Chicken Diseases & Vaccinations

I posted a lot on how to grow different crops or how to process them in the kitchen. Today I want to start a new series on chicken rearing. I came accross a very usefull vaccination table put together by KARI (KALRO) and I will work along their recommendations as that is what I used for our chickens as well.

Mareks Disease

We bought our Kinyeji chickens from a woman in the neighbourhood who keeps large numbers of chickens, quails, turkeys and geese. They all grew up nicely and started laying eggs, but then suddenly one of the hens started to show mild signs of diarrhea and her eyes started to go blind (turn milky). She looked otherwise quite ok so I decided to observe her while I tried to research the cause of chickens going blind. Turns out that chicks who survived Mareks disease often show symptoms weeks later and turn blind. Unfortunately I had to kill her to avoid infection of the other birds as Mareks is highly infectious.

Symptoms:

1. "Floppy broiler syndrom" caused by paralysis.

2. Vision impairment. The iris becomes irregular and increasingly milky until the bird turns completely blind.

3. Cancer on the skin (raised skin around feather folicles) and of the inner organs.

Prevention:

Vaccination of the day old chicks against Mareks. This has to be done by a veterinary as it is a subcutaneous injection and the vaccine has to be kept on ice throughout.

Only buy chicks from hatcheries that vaccinate their day old chicks against Mareks. Maintain high standards of hygiene in your chicken house (all-in/all-out, desinfection in between flocks, regular cleaning of the chicken house and monitoring of the chicks). Symptoms usually start showing at around 6 weeks. Remove sick birds immediately before they spread any disease.

Vaccinating day old chicks

Treatment:

None

Importance:

Mareks is highly contagious as the infection is spread through infected skin particles that are distributed through the air and breathed in by the other birds. The virus survives for long periods.

Professional hatcheries should always vaccinate against Mareks. Farmers who only keep a few chickens at home and always raise their own chicks are at lesser risk of Mareks infection.  

Gumboro (Infectious Bursal Disease)

Apparently Gumboro affects mostly White Leghorn hens and is less common in broilers or hens that lay brown eggs. It is one of the more commonly administered vaccinations in Kenya as it can be done by the farmer himself by mixing the vaccine into the drinking water. It is important to know though, that for a full immunisation two vaccinations at day 10 and again at day 18-24 are necessary.

Symptoms:

Gumboro disease starts very suddenly. It usually affects chickens at 4-6 weeks of age. The chickens are listless, lose their appetite and stop moving around as they have difficulties walking. They might try to hide. They develop diarrhea, which looks like water.

Prevention:

Vaccination with Gumboro vaccination at day 10 (1st dose) and again at day 18 - 24 (2nd dose). The vaccine needs to be kept on ice throughout and is mixed into the drinking water according to number of chickens and instructions on the lable. Only buy this vaccine from agrovets or pharmacies that keep it refrigerated at all times. High standards of hygiene as described above and regular monitoring of the flock also help to prevent an outbreak.

Treatment:

None. Mortality can be reduced by providing affected chickens with water nearby as they stop moving towards the water containers and often die of dehydration.

Importance:

Not all chicken affected by Gumboro disease die. The mortality rate is usually between 20-60%. Nevertheless, chicken that survived Gumboro will always be prone to other diseases as their immune system is compromised. They will never be very productive birds and the commercial damage is significant.
The virus is very longlived and is still found in the excretions of chickens 2 weeks after recovery and in the litter for up to 8 weeks.

New Castle Disease

Whenever a farmer reports dramatic conditions in his chickens well-meaning neighbours and friends suspect New Castle disease. It can however very easily be confused with other chicken diseases. Nevertheless, the repeated vaccination agains New Castle Disease is one of the most important ones and shouldn't be missed. Chickens sometimes show symptoms of gasping and eye infections after the vaccination. These are not dangerous and can be lessend by an antibiotic to avoid other infections. 

