Monograph

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definition: 

Chicken salmonellosis is a contagious infectious disease of bacterial origin that affects birds and humans.

The dramatic development of collective food toxi-infections in humans caused by S.thyphimurium and S.enteritidis has stressed the hygienic importance of the contamination of the poultry industry by these bacteria, and of the egg industry in particular.

Only S. enteritidis and S. typhimurium infections, exclusively in the species Gallus gallus, are on the list of diseases deemed contagious. Chicken salmonellosis and salmonellosis swine flu are on the list of notifiable diseases.

Situation in America: 

Chicken salmonellosis is universally widespread.

The carribbean region had reported a total of 429 cases in 2002. New outbreaks occur regularly. For example one case was detected in 2006 in a Guadeloupean egg chicken farm.

Susceptible species: 

Species affected: salmonellosis affects the majority of animals (including hens and other birds) and humans.

Etiological agent: 

Chicken salmonellosis is caused by Salmonella enteritidis and S. thyphimurium, two serotypes of enterobacteria belonging to the genus Salmonella, an enterica species.

Methods of transmission
Source: 

The virulent material is primarily droppings.

Transmission: 

Transmission of the disease can be horizontal, direct or indirect, or vertical (ovarian transmission or contamination of the shell while passing through the cloacae).

Chronic or non-apparent carrying is common and is responsible for a major spread of the disease.


Salmonella are usually transmitted to humans by eating food contaminated with animal feces. Contaminated food usually looks and smells normal.

Symptoms: 
  • Animals

Incubation period: 24 to 48 hours

These are non-specific and are primarily observed in chicks aged under 15 days and very rarely in chickens aged over four weeks:

- Septicemia form (chicks): general pronounced symptoms (exhaustion, ruffled feathers, etc.) and diarrhea
- Localized form: diarrhea and more or less pronounced exhaustion

  • Humans

Incubation period : 12 to 72 hours

Most persons infected with Salmonella develop diarrhea, fever and abdominal cramps.

The illness usually lasts 4 to 7 days, and most persons recover without treatment. However, in some persons, the diarrhea may be so severe that the patient needs to be hospitalized. In these patients, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics.

The elderly, infants, and those with impaired immune systems are more likely to have a severe illness.

Lesions
Macroscopic lesions: 

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

Diagnostics
Laboratory diagnosis: 

- Detection of the pathogenic agent through isolation, identification and typing of salmonella in droppings or liver sample from a chick

- Detection of antibodies using an ELISA test

Treatment: 

Animals

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

Humans

Salmonella infections usually resolve in 5-7 days and often do not require treatment other than oral fluids. Persons with severe diarrhea may require rehydration with intravenous fluids. Antibiotics, such as ampicillin, trimethoprim-sulfamethoxazole, or ciprofloxacin, are not usually necessary unless the infection spreads from the intestines. Some Salmonella bacteria have become resistant to antibiotics, largely as a result of the use of antibiotics to promote the growth of animals.

Prophylaxis: 

Sanitary:

Adherence to standard hygiene measures of breeding farms (sufficient aeration, avoiding overcrowding, clean litter, etc.)

Systematic and regular inspection of breeding farms

In the event of an outbreak, the total slaughter of animals, the destruction of eggs combined with the disinfection of contaminated premises and equipment and a depopulated period

Vaccines: 

Attenuated and modified vaccines against S.enteritidis and S.typhimurium. These vaccines enable a reduction, but not a suppression of fecal excretion.


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