Research Article: Leptospirosis Cases Infected with Uncommon Serogroups, Puerto Rico, 2013–2015

Date Published: January 06, 2018

Publisher: The American Society of Tropical Medicine and Hygiene

Author(s): Hector Gorbea, Enid J. Garcia-Rivera, Hilda Torres, Olga D. Lorenzi, Aidsa Rivera, Renee L. Galloway, Tyler M. Sharp.


Leptospirosis is an emerging bacterial zoonosis that is endemic but underrecognized throughout the tropics. Through prospective surveillance for acute febrile illness (AFI) among patients who presented to the emergency department of a hospital located in an urban region of Puerto Rico, four patients with laboratory-confirmed leptospirosis were identified. All patients had signs and symptoms of AFI, including fever, headache, and dehydration. Three patients had leukocytosis with thrombocytopenia and were admitted to the hospital. One hospitalized patient presented with jaundice, icteric sclera, and hematuria and developed rhabdomyolysis, whereas another patient with pulmonary edema was admitted to the intensive care unit. Microscopic agglutination titers among the four patients were highest against serogroups Icterohaemorrhagiae (serovar Mankarso), Australis (serovar Bratislava), Bataviae (serovar Bataviae), and Canicola (serovar Canicola). These case reports demonstrate that infection with these apparently uncommon serogroups can result in illness ranging from mild to life-threatening.

Partial Text

Leptospirosis is a bacterial zoonosis that is endemic throughout the tropics and is caused by infection with Leptospira species bacteria that are transmitted through direct or indirect contact with animal urine.1 Most patients infected with Leptospira spp. will experience either no symptoms of disease or a self-limited acute febrile illness (AFI).1 Among hospitalized leptospirosis patients, 5–15% die typically because of organ (e.g., kidney and liver) failure, pulmonary hemorrhage, and/or septic shock.1,2 Each year an estimated 1 million cases of leptospirosis and nearly 60,000 deaths3 result in a loss of 2.9 million disability-adjusted life years.4

Data were collected during July 29, 2013, through August 24, 2015, from the Sentinel Enhanced Dengue Surveillance System (SEDSS) site located at the University of Puerto Rico (UPR) Hospital, Carolina. Patients presenting to the emergency department (ED) with fever or a history of fever in the past 7 days were eligible for participation. Clinical specimens were collected upon enrollment and upon hospital discharge or follow-up visit, and diagnostic testing was performed as previously described.14 All patients enrolled in SEDSS provided informed consent. Additional data were collected through chart abstraction for leptospirosis patients. The Institutional Review Board of the UPR Medical Sciences Campus approved the protocols for SEDSS and this study.

Serologic evidence of infection with serogroups Icterohaemorrhagiae, Australis, Canicola, and Bataviae was found among patients with leptospirosis in Puerto Rico. Evidence of circulation of serovars from these serogroups has been infrequently documented in Puerto Rico, and most previously identified leptospirosis patients had serologic evidence of infection with Icterohaemorrhagiae.12 However, because serologic diagnostic testing may not accurately identify the infecting serogroup,1 we cannot rule out the possibility that patients may have been infected with a serogroup distinct from those identified by MAT. Nonetheless, because Icterohaemorrhagiae has been associated with increased likelihood of fatal outcome,6,7 this may suggest that other serogroups are comparatively less pathogenic in humans. Although Icterohaemorrhagiae is most frequently associated with exposure to the urine of rats, serogroup Bataviae is also associated with dogs, whereas Bratislava is associated with horses.1 This observation underscores the need for public awareness that not only rats but also many species of mammals can harbor infectious leptospires.




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