Common Bacterial, Fungal, Viral Diseases Of Poultry: Signs, Diagnosis And Treatment


Here is a concise information about poultry diseases so you can keep your flock healthy and disease-free. Diseases are often characterized according to their biology, such as:

     Virus, Bacteria, Parasites, Fungi, and their causes, e.g. nutritional disorders.

However, in the following the most important diseases in poultry are divided into three categories according to their severity and importance in village-based small-scale production systems. Distinct features, such as their characteristics during outbreaks (symptoms), and possible treatments (prevention or control), as well as the time of occurrence, will be presented.

    The importance of a disease is judged by mortality rates and effect on production, and will vary greatly from area to area and from season to season.

Combination of diseases
Some less important diseases may interact with other diseases to create a more severe effect on the birds. This is the case for: E. coli infections, nutritional deficiencies and internal parasites. Such diseases rarely kill the individual bird, but have a remarkable effect on the immune system of the birds, thus creating the basis for easy infection by other diseases.

    (▼▼▼) = High importance, is a common disease w/ high mortality (+30% of the flock), highly contagious & difficult to treat.
    (▼▼) = Medium importance  common, medium mortality (10-30%) of the flock and/or difficult treatment.
    (▼) = Less importance signifies not common, lower mortality and/or easy treatment.

    Newcastle Disease: (▼▼▼)

Description:The disease is very common during dry seasons, and is often seen in young chicks, but also in adults.

Effect: High flock mortality, often between 30% and 80% of the birds die when the disease hits.

Symptoms: The chickens lose appetite and have poor digestion. They might show heavy breathing, greenish droppings, and sometimes bloody diarrhea. They may show nervous symptoms, paralysis and die suddenly, and the symptoms may occur all at the same time.


    The disease is a virus, so there is no treatment, but it may be prevented through vaccination of all birds including chicks from two weeks of age.

    Avian Influenza (AI): (▼▼▼)

Description: The disease is found naturally in ducks and other waterfowl, and may spread as a highly contagious and potentially dangerous form to chickens

Effect: High flock mortality

Symptoms: blue and swollen comb and wattles. It infects through contaminated feed and drinking water from ponds.

The disease is a virus, so there is no treatment. Best prevention is strict hygiene and slaughter of sick birds. AI can presently NOT be prevented through vaccination of birds.

    Culling and burning of all birds in the flock and strict cleaning of chicken houses must be considered after a disease outbreak. Always call a veterinarian, if you suspect an AI outbreak. Do not eat infected birds.

    Fowl pox: (▼▼▼)

Description: It is often seen in young chicks, but also in adults. The disease is common during dry seasons, but may be found all year around

Effect: Flock may decrease by 30-50%, w/ high infection rates

Symptoms: Shows as pocks (small lumps) on wattles, comb and face. High body temperature, tiredness followed by sudden death.


    The disease is a virus, so there is no treatment, BUT a Vaccine is available and highly effective.

    E. coli infection: (▼)

Description: It is common among newly hatched chicks, causing infection in the stomach region.

Effect: Stop of egg production, immune system weakening.

Symptoms: In older birds - Respiratory distress or infection in the egg organ with stop of egg production.


    The best prevention is improved hygiene of eggs for hatching and of the nests. Treatment of sick chicks might be possible with antibiotics.

    Fowl cholera (pasteurellosis): (▼▼▼)

Description: It can occur any time in all ages.

Effect: Infection is through contaminated feed and drinking water. May occur as a chronic disease or hit as sudden death.

Symptoms: severe diarrhoea, respiratory symptoms, loss of appetite, blue combs and wattles.


    There is no treatment. Best prevention is strict hygiene and vaccination. Kill and burn affected birds. Vaccine is usually available.

    Pullorum disease (Bacillary white diarrhoea): (▼▼)

Description: It is common in young chicks
Effect: Disease is transmitted to chicks from the eggs of infected hens, which may not show signs of being ill.
Symptoms: Chicks walk with difficulty, show big bellies and drag their wings. Their faeces are liquid and turn white.

     There is no treatment. Prevention is strict hygiene. If illness occurs, isolate or kill and burn the birds. 

    Fowl typhoid: (▼▼)

Description:It is common in older birds.
Effect: Can be deadly, do not buy chicks from unknown sources, and do not use eggs for hatching from hens that have been ill.
Symptoms: high body temperature, tiredness, blue comb, sudden death.

    No treatment. Prevention is through strict hygiene and culling of ill hens.

    Coccidiosis (internal parasites): (▼▼▼)

Description: The disease may occur at any time at all ages

Effect: It causes death in young chicks. If the chicks survive, they will remain thin and be late in laying

Symptoms: Sick, tired, head down, ruffled feathers, bloody diarrhoea


    Regular and careful cleaning of troughs and poultry houses. Anticoccidiostatics in drinking water or feed.
    Do not crowd birds together. Avoid different age groups of birds in the same house, as the disease may spread from adults to young chicks.

    Roundworms and tapeworms (internal parasites): (▼▼)

Description: Internal parasites are very common in all ages in the village based production systems.

Effect: Internal digestion is filled with parastic organisms capable of starving and/or infecting chicks

Symptoms: poor health, weight loss, drop in egg production, and bloody diarrhea.


    The best treatment is adding antihelmintics in the drinking water once or twice a year, at best two weeks before vaccination against nutritional deficiencies. Careful hygiene may prevent heavy infection.

    External parasites: (▼▼)

Description: Attacks all ages any time, but occurs more frequently in humid chicken houses with bad hygiene.

Effect: If not treated, mites, lice, fleas, ticks will cause weight loss and possibly loss of feathers due to the parasites sucking blood and to skin irritation.

Symptoms: Adult birds are clearly disturbed and spend a lot of time pecking and polishing feathers.Young chicks may die from anemia. Lice can be seen around eyes and nose. Fleas can be seen on the belly.


    Spray or dust with pesticides, ashes, and oil. Ashes and sulphur powder may be used where the hens do dust bathing. Nests may be protected by putting a few tobacco leaves mixed with ashes in the nests.

    Scaly legs: (▼)

Description: Scaly leg is caused by an external parasite irritating the skin on the birds’ legs

Effect: Irritates hens and could lead to further paristic infection.

Symptoms: Legs clearly have scales and wounds and may become crippled in their appearance.


    Dip the legs daily in kerosene, oil or in an insecticide until the scales disappear.

    Nutritional diseases: (▼)

Description: Nutritional diseases may be avoided when the birds have access to normal vegetation and are therefore rare in scavenging chickens.

Effect: Some deficiencies may cause feather loss.

Symptoms: Bone deformation and feather loss.The birds walk with difficulty; they limp. Legs are deformed.


    If detected in time, give supplementary vitamins and calcium, fresh grass, and cow dung.

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