Pathologic Studies of Leptospirosis, Ten-Years Experience at Centers for Disease Control and Prevention
W-J Shieh, P Chris, J Guarner, SR Zaki. Centers for Disease Control and Prevention, Atlanta, GA; Children's Hospital of Atlanta, Emory University, Atlanta, GA
Background: Leptospirosis is a zoonotic disease caused by spirochetes of the genus Leptospira. It is a common infection affecting many species of wild and domestic animals worldwide. Human infection can occur either through direct contact with infected animals or more commonly through indirect contact with water or soil contaminated with the urine of infected animals. Pathologic studies are rarely performed and the pathogenesis of leptospirosis remained largely unknown.
Design: One hundred and sixty-five cases with positive immunohistochemical (IHC) test results for leptospira were identified from 19982008 database at Infectious Disease Pathology Branch, CDC. Although a few cases were from the US, most came from South America, Central America, and South East Asia. Histopathologic evaluation on available tissue samples was performed. The IHC assay was an indirect immunoalkaline phosphatase technique with a mixture of 16 rabbit polyclonal anti-leptospira antisera. Steiner's silver stain was also performed on selected cases.
Results: Histopathologic changes in the liver included hyperplasia of Kupffer cells, mild to moderate inflammatory infiltrate in portal tracts, and occasional hepatocellular necrosis. The lung frequently showed prominent intra-alveolar hemorrhage. The most consistent histopathology was a diffuse tubulointerstitial inflammation in the kidney, characterized by a mixed infiltrate of inflammatory cells. Although silver stains can highlight leptospires in tissues, they were not able to demonstrate fragments of bacteria disintegrated by host response or antibiotics treatment. IHC assay readily demonstrated granular, short filamentous, or spirochetal immunostaining of bacterial antigens, and is more useful for diagnosis.
Conclusions: The diagnosis of leptospirosis suspected by history and clinical manifestations can be supported by histopathologic findings, including interstitial nephritis and pulmonary hemorrhage. However, these features can occur in a variety of viral and bacterial infections. Silver stains are generally not a sensitive method for diagnosis because the detection of leptospires can be confounded by duration of illness and antibiotics treatment. IHC assay can detect leptospiral antigens in tissues and is a more sensitive and specific method for diagnosis. It is also instrumental for the studies of pathogenesis of leptospirosis.
Monday, March 9, 2009 11:15 AM
Platform Session: Section G 2, Monday Morning