Categorised as typhoidal and non-typhoidal serotypes.

Increasing resistance to various types of antibiotics.

Typhoidal: cause typhoid and para-typhoid fever.

Non-typhoidal: 1 of 4 key global causes of diarrhoeal diseases; most cases of salmonellosis are mild; but sometimes they can be life-threatening.

S. Typhi and S. Paratyphi A and B are highly invasive bacteria that pass through the intestinal mucosa  of humans rapidly and efficiently to eventually reach the underlying lymphoid tissue and spread to other organs.

Salmonella Typhi is usually spread through contaminated food or water.

Non-typhoidal Salmonella is usually spread through contaminated food, water or direct contact with animals.

Typhoidal Salmonella causes prolonged fever, fatigue, headache, nausea, abdominal pain, and constipation or diarrhoea. Some patients may have a rash. Severe cases may lead to serious complications or even death.

Non-typhoidal Salmonella  is usually characterized by acute onset of fever, abdominal pain, diarrhoea, nausea and sometimes vomiting. Symptoms of salmonellosis are relatively mild, but in some cases, particularly in children and elderly patients, the associated dehydration can become severe and life-threatening.