The diagnostic MAT titre recommended is 1:400 in single samples . In endemic areas , this titre is adequate as persistent antibodies of previous infections can interfere with diagnosis . In non-endemic areas , a titre of 1:100 or 1:200 has been suggested . There is a consensus that 1:400 would be adequate to diagnose leptospirosis . Some insist that high titres , such as 1:800 or 1: 1600 would be needed to confirm the diagnosis . It would be preferable to combine MAT with Rapid tests such as Elisa IgM to improve the sensitivity of diagnosis of leptospirosis .
Article Diagnosis of Leptospirosis - Role of MAT
The MAT is considered the gold standard for diagnosis of leptospirosis , because of its unsurpassed specificity , but has low sensitivity for diagnosis of current infection . Leptospirosis can present as asymptomatic leptospiral infection or symptomatic leptospiral disease . The prevalence rate can be obtained by doing serosurveys of asymptomatic persons , while incidence rates can be obtained from symptomatic patients . The MAT can be used to obtain prevalence rates using titres in the range of 1/50 - 1/100 . To obtain incidence rates , higher MAT titres ( 1/400 or above ) are needed to confirm the diagnosis in endemic areas , as persistent titres of asymptomatic / symptomatic ( previous ) infection , would interfere with diagnosis of current infection . Therefore , the endemicity of leptospirosis in a given area has to be determined by MAT obtained from serosurveys , to determine the cut-off titre for diagnosis of current infection . Since Elisa IgM persist for a shorter duration & is present only in current infection , combining this test with MAT would confirm the diagnosis of current infection in single samples . Seroconversion / four fold rise of MAT titres would confirm diagnosis of current leptospirosis , but a second sample would be needed .
Most of the patients have mild leptospiral disease & recover rapidly with antibiotics . It is very difficult to obtain a second sample after the patient has completely recovered , as they may not come for follow up . The first sample is usually obtained between the 5th to the 10th day & the MAT titres are usually in the range between 1/100 - 1/200 . It would be difficult to obtain higher single titres in this period , unless repeat samples are available . At this time , the Rapid tests would be positive. Therefore , a combination of positive Elisa IgM with lower MAT titre would definitely confirm leptospirosis .
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