A 36‐year old previously healthy hairstylist presented with a 3‐day history of fever, dry cough, and “throbbing” headache with mild photophobia. She reported generalized weakness and lethargy, but no confusion. She had no recent travel but had fallen into a Midwestern river while canoeing 2 weeks prior to her acute illness. Examination showed fever (100.8°F), conjunctival suffusion, and bibasilar crackles on chest auscultation. There was no neck stiffness, and the liver and spleen were not palpable. A complete neurologic examination was normal. Laboratory tests showed a WBC count of 3 K/mm3, hemoglobin 11.7 g/dL, platelets 110 K/mm3, creatinine 1.5 mg/dL, elevated AST, ALT, and alkaline phosphatase (576, 584, and 282 IU/L, respectively), and bilirubin 1 mg/dL. Cerebrospinal fluid examination was normal. Serum acetaminophen level and acute viral hepatitis panel were negative. Chest X‐ray showed a left lower lobe infiltrate, and oral azithromycin and IV ceftriaxone were started. On day 2, she had increased cough, hypoxia, diffuse myalgia, and a faint maculopapular skin rash over the chest and both lower legs. A chest CT showed multifocal patchy areas of pneumonia with bilateral pleural effusions. Bronchoscopic visualization and lavage samples were normal. The patient's symptoms, her conjunctival suffusion, rash, pancytopenia, renal failure, and transaminitis were most consistent with leptospirosis or ehrlichiosis, and oral doxycycline was started. Blood cultures were negative. An extensive serologic workup including Legionella, Mycoplasma, CMV, EBV, HIV, Toxoplasma, Ehrlichia, Leptospira, Q‐fever, fungal, adenovirus, cryoglobulin, and rheumatologic tests was normal. She showed clinical improvement, although the etiology of her acute illness remained unknown at discharge. At her 3‐month follow‐up, she was doing well. A repeat Leptospira antibody assay was positive (1:100 titer).
Leptospirosis is a zoonotic infection that is transmitted to humans via water, food, or soil contaminated with infected animal urine. Following an incubation period of 4‐28 days, adults commonly present with a flulike prodrome (fever, chills, myalgias, headache) and evidence of endothelial damage and vasculitis causing meningitis, liver disease, renal failure, pulmonary alveolar hemorrhage, serositis, and skin rash. The disease is fatal in 1%–5% of cases. The microscopic hemagglutination test is the diagnostic gold standard. Because of the wide range of nonspecific symptoms, a strong clinical suspicion is required to establish the diagnosis of leptospirosis, confirmed with serologic testing. The organism has had a recent resurgence in Midwestern lakes and rivers.
Clinicians should be aware that initial antibody assays during the acute illness may be falsely negative because of an inadequate humoral response or the prozone phenomenon. As seen in this case, treatment with doxycycline and repeat serologic testing in convalescence are recommended in all clinically suspected cases with an initial negative test.
S. Nichani, none; P. Gupta, none; S. Cinti, none.
To cite this abstract:Nichani S, Gupta P, Cinti S. Convalescent Serologic Testing: Second Time's the Charm. Abstract published at Hospital Medicine 2009, May 14-17, Chicago, Ill. Abstract 178. Journal of Hospital Medicine. 2009; 4 (suppl 1). https://www.shmabstracts.com/abstract/convalescent-serologic-testing-second-times-the-charm/. Accessed November 11, 2019.