I have been keeping improved ‘Kienyeji’ flocks for a while now and my bird population is increasing. I can now boast a combined population of more than 1,000 chickens of different ages and my target is to keep over 2,000 improved birds ready for Christmas period. I have noticed a worrying trend in my batch where some chicks are showing swollen eyes from one house and it seems to be spreading to the younger generation. The others are showing black spots on the head, wattle and they are not feeding well. I visited an agrovet and the attendant said it could be fowl pox. Please help. [Concerned farmer]
Dear concerned farmer
Over the years that I have worked with livestock farmers, I have found poultry farmers very observant and extremely attached to their flocks. They are genuinely concerned when things are not alright and are quick to seek help. It is thus good of you to seek to know what’s going on in your farm.
First, swollen eyes in chickens can be due to different reasons. Some could be due to infectious diseases like Mycoplasma, Coryza, E. coli or due to mechanical irritation caused by dust particles, excessive ammonia or mould. In your case, from what you have presented, I highly suspect fowl pox infection. Here are some facts you need to know about this disease.
1. The cause
This disease is caused by a Pox virus and is common in backyard flocks that are not routinely vaccinated. These carrier birds then become responsible for the spread of infection to our commercial flocks as they roam around. It is important that we keep our precious flocks indoors, with locked doors all the time and restrict any visitation by unauthorised personnel. If they must visit the farm, have them wear protective clothes and foot wear.
2. The host
This disease affects all type of chicken, turkeys, pheasants, ducks and pigeons. It can also attack wild birds that end up spreading infections far and wide. It is common in warm or hot tropical environment where it is spread by biting insects. It is therefore paramount that our flock houses are covered with bird proof netting or chicken wire to deter entry of wild birds. Likewise, farmers should install fly traps against insects and ensure that birds are free from mite infestation.
3. Signs of infection
The most prominent sign of this disease is presence of wart like lesions on the surface of the skin of the head, comb, wattles and legs. When you spot such, inform the Vet nearby. Other signs include swollen eyes and nasal discharge.
4. Mortality/Death rate
It is not a killer disease and in untreated flock, growth rate may be retarded. If the internal organs are affected by the disease, birds may have trouble in breathing, digesting food and mortality may reach 20 per cent. In mild infection, farmers may only incur drop in egg production.
5. Can one diagnose the problem in the field?
The type of Pox disease that show typical wart like growth on the wattles, comb, skin, feet can easily be identified by an observant farmer, otherwise you need to take birds for further laboratory tests.
6. The Control
Once flocks are infected, there is no known treatment against fowl pox disease. Affected birds tend to recover on their own if there are no secondary bacterial infections. Knowing that the virus is very resistant and can survive for months in the poultry house, it is important that the units are properly cleaned and disinfected and rested for 21 days before allowing the next lot. To control the disease, one must vaccinate the birds at 6-8 weeks of age using live vaccines applied through wing web stab.
[The writer is the head vet at Kenchic]