic, but where enough data have been collected, can be seen to follow infection dynamics in the reservoir hosts. In Western Europe, for example, infection of cats, elephants and humans is most common in the autumn, and can be seen to follow the infection and population dynamics of wild rodents (Bennett et al., 1986; Pilaski et al., 1988; Bomhard et al., 1992; Baxby et al., 1994).

Zoonoses and Food Safety

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Cowpox is a zoonosis, human infection occurring usually through contamination of a break in the skin (Baxby et al., 1994). Infections are usually self-limiting if painful. The immunosuppressed are particularly at risk of severe disease (Czerny et al., 1991). Many human cases can be traced to contact with an infected cat, and some to direct or indirect contact with rodents (Postma et al., 1991). However, human cowpox is rare; approximately 1-2 cases are reported each year in the UK, despite widespread infection of wild rodents (Baxby and Bennett, 1997).

Disease Treatment

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There is no specific treatment, although cidofir has been used successfully to treat experimental cowpox in laboratory animals (Bray et al., 2000).

Prevention and Control

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Elephants and other zoo animals are sometimes vaccinated with vaccinia virus (Pilaski et al., 1988), although stocks of this can be hard to come by. Generally, the incidence in non-wild animals is too low to make prevention and control schemes cost-effective. General good practice in hygiene in dairy farms reduce the chances of disease transmission.


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Baxby D, 1977. Is cowpox misnamed? A review of 10 human cases. British Medical Journal, 1:1379.

Baxby D, Ashton DG, Jones DM, Thomsett LR, 1982. An outbreak of cowpox in captive cheetahs: virological and epidemiological studies. Journal of Hygiene, 89:365-372.

Baxby D, Bennett M, 1997. Cowpox: a re-evaluation of the risks of human cowpox based on new epidemiological information. Archives of Virology, Supplement, No. 13:1-12; 57 ref.

Baxby D, Bennett M, 1999. Cowpox virus (Poxviridae). In Encyclopedia of Virology, 2nd Edition. London: Academic Press. pp 298-304.

Baxby D, Bennett M, Getty B, 1994. Human cowpox; a review based on 54 cases, 1969-93. British Journal of Dermatology, 131:598-607.

Baxby D, Shackleton WB, Wheeler J, Turner A, 1979. A comparison of cowpox-like viruses isolated from European zoos. Archives of Virology, 61:337-340.

Begon M, Feore S, Bown K, Chantrey J, Jones T, Bennett M, 1998. The population dynamics of cowpox virus infection in bank voles: testing fundamental assumptions. Ecology Letters, 1:82-86.

Begon M, Hazel SM, Baxby D, Bown K, Cavanagh R, Chantrey J, Jones T, Bennett M, 1999. Transmission dynamics of a zoonotic pathogen within and between wildlife host species. Proceedings of the Royal Society, B, 266:1-7.

Bennett M, Crouch AJ, Begon M, Duffy B, Feore S, Gaskell RM, Kelly DF, McCracken CM, Vicary L, Baxby D, 1997. Cowpox in British voles and mice. Journal of Comparative Pathology, 116(1):35-44; 28 ref.

Bennett M, Gaskell CJ, Baxby D, Gaskell RM, Kelly DF, Naidoo J, 1990. Feline cowpox virus infection. Journal of Small Animal Practice, 31(4):167-173; 34 ref.

Bennett M, Gaskell CJ, Gaskell RM, Baxby D, Gruffydd-Jones TJ, 1986. Poxvirus infection in the domestic cat: some clinical and epidemiological observations. Veterinary Record, 118(14):387-390; 26 ref.

Bennett M, Gaskell RM, Gaskell CJ, Baxby D, Kelly DF, 1989. Studies on poxvirus infection in cats. Archives of Virology, 104(1-2):19-33; 24 ref.

Bhreathnach R, Markey B, 1996. Feline dermatology. Irish Veterinary Journal, 49(5):307-310; 10 ref.

Bomhard Dvon, Pfleghaar S, Mahnel H, 1992. Epidemiology, clinical features, pathology and virology of pox in cats. Kleintierpraxis, 37(4):219.230; 38 ref.

Boulanger D, Brochier B, Crouch A, Bennett M, Gaskell RM, Baxby D, Pastoret PP, 1995. Comparison of the susceptibility of the red fox (Vulpes vulpes) to a vaccinia-rabies recombinant virus and to cowpox virus. Vaccine, 13(2):215-219; 32 ref.

Boulanger D, Crouch A, Brochier B, Bennett M, Clément J, Gaskell RM, Baxby D, Pastoret PP, 1996. Serological survey for orthopoxvirus infection of wild mammals in areas where a recombinant rabies virus is used to vaccinate foxes. Veterinary Record, 138(11):247-249; 38 ref.

