Fowl cholera

Fowl cholera is a highly contagious disease caused by the bacterium Pasteurella multocida.

Fowl cholera is a highly contagious bacterial disease with worldwide distribution. The disease is found throughout Queensland.

In acute cases the incubation period is as short as 2-3 days. The impact of disease is sudden and death may be the first sign of disease.

Affected birds may show symptoms including:

• fever
• cyanosis (bluish discolouration of the skin, wattle and comb)
• loss of appetite
• ruffled feathers
• mucous discharge from the mouth
• green watery diarrhoea
• respiratory difficulty
• sudden deaths.

Just before death, the combs and wattles swell and turn bluish or purple in colour.

Birds that survive either become chronically infected or recover, while others die through extreme weight loss and dehydration. Birds that recover may remain carriers.

Signs of chronic infection are localised swelling in the:

• joints
• foot pads
• eyes
• throat.

Mortality rates of 5–20% are fairly common in the early stages of disease and may even reach as high as 45%. As the disease becomes chronic, mortality may drop to 2–5% a month.

Chronically infected birds may die, remain infected for long periods or recover. A high percentage of a flock may become carriers while appearing normal.

Losses usually occur in birds over 16 weeks of age.

The disease may be introduced to the flock by:

• carrier birds
• wild birds
• pigs
• dogs
• cats
• rodents.

Contaminated equipment and people can also cause the disease to spread. Once in a flock, the disease can remain due to chronically infected and carrier birds.

Stress conditions can trigger an outbreak, such as:

• overcrowding
• cold weather
• unhygienic sheds
• poor ventilation.

Fowl cholera can spread through the flock via contaminated drinking water, droppings and nasal discharges.

Carcasses of birds that have died from fowl cholera are highly infectious.

Medication

Medications reduce the mortality rate in an acute outbreak. However, you should obtain advice from a veterinarian as restrictions apply to the sale, use and withholding periods of prescribed drugs. Remove sick birds from the flock.

Vaccination

Vaccination for fowl cholera may provide protection. However, there are a number of different serovars of the bacterium P. multocida. The disease can be positively diagnosed through laboratory testing. The typing of the strain in the laboratory helps guide the choice of vaccine if vaccination is to be part of a prevention and control program. Consult a veterinarian.

Biosecurity measures

Good biosecurity practices may help to prevent the disease from spreading, including controls for the entry of people, vehicles and equipment.

Cleaning and disinfection of housing and equipment and having a rodent control program in place will help to prevent fowl cholera.

Always purchase healthy poultry from a reputable, disease-free source and keep domestic animals away from the flock.