Background: Leptospirosis is an emerging infectious disease. The differential diagnosis of leptospirosis is difficult due to the varied and often "flu like" symptoms which may result in a missed or delayed diagnosis. There are over 230 known serovars in the genus Leptospira. Confirmatory serological diagnosis of leptospirosis is usually made using the microscopic agglutination test (MAT) which relies on the use of live cultures as the source of antigen, often performed using a panel of antigens representative of local serovars. Other techniques, such as the enzyme linked immunosorbent assay (ELISA) and slide agglutination test (SAT), can detect different classes of antibody but may be subject to false positive reactions and require confirmation of these results by the MAT.

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A prospective study of 989 patients with acute febrile illness was performed in northeast Thailand to define the yield of Leptospira from four different types of blood sample. Based on a comparison of the yields from whole blood, surface plasma, deposit from spun plasma, and clotted blood samples from 80 patients with cultureproven leptospirosis, we suggest a sampling strategy in which culture is performed using whole blood and deposit from spun plasma.

Abstract. A prospective study in Thailand identified 106 patients with culture-proven leptospirosis. The accuracy of the microscopic agglutination test (MAT) in predicting the infecting serovar was evaluated in 78/106 (74%) patients with a diagnostic titer. MAT correctly determined the infecting serovar in 26 cases (33%), indicating that this assay is a poor predictor of infecting serovar in our setting.Leptospirosis is an acute febrile illness caused by pathogenic members of the genus Leptospira . This disease has a worldwide distribution but is most common in tropical regions, including Thailand. [1][2][3][4][5] In a prospective observational study of undifferentiated fever in 845 patients in rural Thailand, leptospirosis was reported to be responsible for 36.9% of cases.4 Leptospira isolation is the gold standard for confirmation of leptospirosis in humans. This provides definitive identification of the infecting serovar and is an important technique for the study of outbreaks and global epidemiology. It has a number of significant drawbacks, however, including low diagnostic sensitivity, prolonged culture period, and the associated expertise necessary for identification of the infecting serovar together with related costs.The microscopic agglutination test (MAT) is commonly used to reach a serologic diagnosis of leptospirosis and is performed by detecting agglutinating antibodies by mixing patient serum with a panel of Leptospira serovars that are considered to be representative of the endemic strains for a given region. 3A positive diagnostic result for the MAT is a 4-fold change in titer or a single pre-defined titer. MAT has also been used to provide an indication of the presumptive serovars causing leptospirosis in a given region. The ability of MAT to accurately determine the prevalent serovars was called into question by a retrospective study conducted in Barbados where disease in 151 individuals was caused by four serovars ( L. kirschneri serovar Bim, L. interrogans serovar Copenhageni, L. borgpetersenii serovar Arborea, and L. noguchii serovar Bajan); serologic analysis was found to have a low degree of accuracy for determining the infecting serovar in this setting. 6 The epidemiology of infecting isolates in Thailand differs markedly, with a recent study showing that the majority of human disease was caused by L. interrogans serovar Autumnalis. 7 The aim of this study was to determine whether MAT provides an accurate guide to the infecting serovars of Leptospira in Thailand.A prospective study was conducted in hospitals situated in six provinces in northeast Thailand (Udon Thani, Burirum, Loei, Nakhon Ratchasima, Maha Sarakham, and Yasothon) between October 2000 and December 2006 to identify patients with culture proven leptospirosis. The study protocol was approved by the Ethical Committee of the Ministry of Public Health, Royal Government of Thailand. Admitting physicians were asked to recruit patients of all ages who they suspected on clinical grounds to have leptospirosis. Clinical features cons...

We defined the positive predictive accuracy of a hospital-based clinical diagnosis of leptospirosis in 9 provinces across Thailand. Of 700 suspected cases, 143 (20%) were confirmed by laboratory testing. Accuracy of clinical diagnosis varied from 0% to 50% between the provinces and was highest during the rainy season. Most confirmed cases occurred in the north and northeast regions of the country.