Bray M, Martinez M, Smee DF, Kefauver D, Thompson E, Huggins JW, 2000. Cidofir protects mice against lethal aerosol or intranasal cowpox virus challenge. Journal of Infectious Diseases, 181:10-19.

Brown A, Bennett M, Gaskell CJ, 1989. Fatal poxvirus infection in association with FIV infection. Veterinary Record, 124(1):19-20; 14 ref.

Chantrey J, Meyer H, Baxby D, Begon M, Bown KJ, Hazel SM, Jones T, Montgomery WI, Bennett M, 1999. Cowpox: reservoir hosts and geographic range. Epidemiology and Infection, 122(3):455-460; 33 ref.

Claudy AL, Gaudin OG, Granouillet R, 1982. Poxvirus disease in dariers disease. Clinical and Experimental Dermatology, 7:261-266.

Cronqvist J, Ekdahl K, Kjartansdottir A, Bauer B, Klinker M, 1991. Cowpox - en kattsjuka hos manniska. Lakartidningen, 88:32-33.

Crouch AC, Baxby D, McCracken CM, Gaskell RM, Bennett M, 1995. Serological evidence for the reservoir hosts of cowpox virus in British wildlife. Epidemiology and Infection, 115(1):185-191; 29 ref.

Czerny CP, Eis-Hübinger AM, Mayr A, Schneweis KE, Pfeiff B, 1991. Animal poxviruses transmitted from cat to man: current event with lethal end. Journal of Veterinary Medicine. Series B, 38(6):421-431; 37 ref.

Czerny CP, Zeller-Lue C, Eis-Hübinger AM, Kaaden OR, Meyer H, 1997. Characterization of a cowpox-like orthopox virus which had caused a lethal infection in man. Archives of Virology, Supplement, No. 13:13-24; 52 ref.

Feore SM, Bennett M, Chantry J, Jones T, Baxby D, Begon M, 1997. The effect of cowpox virus infection on fecundity in bank voles and wood mice. Proceedings of the Royal Society, B, 264:1-5.

Fondati A, Grivetto V, 1997. Case of cowpox virus infection in a cat. Quaderni di Dermatologia (Supplemento della rivista Veterinaria), Supplement 4:23-25; 5 ref.

Gaskell RM, Gaskell CJ, Evans RJ, Dennis PE, Bennett AM, Udall ND, Voyle C, Hill TJ, 1983. Natural and experimental poxvirus infection in the domestic cat. Veterinary Record, 112:164-170.

Gibbs EPJ, Johnson RH, Collings DF, 1973. Cowpox in a dairy herd in the United Kingdom. Veterinary Record, 92:56-64.

Henning K, Czerny CP, Meyer H, Müller T, Kramer M, 1995. A seroepidemiological survey for orthopox virus in the red fox (Vulpes vulpes). Veterinary Microbiology, 43(2/3):251-259; 28 ref.

Hentschke J, Meyer H, Wittstatt U, Ochs A, Burkhardt S, Aue A, 1999. An outbreak of cowpox in beavers (Castor fiber canadensis) and bearcats (Ailurus fulgens) in a Berlin zoo. Tierärztliche Umschau, 54(6):311-317; 8 ref.

Lvov SD, Gromashevskyi VL, Marennikova SS, Bogoyavlenskyi GV, Bajluk FN Butenko AM, Gushchina E, Shelukhina, EM, Thukova OA, Morozova TN, 1988. Poxvirus isolation from Microtus oeconomus Pal. 1776 in Colsky peninsula. Vop Virus, 1:92.

Maenhout T, Declercq J, Keuster Tde, Hoorens JK, 1991. Cowpox virus infection in three cats in Belgium. Vlaams Diergeneeskundig Tijdschrift, 60(2):64-67; 13 ref.

Mahnel H, Czerny CP, Mayr A, 1989. Detection and identification of poxvirus in domestic cats. Journal of Veterinary Medicine, B (Infectious Diseases, Immunology, Food Hygiene, Veterinary Public Health), 36(3):231-236; 22 ref.

Marennikova SS, Ladnyj ID, Ogorodnikova ZI, Shelukhina EM, Maltseva NN, 1977a. Identification and study of a poxvirus isolated from wild rodents in Turkmenia. Archives of Virology, 56:7-14.

Marennikova SS, Maltseva NN, Korneeva VI, Garanina NM, 1977b. Outbreak of pox disease among carnivora (Felidae) and Edentata. Journal of Infectious Diseases, 135:358-366.

Marennikova SS, Shelukhina EM, Efremova EV, 1984. New outlook on the biology of cowpox virus. Acta Virologica, 28(5):437-444; 48 ref.

Marennikova SS, Shelukhina EM, Fimina V, 1978. Pox infection in white rats. Laboratory Animals, 12:33-36.