Symptoms:

1. Twisted neck. Birds are trembling and might get paralysed and show a very characteristic twisting of their necks.

2. Respiratory symptoms like coughing and difficulties breathing, sometimes also discharge from the nose.

3. Diarrhea that is bright green and watery.

4. The birds are very obviously sick and lose their appetite.

5. Low number and malformed eggs are early warning signs.

6. Sudden Death.

Prevention:

Vaccination against New Castle disease is administered as an eye drop. The first dose can be given together with the second dose against Gumboro at around 3 weeks.
The second dose is given at 8 weeks and the third dose at 18 weeks. Thereafter it should be repeated every 3 months. This can be done by a veterinarian or an experienced farmer. Other vaccines against New Castle disease can be given with the drinking water. Vaccines need to be kept on ice throughout and should only be bought from agrovets or pharmacies that keep it refrigerated at all times.

The virus can survive in the chicken litter for a whole year. Cleaning and desinfecting the chicken house between restocking flocks will help control the spread of the virus to the next flock. Desinfection can also be done with vinegar.

Treatment:

None.

Importance:

New Castle disease is one of the most common in East Africa and mortality is up to 100%. It should be controlled by consistantly vaccinating flocks.

Fowl Pox

Two forms of fowl pox exist, a dry and a wet form, both showing different symptoms. The wet form is far more lethal than the dry form, with a general mortality rate up to 50%. It is more common on cocks than hens as it is mostly spread through wounds in the skin caused by pecking or fighting. It can also be transmitted by mosquito bites and tends therefore to be seasonal following the rains.

Symptoms:

In dry fowl pox small white and black bumps (lesions) appear on the comb and and scab over after a short while. The chickens are listless and lose their appetite. Growth is stunted. Hens lay very few eggs.

In the wet form of fowl pox the chickens develop yellowish-whitish sores in their mouth, throat and sometimes also in the eyes. They might have difficulties breathing. They are weak and lose their appetite resulting in poor growth and very few eggs.

Prevention:

Fowl pox vaccination at 6-8 weeks or as early as 3 weeks if it has occured in your area before. This vaccination is a wing stab puncture, which should be administered only by experienced people.

Spread one of the chicken's wings and remove the feathers from a small area on the underside of the wing. Use a double pronged needlde (supplied together with the vaccination). Dip the needles into the vaccine before each stab. Do not apply on feathers and avoid blood vessels.  

Ensure also to keep your chickens free of biting insects as they can transmit the disease.

Treatment:

None. Antibiotics can help to avoid secondary diseases. Ensure your chickens have easy access to feed and water and you might want to give them a supplement with the drinking water to avoid high weight loss.

Importance:

Still very common in Africa and Asia.

Fowl Typhoid

Fowl typhoid is a Salmonella infection. Most poultry diseases affect young chicks or young hens. If your hens get sick when they are already mature you should suspect Fowl typhoid. But it can also appear right after hatching as infection from egg to chick is also possible. It can also appear in fast-growing broilers, which get too fat too fast and end up sitting in their own wastes because their legs are too weak to allow them to walk.

Symptoms:

In newly hatched chicks it will appear after the first week. Chicks will be weak and show no appetite. They will make shrill chirping sounds. Mortality is up to 50% but survivors will show poor growth and there is big danger of them infecting other chicks later in life.

Symptoms in an outbreak among mature birds are yellow diarrhea and difficulties breathing. Birds are visibily sick and lose their appetite. Their feathers look thin and ruffled. Chickens can continue to get sick and die over a long period and also develop a chronic form.

Prevention:

Vaccination at 8 weeks and again at 12 weeks. This must be administered by a veterinarian as it is an intramuscular injection.
Only buy day old chicks from trustworthy hatcheries that are fowl typhoid free and practise strict all-in/all-out and clean and desinfect the chicken house inbetween.

Remove faeces regularly and keep feeding areas sanitized.

Treatment:

As Salmonella is a bacterium and not like the pathogens of the forementioned diseases a virus, it can be treated with antibiotics.  avet should confirm the diagnosis. The responsible thing to do though, would be to kill all at least all infected birds if not the whole flock as chicken that have recovered from the disease tend to become bearers of the disease and are very likely to infect others.

