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==Pathogenesis==

==Pathogenesis==

The myxoma virus infects several cell types including mucosal cells, lymphocytes, and fibroblasts. In addition to primary and secondary tumour development, there is severe immunosuppression leading to overwhelming infections by opportunistic gram-negative bacteria particularly affecting the conjunctiva and nasal passages.  

The myxoma virus infects several cell types including mucosal cells, lymphocytes and fibroblasts. In addition to primary and secondary tumour development, there is severe immunosuppression leading to overwhelming infections by opportunistic gram-negative bacteria particularly affecting the conjunctiva and nasal passages.  

Virus multiplication and tumour-like lesions occur initially at the site of intradermal inoculation. This is followed by spread to regional lymph nodes and cell-associated viraemia, with generalization to the skin and internal organs. Gelatinous proliferative nodules develop all over the body, especially at orifices such as the eyes, anus, nose. The rabbit usually dies within 12 days, if not killed by predators.

Virus multiplication and tumour-like lesions occur initially at the site of intradermal inoculation. This is followed by spread to regional lymph nodes and cell-associated viraemia, with generalization to the skin and internal organs. Gelatinous proliferative nodules develop all over the body, especially at orifices such as the eyes, anus, nose. The rabbit usually dies within 12 days.

==Clinical signs==

==Clinical signs==

The clinical disease varies with the virus strain and host species. Sylvilagus species are relatively resistant, and are probably the natural host of the virus.  In this species, infection usually results in the development of skin tumours at the site of innoculation.  The tumours appear 4-8 days after exposure and persist for up to 40 days.

The clinical disease varies with the virus strain and host species. Lepus species (hares are highly resistant; occasional individuals develop mild to severe generalized myxomatosis. Sylvilagus species are relatively resistant and are probably the natural host of the virus.  In this species, infection usually results in the development of skin tumours at the site of innoculation.  The tumours appear 4-8 days after exposure and persist for up to 40 days.  

In the European rabbit (Oryctolagus cuniculus), infection with a virulent virus (i.e. the South American or California strains) results in severe disease with up to a 99% case fatality rate. Initial signs include oedema of the eyelids accompanied by inflammation and oedema around the anal, genital, oral, and nasal orifices.  Oedema of the head and ears, drooping ears, and bacterial infections resulting in mucopurulent conjunctivitis and pneumonia are seen. Severe pyrexia is frequently reported.  Death (8-15 days post infection) is usually preceded by dyspnoea and seizures. Lepus species (hares) however are highly resistant; occasional individuals develop mild to severe generalized myxomatosis. The mortality rate is affected by environmental temperature, with the disease being more lethal at low temperatures.

In the European rabbit (Oryctolagus cuniculus), infection with a virulent virus (i.e. the South American or California strains) results in severe disease with up to a 99% case fatality rate. Initial signs include oedema of the eyelids accompanied by inflammation and oedema of the anal, genital, oral and nasal orifices.  Oedema of the head and ears, drooping ears and bacterial infections resulting in mucopurulent conjunctivitis and pneumonia are seen. Severe pyrexia is frequently reported.  Death (8-15 days post infection) is usually preceded by dyspnoea and seizures. The mortality rate is affected by environmental temperature, with the disease being more lethal at low temperatures.

==Pathology==

==Pathology==

==Prevention==

==Prevention==

Vaccination and control of insect parasites are the most important means of disease prevention in domestic rabbits. In order to control fleas, wild rabbits should be kept away from pet rabbits and spot-on products may be used. Mosquito control can be achieved using insect repellent strips and fine mesh netting.

Vaccination and control of insect parasites are the most important means of disease prevention in domestic rabbits. In order to control fleas, wild rabbits should be kept away from pet rabbits and spot-on products may be used. Mosquito control can be achieved using insect repellent strips and fine mesh netting.

The myxomatosis vaccine currently used in the UK is a live vaccine containing ''Shope fibroma'' virus (Nobivac Myxo, Intervet). Antibodies made against ''Shope fibroma'' provide cross immunity against myxomatosis. Intradermal vaccination is performed in order to achieve adequate immunity and annual booster vaccination is recommended. Live attenuated vaccines have been used elsewhere in Europe but have been associated with other side effects such as immunosuppression.

The myxomatosis vaccine currently used in the UK is a live vaccine containing ''Shope fibroma'' virus (Nobivac Myxo, Intervet). Antibodies made against ''Shope fibroma'' provide cross immunity against myxomatosis. Intradermal vaccination is performed in order to achieve adequate immunity and annual booster vaccination is recommended. Live attenuated vaccines have been used elsewhere in Europe but have been associated with other side effects such as immunosuppression.

==References==

==References==

*Fraser, S. G. (2009) '''Rabbit Medicine and Surgery for Veterinary Nurses''' ''Wiley-Blackwell''

*Fraser, S. G. (2009) '''Rabbit Medicine and Surgery for Veterinary Nurses''' ''Wiley-Blackwell''

*Harcourt-Brown, F. (2002) '''Textbook of Rabbit Medicine''' ''Elsevier Health Sciences''

*Harcourt-Brown, F. (2002) '''Textbook of Rabbit Medicine''' ''Elsevier Health Sciences''

[[Category:To_Do_-_SophieIgnarski]]

[[Category:To_Do_-_SophieIgnarski]]