The following is the diary of Dr Subiri Obwogo is a poultry farmer and a medical doctor.

Knowledge is one asset any farmer must invest in and one should be prepared to learn every day to stay ahead of new developments like diseases.

I had assumed the disease that had struck my farm in Nairobi a week ago had subsided after my agrovet recommended a course of antibiotics. The response to the drugs was poor and I had initially lost 20 birds.

I am always up-to-date with vaccinating my birds because that is the only sure way to keep most diseases at bay.

I had already administered the first and second Gumboro vaccines at day 10 and 18 and the first Newcastle Disease (NCD) vaccine at week three. I had also given them fowl pox vaccine at week six – the growers are between 9 and 13 weeks.

“Could this be a reaction to the fowl pox vaccine injection I had administered nine days before?” I wondered.

Unlike NCD and Gumboro vaccines given in water, fowl pox is administered as a wing web stab (injection) and if the same needle is used on many birds, this can spread infections.

The viral disease is characterised by pimples or scabs on the featherless skin, mainly on the comb, wattle and eyelids.

Unable to decipher the problem, I called my vet, Stephen Omari, and he came to the farm late afternoon that Tuesday.

“This is CRD, what you need is a broad spectrum antibiotic like Tylosin. What you have been using so far cannot work,” he said after examining the birds for about a minute as I wondered what CRD is.

CRD stands for Chronic Respiratory Disease, caused by a bacteria called Mycoplasma Avium (this disease should not be confused with Avian Influenza (bird flu), a viral disease).

Birds affected with CRD become droopy, refuse to feed and may develop swellings around the eye. The poor feeding causes stunted growth and weight loss. In worst case scenario, the disease leads to starvation and death. Other CRD symptoms include coughing, sneezing and nasal discharge.

CRD, however, is not the only bacterial infection in poultry. Other common ones include fowl typhoid, fowl cholera, pullorum disease, colibacillosis and infectious coryza.

Fowl typhoid and fowl cholera should not be confused with typhoid fever and cholera in humans and the causative organisms are different.

As a rule, bacterial infections respond to treatment with appropriate and specific antibiotics.

Omari advised me to identify all birds with the symptoms I have mentioned above, which are similar to those of the deadly bird flu, and isolate them.

According to him, the disease had struck my growers of the Kari Kienyeji breed due to poor hygiene and congestion in the coop.

I have about 250 birds in a room measuring about 7 by 3 metres, which I have divided into two. The smaller room hosts the growers.

In the other I keep older hens and cocks above one year, and they were not affected at all.

To be comfortable, one bird requires a 30x30cm (90 square cm) floor area. In my case, two birds occupy a 90 square cm floor area. When there is congestion, organisms may be transmitted by direct contact between infected birds.

Further, I have tried unsuccessfully to enforce basic hygiene habits for my workers like changing foot wear before entering the coop and using the footbath.

The congestion is partly my fault, and I told that to my vet. “It is very easy for infection to spread if there is congestion. Other predisposing factors include poor ventilation, ammonia and dust,” Omari says.

The disease is common during the cold and wet weather conditions because they affect innate immunity of birds, he added. Hygiene is also poor during the rainy season.

The mortality rate from the respiratory disease in chickens is between 5-10 percent, which looks a small number but if you have a large flock, these are many birds.

The vet administered a combination of Doxycycline and Tylosin on the isolated birds.

For the antibiotics to work effectively, they must be broad spectrum, meaning they are effective against a large variety of disease-causing organisms.

The vet, who came with the drugs and charged me Sh2,000, including his consultation fee, mixed them in water and left for the birds to drink. I continued with the treatment for 10 days and instituted basic hygiene measures.

Other broad spectrum antibiotics I was informed I could use were Aureomycin, Terramycin and Gallimycin.

I buried the 41 birds in a deep pit to prevent spread of the disease. The surviving birds have responded well to treatment and I believe I have overcome the disease.

Smarting from the 41 birds’ loss, which translate to over Sh20,500 if I sell each at Sh500, I called a fellow farmer in Nairobi and he informed me he was also battling with a disease of similar symptoms.

Another one called me from Kisumu to seek help. This means the CRD may soon reach your poultry farm during this cold season.