Radovan Cekanac

Prevalence of Borrelia burgdorferi in Ixodes ricinus Ticks in Belgrade Area

OBJECTIVE Lyme borreliosis is vector-borne zoonosis. The causative agent of Lyme borreliosis is a spirochete of Borrelia burgdorferi (Bb) sensu lato complex, which is transmitted by ticks of the Ixodes ricinus complex. The aim of our paper is to estimate the prevalence of I. ricinus ticks, the level of their infectivity by Bb, and the prevalence of certain genospecies of Bb sensu lato in ixodide ticks inhabiting Belgrade. MATERIALS AND METHODS An estimate of the tick population density was expressed by the value of flag/hour. For isolation and cultivation of Borrelia, selective Barbour-Stonner-Kelly II media was used. Typization of Borrelia was made by applying the species-specific polymerase chain reaction (PCR) and polymerase chain reaction-restriction fragment length polymorphism analysis. In statistical analysis, Chi(2) test was used. RESULTS Values of flag/hour have varied in relation to year observed and type of habitat: The lowest values were recorded in the city parks (17.9). The values were higher in parks-woods (19.7 and 33.4, respectively). The highest values were detected in localities similar to wooded areas (48.0). The estimated average infestation of ticks with Bb was 21.9%, excluding statistically significant differences by years of investigation. We found the dominance of Borrelia afzelii (75%). Bb sensu stricto (22.2%) as well as Borrelia garinii (2.8%) was much less present. Statistically significant difference was established in the prevalence of the above-mentioned genospecies in relation to the examined localities. CONCLUSIONS We have established the prevalence of all three genospecies in the city of Belgrade. Bb sensu lato was found, with the dominance of B. afzelii.

Evidence of recombination in Tula virus strains from Serbia.

Tula hantavirus (TULV) belongs to Bunyaviridae family, with negative sense RNA genome. Segmented nature of hantaviral genome allows for genetic reassortment, but the evidence of homologous recombination also exists. In this study we analyzed TULV sequences isolated in Serbia on different occasions and from different rodent hosts: 1987 strain from Microtus subterraneus and 2007 strain from Microtus arvalis. Phylogenetic analysis of both L and S segment sequences is suggestive of geographically related clustering, as previously shown for majority of hantaviruses. Reconstruction of phylogenetic tree for TULV S segment showed that both sequences from Serbia clustered together with sequences from East Slovakia, which had previously been shown to be recombinants (Kosice strain). Exploratory recombination analysis, supported by phylogenetic and amino acid pattern analysis, revealed the presence of recombination in the S segment sequences from Serbia, resulting in mosaic-like structure of TULV S segment similar to the one of Kosice strain. Although recombination is considered a rare event in molecular evolution of negative strand RNA viruses, obtained molecular data in this study support evidence of recombination in TULV, in geographically distant regions of Europe.

Risk of Lyme disease development after a tick bite

BACKGROUND/AIM Despite numerous research of Lyme disease (LD), there are still many concerns about environmental of infectious agent of LD, as well as its prophylaxis, diagnosis and treatment. The aim of this work was to determine the risk of LD in relation to the way of removing ticks and duration of tick attachment. METHODS In the period from 2000 to 2007 a prospective study was conducted including persons with tick bite referred to the Institute of Epidemiology, Military Medical Academy, and followed for the occurrence of early Lyme disease up to six months after a tick bite. Epidemiological questionnaire was used to collect relevant information about the place and time of tick bites, the way of a removing tick, duration of tick attachment, remnants of a tick left in the skin (parts of the mouth device) and the signs of clinical manifestations of LD. Duration of tick attachment was determined on the basis of size of engorged tick and epidemiological data. Removed ticks were determined by the key of Pomerancev. Professional removing of attached tick was considered to be removing of tick with mechanical means by healthcare personnel. Fishers exact test, Chi squares test and calculation of the relative risk (RR) were used for data analysis. RESULTS Of 3 126 patients with tick bite, clinical manifestations of LD were demonstrated in 19 (0.61%). In the group of subjects (n = 829) in which a tick was not removed professionally there were 17 (2.05%) cases with LD, while in the group of respondents (n = 2 297) in who a tick was removed professionally there were 2 (0.09%) cases with LD after tick bite (RR, 23.55; p < 0.0001). The disease was most frequent in the group of respondents with incompletely and unprofessionally removed ticks (2.46%). In the groups of patients with unprofessionally but completely removed ticks LD occurred in 0.89%, while in the group of subjects with a tick removed by an expert, but incompletely in 0.78% cases. The disease occurred rarely in the group with a tick removed completely and professionally (0.05%). There was no case of LD in the group of patients with a tick removed within 24 hours. The longer time of exposure after 24 hours, the higher absolute risk of disease was reported. CONCLUSION In prevention of Lyme disease it is important to urgent remove a tick, to use a correct procedure of removing and to remove the whole tick without any remnants.

Molecular characterization of Borrelia burgdorferi sensu lato strains isolated in the area of Belgrade, Serbia

This is the first report of the molecular characterization and identification of Borrelia burgdorferi sensu lato strains isolated in Serbia. Isolates A1, A2 and M1, from Ixodes ricinus, belong to Borrelia burgdorferi sensu stricto, while isolate K1 from Apodemus flavicollis is a mixture of Borrelia afzelii and B. burgdorferi s.s.

Genetic detection of Dobrava-Belgrade hantavirus in the edible dormouse (Glis glis) in central Serbia

Hantaviruses are endemic in the Balkans, particularly in Serbia, where sporadic cases and/or outbreaks of hantaviral human disease have been reported repeatedly, and evidenced serologically. Here, we present genetic detection of Dobrava-Belgrade virus (DOBV) hantaviral sequences in wild rodents trapped in central Serbia. All the animals were pre-screened serologically by indirect immunofluorescence (IF) test and only those with a positive finding of hantaviral antigens were further tested by polymerase chain reaction. Of the total of 104 trapped animals, 20 were found to be IF positive and of those three were positive for hantaviral RNA: one Microtus arvalis for Tula virus, and one each of Apodemus agrarius and Glis glis for DOBV. Phylogenetic analysis of the obtained sequences implies putative DOBV spillover infection of A. agrarius and G. glis from Apodemus flavicollis. However, future investigations should help to identify the most common natural host and geographical distribution of DOBV in its reservoir hosts in Serbia.