Last Saturday, I shared a case of layer birds on a farm in Ruiru that had profuse watery diarrhoea, which made them appear to be peeing.
Well, all’s well that ends well. Bonnie, the farm manager, sent me photos on WhatsApp the other day that told the whole story in a way that was better than the proverbial one thousand words. The “peeing” chickens had dramatically recovered.
“The birds have a big improvement. Now there is the normal dry droppings. I estimate only about 5 per cent of the birds are still sick. This is day three of treatment and second day of observation,” he wrote.
He inquired if he should continue with the medicine for the entire five days I had prescribed or stop now that the birds appeared to have recovered.
His report was quite a relief to my team as I awaited the laboratory results. Fortunately, the results came soon after.
You see, in a disease outbreak investigation, the doctor has to give tentative treatment while awaiting the laboratory results to check if the disease is life-threatening, badly erodes the quality of life of the patients or appears to be spreading to the other birds.
Laboratory investigation takes time, especially where disease agents have to be cultured, isolated and tested for sensitivity to various antimicrobials for the doctor to know the most appropriate medicine to give.
In Bonnie’s case, I evaluated the drugs on the market that could be used before obtaining the laboratory results. I settled on two preparations and selected the one that could kill the widest range of bacteria and also coccidia parasites.
From my experience, poultry disease-causing microorganisms appear not to have developed resistance to the drug combination.
Farmers rarely use the preparation due to its high cost and the requirement that eggs be withdrawn from human consumption for seven days from the last treatment and meat for 28 days.
When I gave the prescription, my greatest concern was what I would do if the treatment failed as it was the highest I could go. Bonnie’s report lifted the weight off my chest.
NEUTRALISE THE VIRUS
I advised him to give the medicine for at least four days to increase the chance of eliminating all the infecting micro-organisms. I also told him that even without the laboratory results, we knew the challenge was mainly from bacterial sources.
When Dr Joyce, my colleague, and I visited the firm, we had methodically evaluated the disease outbreak and strongly suspected bacteria as the cause.
Since the condition had lasted for 35 days, any virus involved would have been eliminated or tamed by the body’s immune system.
This normally happens within 14 to 21 days when the infected bird will die, neutralise the virus or learn to live with it.
We had also ruled out parasitic infections because scientifically, parasites have no known mechanism to cause prolonged watery diarrhoea in poultry.
Addition of molasses and excess protein in the feed could cause watery diarrhoea but we could not detect traces of molasses in the feed and the manufacturer confirmed they did not use molasses as an ingredient.
Furthermore, all the 8,000 birds on the farm were eating the same batch of feed but only 1,800 in one unit were affected.
Dr Joyce and I visited the farm again last Tuesday to present the investigation report to the owner and her employees.
The laboratory findings were the most essential part of the report. We had taken faecal samples from the cloaca of some of the sick birds to do bacterial culture, isolation and testing for sensitivity against antimicrobials.
Scientifically, this is called the culture and sensitivity test – abbreviated as C&S. We had also collected water samples from the drinking nipples in cages of sick birds for C&S and detection of moulds and yeasts.
We submitted the reports to three different laboratories because none of them had the capacity to do all the tests we required.
IMPROVE THE HYGIENE LEVELS
When investigating a disease outbreak, the doctor must request for general culture of bacteria and also culture and isolation of the bacteria that would most likely cause the disease being investigated, either as individual organisms or in combination with others.
The first laboratory tested for the most notorious and dangerous bacteria of the poultry intestines comprising Salmonella, Shigella, Campylobacter, Aeromonas, Escherichia coli serotype 0157, Yersinia enterocolitica and Vibrio.
The birds were free of those bacteria. However, a rare organism, Citrobacter braakii, occurred in large numbers. It was sensitive to three antibiotics used in humans and one commonly used in both humans and poultry. Unfortunately, it was resistant to a very commonly used poultry antibiotic combination.
The second laboratory showed the water was heavily contaminated with moulds and yeast to about three times higher than the acceptable levels as set out by the Kenya Bureau of Standards.
Results from the Veterinary Research Laboratories at Kabete further showed the water had high levels of contamination with Escherichia coli (E.coli), Proteus and Bacillus subtilis (B. subtilis) bacteria. There was heavy growth of E. coli in the faecal samples.
B. Subtilis is a good bacterium in the intestines of chicken and helps in containing the growth of bad bacteria. Proteus and E.coli, on the other hand, can cause serious disease in birds when they are present in the intestines in large numbers.
We concluded the infection on the farm had been caused by mainly E. coli and Citrobacter that responded to treatment with the top-range drug combination in the market.
We advised the farmer to improve the levels of hygiene on the farm and biosecurity and ensure prompt investigation of diseases that fail to respond to initial treatment.
As we left the farm, Bonnie confirmed the treated birds had already increased production from 20 to 32 per cent.