Keeping Salmonella disease at bay

Salmonella is a bacterial disease of land fowl or galliform birds that do not fly, including turkeys, chickens, and quails.

The disease is caused by Salmonella enterica and affects birds and the human population.

There are over 2,500 species of salmonella organisms in the world.

While most are not harmful, the few that affect poultry and humans can result in serious disease, poor performance and even death.

In poultry, the most common diseases associated with salmonella are Fowl typhoid and Pullorum infection. In human beings, Salmonella enteritidis and Salmonella Typhimurium may cause human gastroenteritis, seen as severe diarrhoea and vomiting.

In poultry, it can lead to 60 per cent mortality in a flock, wiping all your investments. The good news, however, is that the disease can be prevented by strict biosecurity measures and rodent control.

Salmonella organisms can persist in faecal material from infected birds for not less than 30 days. It can be picked by rodents, dogs, wild birds, flies, insects and boot contamination into a clean flock when the organisms are swallowed into the gut.

The bacteria move through the crop, proventriculus, gizzard and into the chicken intestines. The organisms grow in the caeca and can reach a population of 10 billion colony-forming units in the hindgut.

Because chickens are coprophagic they eat their faeces), the spread in a population is very fast and no chickens will be spared within 4-6 days.

The first sign is loss of appetite and failure to eat normal feed ratio.

If the birds are in lay, there will be a drastic drop in egg production.

The birds appear depressed with ruffled feathers and with closed eyes.

There is accompanied by rapid breathing and notable watery to mucoid yellow diarrhoea as the condition spreads, mortality will reach 60 per cent in an untreated flock.

It is important to alert your veterinarian for post-mortem analysis, in which case a consistent finding includes swollen and friable liver among other symptoms in the spleen, heart and intestines.

Some antibiotics can be used to reduce the death rate.

However, there is no antimicrobial that can eliminate this condition in your flocks once infected.

The treated flocks become carriers for life and become the next source of infection to any new flocks, a recycling habit that can only be stopped by the complete eradication of infected flocks.

Vaccination is the best option for controlling the disease.

Administer two vaccinations - at six weeks and again at 18 weeks before the point of lay.

Keep your farm neat and clean all the time and practice good husbandry.

Only allow essential people into the flock houses during vaccinations and weighing when you need additional help.

All authorised visitors must change into or wear protective clothing, hair nets, and rubber or disposable boots on location before entering the premises.

Hands must be washed and sanitised when entering each house.

Between flocks, eliminate any rodents as they carry many diseases that adversely affect the health of poultry.

This involves weekly monitoring of rodent bait stations. All feed spills and/or damaged equipment must be repaired and cleaned up to prevent attracting wild birds and rodents.

A one-metre barrier around each house free of grass (preferably some concrete “apron”) must be maintained to prevent rodents from entering poultry houses.

The farm needs to have a foot bath using a broad-spectrum disinfectant at each entrance. Keep all doors locked to prevent unwanted intrusion.

Your layer flocks must be vaccinated against Salmonella Typhimurium and ensure there is a strict hygienic environment and biosecurity on the farm.

Do not feed suspected eggs to our young ones, pregnant mothers, the old and those battling chronic illnesses as they are more susceptible to this infection. 

[Dr Messo is the company veterinarian, Kenchic; [e-mail]]