Salmonella bacteria is a pathogen that is found mostly in the intestinal tract of humans and animals [1] . Every year it affects thousands of livestock and millions of humans. It can commonly occur in the form of gastroenteritis. Most people contract fever, diarrhoea or abdominal cramps within twelve and seventy two hours of infection. This gets cured somewhere between a period of four to seven days, without serious treatment [2] .
Diseases Commonly Caused By Salmonella
There are three major clinical disease forms of salmonellosis, namely gastroenteritis, septicemia and enteric fever. In the septicemic stage, the patient is an intermediate zone, where he or she is not experiencing any abdominal symptoms, and the bacteria is still isolated in the faeces. The severity of the disease gets completely dependent on the immunity of the patient, or the strength of the bacterial isolate.
Salmonella gastroenteritis can incubate any time between six to forty eight hours, depending on the dosage of bacteria. As a result, nausea, stomach pain, vomiting and diarrhoea can take place. Headaches and myalgia are normal symptoms. Sometimes it can be accompanied by a fever of 38°C to 39°C.
A more dangerous systematic fever form of salmonellosis is an enteric fever. The bacteria can incubate any time after 10 to 14 days of infection. Typhoid is the most commonly caused enteric fever, by bacteria Salmonella typhi. Gastroenteritis usually occurs a few days before this fever; the major symptoms can be headaches, myalgia, fever, loss of weight and constipation. It can be fatal if not treated on time.
Symptoms Of Salmonella Infection
The common symptoms of salmonellosis include gastroenteritis, septicaemia, enteric fever, infections and asymptomatic carrier stage. Serovars like S. typhi, S. paratyphi-A usually showcase strong symptoms in the body. S. choleraesuis causes focal infections or septicaemia. S. typhimurium leads to gastroenteritis. However, a serovar can produce any symptom depending upon the situation.
Non-typhoid salmonella enters the body through unhygienic food and can spread from one person to another. The bacteria must have certain attributes to be called a virulent pathogen:
• It should be able to attack cells.
• A full lipopolysaccharide coat must be present.
• It should be able to multiply intracellularly.
• It can enhance the toxins within the body.
This bacteria once ingested, can make colonies inside ileum and colon. It attacks the epithelium in the intestinal layer and rapidly grows inside the follicles. Their ability to invade the system depends on the rearrangement of cytoskeleton cells; they undergo a process called ruffling once they attack.
Salmonella proliferates intracellularly and then gradually spread to lymph nodes and other body parts through blood circulation. Their spread and confinement are controlled by reticuloendothelial cells. However, depending on the host defence mechanism, the pathogens can cause infection in the liver, gallbladder, bones, spleen, meninges, etc. They get killed mostly when they try to spread beyond intestine
Our body can show symptoms of ulcers, which is an intense inflammatory response of the body, against salmonella. This enhances the effects of cytotoxins, which prevent protein synthesis. Once the mucosa layer in the epithelium is attacked, it produces inflammatory cytotoxins like IL-1, IL- 8, IL-6, TNF-2, etc. They cause a burning sensation and may even disrupt the intestinal functions. This can easily cause symptoms like fever, shocks, abdominal pain, diarrhoea and leucocytosis. The faeces may contain blood and stool.
Once salmonella invades the epithelium, it does not escape the phagosome and secrets fluid that causes diarrhoea. Hence, the intracellular spread does not escape beyond intestines; it stays confined and limited. Once the bacteria reach lamina propria, it causes enteric fever.
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