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For further information, see CMDT Part 35-17: Salmonellosis
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Essentials of Diagnosis
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Gradual onset of headache, vomiting, abdominal pain
Rose spots, relative bradycardia, splenomegaly, and abdominal distention and tenderness
Slow (stepladder) rise of fever to maximum and then slow return to normal
Leukopenia; blood, stool, and urine cultures positive for Salmonella
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General Considerations
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Caused by typhoidal serotypes of Salmonella, S typhi (typhoid fever), and to a lesser extent S paratyphi (subtypes A, B and C)
Unlike other strains of Salmonella, the S typhi and S paratyphi subtypes A, B, and C are restricted to humans
Infection begins when organisms breach the mucosal epithelium of the intestines
Having crossed the epithelial barrier, organisms invade and replicate in macrophages in Peyer patches, mesenteric lymph nodes, and the spleen
Serotypes other than typhi usually do not cause invasive disease, presumably because they lack the necessary human-specific virulence factors
Bacteremia occurs, and the infection then localizes principally in the lymphoid tissue of the small intestine
Peyer patches become inflamed and may ulcerate, with involvement greatest during the third week of disease
The organism may disseminate to the lungs, gallbladder, kidneys, or CNS
May have a long incubation period (6–30 days)
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Increasing malaise, headache, cough, and sore throat
Abdominal pain and constipation are often present while the fever ascends in a stepwise fashion
During the early prodrome, physical findings are few
There may be marked constipation
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After about 7–10 days, the fever reaches a plateau and the patient is much more ill, appearing exhausted and often prostrated
Marked constipation may develop into "pea soup" diarrhea
Splenomegaly, abdominal distention and tenderness, relative bradycardia, and occasionally meningismus appear
A rash (known as rose spots) commonly appears during the second week of disease
The individual spot, found principally on the trunk, is a pink papule 2–3 mm in diameter that fades on pressure
It disappears in 3–4 days
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Differential Diagnosis
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Tuberculosis
Infective endocarditis
Brucellosis
Lymphoma
Q fever and other rickettsial infections
If there is history of recent travel to endemic areas, consider
Viral hepatitis
Malaria
Amebiasis
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Best diagnosed by isolation of the organism from blood culture, which may be positive in the first week of illness in approximately 80% of patients who have not taken antimicrobial agents
Cultures of bone marrow occasionally are positive when blood cultures are not
Leukopenia, rather than leukocytosis, is generally observed
Transaminitis is common
Anemia and thrombocytopenia may also occur
Stool cultures are often negative by the time systemic symptoms develop