Evidence of leptospira and Hanta virus co-infections amongst patients hospitalised for leptospirosis-like illness

Abstract

INTRODUCTION: Hantavirus infection and leptospirosis are zoonoses with similar epidemiology and disease forms. Both infections spread to humans from infected rodents. OBJECTIVES: To assess the frequency and clinical manifestations of hantavirus infection in patients hospitalised with leptospirosis-like illness. METHODS: Two groups of patients admitted with leptospirosis-like illness to the University Medical Unit, Ragama, were investigated for evidence of both hantavirus infection and leptospirosis. Demographic data were obtained prospectively from 39 patients (Group 1) (M:F=34:5, mean age 35 yrs) (1996-1997), and retrospectively from 35 patients (Group 2) (M:F=34:1, mean age 30 yrs) who had been admitted to the unit during the previous year (1995-1996). Paired sera from 31/39 patients in Group 1 were tested for IgM antibodies and a single serum sample from 24/35 patients in Group 2 was tested for IgG antibodies to Hantaan and Puumala serotypes of hantavirus using m-capture ELISA separately. The same panels of sera were also tested for the presence of anti-leptospiral IgM (in Group 1) and IgG (in Group 2) antibodies. RESULTS: In Group 1, 9/31 and 25/31 sera were positive for hantavirus and leptospira IgM antibodies respectively. 5/31 were negative for both antibodies. 8/9 hantavirus IgM positive sera were also positive for leptospira IgM antibodies indicating co-infection. 1/9 showed seroconversion to hantavirus only, and 17/31 showed seroconversion to leptospira only. Based on the reactivity of hantavirus IgM antibody positive sera against recombinant hantavirus neucleocapsid proteins by m-capture ELISA, 5/9 had Puumala-like and 2/9 had Hantaan-like predominant antigenic specificities. The other 2/9 showed specificity to Puumala only. In Group 2, 10/24 and 23/24 sera were positive for hantavirus and leptospira IgG antibodies respectively. 1/24 was negative for both. All 10 hantavirus IgG antibody positive sera were also positive for leptospira IgG antibodies. 7 of 10 had specificity to Puumala, 2 of 10 had predominantly Puumala and 1 had predominantly Hantaan antigen specificity. Male predominance, occupations related to agriculture and farming, and exposure to rodents were risk factors associated with leptospirosis-like illness. Anorexia, nausea, and myalgia were features common to all patients More patients with hantavirus infection or with or without leptospirosis than those with leptospira infections only had hepatic (78% Vs. 17%) and renal (56% Vs. 17%) involvement during the course of their illness. Conclusions: In our study, hantavirus infection or co-infection with leptospirosis occurred in about one third of patients with leptospirosis-like illness admitted to hospital. The majority had hepatic and renal involvement. Three hantavirus serotypes, Puumala, Puumala-like and Hantaan-like, were detected.