👉 Typhoid fever is a bacterial infection caused by Salmonella typhi, which can affect both children and adults. It typically starts with a high fever, followed by diarrhea, abdominal pain, nausea, and vomiting. Symptoms may vary from person to person, but they often include malaise, headache, fatigue, and loss of appetite. In severe cases, it can be life-threatening if not treated promptly.