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During a recent large tularemia outbreak in Bulgaria we found several cases that were remote from the main focus. One case had an unusual mode of transmission. A hunter acquired tularemia through a nail scratch from a buzzard (Buteo buteo) and consequently developed a typical ulceroglandular form of the disease. The diagnosis was confirmed by serological methods and successful cultivation. Comparative strain typing was performed by high-resolution multi-locus variable-number tandem repeat analysis (MLVA). The isolated strain was identical to one of the outbreak genotypes. We consider that this case represents a bird-to-human transmission of F. tularensis.

In this study, cultures of patients with tularemia were evaluated, and antimicrobial susceptibilities of two Francisella tularensis strains were tested by disk diffusion and E-test methods. A high-resolution multiple-locus variable-number tandem repeat analysis (MLVA) comprising six variable-number tandem repeat loci was applied to elucidate the genetic relatedness among Turkish and Bulgarian isolates which were isolated in a recent outbreak. The patients were diagnosed in two outbreaks in two cities of Turkey in 2005 and 2006. A total of 16 samples from 12 patients were cultured, and PCR tests were carried out on 15 samples that were positive in five lymph node aspirates and two soft tissue aspirates. F. tularensis was isolated from the lymph nodes of two patients. Aminoglycosides, quinolones, chloramphenicole, tetracyclines, nitrofurantoin, and rifampicin inhibited growth of the isolates. The Turkish isolates appeared to share a common MLVA pattern with one of the four Bulgarian outbreak genotypes.

The 1997-2005 tularemia outbreak in Bulgaria affected 285 people. Ten strains were isolated from humans, a tick, a hare, and water. Amplified fragment length polymorphism typing of the present isolates and of the strain isolated in 1962 suggests that a new genetic variant caused the outbreak.

During the last 40 y, 2 large tularaemia outbreaks occurred in Bulgaria. We report the second outbreak, in 1998--2003, including a total of 262 laboratory confirmed cases. The majority of the patients presented with oropharyngeal tularaemia (89.7%). Less common were the glandular, pulmonary and oculoglandular forms. The diagnosis of tularaemia was confirmed serologically. In 5 cases, F. tularensis was detected by immunofluorescent assay in lymph node biopsies. By PCR, all 5 samples yielded successful amplification of the tul4 gene and the feredoxin gene of F. tularensis. Cultivation of the biopsies resulted in 2 F. tularensis isolates. Three additional F. tularensis isolates were obtained from an open well, a dead hare and a tick. All 5 isolates were identified as F. tularensis subsp. holarctica seu palaearctica. F. tularensis was detected by PCR amplification of the tul4 gene in spleen samples from 9 (21%) of 42 captured rodents. Our study indicated food and water contamination by rodents as important sources of human infection. The high prevalence of the oropharyngeal form of tularaemia supported the assumption that humans contracted the infection by alimentary route.