Dear Dr Messo, I am a poultry farmer in Kakamega County, currently experiencing a serious challenge of the disease. Kindly assists answer the following questions.
- How do I prevent infections?
- Is there a vaccine to administer, if yes, how is it applied?
- What is the treatment regime for sick poultry?
Kindly assist, Francis
Dear Francis
Before I delve deep into these important questions that you have raised in this column today, it would be important for me to put some facts straight to anyone reading this scientific discourse right at the beginning. A disease can be described as any impairment of normal physiological function affecting an organism especially a change caused by stress or infections etc. producing characteristic symptoms, illness, or sickness in general. To arrive at a diagnosis of a disease, it takes in-depth investigation coupled with experience from a qualified veterinary medical practitioner and sometimes with the aid of further laboratory services. Most respiratory diseases in poultry tend to exhibit similar characteristics and clinical signs and therefore it is extremely important that an accurate diagnosis is made before a control and management program is implemented. Having said that, lets look at this disease called Coryza in poultry.
What is infectious Coryza
This is an acute respiratory disease of chickens caused by a bacteria called Avibacterium gallinarum. Birds that are infected by this organism generally show nasal discharge, they keep sneezing and more than often they show swelling around the nose and eyes. In some instances, farmers have complained of swollen eye, completely closed with pus in chicken presented for treatment. This condition is common in chronically complicated respiratory infections, where it starts with sneezing, coughing, respiratory rales, tearing or wet eyes and mild inflammation of the eyes(conjunctivitis). It can affect one eye or both, in severe cases there is swelling of the wattles and accumulation of water between the mandibles. Where both eyes are affected, the chickens fail to locate feed and water and will die of starvation. The other diseases that can present similar signs include, fowl pox, E. coli complicated infection, infectious bronchitis, mycoplasmas, swollen head syndrome, infectious laryngotracheitis, etc.
How The Disease Is Spread
The primary method through which these disease-causing microorganisms are spread between poultry flocks is by use of contaminated equipment or exposure to contaminated clothing and footwear of humans. Infected animals, such as wild birds and rodents, can also be a source of disease for poultry flocks. Disease causing microorganisms can be transported from one flock to another by shared equipment, trucks, etc. Insects such as flies, beetles, and mosquitoes are well known to be carriers of disease microbes as well. Direct contact with infected birds has also been confirmed as a serious breach especially in farms with multiage flocks reared in proximity. Drinking contaminated water is another source of infections and this makes water sanitation play a big role in disease prevention and control.
Diagnosis Of The Disease
Presence of clinical signs is not a sure way of identifying this disease in the field, one needs to supply a veterinarian with recently dead birds for postmortem analysis. The most common symptoms at postmortem include greyish exudates in the infra-orbital sinuses, some pathological changes in the trachea, bronchi, and air sacs. A definitive diagnosis can only be arrived at by isolating and identifying the organisms from the tracheal samples in a laboratory. PCR testing can identify the organisms within two days.
Treatment
The good news is that there are antibiotics available in the market to deal with infections in the farms as soon as the offending organisms are promptly identified by laboratory-based diagnosis by a qualified Vet.
Control
There are vaccines that can be administered to flocks following a prescription by your local vet who understands the history of the disease in your locality. It is generally given to long living birds at around 6-8 weeks and again at 14-16 weeks of age. It is important to keep the poultry units clean and disinfected prior to placement. Ensure that the poultry house is well isolated away from indigenous backyard flocks, flock visitation to be completely restricted and keep flocks of the same age in one site, what we refer to us ‘All-in All-out’ program.
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