Introduction to Poultry Diseases – SS1 Livestock Farming Lesson Note (Second Term)

Poultry diseases are illnesses of birds such as chickens, caused mainly by viruses, bacteria and parasites.

Behavioural objectives

By the end of the lesson, students should be able to:

1. State the main causes of poultry diseases.
2. Describe the signs and symptoms of Newcastle disease, coccidiosis and fowl pox.
3. Explain how each of these diseases is prevented and controlled.
4. Explain why Newcastle disease and fowl pox have no cure.
5. List and explain the “3 S’s” of a healthy poultry farm.

Why do poultry diseases matter?

Poultry diseases matter because one outbreak can kill most or all of the birds on a farm.

• Feed and housing are not enough: even well-fed birds in a good pen can die if disease enters.
• Heavy losses: sick birds grow slowly, lay fewer eggs or die, so the farmer loses money.
• The farmer’s role: a poultry farmer must act like a nurse and watch daily for signs that something is wrong.

What causes poultry diseases?

Poultry diseases are caused mainly by disease-causing organisms (pathogens), and also by poor feeding and poor housing.

• Poor feeding: lack of vitamins or minerals makes birds weak and easy to infect.
• Poor housing: damp, dirty or crowded pens help germs spread.

How do you know a bird is sick?

A sick bird shows signs that differ from the behaviour of healthy birds in the flock.

• Dullness: the bird is drooping, sleepy and stays away from the others.
• Loss of appetite: it eats and drinks less than usual.
• Rough feathers: the feathers look ruffled and untidy.
• Abnormal droppings: they are watery, bloody, green or yellow.
• Breathing problems: the bird sneezes, coughs or gasps.
• Fewer eggs: laying birds produce fewer eggs.

What are the common poultry diseases?

What is Newcastle disease?

Newcastle disease is a highly contagious viral disease of poultry that affects the breathing, nerves and gut.

• Cause: a virus.
• Spread: through the air, contaminated water, feed, droppings and visitors’ shoes and clothes.
• Importance: it is one of the most feared poultry diseases in Nigeria because it spreads fast.

Signs and symptoms of Newcastle disease

• Respiratory problems: birds sneeze and gasp for breath, and you may hear a rattling sound.
• Twisted neck: the neck twists in a strange way (torticollis), which is the most obvious sign.
• Greenish diarrhoea: droppings become watery and green.
• Sudden death: many birds may be found dead with little warning.

How is Newcastle disease prevented and controlled?

• Vaccination: this is the main way to prevent it, using vaccines such as Lasota and I-2.
• Biosecurity: these are measures that keep germs out of the farm, such as not allowing strangers into the pen.
• Treatment: there is no cure, but vitamins can help birds that are not yet badly sick.

What is coccidiosis?

Coccidiosis is a disease of the gut caused by protozoa (tiny parasites) that live in soil and wet litter.

• Cause: a protozoan parasite.
• Spread: birds pick up the parasite from dirty, wet floors and drinkers.
• Common name: the “disease of dirty floors”.

Signs and symptoms of coccidiosis

• Bloody droppings: this is the “red flag” for coccidiosis.
• Huddling: birds look cold and droopy and crowd together even when it is hot.
• Weight loss: birds stop eating and become thin very quickly.

How is coccidiosis prevented and controlled?

• Dry litter: keep the wood shavings dry and pack out wet patches at once.
• Coccidiostats: these are medicines added to feed or water to kill the parasites.
• Hygiene: wash the drinkers every morning.

What is fowl pox?

Fowl pox is a viral disease of poultry that causes sores and scabs on the skin.

• Cause: a virus.
• Spread: mainly by mosquitoes that bite the birds.
• Speed: it usually moves more slowly than Newcastle disease.

Signs and symptoms of fowl pox

• Sores and warts: small bumps or scabs appear on bare parts such as the comb, wattles and around the eyes.
• Loss of vision: sores near the eyes can blind the bird, so it cannot find food.
• Difficult breathing: sores inside the mouth and throat (the “wet form”) make breathing and eating hard.

How is fowl pox prevented and controlled?

• Vaccination: the vaccine is usually given by a prick in the wing web.
• Mosquito control: clear bushes around the pen and remove standing water where mosquitoes breed.
• Treatment: there is no cure, but Gentian Violet (the purple medicine) on the sores helps them dry up.

What is fowl typhoid?

Fowl typhoid is a bacterial disease of poultry that causes diarrhoea and weakness.

• Cause: bacteria.
• Main sign: yellowish diarrhoea.
• Control: antibiotics given as advised by a veterinary doctor, and clean drinking water.

Why do Newcastle disease and fowl pox have no cure?

They have no cure because they are caused by viruses, and medicines for treating sick birds do not kill viruses.

• Viruses live inside cells: they are hard to reach without harming the bird.
• Antibiotics act on bacteria: they have no effect on viruses.
• Treatment only helps: vitamins and Gentian Violet support the bird but do not kill the virus.
• Prevention is the answer: vaccinate healthy birds before the virus reaches them.

How do the common poultry diseases compare?

The table compares the four diseases explained above.

What are the general rules for a healthy farm?

The “3 S’s” are three rules that help keep a poultry farm free from disease.

• Sanitation: scrub feeders and drinkers, and remove wet droppings from the floor.
• Separation: isolate a sick bird at once in a separate cage far from the healthy ones.
• Strictness: do not buy “cheap” birds from a source you do not trust, and start with healthy chicks from a reputable hatchery.

Evaluation

1. If you walk into your pen and see red or bloody spots on the floor, which disease do you suspect? What is the first thing you should check on the floor?
2. Why can we not cure Newcastle disease with antibiotics once it starts?
3. Name the cause of coccidiosis and state two ways of preventing it.
4. List the “3 S’s” of a healthy poultry farm.
5. State two signs of fowl pox.

Assignment

Check whether there are bushes or stagnant water near where people keep chickens, then explain to your parents or neighbours why this can cause fowl pox.