Leptospirosis Outbreak after a Heavy Rainfall Typhoon in the Philippines: Clinical Features, Outcome and Prognostic Factors for Mortality

Evalyn A. Roxas,1,2 Marissa M. Alejandria,2,3,4 Myrna T. Mendoza,2,5
Arthur Dessi E. Roman,2,6 Katerina T. Leyritana2 and Joann Kathleen B. Ginete-Garcia5

1Department of Medical Microbiology,
College of Public Health, University of the Philippines Manila
2Section of Infectious Diseases, Department of Medicine,
College of Medicine and Philippine General Hospital, University of the Philippines Manila
3Department of Clinical Epidemiology,
College of Medicine, University of the Philippines Manila
4The Medical City
5National Kidney and Transplant Institute
6Manila Doctors Hospital

Background and Objectives. In September 2009, Metro Manila was hit by a heavy rainfall typhoon Ketsana inundating several cities of Metro Manila causing an outbreak of leptospirosis. We analyzed the prognostic factors associated with mortality among leptospirosis patients admitted after the typhoon at nine tertiary hospitals from September to November 2009.

Methods. We reviewed the charts of patients with probable and confirmed leptospirosis. Confirmed leptospirosis was based on any of the following: positive leptospiral culture of blood or urine, single high leptospira microagglutination titer (MAT) of 1:1600 of a fourfold rise in MAT antibody titers or seroconversion. Patients with negative serology or cultures but with history of wading in floodwaters plus any of the following signs and symptoms: fever, headache, myalgia, conjunctival suffusion, diarrhea and abdominal pain, jaundice, oliguria and changes in sensorium were considered probable cases.

Results. We analyzed 332 probable and 259 confirmed leptospirosis patients. Mean age was 37.95 +/- 14.09, mostly males (80.2%). Almost all patients (98%) waded in floodwaters. Majority had moderate to severe form of leptospirosis (83%). Acute renal failure was the most common complication (87.1%). Mortality was 11.3% mostly due to pulmonary hemorrhage. On multivariate analysis of confirmed and probable cases, the factors independently associated with mortality were pulmonary hemorrhage (OR 2.75, 95% CI 1.46 to 5.20), severity of the disease (OR 3.85, 95% CI 1.60 to 9.26), thrombocytopenia (OR 3.16 95% CI 1.22-8.16), duration of illness before admission (OR 0.88, 95% CI 0.78-0.99) and age (OR 1.03, 95% CI 1.00-1.06).

Conclusion. Pulmonary hemorrhage remains a poor prognostic factor and strong predicator of mortality among patients with severe leptospirosis. Early consult through heightened awareness of the public and prompt recognition of leptospirosis among clinicians can decrease the risk for progression to complications of leptospirosis and mortality.

Key Words: leptospirosis, clinical profile, predicators of mortality, typhoon, Philippines, outbreak