Importance:

In the Western world Fowl typhoid is a disease that needs to be reported to the veterinary office. Eradication of the disease is preferred, but in East Africa it still accounts for an estimated 10% of all chicken deaths. It needs to be controlled especially because of the danger of longterm re-infection of flocks.

Coccidiosis

Coccidiosis can also occur in goats, sheep and calves. It is most easily recognized by the bloody diarrhea it causes.

Symptoms:

1. Infected chickens look pale and sick with ruffeled feathers.

2. In some cases bloody diarrhea.

3. Chickens die suddenly and mortality rate is high.

Prevention:

Coccidiosis is caused by parasites, so it can not be prevented by vaccination. Instead the chicken farmer has to make sure that the housing and feeding conditions do not promote a build up of the parasite. This includes:

1. Keep feeding areas clean and separate
2. Ensure watering containers are kept clean and water fresh
3. Remove wet or dirty litter and faeces regularly
4. Avoid overcrowing
5. In case of an outbreak separate sick birds and start treatment immediately
6. Practise all-in/all-out and desinfect the chicken house inbetween
7. In case of earlier outbrakes coccidiostats can be mixed into the feed

Treatment:

The disease should be confirmed by a vet before treatment starts. Suphur drugs are used to treat coccidiosis but should also be administered by the vet to ensure they are given at correct intervals and contraindications with other drugs are prevented.

Importance:

Common and causing big losses as mortality is high. Coccidiosis can also develop a chronic form which will cause re-occuring outbreaks.

Diarrhea

Normal, healthy chicken droppings are firm and have a white part (the bird's urine) and a brownish-blackish part, the faeces.

Normal chicken dropping

Every tenth time or so chickens clean out the caecal part of their intestines, resulting in a slightly foamy, soft and brown dropping. This is also normal and healthy.

Healthy caecal dropping

Watery, bright green, yellow or bloddy droppings on the other hand are signs of diarrhea. It can fastest be detected by soiled feathers around the cloaca. Healthy chicken defecate without messing their bums.

Soiled bum of a sick chicken

Different kinds of diarrhea are shown in the pictures below.

Sick birds usually are listless, avoiding to move around, have no appetite and have drooping wings and tails. They show signs of weakness and distress.

Sick Chicken

Causes of diarrhea

All of the above mentioned diseases cause diarrhea. If a larger number of chickens starts to show signs of diarrhea you should consult a vet. To start with you can check on a few other causes though:
1. Dirty drinking water and mouldy food can cause bacterial diarrhea
2. Sudden changes in feed, or feeds too high in protein or salt
3. Heat stress
4. Parasites

Prevention:

1. Keep feeding and drinking areas separate from roosting areas
2. Keep feeding and water containers clean
3. Change water daily and ensure it is from a clean source
4. Keep feeds in airtight containers to avoid contamination with moisture
5. Use feeds from a reliable, trusted source
6. Sanitize the chicken house between new flocks
7. Keep litter dry and remove dirty litter and faeces regularly
8. Ensure good ventilation
9. Deworm flocks with Fenbendazole after all vaccinations are done at around the 19th week to remove any parasites and repeat deworming every 3 months.

Treatment:

To decide on the right treatment it is necessary to first determine the cause correctly. If the chicken shows no signs of illness besides the diarrhea simply check on the quality of water and feed and consider deworming the chickens. If the chicken seem seriously sick and are dying it is necessary to get assistance from a vet who can advise on the right treatment. In most cases prevention is the best treatment.
Isolate sick birds from the rest of the flock to avoid spreading of any disease and make sure chickens have easy access to clean feeds and water. In many cases sick chickens die because they are weakened and dehydrated as they stop feeding and drinking. Supplements in the water can also help to strengthen them.

Importance:

Diarrhea is always a sign that something is wrong with your chicken. At the first signs of diarrhea you should start monitoring the flock closely for any signs of serious disease. Diarrhea should also always prompt you to check on the housing, feeding and water to ensure you are not killing your chickens with the bad conditions you provide. Diarrhea always weakens the chicken as nutrients and water are not taken up in the needed amounts and growth and egg laying will be reduced. Diarrhea therefore always causes financial losses and should be avoided.