Final answer:
Salmonella enterica serovar Typhi causes typhoid fever, a severe systemic illness with symptoms like high fever and intestinal hemorrhage, while nontyphoidal Salmonella serotypes generally cause a milder illness known as salmonellosis or gastroenteritis with symptoms such as diarrhea and vomiting.
Step-by-step explanation:
Salmonella typhi vs Nontyphoidal Salmonella
Salmonella enterica serovar Typhi, the causative agent of typhoid fever, is a Gram-negative, rod-shaped gamma proteobacterium. Typhoid fever is spread through feces and causes intestinal hemorrhage, high fever, delirium, and dehydration. Notably, carriers of Salmonella typhi can be asymptomatic, such as the historical figure "Typhoid Mary" who unwittingly spread the disease to many individuals. The disease is severe, with a significant mortality rate, particularly when left untreated. In contrast, nontyphoidal Salmonella serotypes, which are more commonly associated with salmonellosis or gastroenteritis, cause milder symptoms such as inflammation of the intestines, fever, vomiting, and diarrhea. These serotypes include S. enterica serotypes like Enteritidis and Typhimurium, which generally have a lower mortality rate in healthy adults. It is important to note the difference in the infectious dose required to cause these different illnesses. While nontyphoidal Salmonella can infect with a very low infectious dose and lead to salmonellosis, Salmonella typhi requires a higher infectious dose to cause typhoid fever. However, typhoid fever is far more severe and systemic, with symptoms including fever, abdominal pain, and skin rashes.