Symptoms of Salmonella infection include painful abdominal cramps, diarrhea, and fever.
Salmonella infections can have a broad range of illness, from no symptoms to severe illness. The most common clinical presentation is acute gastroenteritis. Symptoms include diarrhea and abdominal cramps, often accompanied by fever of 100°F to 102°F (38°C to 39°C). Other symptoms may include bloody diarrhea, vomiting, headache and body aches.
The incubation period, or the time from ingestion of the bacteria until the symptoms start, is generally 6 to 72 hours; however, there is evidence that in some situations the incubation can be longer than 10 days. People with salmonellosis usually recover without treatment within three to seven days. Nonetheless, Salmonella bacteria can persist in the intestinal tract and stool for many weeks after the resolution of symptoms—on average, one month in adults and longer in children.
S. Typhi and S. Paratyphi are capable of causing systemic illness if they invade the bloodstream (termed “bacteremia”). “Septicemia” or “sepsis” (bloodstream infection or “blood poisoning”) occurs if the bacteria multiply in the blood and cause the immune system to respond by activating inflammatory mechanisms. This may result in the development of “systemic inflammatory response syndrome,” or “SIRS.” By definition, SIRS includes tachycardia, tachypnea, fever, and abnormal white blood cell count. When the bacteria involved are S. Typhi or S. Paratyphi, this serious illness is called enteric typhoid, or paratyphoid fever. Symptoms may start gradually and include fever, headache, malaise, lethargy, and abdominal pain. In children, it can present seemingly innocuously as a non-specific fever. The incubation period for S. Typhi is usually 8 to 14 days, but it can range from three to 60 days. For S. Paratyphi infections, the incubation period is similar to that of nontyphoidal Salmonella—one to 10 days.