Human leptospirosis in Bulgaria, 1989-2001: epidemiological, clinical, and serological features.

A total of 455 confirmed and reported to the Bulgarian Ministry of Health leptospirosis cases between 1989 and 2001 were analysed. Overall incidence of the disease was 0.42/100.000 population (range 0.20-0.64/100.000). The overall fatality rate was 6.6%. Infection was acquired through occupational (30.3%), recreational (45.1%), and accidental (4.6%) exposure or was home contracted (5.1%). A tendency towards the main mode of transmission moving from occupational to recreational exposure was noted. Fishing and livestock farming together accounted for more than half of all leptospirosis cases. Leptospirosis was contracted more frequently through indirect contact with animal excreta and less commonly through direct contact with animal urine or tissue. Serovars belonging to 10 different serogroups caused infection during the 13-year study period. Two serogroups, Icterohaemorrhagiae and Pomona, accounted for more than 87% of all leptospirosis cases. The third main cause was serogroup Australis. The significant change in the infecting serovars has to be related to widely performed vaccinations of cattle and pigs but still inefficient measures for rodent control. The most frequently reported symptoms were fever, myalgia, jaundice, and hepatomegaly. Anicteric cases (40.3%) had milder flu-like course. Acute renal failure was reported in 52 (33.8%) of the patients, all of them with icteric leptospirosis. Knowledge of epidemiological, clinical, and serological features of leptospirosis in Bulgaria during the 13-year study period is an appropriate base to outline measures for successful prevention and early diagnosis of the disease.