Salmonella is a type of bacteria that infects the intestines of humans. Most people get salmonella-related sicknesses from drinking contaminated water or eating salmonella-infected foods. There are many different strains of salmonella bacteria (more than 2,000), and roughly 12 of those cause symptoms in humans. The signs of salmonella infection may appear as soon as a few hours after exposure to the bacteria, or not until close to three weeks post-infection, depending upon the strain.
Signs that Appear Within 3 Days After Infection
Salmonellosis (salmonella infection) may be classified as gastroenteritis, which is an inflammation of the stomach and intestines. Signs of salmonellosis begin within a few hours or up to three days after being infected with the salmonella bacteria. Symptoms include headache, abdominal pain, nausea, vomiting, diarrhea, blood in the stool, and muscle aches and pains. These symptoms are also typically accompanied by fever and chills.
Signs that Appear 5 to 21 Days After Infection
While the incubation period for the type of salmonella bacteria that causes salmonellosis is usually one to three days, the incubation period for a different salmonella bacteria--one that causes typhoid fever (another type of bacterial infection more common in developing countries)--is potentially much longer. Signs of typhoid fever do not usually develop until at least five days after exposure to the bacteria (and potentially as many as 21 days post-infection). Common symptoms include changes in bowel function (either diarrhea or constipation), cough, mental confusion, slowed heart rate and raised reddish spots on the upper chest. Physical examination may also reveal enlargement of the liver and spleen. Those with typhoid fever often have a high fever, over 102 degrees Fahrenheit.
Serious Signs
Children, older adults and those with weakened immune systems may be particularly susceptible to developing complications from salmonella. Those with a history of salmonella infection are more likely to develop a condition called Reiter's Syndrome, or reactive arthritis, which causes irritation of the eyes, painful urination and painful joints.
Another common complication is dehydration, which can result from an inability to replace the fluids lost from diarrhea and vomiting. Signs of dehydration include decreased urine output, reduced tear production, dry mouth and sunken eyes.
Salmonella can be especially dangerous if it enters the bloodstream (a condition called bacteremia), where it can spread and infect tissues throughout the body. The central nervous system may be affected, causing meningitis---a condition characterized by swelling of the membranes around the brain and spinal cord. Endocarditis---inflammation of the membranes covering the heart---can also occur, as can osteomyelitis which is an infection of the bone.
