Salmonella enteritidis in chickens

Salmonella Enteritidis and S.Typhimurium are presented separately from other sero-types of Salmonella because, on the one hand, these bacteria are often specifically cited in zoonosis control legislation, and, secondly, because there are differences in the epidemiology as compared to other salmonellae. These are the predominant sero-types associated with human disease in most countries.

Salmonella Enteritidis, especially phage type 4, has become much more common in both poultry and humans since the early 80s. The prevalence of S.Typhimurium has remained relatively stable though the spread of the highly antibiotic-resistant strain DT104 in various farmed species gives some reason for concern. Infections in chickens, turkeys and ducks cause problems worldwide with morbidity of 0-90% and a low to moderate mortality. Many infected birds are culled and others are rejected at slaughter. The route of infection is oral; many species are intestinal carriers and infection may be carried by faeces, fomites and on eggshells.

Vertical transmission may be either by shell contamination or internal transovarian contamination of yolk. Feed and feed raw material contamination is less common than for other sero-types. The bacteria are often persistent in the environment, especially in dry dusty areas, but are susceptible to disinfectants that are suitable for the particular contaminated surfaces and conditions, applied at sufficient concentrations. Temperatures of around 80°C are effective in eliminating low to moderate infection if applied for 1-2 minutes. This approach is often used in the heat treatment of feed. Predisposing factors include nutritional deficiencies, chilling, inadequate water and other bacterial infections.

Dejection.
Ruffled feathers.
Closed eyes.
Diarrhoea.
Vent pasting.
Lost of appetite and thirst.
Stunting in older birds.

In acute disease there may be few lesions.
Dehydration.
Enteritis.
Focal necrotic intestinal lesions.
Foci in liver.
Unabsorbed yolk.
Cheesy cores in caecae.
Pericarditis.
Perihepatitis.
Misshapen ovules in the ovaries in S.E. infection

Isolation and identification. In clinical cases direct plating on Brilliant Green and McConkey agar may be adequate. Enrichment media such as buffered peptone followed by selective broth or semi-solid media (e.g. Rappaport-Vassiliadis) followed by plating on two selective media will greatly increase sensitivity. However this has the potential to reveal the presence of salmonellae that are irrelevant to the clinical problem under investigation.

Differentiate from Pullorum/Typhoid, other enterobacteria such as E. coli. S.Enteritidis causes cross-reactions which may be detected with S.Pullorum serum agglutination tests. It is possible to detect reactions with specific antigens in agglutination tests but competitive and direct Elisa tests are more commonly used today.

Sulphonamides, neomycin, tetracyclines, amoxycillin, fluoroquinolones in accordance with the sensitivity. Good management. Chemotherapy can prolong carrier status in some circumstances.

Uninfected breeders, clean nests, fumigate eggs, all-in/all-out production, good feed, competitive exclusion, care in avoiding damage to natural flora, elimination of resident infections in hatcheries, mills, breeding and grow-out farms. Routine monitoring of breeding flocks, hatcheries and feed mills is required for effective control. Early depletion of infected breeding stock is required in some countries such as those of the European Union. Infection results in a strong immune response manifest by progressive reduction in excretion of the organism and reduced disease and excretion on subsequent challenge.

Vaccines are increasingly being used for S. Enteritidis and S. Typhimurium infection; both inactivated (bacterins) and attenuated live organisms.

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Nov 22, 2006 (CIDRAP News) Sampling by the US Department of Agriculture (USDA) over the last 5 years has shown a fourfold increase in the number of broiler chicken carcasses contaminated with Salmonella enterica serotype enteritidis, a strain previously associated mainly with eggs.

The findings, published yesterday in the December issue of Emerging Infectious Diseases (EID), do not necessarily signal an overall increase in the risk of chicken-related Salmonella infection, but they appear to reinforce other evidence about the emergence of S enteritidis in chicken.

