by 10.0 to 16.0 microns; long specimens up aldehyde solution or mordanted with to 30.0 microns are frequent. The spirals, KMn04 . 8 to 12 in number, are regular and deep. Wassermann reaction is negative. Spiral amplitude, 1.0 to 1.2 microns; spiral Pathogenicity: The disease is transmissi- depth, 0.6 to 1.0 micron. A delicate, ter- ble to healthy rabbits producing papular minal filament is present at one end, some- lesions in the genitoperineal region. Non- times at both ends. Entangled masses of pathogenic for monkeys, mice and guinea long threads often occur; sometimes occur pigs. in a stellate arrangement. Staining proper- Source: From lesions in the genitoperi- ties are the same as for yreponewa pa/h"rfM?n: neal regions of five rabbits. both are readily stained by ordinary basic Habitat: The cause of rabbit spirocheto- aniline dyes when fixed in a buffered form- sis. Genus III. Leptospira Noguchi, 1917 * (Jour. E.xp. Med., 25, 1917, 753.) Lep.to.spi'ra. Gr. adj. leptits thin, small; Gr. noun spira a spiral; M.L. fem.n. Leptospira thin spiral. Finely coiled organisms which measure 6 to 20 microns in length. The spirals measure 0.3 micron in depth and 0.4 to 0.5 micron in amplitude. In liquid media either one or both ends of the cells are bent into a semicircular hook, each involving }{o to % of the organism. Spin- ning movements occur in liquid media, and vermiform movements occur in semisolid agar, forward or backward. In living preparations the cells are observed most clearly with dark- field and much less clearly with phase-contrast microscopy; not visible with ordinary illumi- nation. Stain with difficulty except with Giemsa's stain and silver impregnation. Axial fila- ment can be demonstrated by electron microscopy. Require oxygen for growth. The tj'pe species is Leptospira icterohaemorrhagiae (Inada and Ido) Noguchi. Before any of the parasitic leptospires were known, Wolbach and Dinger (Jour. Med. Res., SO, 1914, 23) applied the name Spirochaeta biflexa to non-pathogenic leptospires isolated from stagnant fresh water; later, Noguchi (Jour. Exp. Med., 25, 1917, 753) placed this species in a new genus, Leptospira. These water strains will grow in simple media such as hay infusions or in the feces medium recommended by Hindle (Brit. Med. Jour., 2, 1925, 57); as parasitic leptospires will not grow in media of this type, a means of differentiating between sapro- phytic and parasitic leptospires is furnished. Babudieri and Archetti (Rend. Istit. Sup. di Sanitd, 10, 1947, 962; Ann. Inst. Past., 75, 1948, 552) examined a large series of strains of water leptospires and found them to be composed of a number of antigenic fractions. The apparently random distribution of the same or closely similar antigens among the different strains led to a wide variety of extremely complicated serological relationships. Satisfactory means of differentiating species of saprophytic leptospires have not been developed, so it has become a custom to identify the non-pathogenic leptospires found in stagnant water or similar materials as Leptospira biflexa Noguchi. Pathogenic leptospires were first isolated from human cases of Weil's disease by Inada and Ido (Tokyo Ijishinshi, 1915, No. 1908), and, in the first record of their work published in English, the organisms were named Spirochaeta icterohaemorrhagiae by Inada, Ido, Hoki, Kaneko and Ito (Jour. Exp. Med., 2S, 1916, 377). Since that time other leptospires, serologi- cally distinct from Leptospira icterohaemorrhagiae, have been recognized as causing disease in man and other animals and as having host-carrier relationships. As examples, L. canicola (dogs), L. grippotyphosa (voles) and L. pomona (pigs) may be mentioned, but knowledge of
- Completely revised by Prof Dr. J. W. Wolff, Koninklijk Instituut voor de Tropen,
Afd: Instituut voor Tropische Hygiene en Geograph. Path., Amsterdam, Holland, and Dr. J. C. Broom, The Wellcome Laboratories of Tropical Medicine, London, England.
