Zoonoses disease-listeriosis, Biology

Listeriosis

Listeriosis is an important food-borne zoonosis caused by pathogenic species of Listeria. The disease affects both in man and animals. It is a serious invasive disease characterized by neural, visceral and reproductive clinical entities and may lead to septicaemia, abortion, stillbirth, meningitis and meningoencephalitis. The disease is also known as leucocytosis, listerial infection, listeriasis, listerellosis, circling disease in animals.


Epidemiology:
Listeriosis occurs throughout the world with varying degree of prevalence. The incidence ranges from sporadic cases to major epidemics. The genus Listeria comprises of 6 species namely L. monocytogenes, L. innocua, L. ivanovii, L. seeligeri and L. welshimeri and L. grayi. Of these, L. monocytogenes and L. ivanovii cause the disease in man and animals. L. monocytogenes is a gram-positive, facultatively anaerobic coccobacillus, motile at 20oC to 25oC and a facultative, intracellular parasite of the reticuloendothelial system. It is widely distributed in animals and man, as well as in the environment and has been isolated from numerous sites, including soil, sewage water and decaying plant material, especially poorly fermented silage.


Clinical features: The symptoms of listeriosis in human are mainly due to septicaemia and encephalomeningitis. Listerial abortion in women usually occurs in the second half of pregnancy and more frequent in the third trimester. The suffering mother may show the symptoms like chills, fever, dizziness and sometimes gastrointestinal disturbances before miscarriage or delivery. Listerial septicemia also occurs among weakened adults, especially patients undergoing long term treatment with corticosteroids or antimetabolites. It may also result in endocarditis, external and internal abscesses and endophthalmitis. A cutaneous eruption has been described among veterinarians who handled infected fetuses of animals. The case fatality is comparatively high that may be as high as 25 to 30 %.


Diagnosis: Diagnosis of listeriosis is made by isolation of the pathogen from blood, cerebrospinal fluid, amniotic fluid or biopsy materials.Conventional serological tests are used for epidemiological surveillance of listeriosis. Outer membrane protein (OMP) of Listeria spp. is also used for developing genus and species specific ELISA. The pathogenicity testing of Listeria isolates by in-vivo methods namely chick embryo and mouse inoculation tests is preferred to confirm the link between isolates and causation of disease. PCR based detection me tho d s ha ve b ee n e mplo ye d a s a d ditio nal to o ls fo r the ide ntific a tio n o f microorganisms. A fragment containing the gene encoding delayed-hypersensitivity- inducing protein is used as a probe to differentiate between pathogenic and non- pathogenic strain of Listeria in clinical, environmental and food samples. PCR- ELISA technique has also been developed to detect and quantify L. monocytogenes in food products.


Prevention and control: Animals with encephalitis and abortion should be separated  and the placenta and fetus should be properly destroyed. New animals should only be added to a herd after undergoing a reasonable period of quarantine.  A common recommendation is to properly ensilage the fodder and avoidance of feeding contaminated, decayed and mouldy silage. Other measures include pasteurization of milk, rodent control and common practices of environmental and personal hygiene. Food from suspected origin should always be adequately cooked. Vegetables that are eaten raw should be washed thoroughly and raw meat should be kept separately from other foods. Veterinarians must take precautions when dealing with parturition, abortions and during autopsies.

Posted Date: 9/20/2012 2:43:37 AM | Location : United States







Related Discussions:- Zoonoses disease-listeriosis, Assignment Help, Ask Question on Zoonoses disease-listeriosis, Get Answer, Expert's Help, Zoonoses disease-listeriosis Discussions

Write discussion on Zoonoses disease-listeriosis
Your posts are moderated
Related Questions
Q. Non-Modifiable Risk Factors for coronaru heart diseases? Non-Modifiable Risk Factors 1. Age 2. Sex 3. Heredity 4. Endomorphic Body Build Family history: Pe

What are the processes involved in the preparation of plant tissue for free hand sectioning?

Person Z swallowed a large amount of substance X and, as a result, has convulsions (abnormal violent contractions of skeletal muscles).  Swallowing which of the following substance

The Social Environment   When the child is admitted to the hospital his social environment is totally changed and all health team members are strangers for him. It is your resp

Hypertensive emergencies should be treated within one hour. Hypertensive urgencies may be treated more slowly. The term accelerated malignant hypertension is used when retinal haem

Natality Rate - Natality Natality rate or birth rate is determined by dividing the number of individuals born by unit time and is expressed as follows: Natality rate =  ΔNn

Q. What are carcinogens? The Carcinogens are factors capable of producing neoplasias and any mutagen, a substance that can induce DNA mutation, is a potential carcinogen. Insta

Unfortunately, unlike heart failure due to systolic dysfunction, diastolic heart failure has been studied in few clinical trials, so there is little evidence to guide the care of p

What are target organs of the hormones? Target organs, target tissues and target cells are those exact organs, tissues and cells upon which each hormone acts and makes its effe

Q. Role of Exercise and Drugs in management of diabetes? Aerobic exercise for at least 20-30 minutes four or more times a week is recommended. Exercise after meals is preferre