The authors, led by Sean F. Altekruse of the USDA, note that two recent US case-control studies from the Foodborne Diseases Active Surveillance Network (FoodNet) associated eating chicken with sporadic human infections with S enteritidis. Though the overall incidence of human salmonellosis was lower in 2005 than in the mid 1990s, FoodNet surveillance indicated the incidence of S enteritidis infections was about 25% higher.

The USDA researchers tested rinse water samples collected from 2000 through 2005 at plants that slaughter broiler chickens. Eligible poultry processors were randomly selected each month for sampling, which involved collecting rinse water used on one chilled broiler chicken carcass per day for 51 days. Samples were sent for analysis to USDA Food Safety and Inspection Service (FSIS) laboratories in Georgia, California, and Missouri.

Over the 6-year study, researchers identified 280 S enteritidis isolates from 51,327 broiler rinses; the annual number of isolates rose from 23 in 10,057 samples in 2000 to 120 in 9,592 samples in 2005. As a proportion of all Salmonella strains found, S enteritidis increased from 2.5% in 2000 to 7.7% in 2005.

The proportion of establishments that had positive tests increased from 17 of 197 (9%) in 2000 to 47 of 187 (25%) in 2005. In addition, the number of states where the strain was found increased from 14 in the 2000-2002 period to 24 in the ensuing 3 years. Two S enteritidis phage types accounted for most isolates from broiler rinse water: PT 8 and PT 13.

The researchers write that the sampling program is not designed to estimate national prevalence of poultry contamination, because it doesn't consider production volume or regional or seasonal effects, but the findings are significant.

"Enteritidis in broilers is noteworthy given the increase in human Salmonella enteritidis infection rates in the United States and recent findings that eating chicken is a new and important risk factor for sporadic infection," they state.

They point to a recent FoodNet report that showed a strong association between infection with S enteritidis phage types 8 and 13 and eating chicken. "The possible emergence of these two phage types in broiler chickens suggests that industry should implement appropriate Salmonella enteritidis controls for broiler chickens," the authors write.

Craig Hedberg, PhD, a foodborne disease expert and associate professor of environmental and occupational health at the University of Minnesota in Minneapolis, said the identification of a different serotype in broiler chickens by itself doesn't mean that eating or handling chicken is becoming more dangerous.

"The implications are mostly for how we evaluate our surveillance system," he told CIDRAP News. "There are about 50 different serotypes, and the clinical illness is the same [for all serotypes]."

Hedberg said the findings should prompt renewed attention to S enteriditis control programs in egg production and that it's difficult to disentangle the risk factors for the organism in chickens. The egg and broiler industries are very different and their disease-control strategies vary, he said.

Earlier this year, the USDA reported evidence of a steady increase in overall Salmonella contamination in broiler chickens since 2002, with 16.3% of samples testing positive in 2005. The trend prompted the FSIS to announce plans to report test results faster and increase monitoring of processing plants that have high numbers of positive samples. The Salmonella initiative is patterned after a recent FSIS program aimed at ground beef, which the agency says led to a 40% reduction in the number of Escherichia coli O157:H7 illness cases.

Meat and poultry producers that haven't reduced the percentage of positive Salmonella tests to no more than half the FSIS performance standard by July 2007 will face consequences, the USDA authors report. For example, the FSIS may post test results, including processing plant names, on the Web for products that have not made sufficient progress.

However, they say that voluntary quality-assurance programs enacted by the egg industry in the 1990s were enough to control S enteritidis in eggs. Many of the interventions are adaptable to broiler chickens, the authors write, including monitoring and sanitation of breeding flocks, hatcheries, broiler flocks, and slaughtering facilities.

Altekruse SF, Bauer N, Chanlongbutra A, et al. Salmonella enteritidis in broiler chickens, United States, 2000-2005. Emerg Infect Dis 2006;12(12):1848-52 [Full text]

Eating eggs infected with Salmonella Enteritidis can make people ill.

Salmonella Enteritidis (SE) is a bacterial disease of poultry and can cause foodborne illness in humans such as gastroenteritis (commonly known as ‘gastro’) when contaminated food is consumed.

In poultry the disease often goes unnoticed but sometimes may present clinically in birds as depression, poor growth, weakness, diarrhoea and dehydration.

