Water-borne outbreak of oropharyngeal and glandular tularemia in Georgia: investigation and follow-up.

BACKGROUND: In November 2006, an outbreak of waterborne tularemia occurred in an eastern region in the Republic of Georgia. Outbreak investigation revealed 26 cases: 21 oropharyngeal and 5 glandular tularemia cases. METHODS: The presentation of the index case triggered an outbreak investigation involving the collection of clinical/ epidemiological data, application of tularine skin test, and laboratory confirmation of the possible cases using the tube agglutination test and polymerase chain reaction (PCR) testing. Serology results were verified by enzyme-linked immunosorbent assay (ELISA) and Western blot. A case- control study along with follow-up was conducted 4 months after the index case presentation. RESULTS: Exudative pharyngitis, predominantly laterocervical adenitis, fever, and headache were the most prevalent clinical signs/symptoms observed. Depressed mood, concentration difficulties, and sleep disturbance were also detected. Bubo aspirates tested by PCR were positive in 4/4 cases and pharyngeal swabs also tested by PCR were positive in 2/3 cases. Francisella tularensis was isolated from the water samples. Comparison of the cases and controls did not reveal any statistically significant risk factors. A follow-up investigation revealed cases with protracted symptoms of fatigue, headache, and sleep disturbance. Additionally, 8/26 cases still had cervical adenopathy of prominent size. A delay in diagnosis was associated with persistent lymphadenopathy on follow-up examination (p = 0.05). CONCLUSION: We observed unique features of persistent neuropsychiatric symptoms and lymphadenopathy 5 months after tularemia infection which were associated with delayed diagnosis and the lack of prompt response to therapy. This outbreak of oropharyngeal tularemia emphasizes the importance of a rapid diagnostic and investigative response to tularemia. This type of response can prevent ongoing exposure, as well as provide expeditious treatment to mitigate persistent symptoms.

[Dynamics of epizootic activity of natural foci of plague in Georgia].

Based on long term (1960-1990) surveillance data analysis of the plague natural foci activity on the territory of Georgia hypothetical parameters of epizootic activity algorithm have been revealed and potential role for susceptibility of noncultivated forms in the ecology of plague has been suggested. The article emphasizes the importance of circumstances, when reversal of noncultivated forms of Y. pestis creates real opportunity of microfoci development, however lack of appropriate density of rodent's population and index of abundance limit this process and do not allow initiation of epizootic processes. It is suggested that in case of surveillance of the plague foci, along with another factors more attention should be paid to identification of "additional" reservoirs and vectors, and also determine conditions, under such, they could be connected to epizootic processes. Significance of the study of influence Mingenchaury reservoir on the ecology of plain- foothill foci of plague has been also pointed out. Special attention is devoted to the fact that now when global scale of terrorism is taking place; it becomes extremely important to work toward the ensuring of biosecurity. A possibility of using biological weapons not only for bioterrorism but also for biodiversity, without much publicity for responsibility for the completed action, has been also discussed. In this case selected infectious agent is usually not exotic for the given country or region. Considering all stated above, it is becoming clear, that it is important to have strong monitoring on the natural foci of plague and detailed molecular-biological passportisation of Y. pestis strains circulating in these foci.

Characterisation of Yersinia pestis isolates from natural foci of plague in the Republic of Georgia, and their relationship to Y. pestis isolates from other countries.

Forty Yersinia pestis isolates from endemic foci of plague in the Republic of Georgia, and six Y. pestis isolates from neighbouring former Soviet Union countries, were analysed for their biochemical and phenotypic properties, and their genetic relatedness was compared with Y. pestis strains KIM and CO92 by pulsed-field gel electrophoresis (PFGE). In addition, 11 Y. pestis isolates from the USA, together with published nucleotide sequences from Y. pestis strains KIM, CO92 and 91001, were compared with the 46 isolates in the present collection using multilocus sequence typing (MLST), based on sequence data for the 16S rRNA, hsp60, glnA, gyrB, recA, manB, thrA and tmk loci. Four virulence gene loci (caf1, lcrV, psaA and pla) were also sequenced and analysed. Two sequence types (ST1 and ST2), which differed by a single nucleotide, were identified by MLST. With the exception of a single isolate (771G), all of the Georgian Y. pestis isolates belonged to ST2. PFGE also grouped the Georgian Y. pestis isolates separately from the non-Georgian isolates. Overall, PFGE discriminated the Y. pestis isolates more effectively than MLST. The sequences of three of the four virulence genes (lcrV, psaA and pla) were identical in all Georgian and non-Georgian isolates, but the caf1 locus was represented by two allele types, with caf1 NT1 being associated with the non-Georgian isolates and caf1 NT2 being associated with the Georgian isolates. These results suggest that Georgian Y. pestis isolates are of clonal origin.