Mystery Listeria in poultry, listeriosis in birds is caused by a bacterium (Listeria monocytogenes). Although many species of birds, including chickens, turkeys, pigeons, ducks, geese, pheasants, canaries, and cockatiels, are susceptible to natural infections, clinical diseases in birds are rare.
Zoonotic disease is dangerous. L monocytogenes is an important foodborne pathogen in people and is a major concern to the public and the poultry industry. Outbreaks of listeriosis typically occur after exposure to raw or undercooked poultry products, but also occur after consumption of contaminated ready-to-eat poultry meat products.
In general, young birds are more susceptible and more susceptible to clinical disease than older birds. In backyard poultry, disease occurs intermittently such as septicemia or encephalitis, is an intracellular pathogen that has a unique ability to spread from cell to cell, allowing it to cross the blood-brain, intestinal and placental barriers and spread the organism in nature.
It has been isolated from animals, humans, food sources (milk, meat, meat products, seafood, vegetables, fresh fruits) and the environment (soil, decomposing plants, water) and is known to cause sporadic outbreaks worldwide.
The cause of listeriosis in poultry
(L monocytogenes) is a non-forming, facultative intracellular Gram-positive, facultatively anaerobic, rod-shaped bacterium. They are ubiquitous and commonly found in the environment, including soil, sewage, animal feces, and surface water. In temperate regions, the primary hosts for the organism are soil and decomposing plants. This organism is common in poorly preserved corn forages.
L monocytogenes has been isolated from the intestines of healthy animals, including various types of mammals, birds, and fish. Transmission occurs by ingestion or inhalation, as well as by contamination of the wound. In ruminants, the cerebral form of listeriosis develops after entering the organism through minor injuries to the conjunctiva or oral and nasal mucosa, with subsequent migration along peripheral nerves to the brain.
It is not known if this same pathway of infection occurs in birds. Contamination of poultry farms with fecal material from nearby food animal farms (eg cattle or pig farms) is an important source of infection, especially after rain or floods, beak trimming wounds, and injections of pollen are potential sites of entry for the organism.
Listeriosis occurs most commonly in birds that live in northern and southern latitudes, temperate climates, and in the northern hemispheres, listeriosis has been found to occur most frequently between December to May. Listeria reproduces perfectly at temperatures from 30-37 °C but can withstand temperatures between 0 and 43 °C (4, 5), in addition to being able to survive in a wide range of temperatures.
It can grow in a variety of salt concentrations, high osmotic pressures, and low pH environments, but it is subject to pasteurization, and there are at least six known species of Listeria.
Symptoms of listeriosis in poultry
In the listeriosis toxemia form, clinical signs are nonspecific and include a short period of depression and lethargy, followed by death, sudden death may occur without initial clinical symptoms, in the cerebral form, ataxia occurs, lateral recumbency with rowing of the leg, twisting, and retraction of the neck back, paralysis in infected birds.
Necrosis and inflammation of the heart muscle (myocarditis) is the most common lesion in birds with listeriosis septicemia. In aggregate, the affected areas of the heart muscle are yellow and dry due to necrosis. Often, there is an enlargement of the spleen, necrotic foci in the liver Pericarditis. Other reported lesions in broilers include dropsy, petechiae in the myocardium, liver, kidney, and spleen.
In the cerebral form, there are no gross lesions of the brain, but histopathological lesions are noticeable and include foci of necrosis, mixed inflammatory infiltrates composed predominantly of lymphocytes, marked perivascular lymphatic cuffs, and glia.
The lesions are usually regionally widespread and found in the medulla oblongata, where they are generally more severe in the optic lobes and cerebellum. Gram staining of tissues usually reveals Gram-positive bacteria within the lesions. L monocytogenes is usually abundant in myocardial lesions but not in brain lesions.
Diagnosis of listeriosis in poultry
In the form of sepsis, gross and histological lesions of the myocardium should provoke and allow the initial diagnosis of listeriosis, the diagnosis is confirmed by immunohistochemical staining to show (L monocytogenes) in tissues or by isolation of the organism, usually from the liver and spleen in the form of septicemia and the brain, in the form of encephalitis.
Direct culture of the brain may not always be successful due to the small number of organisms in the tissue. Recovery of (Lmonocytogenes) is greatly increased if a portion of the sample is refrigerated for 4-8 weeks and cultured weekly, alternatively, the tissue can be eroded or mixed with general nutrient broth (eg, Trypticase soy broth, brain heart infusion) in a ratio of 1: 10, The broth medium is incubated at 35°C (95°F), for 5-7 days and checked daily for growth.
The differential diagnoses of listeriosis include septicemia other types of bacterial septicemia such as colibacilli, Pasteurella, and for cerebral listeriosis, differential diagnoses include viral brainstems, such as Marek's disease and exotic Newcastle disease, with the latter the neurological signs usually follow High mortality in the herd and disease lesions are present in the visceral organs.
Treatment and prevention of listeriosis in poultry
Antibiotics can be used successfully to treat the septicaemic form of the disease. In vitro, L monocytogenes are susceptible to penicillin, tetracycline, erythromycin, gentamicin, and trimethoprim-sulfamethoxazole, encephalitis treatment is usually unsuccessful and prevention should focus on identifying and eliminating potential sources of infection.
Supportive care is important, we must isolate the bird from the flock and put it in a safe, comfortable, and warm place with easy access to water and food, stress must be reduced, and contact the veterinarian, Enrofloxacin can be given 25 mg/kg of body weight given intramuscularly for 5 days and Virginiamycin 22 mg/kg QD administered in feed.
There was no change in disease after treatment with different antibiotics, so the efficacy of antibiotic treatment was unclear, and good standards of hygiene and biosecurity are likely to reduce disease spread and reduce any zoonotic risks.
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