«Infectious Diseases of Poultry A. Janmaat* and R. Morton, Biosecurity and Product Integrity, Darwin * Formerly of DoR INTRODUCTION Poultry that have ...»
(c) *Fowl pox This is a highly infectious disease caused by various host-specific strains of the pox virus. Many birds are affected by these viruses to some extent. The virus can be transmitted directly by infected birds, or be carried by mosquitoes, or other blood sucking insects. By eliminating breeding areas for these insects, the rate of spread of the virus will decrease.
The fowl pox virus attacks the skin and the surface of the mouth and throat. Depending on its location, pox is referred to as either skin pox or wet pox. Skin pox forms wart-like sores, which eventually enlarge and form masses of yellow, dirty crusts. In about a week, these scabs darken and fall off. Wet pox forms cheesy masses in the mouth, nose and throat, which interfere with eating and drinking.
This virus is capable of surviving for a long time in infected material, such as scabs and litter. Such material should therefore be incinerated.
(d) *Infectious bronchitis (IB) IB is an acute, highly infectious disease of poultry, which may kill young chicks and lower egg production in adult birds. Birds sneeze and have a moist cough. The entire flock will be affected. Laying birds will stop laying and it may take a very long time for them to return to production. There is no effective treatment for this disease.
Maintenance of a correct, even temperature in the brooder and a high quality diet will help to minimise losses.
Commercial flocks are routinely vaccinated.
(e) *Infectious laryngotracheitis (ILT) ILT is a disease of all ages of poultry, although usually it is seen in adult birds. An acute form may attack 100% of a flock and cause severe mortality. In the acute form, affected birds exhibit a nasal discharge, gurgling breath sounds, gasping and coughing up of blood-stained mucus. In the mild form, birds are unthrifty, lay poorly and have watery eyes and a persistent nasal discharge. There is no effective treatment but vaccination of unaffected birds may limit an outbreak. Vaccination is effective in preventing the appearance of the disease.
(f) Reticuloendotheliosis (RE) RE became an important disease of commercial flocks in 1976 and, occasionally, still appears in an epidemic form. It causes runting, increased susceptibility to other diseases and feathering defects in growing chicks. In adult birds, it causes Iymphoid tumours. No treatment or vaccination is available.
(g) Avian encephalomyelitis (AE) AE is a disease of poultry, turkeys, pheasants and quail, which affects only chicks from hatching to about two months of age. The symptoms are dullness, tremors of the head, staggering, paralysis and prostration. Adult birds show no symptoms other than a decline in egg production, but they carry the virus and pass it on through the egg.
The disease may also spread from chick to chick and up to 60% of birds may be affected. There is no treatment for AE but vaccination will prevent it.
EXOTIC DISEASESExotic diseases are those which are present elsewhere in the world but not in Australia. There are three which particularly threaten the Australian poultry industry.
(a) Newcastle disease This virus is found in Australia in a mild form only. The dangerous form is widespread throughout the rest of the world. If it became established in Australia, the cost to the poultry industry could be enormous.
Newcastle disease is a highly contagious, lethal disease of chickens and turkeys, although nearly all avian species are susceptible. It may also cause conjunctivitis in humans. In poultry, it may take the form of haemorrhagic enteritis and paralysis, or an acute respiratory disease.
(b) Avian influenza or bird flu It is potentially a fatal disease affecting several bird species and humans. Its symptoms range from mild upper respiratory disease to an acute, generalised, fatal condition. The virus may remain infective in droppings and water for at least a month.
For further information on bird flu consult Agnote K53, Bird Flu: What Bird Keepers Should Know and Do.
© Northern Territory Government Page 5 of 6 (c) Infectious bursal disease (IBD) The virus of IBD is present in Australia but the strain is of low virulence. The hyper-virulent strain has been found in Europe, the USA, Japan and South-East Asia. This strain is very infectious and causes up to 60% mortality in young laying birds. Affected birds peck at their own vent and later exhibit white, watery diarrhoea, depression, trembling and prostration. Less severe outbreaks may show few symptoms apart from low production. The virus may remain infective for over a month in buildings, water, feed and droppings.
Entry of exotic diseases Migratory birds may be a threat as carriers of Newcastle disease and avian influenza from Asian countries. Live birds or bird products smuggled into the country may carry exotic diseases and threaten the poultry industry.
However, Australian regulations are stringent and, so far, effective. Although these diseases may be controlled by vaccination to a certain extent, this will not be attempted if they appear in Australia. They will be eradicated by the slaughter and quarantine of infected and in-contact flocks.
TREATMENT OF BIRDSIf a number of birds are sick or dead, it is wise to seek veterinary advice before undertaking treatment.
When treatment of a disease with drugs is needed, the manufacturer's instructions should be carefully followed. If the drug is to be mixed with drinking water or feed, make sure that the birds have no water or feed for a few hours prior to treatment to ensure that all birds drink or eat enough to get an adequate dose.
WITHHOLDING PERIODAll drugs, including antibiotics and chemicals which are used for the treatment of birds and their yards and sheds, have the potential to form residues in eggs and/or in meat of treated birds. The residues may persist for some time in the birds and necessitate a withholding period before their meat or eggs are free of residue and safe for human consumption. Withholding periods vary. Directions on the container will indicate the necessary withholding period after treatment. Birds should not be killed for consumption during this period and any eggs laid during the period should be discarded. A withholding period also applies to medicinal feed additives.
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www.nt.gov.au/d © Northern Territory Government ISSN 0157-8243 Serial No. 668 Agdex No. 450/653 Disclaimer: While all care has been taken to ensure that information contained in this document is true and correct at the time of publication, the Northern Territory of Australia gives no warranty or assurance, and makes no representation as to the accuracy of any information or advice contained in this publication, or that it is suitable for your intended use. No serious, business or investment decisions should be made in reliance on this information without obtaining independent and/or professional advice in relation to your particular situation.