Detection of dengue infection in patients being investigated for leptospirosis in Barbados

ABSTRACT

Leptospirosis in endemic in Barbados, with an annual incidence of approximately 13 cases per 100,000 of the population admitted to hospital. The peak incidence occurs in October to December of each year, coinciding with the months of heaviest rainfall. During the second half of 1995 there was an epidemic of dengue type I infection, with almost 1000 laboratory-confirmed cases. During the same period, the mortality rate due to leptospirosis was twice the average. It is postulated that some cases of leptospirosis were being mis-diagnosed as dengue during the early stages of infection. A retrospective analysis of sera from patients investigated for leptospirosis was done to determine whether dengue was being mis-diagnosed as leptospirosis. Patients entered into a protocol for diagnosis of leptospirosis were studied if the first sample was collected during the months of July to December in the years 1995 to 1996. During 1995 and 1996, respectively, 27/106 and 22/65 patients were confirmed as having leptospirosis. The remaining sera from 79 and 43 leptospirosis-negative patients were tested for IgM antibodies to dengue virus, using a monoclonal antibody capture ELISA (MRL Diagnostics, CA). The results concluded that dengue fever may be under-diagnosed during non-epidemic periods. (AU)