Lateral-Flow Assay for Rapid Serodiagnosis of Human Leptospirosis

Abstract

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.As the clinical symptoms and signs of leptospirosis often are nonspecific, the disease is easily mistaken for other major infectious diseases. Manifestations of leptospirosis may vary, and different types of disease may be observed, from relatively mild influenza-like symptoms to severe disease with renal failure, liver impairment, and haemorrhage (Weil's syndrome). Meningismus and (aseptic) meningitis can be observed as well. Because of the wide variety of symptoms, leptospirosis is easily confused with many other fibril illnesses including haemorrhagic fevers, e.g., dengue fever (7). Laboratory testing to confirm the clinical diagnosis thus is essential for optimal treatment and patient management. The laboratory diagnosis of leptospirosis mainly depends on serology (8). The microscopic agglutination test (MAT) (5, 31) is considered the reference test for leptospirosis, but the enzyme-linked immunosorbent assay (ELISA) (2, 15-17, 19, 32, 34, 36) and a number of other tests including the immunofluorescent-antibody test (IFAT) (3), the slide agglutination test (9), the macrocapsule agglutination test (4), and the hemagglutination test (13,28,29) can be used as well. Drawbacks of the standard diagnostic assays like MAT, ELISA, and IFAT are that they are not very easy to perform, require special and expensive equipment, depend on the availability of electricity and refrigeration, or can be applied only by trained personnel. Hence, these assays are available only in a few specialized laboratories. MAT, which is considered the reference test for leptospirosis, is rarely performed by routine diagnostic laboratories.Leptospirosis has been reported from countries all over the world (1). Sporadic cases of leptospirosis may occur in countries with moderate climates. The disease, however, can be endemic in countries with wet and warm climates. People living under poor socioeconomical and hygienic conditions are at particular risk of getting the disease. Outbreaks have been reported (6, 11, 12, 14, 20-23, 27, 30, 33). Most people at risk cannot depend on health care facilities supported by laboratories capable of performing the more complicated standard laboratory assays. We previously developed a dipstick assay for the detection of Leptospira-specific immunoglobulin M (IgM) antibodies in human sera (10,20,(24)(25)(26)35). This assay can be used outside the specialized laboratory and may e...

Identification and evaluation of LPS antigen for serodiagnosis of uveitis associated with leptospirosis

“…Several commercial kits are available for the diagnosis of systemic leptospiral infection using broadly reactive Leptospira antigen (Cumberland et al, 1999;Smits et al, 1999Smits et al, , 2000Smits et al, , 2001Sehgal et al, 1999;Eapen et al, 2002). However, the nature of the antigen has not been described in the literature.…”

Referral pattern of leptospirosis cases during a large urban epidemic of dengue.

“…Screening for leptospirosis among febrile outpatients requires a highly sensitive and specific test, since the overall prevalence of this disease among ambulatory patients with acute febrile illnesses is expected to be low. Rapid serologic tests such as the Lepto-dipstick [24][25][26] and latex agglutination assay, 27 have been developed, but the reported sensitivities of these tests have been approximately 50% for identifying cases in the first 10 days of symptoms. Recently, the Lepto-dipstick assay was re-evaluated and found to have a sensitivity of 85% for early-phase samples, 26 but the observed specificity (88%) would result in a high proportion of false-positive results in an ambulatory setting.…”

IgM ELISA for leptospirosis diagnosis: a systematic review and meta-analysis

“…Two studies have indicated high risk of bias in the patient selection in the applicability criteria 50,51 , and two studies demonstrated a high risk of bias in evaluating the index test 48,65 . In the other studies, there were some unclear applicability criteria in the index test and reference standard 19,21,[23][24][25][26]29,30,32,34,35,38,40,42,43,46,47,49,53,54,57,64,[67][68][69] . The robustness of the results was tested by repeating the analysis using a different statistical model (random effects model).…”