To fulfill the need for a simple and rapid diagnostic test for human brucellosis, we used the immunochromatographic lateral flow assay format to develop two assays, one for the detection of Brucella-specific immunoglobulin M (IgM) antibodies and one for the detection of Brucella-specific IgG antibodies. The diagnostic values of these tests were examined. The tests are shown to detect acute, persistent, and relapsing disease and can be used to monitor treatment. The sensitivity of Brucella IgM and IgG flow assays calculated for the combined assay results is 96%, and specificity amounts to 99%. The flow assay requires neither specialized training nor equipment, the assay is very easy to perform and to read, and the components are stable without a requirement for refrigeration and well standardized. Together these characteristics indicate that the Brucella IgM and IgG flow assays are ideal for use in clinical settings in rural and suburban areas in which brucellosis is endemic.

A dipstick assay for the detection of Brucella-specific immunoglobulin M (IgM) antibodies was evaluated by studying the serological response of 133 cultures and or serologically confirmed patients with brucellosis in its different stages along with those of 34 healthy controls. As regards patients with illness less than 3 months in duration, 93.1% tested positive by the dipstick assay, a percentage similar to that obtained in the standard serum agglutination test (SAT) (92.0%), somewhat lower than that obtained by culture (100%) and higher than that obtained by IgM enzyme-linked immunosorbent assay (ELISA) (80.5%). SAT was the most sensitive test (87.0%) for patients with illness more than 3 months in duration, followed by culture (50%), the dipstick assay (28.3%), and IgM ELISA (7.5%). The results demonstrate that the dipstick assay could well be used in the serodiagnosis of patients with acute brucellosis, as well as to identify patients with a long history of the illness. Under laboratory conditions this test has the advantage of being quick and IgM antibody-specific.Human brucellosis is still an endemic disease in Asia, Latin America, and Mediterranean countries. In Spain, it is predominant in rural areas, with a morbidity in 1999 of 3.93 per 10 5 inhabitants (2).Owing to the fact that the signs and symptoms of brucellosis are not pathognomonic, the clinical diagnosis should always be validated by bacteriological or serological tests. The isolation of the etiological agent is the only test that provides direct evidence for the presence of the pathogen. Taking into account that it is not always possible to achieve this and that the culture results under optimum conditions cannot be obtained in less than 4 days, it is often necessary to resort to indirect assays based on the identification of specific antibodies in the presence of Brucella antigens (3,6,22).Some of the tests for the diagnosis of human brucellosis (10) have been described for the diagnosis of acute cases and to identify patients with a long history of the illness. To diagnose acute cases, assays have been used to detect the presence of specific immunoglobulin M (IgM) antibodies, and these include the radioimmunoassay (15), the enzyme-linked immunosorbent assay (ELISA) (4), the indirect immunofluorescence assay (8), and the 2-mercaptoethanol test (17). Smits et al. (19) have recently developed a simple dipstick assay for the detection of specific IgM antibodies using a lipopolysaccharide (LPS) extract of Brucella as the antigen. This assay uses strips of nitrocellulose impregnated with LPS of B. abortus 1119-2 and a stabilized nonenzymatic detection reagent that consists of a monoclonal anti-human IgM antibody conjugated to colloidal dye particles (Palanyl red). The assay is performed by incubation of the test strip in a mixture of serum and detection reagent, conjugate binding making IgM antibodies reacting with the LPS epitopes visible.The objective of this work was to evaluate the clinical utility of the dipstick assay for the serodiagnosis ...