Possible sources of infection in commercial layer flocks include transmission from breeder birds, contaminated environments, infected vermin (including rodents) and contaminated feed.

Transmission to progeny from breeders is mainly through eggshell contamination, although transmission through the egg may also occur.

Consumption of infected, uncooked or under cooked eggs can make people ill. Due to the high-risk of it causing foodborne illness in humans, SE is a notifiable animal disease in Australia. This means that there is a legal obligation to notify Agriculture Victoria if you know or suspect that poultry are infected with this disease.

Salmonellosis is one of the most common and widely distributed food borne diseases. Salmonella outbreaks can have particularly severe consequences in highly vulnerable people, like those who are young, old and immunocompromised.

Until recently, the Australian egg industry was considered free of SE, which is a type of Salmonella that is present in most international egg industries. As of May 2019, SE has been detected in several NSW egg layer farms and one Victorian egg layer farm.

Salmonella Enteritidis can be spread from property to property through the movement of produce including eggs, packaging materials, equipment, feed, rodents, people and vehicles.

For information on gastroenteritis caused by salmonellosis in people, please visit the Better Health Channel.

Advice for farmers and industry providers

How is Salmonella Enteritidis detected?

Salmonella Enteritidis (SE) can be identified in poultry flocks through:

Investigation of health and disease issues of birds to determine the cause of the symptoms that may be associated with SE.
Tracing back to farms or other businesses associated with an SE-affected farm or business.
Tracing back to farms when there are cases of food-borne illness in humans.
Routine Salmonella monitoring programs on poultry farms and facilities (e.g. grading floors).

How can I prevent the spread of Salmonella Enteritidis and protect my business?

Good farm biosecurity is critical to managing the risk of SE. You should have a documented biosecurity program to monitor for and prevent the introduction of SE to your property or the spread between poultry sheds.

Actions you can take include:

Developing and implementing a farm specific, effective biosecurity plan. The farm biosecurity website provides a number of biosecurity resources.

National Farm Biosecurity Manual Poultry Production
National Farm Biosecurity Technical Manual for Egg Production

Providing birds with drinking water derived from town water or water that has been effectively sanitised in line with the National Water Biosecurity Manual - Poultry Production.

Buying pullets that are tested and confirmed to be SE-free.
Buying feed from a mill that monitors for Salmonella.
Participate in an appropriate industry Quality Assurance program.
Having a documented ingredient and feed testing program for home diets, that is sighted during audits.
Not allowing people returning from overseas and suffering from diarrhoea to work on the farm or handle birds.
Storing eggs on-farm in a cool environment, promptly after laying, where the thermostat temperature is set at less than 15⁰C, but greater than 1°C.
Implementing an effective auditable vermin control program and using rodenticides in compliance with Australian Pesticides and Veterinary Medicines Authority (APVMA) label instructions.
Storing feed in areas not accessible to other animals (including vermin or wild birds).
Ensuring workers, particularly in the egg collection processing area, are familiar with and follow personal hygiene measures to minimise the risk of transferring Salmonella from humans to poultry or eggs.
Following recommended industry practices on the farm, particularly in the egg collection and grading area, in order to minimise risks associated with SE cross-contamination between equipment, eggs and humans.
Cleaning and disinfecting shared equipment before use.

Read our factsheets below.

What happens if Salmonella Enteritidis is detected on a poultry farm?

If a farm has a confirmed positive test for SE movement restrictions will be applied by Agriculture Victoria to prevent the further spread of SE.

Tracing of facilities or other businesses with recent contact with this farm, e.g. through egg movements, will be undertaken and samples from those properties will be collected and investigated.

The disease will be managed on-farm by industry in accordance with the industry-owned National Salmonella Enteritidis Response Plan.

What happens to the eggs on a farm that is Salmonella Enteritidis?

Restrictions are placed on the movement and sale of eggs from the farm. Agriculture Victoria may issue a permit for the eggs to go to pulping and pasteurisation to render them safe. Any movement of eggs, birds, manure, etc is only allowed under a permit to an approved facility.

