infectious diseases
Typhoid Fever
Symptoms and Signs of Typhoid Fever
For typhoid fever, the incubation period (usually 8 to 14 days) is inversely related to the number of organisms ingested. Onset is usually gradual, with fever, headache, arthralgia, pharyngitis, constipation, anorexia, and abdominal pain and tenderness. Less common symptoms include dysuria, nonproductive cough, and epistaxis. Without treatment, the temperature rises in steps over 2 to 3 days, remains elevated (usually 39.4 to 40°C) for another 10 to 14 days, begins to fall gradually at the end of the 3rd week, and reaches normal levels during the 4th week. Prolonged fever is often accompanied by relative bradycardia and prostration. Central nervous system symptoms such as delirium, stupor, or coma occur in severe cases. In about 10 to 20% of patients, discrete, pink, blanching lesions (rose spots) appear in crops on the chest and abdomen during the 2nd week and resolve in 2 to 5 days. Splenomegaly, leukopenia, anemia, liver function abnormalities, proteinuria, and a mild consumption coagulopathy are common. Acute cholecystitis and hepatitis may occur. Late in the disease, when intestinal lesions are most prominent, florid diarrhea may occur, and the stool may contain blood (occult in 20% of patients, gross in 10%). In about 2% of patients, severe bleeding occurs during the 3rd week, with a case fatality rate of about 25%. An acute abdomen and leukocytosis during the 3rd week may suggest intestinal perforation, which usually involves the distal ileum and occurs in 1 to 2% of patients. Pneumonia may develop during the 2nd or 3rd week and may be due to secondary pneumococcal infection, althoughS.Typhi itself can also cause pneumonia. Bacteremia occasionally leads to focal infections such as osteomyelitis, endocarditis, meningitis, soft-tissue abscesses, glomerulitis, or genitourinary tract involvement. Atypical presentations of typhoid fever, such as pneumonitis, fever only, or, very rarely, symptoms consistent with urinary tract infection, may delay diagnosis. Convalescence may last several months. In 8 to 10% of untreated patients with typhoid fever, symptoms and signs similar to the initial clinical syndrome recur about 2 weeks after defervescence. For unclear reasons, antibiotic therapy during the initial illness increases the incidence of febrile relapse to 15 to 20%. If antibiotics are restarted at the time of relapse, the fever abates rapidly, unlike the slow defervescence that occurs during the primary illness. Occasionally, a 2nd relapse occurs. 