Salmonellosis, Biology

Assignment Help:

Salmonellosis

The genus Salmonella comprises nearly 2500 serovars, traditionally based on Kauffman-White scheme in which H (flagelar) and O (somatic) antigens determine the serovar. Recent molecular techniques like multilocus enzyme electrophoresis and DNA-DNA hybridization analysis revealed that the genus can be divided into two  species S. Bongori (20 serovars) and S. Enterica (2443 serovars). Serovars of S. Enterica are commonly responsible for causing the disease. Most of the salmonellae species are pathogenic to man and animals, and therefore there is risk of human infection arising out of animal sources and less frequently of animal infection derived from human beings. The presence of organisms in milk or meat derived from infected animals is of great significance in infection of human beings.Salmonella organisms are intestinal pathogens. The organisms are short rods, mostly motile and are gram-negative. They have little resistance to sunlight, heat and drying. Some serovars of the organisms are host specific, e.g. S. Abortus-ovis in sheep, S. Abortusequi in horses and S. Gallinarum and S. Pullorum in fowl. The other serotypes are predominantly of one host but may be found in others. S. Typhimurium is the most common one, found in man, cattle, sheep, pigs, horses, fowl and rodents.


Stress is a pre-disposing factor in most instances of salmonellosis, especially in adult animals, but in young animals, particularly calves, explosive outbreaks occur even without stress. The stress may be due to intercurrent disease, starvation, calving, vaccination or administration of anthelmintics. Sometimes, administration of antibiotics may lead to salmonellosis caused by the antibiotic resistant strains.


Transmission:
Transmission takes place through contamination of water or pasture or feed by faeces of carrier or infected animals. Ingestion is the usual mode of entry. Sheep are frequently affected under drought conditions. Carrier animals bring the infection to the farm. Rodents, wild birds, lizards, turtles and snakes are also responsible for the spread of infection at the farm.

Symptoms: Calves 1 to 2 weeks of age usually develop enteric symptoms when infected with S. Typhimurium and septicaemia with S. Dublin. The septicaemic syndrome occurs in young animals 10-14 days old. There is dullness, high fever, in co-ordination of gait and recumbency. The faeces are blood streaked. Death takes places within 1-2 days or may be delayed to 5-7 days. In calves the carpal and tarsal joints become enlarged. Occasionally pneumonia and enteric symptoms occur. In pigs there is, in addition, a tendency to remain standing or wander; nervous symptoms like tremors, paralysis and convulsions may be present.The enteric syndrome is commonly seen in adult animals. There is high fever followed by severe diarrhoea in which there are clots. The temperature becomes normal or subnormal. Death takes place in about 5 days time. More prolonged cases show dehydration; polyarthritis may follow. Abortions may occur in pregnant animals.In pigs, in addition to enteric syndrome, there may be pueumonic syndrome. When the reproductive system is affected as in sheep and horses, abortions result in pregnant animals.


Lesions: In young animals there may be haemorrhages in myocardium and peritoneum, and acute inflammation of the intestine and bladder. Spleen is enlarged, and mesenteric lymph glands are oedematous and haemorrhagic. In pigs there may be discolouration of skin and haemorrhages throughout the body. In adults there is diffuse haemorrhagic enteritis. The spleen is enlarged and congested. The caecum may show zebra markings. In pigs caecum and colon are mainly affected.
 

Diagnosis:
The symptoms and lesions in dead animals are only suggestive of salmonellosis. The final diagnosis depends upon bacteriological examination.


Treatment: Sulphonamides, antibiotics and nitrofurazones are effective against this organism but treated animals remain as carriers.


Control: It is very important to remove all possible sources of infection, carrier animals and wild rodents contaminating food or water supplied. Killed and attenuated vaccines are being used especially against Salmonella Abortus equi in horses with reasonable success. In developed countries, salmonellosis is becoming an increasing menace


Related Discussions:- Salmonellosis

Mention the name of the causal organism, a) Mention the name of the causal ...

a) Mention the name of the causal organism, symptoms and the mode of transmission of the disease Amoebiasis b) Mention the property that enables the explants to restore into a n

Handling microorganisms, Handling : You can reduce direct contact with mic...

Handling : You can reduce direct contact with microorganisms by careful handling and by wearing protective clothing such as rubber gloves, mask, lab coat, etc. Even if you entirel

Examples of invertebrate nervous system, Q. Using examples of invertebrate ...

Q. Using examples of invertebrate nervous systems how can the process of evolutionary cephalization be described? Considering the example of invertebrates it is observed that e

What are the constituent elements of the blood, Q What are the constituent ...

Q What are the constituent elements of the blood? The blood is made of a liquid and a cellular part the fluid part is called as plasma and in it there are several substances li

Explain the term - diffusion, Explain the term-Diffusion Diffusion occu...

Explain the term-Diffusion Diffusion occurs from the side of greater concentration to the side of lesser concentration. In aqueous humour this occurs from the plasma side in th

Parts of a seed , Parts of a Seed Seed is attached to the fruit by a ...

Parts of a Seed Seed is attached to the fruit by a stalk, the funiculus (funicle). The prolongation of the funiculus running along the seed and terminating at the chalaza is

Principles of homeostasis with negative feedback, The principle of homeosta...

The principle of homeostasis is controlling the heating system with a simple thermostat in a house. These components are essentials thermometer, source of heat turning it on or off

Stratification, Stratification On the basis of the variation in air tem...

Stratification On the basis of the variation in air temperature. the atmosphere has been divided vertically into four layers: (figure shown below) thee troposphere, stratospG,

Biomedical waste management, Waste generated is termed as "Biomedical Waste...

Waste generated is termed as "Biomedical Waste" which means a waste that may contain human pathogens of sufficient virulence and in sufficient concentrations that exposure to it by

Botany, how can i earn money by submitting assignments?

how can i earn money by submitting assignments?

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd