What is Leptospira Antibody - DFM (Dark Field Microscopy) ?

Several techniques are available for the diagnosis of leptospirosis and the microscopic agglutination test is considered the gold standard, but these require sophisticated techniques and instruments. This study was conducted to know the sensitivity and specificity of dark field microscopy (DFM) as compared to IgM enzyme-linked immunosorbent assay (ELISA) in correlation with clinical diagnosis. It is a prospective study of 297 samples received from clinically suspected cases of leptospirosis for DFM and IgM ELISA. We tried to evaluate the easily available technique, DFM. We got promising results with DFM. Specificity and sensitivity were observed to be 61% and 60%, respectively, alone and 95.8% efficacy when combined with IgM ELISA. Thus, DFM should be tried for where other diagnostic tools are not easily available. It is an easy and rapid technique, which can help in the early diagnosis and management of patients

Leptospirosis is an emerging zoonotic disease prevalent worldwide. It commonly occurs in tropical, subtropical, and temperate zones. Most commonly, the infection is acquired by direct or indirect exposure to the urine of reservoir animals through contaminated soil, mud, and water entering via small abrasions or breaches in the skin during occupational, recreational, habitational, or vocational activities. Infection may also be acquired by drinking or inhalation of contaminated water. The infection is commonly associated with field workers, with increased incidence in rural than urban populations.

The causative organism is a spirochete, which is 10-20 µm and 0.1-0.15 µm, spirally coiled bacteria with hooked ends and motile by flagella. They are not visible under ordinary microscopes but can be visualized under darkfield microscopes and phase-contrast microscopes. Leptospirosis presents with protean clinical manifestations ranging from mild flu-like symptoms to very severe conditions such as meningitis and hemorrhages. The signs and symptoms resemble a wide range of bacterial and viral diseases and sometimes can present as food poisoning, chemical poisoning, and snakebite also, due to which the diagnosis is often missed. The most severe form is called Weil's syndrome, which consists of jaundice, bleeding, and oliguria or anuria. In India, leptospires were isolated for the first time in the Andaman Islands.