The incubation period for typhoid fever is 6-30 days, and for paratyphoid fever it is 1-10 days. The initial symptoms of typhoid and paratyphoid fevers include the acute or gradual onset of abdominal pain and tenderness, fever, chills, sweating, headache, anorexia, weakness, cough, sore throat, dizziness, and myalgias. Fever develops slowly beginning as low-grade and rising to sustained temperatures of 102°F-104°F (39°C-40°C) by the fourth day. This usually progresses to a severe illness with bacteremia and high fever that may last for weeks. Hepatosplenomegaly is common. Some patients will develop erythematous macules and papules on the trunk (rose spots), and some will suffer altered mental status. Intestinal hemorrhage and bowel perforation are rare, potentially lethal complications that may occur after 2 weeks of illness. Meningitis, chondritis, cholecystitis, pyelonephritis, orchitis, typhoid hepatitis, pneumonia, localized abscesses, endocarditis, and myocarditis are further rare complications.
About 350 culture-confirmed cases of typhoid fever and 90 culture-confirmed cases of paratyphoid fever were reported annually to the US Centers for Disease Control and Prevention (CDC) National Typhoid and Paratyphoid Fever Surveillance (NTPFS) system during 2008-2015. Most cases in the United States are associated with travel to East Asia and South Asia, though these infections can also occur in travelers to Africa, the Caribbean, Central and South America, and the Middle East. In the United States, 75% of cases occur in patients aged younger than 30 years. Untreated, enteric fever carries a 10%-20% mortality rate. In 15%-20% of treated patients, there is relapse after 2 weeks. Reinfection and chronic carriage can occasionally occur.
The CDC has classified drug-resistant nontyphoidal Salmonella and drug-resistant Salmonella serotype typhi as serious infections.
See salmonellosis for discussion of serotypes Salmonella typhimurium and Salmonella enteritidis.
A01.00 – Typhoid fever, unspecified
A01.4 – Paratyphoid fever, unspecified
4834000 – Typhoid fever
85904008 – Paratyphoid fever
Differential Diagnosis & Pitfalls
- In patients who have traveled to an area endemic for S typhi and return with fever, also consider malaria. Other conditions that can mimic the illness include amebiasis, dengue fever, chikungunya, Zika virus infection, cutaneous leishmaniasis, leptospirosis, melioidosis, and trypanosomiasis.
- Acute bacterial gastroenteritis (Campylobacter, Shigella, Escherichia coli O157:H7)
- Tuberculosis – Can present as a prolonged febrile illness; diarrhea (and dysentery) is not expected.
- Endemic typhus – May be difficult to distinguish from typhoid fever.
- Bacterial abscess – Can present as a prolonged febrile illness.
- Endocarditis – Can present as a prolonged febrile illness.
- Q fever