Birdpox

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As avipox or fowlpox a is pox-like viral disease in birds designated by the representatives of the genus Avipoxvirus (avipoxviruses) in the family of poxviruses ( Poxviridae is caused). In Germany it is one of the notifiable animal diseases . The infectious disease is also subject to mandatory notification in Austria. Birdpox is highly contagious, the incidence rate of infection is 100%, but the mortality rate is low, except for diseases with the canarypox virus . Birdpox manifests itself in skin and mucous membrane changes, but can also be septicemic .

Pathogen

Avipox virus
Avian Pox TEM 01.tif

TEM image of great
tit birdpox virus virions .

Systematics
Classification : Viruses
Area : Varidnaviria
Empire : Bamfordvirae
Phylum : Nucleocytoviricota
Class : Pokkesviricetes
Order : Chitovirals
Family : Poxviridae
Subfamily : Chordopoxvirinae
Genre : Birdpox virus
Taxonomic characteristics
Genome : dsDNA linear
Baltimore : Group 1
Symmetry : complex
Cover : available
Scientific name
Avipox virus
Left
NCBI  Taxonomy: 10260
ViralZone ( ExPASy , SIB): 151

The birdpox viruses form the genus Avipoxvirus in the subfamily Chordopoxvirinae of the family Poxviridae (smallpox viruses). Today ( ICTV , Master Species List 2018b.v2 from March 2019) there are 11 different birdpox viruses:

  • Genus Avipoxvirus

In the case of the pigeonpox virus and turkeypox virus, it was not clear for a long time whether they were separate species or just variants of the chickenpox virus. The canarypox virus also differs significantly from the other representatives immunologically.

Birdpox viruses and diseases have been found in a large number of bird species worldwide. The host specificity is not very high, the individual representatives also pass to heterologous hosts. However, an infection is usually only triggered by insect stings / bites, not by contact with virus-containing secretions as is otherwise the case . A transition from the heterologous host to the actual host probably does not take place. Birdpox virus has also been isolated from skin injuries in rhinos .

Birdpox viruses are very different from other smallpox viruses. The Canarypox virus genome is 359,853 base pairs (bp) in length and is predicted to encode 328 proteins at a GC content of 30%.

Disease emergence

The infection usually occurs through direct contact with infected animals or indirect contact with virus-containing material via the smallest skin and mucous membrane injuries, but only in heterologous hosts, in wild birds mainly through insect bites ( mosquitoes ).

The incubation period is 8 days. At the point of infection, there is initially a circumscribed reddening of the skin , which turns into a papule after one or two days and shortly afterwards into a barky change ("primary pox"). After the virus multiplies at the infection site, it is first washed out into the blood ( viraemia ) and then to colonize the lymphatic organs and the liver . After a further increase, a second viraemia occurs, as a result of which the disease manifests itself on the skin, mucous membranes or lungs .

Infected animals excrete viruses through their nasal and eye secretions and through skin changes.

Clinical picture

Birdpox in a great tit in Sussex .
Young cormorant with birdpox at Lake Zell
Birdpox in a Laysanalbatros chick

After the second viraemia, the disease can manifest itself in different forms:

  • The shape of the skin is characterized by papular changes, especially in unfledged regions, around the eye, at the base of the beak, on the crest and on the posts. The papules dry up, turn yellowish and later brownish and then fall off. If the course is mild, benign skin tumors often occur.
  • The diphtheroid form is caused by fibrinous coatings on the mucous membranes in the beak and pharynx ( oropharynx ) and on the larynx . The diphtheroid form can be combined with skin symptoms.
  • The septicemic form shows itself in general disorders such as fatigue, reluctance to eat and cyanosis . It usually ends fatally without the typical smallpox-like efflorescences occurring.

In parrots also special shapes such as heavy diphtheroid be intestinal inflammation and necrosis of the heart muscle described.

Combat

A therapy is not possible. For prophylaxis one can live vaccine are used. This is given to animals that have not yet been infected, especially when birdpox outbreaks are present. Ornamental birds should at least be vaccinated in larger flocks to protect them from canarypox. The vaccine is given intramuscularly or by piercing the skin ( wing-web method ).

history

Birdpox has long been known. In 1873, Bollinger first demonstrated the inclusion bodies occurring in cells in infected animals . In 1902, Marx and Sticker recognized virus genesis on the basis of filtrates. The definitive proof of the virus nature came from cultivation in 1930.

literature

  • Rolle / Mayr (Ed.): Medical microbiology, infection and epidemic theory . Enke Verlag Stuttgart, 8th edition 2007. ISBN 3-8304-1060-3

Individual evidence

  1. ↑ Annex to Section 1 of the Ordinance on Notifiable Animal Diseases (TKrMeldpflV) in the version published on February 11, 2011 ( Federal Law Gazette I p. 252 ), last amended by Article 381 of the Ordinance of August 31, 2015 ( Federal Law Gazette I p. 1474 )
  2. ↑ § 13 of the Poultry Hygiene Ordinance 2007
  3. ↑ a b B. Lawson, S. Lachish et al. a .: Emergence of a novel avian pox disease in British tit species. In: PloS one. Volume 7, number 11, 2012, p. E40176, ISSN  1932-6203 . doi : 10.1371 / journal.pone.0040176 . PMID 23185231 . PMC 3504035 (free full text).
  4. ↑ a b c d e ICTV: ICTV Taxonomy history: Variola virus , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  5. ↑ David M. Needham, Alexandra Z. Worden et al .: A distinct lineage of giant viruses brings a rhodopsin photosystem to unicellular marine predators , in: PNAS, 23 September 2019, doi: 10.1073 / pnas.1907517116 , ISSN 0027-8424 , here: Supplement 1 (xlsx)