Attestation committee
Accreditation committee
Expert committee
Dispositions, instructions
Normative acts
Nomenclature
Institutions
Scientific councils
Seminars
Theses
Scientific advisers
Scientists
Doctoral students
Postdoctoral students
CNAA logo

 română | русский | english


The consideration of optimization of the Lyme borreliosis epidemiological surveillance


Author: Stela Gheorghiţa
Degree:doctor of medicine
Speciality: 14.00.30 - Epidemiology
Year:2007
Scientific adviser: Valeriu Chicu
doctor, associate professor (docent), State University of Medicine and Pharmacy "Nicolae Testemitanu"
Institution:
Scientific council:

Status

The thesis was presented on the 14 March, 2007
Approved by NCAA on the 19 April, 2007

Abstract

Adobe PDF document0.27 Mb / in romanian

Thesis

CZU 616.98-036.22

Adobe PDF document 1.98 Mb / in romanian
130 pages


Keywords

Lyme borreliosis, Borrelia burgdorferi, source, host population, vector, tick Ixodes ricinus, focus, epidemiological surveillance, case definitions

Summary

This work is a synthesis of the results obtained in the study of peculiarities of foci formation and functioning, of epidemic process manifestation, and also the improvement of epidemiological surveillance system for Lyme borreliosis. For the aim of optimization of the LB epidemiological surveillance system, the epizootological peculiarities and the ones of the epidemic process manifestation in different territories, groups of population and periods of time have been determined. The biocenotic structure of the foci and some peculiarities of the pathogenic agent circulation have been studied, and the evaluation criteria of the foci activity were elaborated, establishing the factors and level of potential risk of contracting LB by humans in various investigated territories.

The study of borrelia circulation in the population of vectors (tick Ixodes ricinus) indicated that in the reference period the average rate of ticks infected with borrelia in our country was 48,5%.

The results of the identifications of pathogenic genospecies of borrelia from tick Ixodes ricinus collected in the investigated territories have demonstrated the presence of specific segment of Borrelia afzelii DNA in 9 tests and of Borrelia garinii - in 3 tests. Territorial distribution of pathogenic genospecies of borrelia coincided with the territories highly populated by the tick in the Northern and Central zones.

The intensity of circulation of casual agent of LB in the rodents population was evaluated by determining the presence of specific anti Borrelia burgdorferi antibodies in blood serum and an average seroprevalence of 20,4% in the country was demonstrated. Anti Borrelia burgdorferi specific antibodies were established in 26,4% and 24,4% of serum samples collected from rodents – species Apodemus uralensis and respectively A.flavicollis. The analysis of territorial distribution of micrommamalian with positive serological results elucidated the higher seroprevalence in rodents collected in the Southern and Central zones - 25,6% and 21,7% respectively, in comparison with the Northern zone – 17,9%.

The average rate of anti Borrelia burgdorferi specific antibodies in bovines and ovines was 56,6%.

In the foci of the selected territory a number of peculiarities were marked out (the presence of pathogenic genospecies of borreliia, density of tick I.ricinus, the rank of pathogenic agents circulation in the host population, the existence of favorable factors in the environment for the maintenance and circulation of pathogenic agents, the closeness of foci to the localities, entertainment zones) and an algorithm for determining of degree of foci activity and risk was elaborated. The classification in territories with high, moderate and minimal risk of contracting LB was proposed.

The algorithm of laboratory diagnostic for LB, in two successive steps was proposed and approved: I step – testing by immunofluorescent assay (IFA) or sensitive enzyme immunoassay (ELISA) as the screening tests, II step - confirmation of positive and equivocal results by Western immunoblot test.

Case definitions for all specialists involved in detecting, diagnosing, reporting of this disease and carrying out of adequate preventing measures were proposed and implemented in practice for LB surveillance system