Leptospirosis-associated hospitalizations, United States, 1998-2009

Abstract

A small percentage of persons with leptospirosis, a reemerging zoonosis, experience severe complications that require hospitalization. The number of leptospirosis cases in the United States is unknown. Thus, to estimate the hospitalization rate for this disease, we analyzed US hospital discharge records for 1998-2009 for the total US population by using the Nationwide Inpatient Sample. During that time, the average annual rate of leptospirosis-associated hospitalizations was 0.6 hospitalizations/1,000,000 population. Leptospirosis-associated hospitalization rates were higher for persons >20 years of age and for male patients. For leptospirosis-associated hospitalizations, the average age of patients at admission was lower, the average length of stay for patients was longer, and hospital charges were higher than those for nonleptospirosis infectious disease-associated hospitalizations. Educating clinicians on the signs and symptoms of leptospirosis may result in earlier diagnosis and treatment and, thereby, reduced disease severity and hospitalization costs.

Keywords: Leptospira; United States; adults; bacteria; environmental exposure; epidemiology; hospitalization; hospitalization statistics and numerical data; humans; incidence; length of stay; leptospirosis; re-emerging; reemerging; seasonality; zoonoses.

Figure 1

Yearly rate of leptospirosis-associated hospitalizations, United States, 1998–2009. Vertical bars indicate 95% CIs. The rate for 2006 is not included because it was unstable (relative SE >0.3).

Figure 2

Monthly percentages of leptospirosis-associated hospitalizations, United States, 1998–2009.