describe signs and symptoms of diseases that are caused by Salmonella, Shigella, and Escherichia coli

Answer 1

Enteric fever is caused by Salmonella typhi and Salmonella paratyphi. Other Salmonella infection is most commonly associated with ingestion of poultry, eggs, and milk products, but many other food products and animal contacts are also sources of infection. Symptoms of Salmonella gastroenteritis typically occur within 8 to 72 hours following exposure. The cardinal features include diarrhoea, nausea, vomiting, fever, and abdominal cramping, and are usually self-limited. Fever generally resolves within 48 to 72 hours and diarrhoea within 4 to 10 days. The cornerstone of therapy of symptomatic Salmonella gastroenteritis is the replacement of fluids and electrolytes. 

Shigella is a common cause of bacterial diarrhoea. It is transmitted by direct person-to-person spread and, less commonly, through contaminated food and water. The incubation period ranges from one to three days. Patients with Shigella gastroenteritis typically present with high fever, abdominal cramps, and bloody, mucoid diarrhoea. Shigella gastroenteritis generally is self-limited,

Intestinal complications of Shigella infection include proctitis, rectal prolapse, toxic megacolon, intestinal obstruction, and colonic perforation.

Systemic complications of Shigella infection include bacteremia, metabolic disturbances (hypovolemia, hyponatremia, protein-losing enteropathy), leukemoid reaction, neurologic disease (seizures, encephalopathy), reactive arthritis, and hemolytic uremic syndrome.

Now let's look at E. Coli. Escherichia coli are normal inhabitants of the human gastrointestinal tract. The different E. coli pathotypes have distinct epidemiologic, clinical, and pathogenic features which are described in the table below for simple understanding.

Enterotoxigenic E. coli (ETEC)	Watery diarrhoea
Enteropathogenic E. coli (EPEC)	Infantile diarrhoea
Enterohemorrhagic E. coli (EHEC)	Hemorrhagic colitis and hemolytic uremic syndrome
Enteroinvasive E. coli (EIEC)	Dysentery(Bloody diarrhoea)
Enteroaggregative E. coli (EAEC)	Persistent diarrhoea in children and patients infected with HIV

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