Pathogen-specific leptospiral proteins in urine of patients with febrile illness aids in differential diagnosis of leptospirosis from dengue.

Leptospirosis and dengue are two commonly seen infectious diseases of the tropics. Differential diagnosis of leptospirosis from dengue fever is often difficult due to overlapping clinical symptoms and lack of economically viable and easy-to-perform laboratory tests. The gold standard for diagnosis is the microscopic agglutination test (MAT). In this study, the diagnostic potential of screening for pathogen-specific leptospiral antigens in urine samples is presented as a non-invasive method of disease diagnosis. In a study group of 40 patients, the serum was tested for anti-leptospiral antibodies by MAT and enzyme-linked immunosorbent assay (ELISA). Urine of these patients was screened for leptospiral antigens by ELISA using specific antibodies against LipL32, LipL41, Fla1, HbpA and sphingomyelinase. Group I patients (n = 23) were classified as leptospirosis-positive based on MAT and high titres of circulating IgM-specific anti-leptospiral antibodies. All of these patients excreted all five leptospiral antigens in the urine. The 17 MAT-negative cases included six patients with pyrexia of unknown origin (PUO; Group II) and 11 confirmed dengue patients (Group III). The latter tested negative for both serum anti-leptospiral antibodies and urinary leptospiral antigens. A salient outcome of this study was highlighting the usefulness of screening for urinary leptospiral antigens in disease diagnosis, as their presence confirmed leptospiral aetiology in two PUO patients. Immunoblots of urinary antigens identified well-defined bands corresponding to LipL32, HbpA and sphingomyelinase; the significance of the 42- and 58-kDa sphingomyelinase bands is discussed.

Evaluation of the clinical utility of a rapid blood test for human leptospirosis.

A rapid assay device for the detection of Leptospira-specific immunoglobulin M (IgM) antibodies was applied on whole blood samples collected from a group of consecutive patients admitted with clinical suspicion of leptospirosis to a district hospital in Kerala, India. The hospital is located in an area that is endemic for leptospirosis. The results of the rapid assay showed an agreement of 94.3% with those of an IgM ELISA routinely used for the serodiagnosis of leptospirosis. The rapid assay was simply performed by the addition of 10 microL blood to the sample well of a plastic assay device followed by the addition of 130 microL sample fluid. The assay was read after 10 min by visual inspection and was scored positive when staining of the antigen line in the test zone was observed. The assay utilizes stabilised components and can be stored without the need for refrigeration. These characteristics make the assay ideal in areas where the disease is common and where laboratory support is not routinely available.

Leptospirosis--clinical spectrum and correlation with seven simple laboratory tests for early diagnosis in the Third World.

Twenty-four patients who were clinically suspected of having leptospirosis were subjected to 7 simple commonly available laboratory tests. The 21 patients who had 3 or more positive tests were confirmed serologically to have leptospirosis. The high frequency of acute abdominal pain (71.4%) as a major presenting symptom and the laboratory findings of raised serum amylase levels in a high percentage of patients (84.2%) were especially noteworthy.

Leptospirosis in Kolenchery, Kerala, India: epidemiology, prevalent local serogroups and serovars and a new serovar.

Leptospirosis is the most widespread zoonosis in the world. It is mostly an occupational disease especially in rural areas. Kolenchery is in the midlands of Kerala. The landscape consists of marshy land and dry land interspersed by rivulets and ponds. Irrigation of dry lands for cultivation during the summer months started in mid 1980s after the irrigation projects were commissioned. Cases of leptospirosis were rarely diagnosed in Kolenchery before 1987. Since then a yearly increase in incidence is observed. No major study on either epidemiology or clinical picture has been done on human leptospirosis in Kerala so far. The aim of this study was to define the major clinical presentations, epidemiology of the infection and demonstrate the predominant serogroups and serovars causing the illness in this limited geographical area. The study involves 976 cases of leptospirosis confirmed by culture and/or serological tests. Serogroups Autumnalis, Australis and Icterohaemorrhagiae were the commonest. Mortality rate was 5.32%. The increase in incidence is probably due to the geographical characteristics, continuous moisture of the soil due to irrigation in summer and year-round cultivation making food and cover available to host rodents. Close interaction of humans, animals, soil and water in this region make the spread of leptospirosis to humans easy. Confirmation of cases has been done by enzyme linked immunosorbent assay (ELISA) and/or microscopic agglutination test (MAT) and/or by culture. Serovar identification has been done in 21 cultures isolated from patients. One new serovar belonging to serogroup Australis has been identified from a patient and named serovar Australis bharathy.

Lateral-flow assay for rapid serodiagnosis of human leptospirosis.

An assay device for the rapid detection of Leptospira-specific immunoglobulin M (IgM) antibodies in human sera is presented. The sensitivity (85.8%) and specificity (93.6%) of the assay compared well (91.9% agreement) with those of an IgM enzyme-linked immunosorbent assay routinely used in the serodiagnosis of leptospirosis. The sensitivity of the assay varied with the stage of the disease. The assay uses stabilized components and is simply performed by the addition of serum and sample fluid to the sample well of the assay device. The assay is read after 10 min, and a positive result is obtained when staining of the test line is observed.

Latex based, rapid and easy assay for human leptospirosis in a single test format.

Leptospirosis is an often severe disease which requires prompt treatment. Laboratory testing is required to reach a valid diagnosis. An agglutination assay for the detection of Leptospira-specific antibodies consisting of individually wrapped agglutination cards containing a stable, dried detection reagent is evaluated. The assay is simply performed by suspending the dried reagent with a drop of serum. The result is obtained within 30 s. The sensitivity of the assay varied with the stage of the disease and was 72.3% for samples collected during the first 10 days of the illness and 88.2% for samples collected at a later stage. The specificity was 93.9% and 89.8%, respectively. These characteristics make the test ideal for use in areas where the disease is common and where laboratory support is not routinely available.