Internal Medicine

0521779407-13 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:15

Leptospirosis, Relapsing Fever 895

■The site of the original bite in rat-bite fever heals initially, but several

weeks later the site becomes swollen, painful, and bluish, ulcerates

and is associated with lymphangitis, regional adenopathy, fevers,

chills, and a diffuse reddish-blue or reddish-brown rash. Symptoms

resolve in several days. Without therapy relapses of fever, generally

without other manifestations of disease, recur at weekly intervals for

several months.

tests

■Leptospirosis – WBC may be normal or high; liver function tests often

abnormal; CXR may show nonspecific infiltrates; CSF in meningitis

characterized by a lymphocytic pleocytosis and elevated protein;

organism can be cultured from blood, urine and CSF in septicemic

phase, but special medium required and growth slow; diagnosis usu-

ally made serologically. PCR not yet widely available.

■Relapsing fever – normal or elevated WBC; lymphocytic pleocytosis

in CSF in meningitis; diagnosis usually made by observing spiro-

chetes in Giemsa- or Wright-stained smears of peripheral blood dur-

ing periods of fever; Proteus OXK agglutinins may be positive; false-

positive nontreponemal tests for syphilis and false-positive serologic

tests for Lyme disease can occur. Animal inoculation and in vitro

cultivation possible in select labs. Little evidence for PCR for clinical

diagnosis.

■Spirillium minus cannot be grown on synthetic medium; diagnosis

made by observing organism in blood, cutaneous lesion or aspirate

of lymph node using Giemsa or Wright stain; false-positive nontro-

ponemal test for syphilis can occur

differential diagnosis

■Leptospirosis must be differentiated from relapsing fever, rat-bite

fever, systemic viral infections, rickettsial infections, bacterial and

viral meningitis and other causes of hepatitis in Weil’s syndrome

(see complications).

■Relapsing fever may be confused with leptospirosis, rat-bite fever,

Colorado tick fever, malaria, dengue.

■Rat-bite fever must be distinguished from other form of rat-bite

infection caused by Streptobacillus moniliformis, which is charac-

terized by severe myalgias and arthritis; other considerations include

relapsing fever, malaria, tularemia and Pasteurella moltocida infec-

tions.