Is there regular monitoring for Salmonella Enteritidis in layer flocks?

There is a voluntary National Salmonella Enteritidis Monitoring & Accreditation Program (NSEMAP) available to all commercial egg producers in Australia.

Factsheets

Salmonella Risk Assessment Toolkit

Report Salmonella Enteritidis in poultry

Salmonella Enteritidis (SE) in poultry is a notifiable disease under the Victorian Livestock Disease Control Act 1994. There is a legal obligation to notify Agriculture Victoria immediately if you know or suspect that birds are infected with this disease.

You can notify suspicion of SE by phoning:

Agriculture Victoria’s Customer Call Centre on 136 186
Your local District Veterinary Officer or Animal Health Officer
The Emergency Animal Disease Watch Hotline on 1800 675 888

Following changes to the Victorian Government structure, the content on this site is in transition. There may be references to previous departments, these are being updated. Please call 136 186 to clarify any specific information.

Salmonella is a bacteria commonly found in animals, including poultry. It can cause illness to humans such as gastroenteritis (commonly known as ‘gastro’) when contaminated food is consumed.

Until recently, Salmonella Enteritidis (SE) had not been detected in NSW poultry. SE is a type of Salmonella that is present in most international egg industries. Salmonellosis is one of the most common and widely distributed foodborne diseases.

SE is high-risk for causing foodborne illness in humans - which can be particularly severe for people who are elderly (over the age of 70), young children, and those with a weakened immune system.

How can Salmonella Enteritidis spread?

Salmonella Enteritidis (SE) can be spread from property to property through the movement of produce, equipment, feed, rodents, people and vehicles.

Current situation in NSW

Agriculture, health and food authorities are responding to a number of cases of human illness linked to Salmonella Enteritidis (SE) in egg production. Usually human illness linked to SE in NSW is associated with recent overseas travel; people getting infected overseas before returning home. Since May 2018, there has been an emergence of cases where people became infected from consuming food locally in NSW.

NSW government agencies have worked collaboratively to identify the sources of these cases.

As a consequence, 13 NSW poultry egg facilities and one Victorian poultry egg facility have had detections of SE. The first detection was in NSW in September 2018 more detections have been occurring as a targeted program of increased testing and surveillance continues across a number of properties. All the properties confirmed to have had SE present are interconnected in that people, eggs or equipment were moving between them.

Every effort is being made by government and industry to limit the spread of SE while assessing management options. Steps taken to minimise consumer exposure to SE include movement restrictions, decontamination and improvements to biosecurity, consumer level and trade level recalls, product withdrawals, consumer advisories, media and surveillance.

For more information visit NSW Health updates and NSW Food Authority recalls & advisories.

How is NSW DPI responding?

NSW DPI is working closely with local and interstate agencies, affected producers and peak industry bodies as part of the ongoing investigation.

NSW DPI has increased surveillance and monitoring at poultry facilities and, where necessary, biosecurity directions (PDF, 483.94 KB) have been issued to individual properties, including the quarantine of premises to stop movement of eggs into the marketplace.

Advice for consumers

NSW has strong systems in place at all points along the food supply chain, from paddock to plate, to help reduce the risk of Salmonella Enteritidis (SE).

In the event there is a food safety risk, the recall of affected products is a normal and routine part of a business’ food safety system. During an egg recall, consumers are advised they should not eat the eggs and to dispose of them in the garbage or return them to the place of purchase for a full refund. Proof of purchase is not required for recalled products.

Salmonellosis symptoms in people include fever, headache, diarrhoea, abdominal pain, nausea and vomiting. Symptoms usually start around six to 72 hours after the contaminated food is eaten and usually last for four to seven days but can continue for much longer.

If you have immediate health concerns you should contact your medical professional in the first instance.

To minimise food safety risks, eggs should be cooked thoroughly, this means they are cooked until whites are completely firm and yolk begins to thicken.

For more information on cooking eggs safely, visit Enjoy eggs safely.

For information on egg recalls visit the NSW Food Authority recalls & advisories and NSW Health updates.

