Observations on the Survival ofLeptospira AustralisA in Soil and Water

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Abstract
Summary: Soil from a sugar-cane farm in North Queensland was infected with leptospirae. In some instances a culture ofLeptospira australisA was added to the soil; in others it was infected by rats,Rattus rattus, known to be excreting leptospirae in their urine.After periods ranging from 8 to 43 days, the soil was flooded with rain water which was subsequently examined for leptospirae by treating guinea-pigs according to the ‘subcutaneous stream’ technique.Leptospirae survived in culture-infected soil for 43 days and in urine-infected soil for 15 days prior to the addition of the rain water. They were recovered from the water at intervals ranging up to 24 days after the flooding of the soil.The infected soil was of pH 6·1–6·2, its moisture content where determined was 34 and 37%, and the prevailing temperature 20–29° C. The reaction of the infected water samples ranged from pH 6·6 to 7·6.The possible significance of these findings in relation to the epidemiology of leptospirosis in North Queensland is briefly discussed.