Crimean-Congo Haemorrhagic Fever (CCHF) is a zoonotic viral disease transmitted by ixodid tick bites, mainly of Hyalomma spp., or through contact with blood/tissues from infected people or animals. CCHF is endemic in the Balkan area, including Bulgaria, where it causes both sporadic cases and community outbreaks.

Crimean-Congo Hemorrhagic Fever, Bulgaria

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.

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