The Incidence of Leptospira Icterohaemorrhagiae in Trapped Rats in Philadelphia

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  • Department of Public Health and Preventive Medicine, University of Pennsylvania Medical School, Philadelphia, Pennsylvania
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Conclusions and Summary

Eleven out of one hundred wild Mus norvegicus rats trapped in Philadelphia were proven to be carriers of Leptospira icterohaemorrhagiae capable of producing symptoms typical of leptospirosis infection in guinea-pigs.

A comparison of the percentage efficiency of the various methods employed to detect infection in the rat materials showed that the darkfield examination of the rat urine was 18.1 per cent; the culture of the urine was 36.6 per cent; the darkfield of the rat kidney emulsion was 18.1 per cent and the culture of the kidney emulsion was 90.0 per cent efficient when compared with the inoculation of albino guinea pigs. Therefore it is suggested that guinea-pig inoculations with rat kidney substance should always be made whenever leptospiral infection is to be investigated in wild rats.