As with most domestic animals, if kept clean and well fed, chooks do not suffer a great deal of disease.

However there are many parasites and diseases waiting to strike your birds if the right conditions occur.
The main external parasites which affect them are:
1. Lice
2. Red Mites
3. Scaly Leg Mites

Lice are small creamy brown insects which live on the bird permanently. They eat the flaky dead skin and feather particles but do not seem to bite the bird itself. The main hazards with lice is that the birds become run-down from the irritation caused by the crawling of the insects on their skin. Lice spend their whole life cycle on the birds and are transmitted by direct contact. A louse-free flock can be infected by new chickens arriving in the yard or by wild birds such as sparrows or starlings. The insects are seen mainly around the vent area of the bird and their eggs appear as large chalky white globules on the base of the feathers in that region. Lice found on chooks cannot infest humans or other animals. They are best controlled with sulphur based dusts or other animal insecticidal dusts. Poultry insecticidal washes are also effective.

Red Mites are tiny blood sucking parasites which live in cracks in perches, walls or anywhere they can hide during the day. They come out after dark and infest the birds, biting them and taking blood. They can build up in great numbers sometimes without the owner realising and it is only when the birds begin to suffer that they are discovered. They can cause anaemia and spread other diseases such as Fowl Pox. Red mites lay their eggs off the birds and can infest homes, kennels and other livestock housing. As nymphs, they appear as greyish dust and in this state can number in the millions. After they engorge on blood, they appear dark reddish brown about a half millimetre in length. They are particularly difficult to eradicate. It is not sufficient to dip or dust the birds as the vermin infest the shed itself. Malathion based sprays can be used ensuring the mixture gets into all cracks and crevices. Creosote can be painted on all perches and framework, some fanciers even use diesel or distillate, but these can be toxic to poultry so great care must be exercised. In my experience, kerosene is best for painting perches and walls. It kills both mites and eggs.

Scaly Leg Mites infest the legs and feet of chooks, living under the scales. They live their entire life cycle on the birds. It is usually indicated when the scales on the birds legs turn upward and if left untreated, cause the legs and feet to become quite grotesque in appearance. As they live in an extremely difficult place to get at, they can be difficult to eradicate. In days past, sump oil was painted on the affected birds legs to kill the mite. I have found a mixture of methylated spirit, olive oil and an aromatic oil such as camphor or eucalyptus to work quite well. The legs and feet are scrubbed with warm soapy water to soften the scales, then the legs are painted with the oil mixture. The aromatic oil has the added advantage of acting as a fumigant which repels other insect pests.

Other pests may infest chickens in different areas.... fleas, ticks and depluming lice are just a few. Most insect pests are treated the same way. Regular checks of the flock for insect parasites are a good way to prevent major outbreaks.

Red mite

Scaly-leg mite

The effects of Scaly-leg mite