Salmonella is a gram-negative bacterium that usually causes gastroenteritis, but can also cause the more serious infection, typhoid fever. There are over 2,000 different types of Salmonella bacteria, providing a range of infection rates and symptoms. The bacteria is excreted by infected humans and animals in waste, causing contamination to water systems that infected people or animals frequent. The good news is that Salmonella tends to be destroyed by stomach acid, so a large amount is required for infection. However, if the person has a stomach acid deficiency, caused by being young, old, or taking antacids, Salmonella is more likely to infect them. Even though Salmonella usually only affects the gastrointestinal tract, it can spread to the bloodstream. Once in the bloodstream, systemic infection can occur causing infections or collections of pus in bones, the respiratory tract, joints, or the urinary tract. If an artery becomes infected it can lead to chronic bacteremia, or blood infection.
If Salmonella infects the intestine, symptoms typically appear from 12 to 48 hours after being ingested. Diarrhea, nausea, vomiting, fever, and abdominal cramps affect the infected person for 1 to 4 days. Occasionally the symptoms will be more severe and last longer. Additionally, 10-30% of adults will develop reactive arthritis weeks to months after diarrhea stops. This commonly affects the hips, knees, and Achilles tendon, causing pain and swelling. If the bloodstream is infected, other symptoms can develop when the infection spreads. Bone infections causes the area around or over it to be painful, heart valve infection can cause shortness of breath, and aortic infection can cause back and abdominal pain.