Usefulness of dark field microscopy after differential centrifugation in the early diagnosis of leptospirosis in dog and its human contacts.

1. We found leptospira in the blood of two out of three police dogs by dark field microscopic examination after high speed centrifugation. One dog had fever and the other was asymptomatic. Leptospira could not be seen in the urine of one police dog which died of jaundice. 11 out of 21 human contacts were found to be positive for leptospira after low speed centrifugation and 5 after high speed centrifugation. One child had jaundice and an another child had fever. Others had mild symptoms of headache to none. Dark field microscopy after differential centrifugation is useful in the early diagnosis of leptospirosis and thereby could prevent later complications like jaundice.

Studies on the incidence of leptospirosis and possible transmission of Leptospira during leptospiraemia.

During the year 1991 and in the first half year of 1992 a total of 179 cases and 288 cases respectively were tested for the presence of Leptospira by dark ground microscopy and 86 cases (48%) and 157 cases (54.5%) were found to be positive for Leptospira in their blood samples only. The disease was endemic and more prevalent in the age group of 5 to 14 years and 15 to 54 years and affected both sexes. Clinical categorisation of 169 cases in 1991 and 266 cases in the first half of the year 1992 along with the dark ground microscopy results showed that there was no strict correlation between the concentration of Leptospira in the blood and the severity of infection. Epidemiological data regarding the occupation and the contacts indicated that students and medical staff accounted for more than fifty percent of leptospiral infection and there was the possibility of transmission of Leptospira during leptospiraemia. Dark ground microscopy studies on blood samples from 20 cases who came for repeat testing showed the presence of Leptospira in blood up to 43 days and suggested that the convalescent carrier may have a role in the transmission of Leptospira during Leptospiraemia.