Salmonellosis is a bacterial disease caused by strains of the Salmonella bacteria. It occurs in animals and humans. The economic impact of Salmonella infections can not be overlooked. The disease in poultry sometimes involves significant losses, which is a real cost to the farmer. In addition, the presence of Salmonella in poultry or poultry products can hinder international trade, as it can be transmitted to humans. With this article we provide you with more information about salmonellosis in poultry.

Salmonella infections in poultry can be divided into host specific infections and non-host specific infections.

Host specific infections

Pullorum disease

Infections with Salmonella pullorum usually cause very high mortality in young chickens and turkeys within the first 2 - 3 weeks of age. In adult chickens, mortality may be high but frequently there are no clinical signs. The route of infection is oral (via feed or litter) or via the navel/yolk. Also transmission via the egg appears.

Clinical findings and lesions: Birds may die in the hatchery shortly after hatching. Affected birds huddle near a heat source, are anorectic, appear weak and have whitish diarrhoea around the vent. Survivors are small in size and frequently become carriers with localized infection of the ovary. These birds can continue to infect other birds. In mature chickens, chronic infections produce lesions indistinguishable from those of fowl typhoid.

Fowl typhoid

Swollen, bile-stained liver infected with salmonella

The causal agent of fowl typhoid is Salmonella gallinarum. Like S. pullorum, S. gallinarum is egg-transmitted and produces lesions in chicks and poults. However, there is a much bigger tendency to spread among growing or mature flocks. Mortality in young birds is similar to that seen in S. pullorum infection but may be higher in older birds.

Clinical findings and lesions: Clinical signs and lesions in young birds are similar to those seen with S. pullorum infection. Older birds may have a fever, be pale, dehydrated, and have diarrhoea. Also the liver is swollen, brittle and often bile-stained.

Non-host specific infections

Paratyphoid Salmonellas are non-host specific (e.g. S. enteritidis and S. typhimurium). They are the cause of Salmonella-food poisoning in humans.

Fowl paratyphoid

Paratyphoid infections can be caused by any one of the many non-host-adapted salmonellae. These salmonellae infect many types of birds, mammals, reptiles, and insects. Paratyphoid infections can be transmitted to humans via contamination of poultry products. S. enteritidis and S. typhimurium are among the most common Salmonella infections in poultry. The prevalence of other species varies widely by geographic location. Transmission usually occurs directly from infected birds, contaminated environments, or infected rodents. Infected birds remain carriers of Salmonella.

Necrotic lesions in the intestine

Clinical findings and lesions: Although not common, clinical signs are sometimes seen in young birds. Mortality is most often limited to the first few weeks of age. Depression, poor growth, weakness, diarrhoea and dehydration are symptoms of the disease. Lesions may include an enlarged liver with necrosis, unabsorbed yolk sac and enteritis with necrotic lesions in the mucosa. Sometimes there may be no lesions due to acute death caused by septicaemia.

Diagnosis

As Salmonella often colonizes in the intestinal tract, this, and its contents, should be cultured. Salmonellae can spread to many tissues including ovary, spleen, liver, yolk sac, heart, heart blood, kidney, gall bladder, joint fluid/pus and the eyes. All of these can be cultured as part of a post mortem examination.

Prevention

Salmonella can be controlled with the successful combination of several strategies:

Hatching eggs should be clean and disinfected or fumigated.

Day old chicks should come from Salmonella-free breeder flocks.

Salmonella negative feed should be obtained. Feed should be heat-treated or treated with acids, to avoid recontamination after production. Also attention needs to be paid to the transport of feed (e.g. no open trucks to prevent contamination via pigeon-droppings).

Drinking water should come from a clean source and ideally should be chlorinated.

Only essential equipment should be allowed into the poultry house, after acknowledging that there are no Salmonella organisms present.

Bedding material is a potential risk of Salmonella infection. Floor feeding should be reflected on, as birds scratch through the bedding and litter, which increases the risk of infection.

Rodents, wild birds and beetles can transmit Salmonella. Prevent them from.

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