Leptospira autumnalis isolated from a human case from Avadi, India, and the serovar's predominance in local rat and bandicoot populations

Leptospira were successfully isolated from the urine of an Indian patient w ho had been clinically diagnosed as having leptospirosis. In an attempt to determine the source of this infection, 28 rats (Rattus rattus) and 58 band icoots (Bandicota bengalensis) living in the vicinity of the patient's home in Avadi, a suburban area of the city of Chennai (Madras), India, were the n investigated. Each animal was checked for infection by microscopical exam ination of fresh and stained urine, serological analysis of serum, and the culture of urine and kidney samples. Direct, dark-field, observation of fre sh urine samples and examination of urine samples after Fontana's silver st aining were found to be the least sensitive of the tests used. The results of the serological microscopic agglutination test (MAT) indicated that four (14.3%) of the rats and nine (16.1%) of the bandicoots had significant agg lutinins, predominantly for the serogroups icterohaemorrhagiae and autumnal is. Leptospira were isolated from at least one culture of samples from one rat and each of four bandicoots. Each of these rodent isolates and the huma n isolate were typed as Leptospira interrogans serovar autumnalis.