Animals & Wildlife Magazine

Garden Bird Health Initiative – Avian Pox

By Philpickin @philpickin

Worth being aware of an looking out for the following...Agent Species affectedThe disease affects a wide variety of bird species across the globe.Since the inception of the Garden Bird Health initiative in 2005 we have seen sporadic cases of the disease in British garden birds, in species such as wood pigeons and dunnocks.In the last few years we have also received reports of skin lesions in great tits caused by avian pox infection, particularly in late summer. It is common for multiple great tits to be affected in one garden, and their lesions may be quite severe (see below).Clinical signsAffected birds develop warty or tumour-like growths, on the head (particularly next to the eye or beak), legs, wings, or other body parts. The growths are usually grey, pinkish, red or yellow in colour. Affected birds often appear to feed and move around normally.In many species (e.g. wood pigeons and dunnocks) the growths can be relatively mild and may regress with time. In some cases (in all species but especially great tits) the growths can become very large and may impede the ability of birds to see, feed or move around. In these cases the birds become more susceptible to predation and other infections.Disease spreadAvian poxvirus is thought to be spread between birds in three main ways: by biting insects (e.g. mosquitoes, mites, flies), by direct bird-to-bird contact, and by indirect contact via contaminated surfaces such as perches or bird tables.The virus is relatively resistant and can persist on contaminated surfaces (perches, bird tables etc.) for long periods of time.Risk to human and domestic animal healthAvian poxviruses do not appear to be infectious to humans or other mammals.However, garden birds in the UK may carry other diseases that can affect humans and pets, for example Salmonella, Campylobacter and E.coli bacteria. The GBHi recommends following sensible hygiene precautions as a routine measure when feeding garden birds and handling bird feeders and tables. Following these rules will help avoid the risk of any infection transmitting to people and help safeguard the birds in your garden against disease (see below).1Clean and disinfect feeders/ feeding sites regularly, e.g. weekly. Suitable disinfectants include a weak solution of domestic bleach (5% sodium hypochlorite) and other specially-designed commercial products (see Further information). Always rinse the feeders thoroughly and air-dry them before re-use.Brushes and cleaning equipment for bird feeders, tables and baths should not be used for other purposes and should not be brought into the house, but be kept and used outside and away from food preparation areas.Wear rubber gloves when cleaning feeders and thoroughly wash hands and forearms afterwards with soap and water, especially before eating or drinking. Avoid handling sick or dead birds directly.The strains of avian poxvirus that infect our garden birds are probably specific to those wild species affected. However, the disease could potentially be infectious to poultry, cage or aviary birds. Aviculturalists or poultry owners who have affected wild birds in their gardens can reduce the risk of infection spreading to their captive birds. They should, for example, employ measures to reduce their birds’ exposure to biting insects where feasible; prevent contact between captive and wild birds as far as possible; ensure wild bird feeders and water baths are inaccessible to captive birds; and wash and disinfect their hands thoroughly after handling wild bird feeders or equipment.DiagnosisAlthough large pox growths can be very characteristic, smaller or medium-sized growths can easily be confused with a number of other conditions, such as ticks. The disease can only be confirmed by further investigation, such as post mortem examination and subsequent laboratory tests.If you wish to report finding dead garden birds, or signs of disease in garden birds, please call the Garden Bird Health initiative on 0207 449 6685.ControlWhilst treatment can be attempted in captive birds, effective treatment of free-living birds under field conditions is not possible.Where an avian pox outbreak exists, general measures for control of disease in wild bird populations should be adopted:Ensure optimal hygiene at garden bird feeding stations, including disinfection (See Further information)Empty and dry bird baths on a daily basis Feeding stations encourage birds to congregate, sometimes in large densities, thereby increasingthe potential for disease spread between individuals when outbreaks occur. If many birds in your garden are affected, consider significantly reducing the amount you feed, or stop feeding for a period (e.g. one month). Gradually reintroduce feeding, whilst continuing to monitor for further signs of ill health (See Further information).PreventionFollowing best practice for feeding garden birds is recommended to help control and prevent transmission of disease at feeding stations all year round (see Further information):Routine good table hygiene Provision of clean and fresh drinking water on a daily basis Provision of fresh food from accredited sources Rotate positions of feeders in the garden to avoid build up of contamination in any one area and payparticular attention to clearing food remains that fall onto the ground.Further informationBest feeding practices should be followed at all times to help ensure that the birds visiting your garden remain healthy. More information can be found in the GBHi booklet “Feeding Garden Birds – Best Practice Guidelines” and in the accompanying GBHi leaflet. Details of how to obtain these publications are available on the GBHi page of the UFAW website, or telephone UFAW on 01582 831818.© Phil Pickin

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