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From: Poultry-keeping – Footsteps 95

Practical advice on all aspects of poultry-keeping, including nutrition, health and business development.

If you keep poultry it is very important to learn how to detect an unhealthy or sick bird, so that you can take action. If you do not, disease may spread to other birds and the whole flock may be lost. 

Diseases may be introduced into the flock by:

Diseases will be very serious in chickens that are not well fed and given clean water at all times. They should be kept in hen houses which have enough fresh air and, whenever possible, be vaccinated against preventable diseases. 

As well as keeping their birds healthy, farmers can control diseases on their farms by not mixing chicks with older birds when brooding and buying chicks from reliable sources only.

Healthy bird

Healthy bird. Illustration: Amy Levene

Unhealthy or sick bird

Unhealthy or sick bird. Illustration: Amy Levene

Common diseases in chickens

Newcastle disease

Newcastle disease is an acute, deadly disease that affects chickens of all ages, as well as some other types of poultry. It is caused by a virus that can remain alive in manure for up to 2 months and in dead carcasses for up to 12 months, however it is easily killed by disinfectants, fumigants and direct sunlight. It spreads rapidly, and may kill most of the chickens in the area. The nervous and respiratory (breathing) systems are usually affected.




There is no treatment. You need to kill and dispose of all sick birds (see page 14).


Vaccination. Maintaining good hygiene and disposing properly of sick chickens.

Fowl pox

Fowl pox is a disease of chickens that spreads gradually by mosquitoes. It is caused by a virus and affects chickens of all ages as well as many other bird species. It is seen in two forms: the dry form which causes skin sores (scabs), and the wet form which causes sores in the mouth and throat. The wet form may cause choking if the windpipe gets blocked.



Post-mortem will find sores, especially scabs, on face, mouth, throat or feet



Chronic Respiratory Disease (CRD)

Chronic respiratory disease is a disease caused by an organism called ‘Mycoplasma gallisepticum’. It is initially introduced to flocks by infected eggs but then spreads by bird-to-bird contact and by contact with droplets that are breathed out by the chickens into the air or onto equipment. Moving, overcrowding or stressing chickens in any way may trigger an outbreak of CRD. The disease is complex because three or more conditions are needed for the disease to develop. One condition is the presence of mycoplasma organisms. The second condition is stress (eg extreme temperatures and humidity, being transported or the addition of new birds into an established flock). The third condition is presence of another bacteria, such as E. coli. CRD also affects turkeys, game birds, pigeons and other wild birds. Ducks and geese can become infected when held with infected chickens.



Post-mortem will find a thick, yellow pus (cheese-like) around the heart, in the lungs and air sacs; the trachea or windpipe is inflamed (red in colour) and sinuses are inflamed (reddened in colour) and contain mucus.


Antibiotics (always consult an animal health worker before treating your chickens).


External parasites

Lice, mites, ticks and fleas are common external parasites of chickens. Lice and mites bite and damage the skin. Mites, ticks and fleas suck the blood and cause anaemia (thin blood) and poor egg production. Certain external parasites can carry other diseases, such as fowl pox.



Consult an animal health worker who will be able to prescribe insecticides to kill the parasite. For leg mites, the legs can be dipped in kerosene. However, great care must be taken not to let the kerosene touch the feathers or skin. Warning: Insecticides can be poisonous if used improperly. Always mix and apply according to the instructions.

This article has been adapted from ‘Where there is no animal doctor’ by Dr Peter Quesenberry and Dr Maureen Birmingham, Christian Veterinary Mission, ISBN 1-886532-11-7. Visit to order a hard copy. 

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