Multilocus sequence typing reveals diverse known and novel genotypes of Leptospira spp. circulating in Sri Lanka

Background Leptospirosis has gained much attention in Sri Lanka since its large outbreak in 2008. However, most of the cases were clinically diagnosed and information onLeptospiragenotypes and serotypes currently prevailing in the country is lacking. Methodology/Principal findings We retrospectively analyzed 24Leptospirastrains from human patients as well as isolated and characterized threeLeptospirastrains from black rats using the microscopic agglutination test with antisera for 19 serovars and multilocus sequence typing. The isolates were identified asLeptospira borgpeterseniisequence types (STs) 143 and 144;L.interrogansSTs 30, 34, 43, 44, 74, 75, 80, 308, 313, 314, 316, and 317; andL.kirschneriST318. Six of the 15 STs were identified for the first time in this study. Five serogroups such as Autumnalis, Grippotyphosa, Hebdomadis, Javanica, and Pyrogenes were detected among the isolates. Contrary to previous studies, various genotypes including novel STs were isolated during an outbreak in Southern Province.L.borgpeterseniiserogroup Javanica ST143 was isolated both from a human and black rat. Conclusions/Significance This study revealed that genetically diverseLeptospirastrains currently circulate in Sri Lanka: some genotypes have been circulating and others have emerged recently, which may explain the recent surge of leptospirosis patients with varying clinical manifestations and frequent outbreaks of leptospirosis. Black rats were identified as the source of infection for humans, but reservoir animals for other genotypes remain unknown. Author summary Leptospirosis is an important but largely under-recognized public health problem in the tropics. It is a re-emerging disease and outbreaks of leptospirosis have been frequently reported in Sri Lanka. Most of the cases, however, were clinically diagnosed, andLeptospiraserotypes and genotypes currently prevailing in the country remain unknown. For the prevention of leptospirosis, doxycycline prophylaxis and health education (early medical help, use of protective wear, etc) are implemented in farmers, which is the highest risk group, in endemic areas. In the present study, we revealed that genetically diverseLeptospirastrains presently cause human leptospirosis in this country. Novel STs were isolated during an outbreak in Southern Province and may be related to the recent surge in leptospirosis patients with new clinical entities. The emergence of new STs also implies the importance of strict quarantine for imported domestic animals that are potential reservoirs ofLeptospiraspp. as well as the unintentional introduction of rodent reservoirs and the existence of unidentified reservoir animals in this country. New information from this study will be valuable in future research for patient management and specific targeted control approaches for reservoir hosts in the prevention and control of leptospirosis in Sri Lanka.