A STUDY OF LEPTOSPIRA DIAGNOSIS USING DIFFERENT LABORATORY TECHNIQUES AND THE IDENTIFICATION OF THE MOST COMMON SEROVARS IN DADRA AND NAGAR HAVELI

Abstract

Leptospirosis is a neglected and re-emerging zoonoses caused by a Gram-negative bacterium belonging to the Spirochaetes phylum, Leptospiraceae family, Leptospira genus1. These microorganisms appear spiral-shaped, with a diameter of 0.1 µm and a length of 6–20 µm and a pointed end that is typically folded into a characteristic hook shape1. Leptospira is highly mobile and performs rotational movements around the central axis, translation, undulation, and flexion thanks to two periplasmic axial flagella located under the cell membrane2. Although Leptospira is a microaerophile, it develops well even in conditions of complete aerobiosis. The optimum temperature for its growth is between 28 ℃ and 30 ℃, although it also grows at 37 ℃. The ideal pH range is between 7.2 and 7.43. Traditional classification divided the genus Leptospira in two species: L. interrogans, pathogenic strains, and L. biflexa, saprophytic strains. On the basis of antigenic agglutination reactions and cross absorption, both species are divided into serovars. There are over 60 serovars belonging to the L. biflexa species, while there are more than 200 Leptospira interrogans3. The invasion of Leptospira into the body occurs through skin lesions (even of minimal entity), via the mucous membrane (conjunctiva and oral mucosa), and by contact with wet skin or by inhalation3. Infiltrated microorganisms invade the bloodstream, causing bacteremia that persists for about 5–7 days4. Once a critical number of bacteria has been reached in the blood, the first symptoms related to their trans-endothelial migration appear. The pathogenetic mechanism of Leptospira is not yet fully understood, and it is hypothesized that virulence factors, such as toxins, adhesins, and other surface proteins, are expressed5.