Mayr A, Lauer J, Czerny CP, 1995. New facts about distribution of orthopox virus infection in cats, foxes and wild boars and about development of a vaccine against feline pox. Praktische Tierarzt, 76(11):961.967; 13 ref.

Meyer H, Ropp SL, Esposito JJ, 1997. Gene for A-type inclusion body protein is useful for a polymerase chain reaction assay to differentiate orthopoxviruses. Journal of Virological Methods, 64(2):217-221; 11 ref.

Meyer H, Schay C, Mahnel H, Pfeffer M, 1999. Characterization of orthopoxviruses isolated from man and animals in Germany. Archives of Virology, 144(3):491-501; 34 ref.

Müller T, Henning K, Kramer M, Czerny CP, Meyer H, Ziedler K, 1996. Seroprevalence of orthopox virus specific antibodies in red foxes (Vulpes vulpes) in the Federal State Brandenburg, Germany. Journal of Wildlife Diseases, 32(2):348-353; 31 ref.

Naidoo J, Baxby D, Bennett M, Gaskell RM, Gaskell CJ, 1992. Characterization of orthopoxviruses isolated from feline infections in Britain. Archives of Virology, 125(1-4):261-272; 30 ref.

Nowotny N, 1996. Serological examinations in domestic cats for virus infections of wild rodents with potential human pathogenicity. Zentralblatt für Hygiene und Umweltmedizin, 198(5):452-461; 33 ref.

Nowotny N, Fischer OW, Schilcher F, Schwendenwein I, Loupal G, Schwarzmann T, Meyer J, Hermanns W, 1994. Poxviral infections in domestic cats: clinical, histopathological, virological and epidemiological studies. Wiener Tierärztliche Monatsschrift, 81(12):362-369; [13 fig.]; 38 ref.

Pfeffer M, Burck G, Meyer H, 1999. Cowpox viruses in Germany: an analysis of 5 cases in 1998. Berliner und Münchener Tierärztliche Wochenschrift, 112(9):334-338; 26 ref.

Pilaski J, Rösen-Wolff A, Darai G, 1988. Poxvirus infection in zoo-kept mammals. Virus diseases in laboratory and captive animals., 83-100; [Series: Developments in Veterinary Virology No.6]; 50 ref.

Postma BH, Diepersloot RJA, Niessen GJCM, Droog RP, 1991. Cowpox-virus-like infection associated with rat bite. Lancet (British edition), 337(8743):733-734; 2 ref.

Schonbauer M, Schonbauer-Langle A, Kobl S, 1982. Pockeninfektion bei einer Hauskatze. Zentralblatt fur Veterinarmedizin, B29:434-440.

Schüppel KF, Menger S, Eulenberger K, Bernhard A, Pilaski J, 1997. Cowpox infection of alpacas (Lama pacos). Erkrankungen der Zootiere: Verhandlungsbericht des 38. Internationalen Symposiums über die Erkrankungen der Zoo- und Wildtiere von 7 bis 11 Mai 1997, in Zürich, Schweiz., 259-265; 13 ref.

Smith KC, Bennett M, Garrett DC, 1999. Skin lesions caused by orthopoxvirus infection in a dog. Journal of Small Animal Practice, 40(10):495-497; 22 ref.

Tryland M, Sandvik T, Hansen H, Haukenes G, Holtet L, Bennett M, Mehl R, Moens U, Olsvik O, Traavik T, 1998. Characteristics of four cowpox virus isolates from Norway and Sweden. APMIS, Acta Pathologica, Microbiologica et Immunologica Scandinavica, 106(6):623-635; 47 ref.

Tryland M, Sandvik T, Mehl R, Bennett M, Traavik T, Olsvik O, 1998. Serosurvey for orthopoxviruses in rodents and shrews from Norway. Journal of Wildlife Diseases, 34(2):240-250; 40 ref.

Tsanava SA, Sakvarelidze LA, Shelukhina EM, 1989. Serologic survey of wild rodents in Georgia for antibodies to orthopoxviruses. Acta Virologica, 33(1):91; 10 ref.

Tsanava ShA, Marennikova SS, Sakvarelidze LA, Shelukhina EM, Yanova NN, 1989. Isolation of cowpox virus from jirds, Meriones libycus.. Voprosy Virusologii, 34(1):95-97; 10 ref.

Willemse A, Egberink HF, 1985. Transmission of cowpox virus infection from domestic cat to man. Lancet, 1(8444):1515; 4 ref.

Yeruham I, Nyska A, Abraham A, Algazi R, 1996. Occurrence of cowpox-like lesions in cattle in Israel. Revue d'élevage et de Médecine Vétérinaire des Pays Tropicaux, 49(4):299-302; 11 ref.

Zwart P, Gispen R, Peters C, 1971. Cowpox in okapi (Okapia johnstoni) at the Rotterdam zoo. British Veterinary Journal, 127:20-24.

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