[Puumala and Dobrava viruses in the northeastern and central regions of Bosnia].

During the epidemic years, the average monthly temperatures in February were by 4.3 times higher than the average temperatures during the nonepidemic years, which may have influenced the early reproduction of rodents and development of "mouse years". The rodents were identified as: Apodemus flavicollis (n = 139), Apodemus sylvaticus (n = 89), Apodemus agrarius (n = 4), Clethrionomys glareolus (n = 117), Sorex araneus (n = 5), Pytimus subterraneus (n = 23), Mus musculus (n = 1), Mycrotus arvalis (n = 1) and Rattus norvegicus (n = 2). Clethrionomys glareolus was predominant in the regions with the altitude higher than 1160 meters and Apodemus species in the regions with the altitude lower than 670 meters. The rodent population density changes seasonally and cyclically. During the epidemic years, the rodent population density was marked as very high, whereas during the nonepidemic years it was designated from low to moderate. Well-known natural hosts of Hantaviruses (A. flavicolis and C. glareolus) are most widely spread species of small rodents, and the increase in their population is closely related with outbreaks of epidemics of HVBS-a. Puumala virus caused HVBS-a in 49.84% (155/311); Dobrava virus in 23.15% (72/311) of cases, whereas Hantaviruses serotype was not identified in 27.00% (84/311) of cases. Infections caused by Puumala virus were more frequent than the infections caused by Dobrava virus during both epidemic and nonepidemic periods. The proportion of humans infected with Puumala and Dobrava viruses correlated with the number of natural hosts of Hantaviruses in the areas of HVBS outbreaks. The study of the prevalence of hantavirus antibodies in the populations of rodents and humans, which had been under way, should elucidate these relationships.