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Cowpox

Last updated Aug. 15, 2018

Human Cowpox infection is a rare, viral skin infection that is found primarily in Europe and Russia. Cowpox is primarily found in wild rodents (small mammals).


What are the other Names for this Condition? (Also known as/Synonyms)

  • Catpox
  • Cowpox Disease
  • Vaccinia

What is Cowpox? (Definition/Background Information)

  • Human Cowpox infection is a rare, viral skin infection that is found primarily in Europe and Russia. Cowpox is primarily found in wild rodents (small mammals)
  • Cowpox is a member of orthopoxvirus family, which also includes the ‘now eradicated’ and deadly smallpox virus
  • Domestic cats and cows are occasionally affected by Cowpox Infection. The infected animals do have the potential to transmit the virus and infect other animals
  • Transmission of the disease from animals to humans is rare. Generally, humans get infected from infected cats and occasionally from cows; but, human-to-human spread has not been reported
  • The condition is characterized by skin infection of the hands, with pus and scar formation
  • The treatment provided is usually supportive. The prognosis of Cowpox is very good, as it is a self-limiting condition

Who gets Cowpox? (Age and Sex Distribution)

  • Human Cowpox Infection is extremely rare and most cases were reported in Europe, former Russia, Britain, Germany, Netherlands, Norway, Finland, Sweden, and Egypt
  • Individuals of any age coming into contact with infected animals (cow or cat) may be affected by Cowpox. However, the condition was more common in children, since they generally tended to play more with (infected) pet cats. Another possible explanation for higher infection incidence among children is that they are presently not vaccinated for smallpox virus, which seems to be protective against Cowpox Infection
  • The disease affects both males and females at equal incidence

What are the Risk Factors for Cowpox? (Predisposing Factors)

The risk factors of Cowpox include:

  • Being around an infected animal for long time periods, especially domestic cats, or exotic pet mammals and even small rodents
  • Not being vaccinated for smallpox
  • Summer: This infection seems to be more common during the hot summer months

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Cowpox? (Etiology)

Cowpox is caused by cowpox virus, a member of the orthopoxvirus family. The deadly smallpox virus belongs to the same family.

  • Humans get infected when they come in contact with infected animals through a broken skin in their body (cut or wound), by a scratch or bite
  • Currently, most human cases are reported to occur through cats. Cats are infected from the rodents they catch in the wild
  • Human to human spread has never been reported
  • Historically, and now rarely, cow’s teat (udder) was the source of infection

What are the Signs and Symptoms of Cowpox?

The signs and symptoms of Cowpox include:

  • The infection characteristically causes skin lesions. Cowpox skin lesions are similar to, but less severe than the extremely contagious and deadly smallpox disease
  • The lesions appear roughly 10 days after coming in contact with an infected animal
  • The lesions are seen only in those skin areas that came in contact with the infected animal (including scratch or bite area). The areas commonly include the hands (fingers and thumbs) and the face
  • The skin lesion evolves from a flat, sore, red patch (macule) to a raised lesion (papule), clear fluid-filled blister, pus-filled blister (pustule), which finally ulcerate
  • This is followed by a thick black sore (eschar) formation, following which healing takes place, after the eschar falls off. During the healing process scars are formed

Other uncommon symptoms may include:

  • Swelling of the lymph nodes
  • Generalized body ache
  • Vomiting
  • Eye lesions such as pinkeye, swelling around the eye

Cowpox Infection can be severe in individuals with weakened immunity, or in individuals with a history of allergies such as atopic dermatitis, hay fever, etc.

How is Cowpox Diagnosed?

The following procedures may be used to diagnose Cowpox Infection:

  • Complete evaluation of the individual’s medical history and a thorough physical examination including the skin, eye, throat, lymph nodes, etc.
  • During history taking the physicians may want to know the following:
    • When the symptoms began and whether they are becoming worse
    • List of prescription and over-the-counter medications currently being taken
    • One’s personal history, history of recent travel, occupation, skin diseases, sick contacts, pets in the house, allergies, etc.
  • A consultation with the dermatologist may often be necessary, as they are the experts in dealing with skin conditions
  • Before a diagnosis of Cowpox is made, the physician may first rule-out other diseases or conditions with similar symptoms such as chickenpox, herpes zoster (shingles), scabies, and even adverse reaction to medications

Other tests may be performed based on diagnostic difficulties and availability. These may include the following:

  • Polymerase chain reaction (PCR) for identifying the organism in the cut/wound
  • Electron microscopy study of the blister for the virus ‘effects’
  • Skin biopsy of the lesion: In this procedure, the physician removes a sample of the skin tissue and sends it to the laboratory for a histopathological examination. The pathologist examines the biopsy under a microscope and arrives at a definitive diagnosis after a thorough evaluation of the clinical and microscopic findings, as well as by correlating the results of special studies on tissues (if required).

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Cowpox?

The complications of Cowpox could include:

  • Scar formation is the main complication that can arise due to Cowpox Infection
  • Scar formation can be emotionally distressing in some individuals
  • Secondary bacterial infections of the skin lesions may be seen
  • In individuals with a history of allergy or weakened immune system, the infection can spread to uninfected skin and different parts of the body. However, only a few cases have been reported with this kind of a clinical situation

How is Cowpox Treated?

Supportive care is the main treatment option for Cowpox for most individuals, because this infection is self-limiting. It could include:

  • Pain medications, bed rest or hospitalization (if required), adequate nutrition, etc.
  • Wound dressing to keep it closed
  • Antibiotics may be prescribed if the skin lesions are infected by bacteria
  • In individuals with a weakened immune system or history of allergies (and if the infection is progressive), anti-viral medications and or intravenous immunoglobulin therapy may be administered

The healthcare provider will recommend the best treatment option based upon each individual’s health condition.

How can Cowpox be Prevented?

Avoiding coming in contact with the infection source (such as an infected cat or cow) is the key to preventing Human Cowpox Infection.

  • Hand washing after touching the pets and animals may prevent transmission of the infection
  • Though human to human transmission has not been reported, research scientists suggest that keeping the wound closed can help prevent infection spread to others
  • Educating animal handlers about Cowpox Infection
  • Individuals with poor immune system should generally avoid any animal contact

What is the Prognosis of Cowpox? (Outcomes/Resolutions)

  • Human Cowpox Infection is a self- limiting disease (one that runs a limited and definite course) and the outlook is good in most individuals. A normal immune response usually controls the viral infection
  • In those with normal immune systems, the disease improves within several weeks. Scars will probably remain, but there are no other long-term effects observed

Additional and Relevant Useful Information for Cowpox:

  • The Cowpox skin lesions emulate smallpox and were the basis of the first smallpox vaccines
  • Cowpox is a large double-stranded DNA virus that replicates in cell cytoplasm (gel-like substance inside cells). Viral particles attach and then enter into the animal’s cell. The virus is then replicated and distributed to surrounding cells, thus spreading the disease
  • Zoonosis: An infection shared in nature by humans and other animals
  • Lymphadenopathy: Enlarged lymph nodes (organs of the immune system) which may be caused by local or generalized infection or inflammatory conditions

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 31, 2015
Last updated: Aug. 15, 2018