Abstract

HERRER, Arístides  and  LICERAS DE HIDALGO, Julia. Leptospirosis en el Perú: II. Incidencia de la infección en las ratas (Rattus norvegicus) de la ciudad de Lima e identificación de la cepa infectante. Rev. perú. med. exp. salud publica [online]. 1960, vol.13, n.1-2, pp.84-107. ISSN 1726-4634.

From May, 1955, to December, 1957, the authors the incidence of leptospirosis in 600 sewer ratas (Rattus norvegicus) captured in the markets of Lirna. A comparison was also made of the various standard methods for laboratory diagnosis. The following strains of leptospira were used for serological identification of cultural isolates, as weIl as for determining antibodies in the rat sera: L. icterohaemorrhagiae AB Wijnberq, L. canicola Ruebush, L. autumnalis AB Akiyama A, L. bataviae Van tienen, L. sejroe Mallersdorf, L. pomona S91, L. ballum S102, L. hyos, L. grippotyphosa Moscow V, L. hebdomadis, y L, pyrogenes Salinem (Strains R23 and R410, isolated by the authors from rats were also included). Using four different laboratory methods of diagnosis, results were as follows: 1. Blood cultures were positive in only 1.2% of the specimens, kidney cultures were positive 49% of the time (varying from. 38.3 to 54.5% from different markets), dark field examinations of kidney tissue revealed leptospiras in 2617c of the rats, and the agglutination-lysis test was positive in 32.8% of serum specimens. When all four technlques were used, positive diagnosis was obtained in 62.417o of 591 rat specimens. 2. The agglutination-lysis test was positive in 195 sera, of which 167 (85.6%) reacted only with L. ictero,haemorrhagiae AB Wijnberg, whereas six reacted with only one of the other strains; cross-react;on w`th two or three antigens werz obtained w;th 22 sera. From 19 of these 28 rats, strains of leptospira have been isolatd, 16 of which were identified as L. icterohaemorrhagíac. 3. The titers of the antibodies against L. icterohaemo,rrhagiae AB Wijnberg were relatively low, ranged from: 1:100 to 1:30,0 in 88.7% of the cases. The highest positive titer obtained was 1:3000. However, in 418 sera in which L. ieterohacinorrhagiae AB Wijnberg and R23 and R410 were used as antigens, the titers were higher with the Peruvian strains. 4. Seven ratas with positive blood culture showed negative agglutination-lysis tests (also with the Peruvian strains). 5. In total, 285 leptospiral isolates were made. By means of antisera against the 11 serotypes mentioned above, 203 were identified afl as L. icterohaemorrhagiae.

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