Seroprevalencija i epidemiološke karakteristike krpeljskog encefalitisa u Vojvodini - PhDData

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Seroprevalencija i epidemiološke karakteristike krpeljskog encefalitisa u Vojvodini

The thesis was published by Pustahija Tatjana, in September 2023, University of Novi Sad.

Abstract:

Introduction: Tick-borne encephalitis is a viral vector-borne disease with focal distribution, which occurs endemically in a wide area of Europe and Asia. Globally, tick-borne encephalitis is becoming an increasing public health problem, because existing endemic foci are spreading and new ones are emerging, which results in a gradual and constant increase in the incidence of this disease in human population and the appearance of autochthonous cases in countries where they have not been registered so far. In the Republic of Serbia, epidemiological surveillance of tick-borne encephalitis is passive and insufficient, and laboratory diagnostics are available in a small number of institutions. The aim of the research was to detect the presence of the tick-borne encephalitis virus and determine its subtype and prevalence in the tick population in the territory of Fruška Gora, and to determine the seroprevalence of specific antibodies against the tick-borne encephalitis virus among the population of the Fruška Gora region and population of Vojvodina outside the territory of Fruška Gora, as well as the incidence rate of tick-borne encephalitis in Vojvodina. Material and methods: Detecting the presence of the tick-borne encephalitis virus and determining its prevalence in ticks from the territory of Fruška Gora was conducted prospectively. Ticks were collected in the period from June 2019 to October 2019, during May 2020 and in the period March-June 2022 at 109 locations in 49 places of Fruška Gora using the flag-hour method. The determination of ticks was carried out according to the most important morphological characteristics, according to taxonomic keys. Ticks were tested for the presence of viral RNA using the PCR method. Determining the presence, frequency and prevalence of tick-borne encephalitis in the human population in Vojvodina was conducted prospectively from August 1, 2021 to October 31, 2022. The subjects were hospitalized patients, who were suspected for tick-borne encephalitis, based on the case definition of the European Center for Disease Control and Prevention. The blood sera and/or cerebrospinal fluid of these patients were examined by ELISA test for the presence of specific antibodies to the tick-borne encephalitis virus. All seropositive and borderline samples were further tested with a neutralization test. Seroepidemiological study was conducted prospectively. Based on the criteria for the inclusion of subjects in the research, that is, exclusion from the research, 1000 samples of residual blood serum of residents of 49 places in the Fruška Gora region were collected. Each subject of this group by gender and age was matched by one from the group of subjects, which consisted of 1000 blood sera of residents of Vojvodina outside the territory of Fruška Gora. Laboratory testing of blood serum samples was performed using an ELISA test for the presence of specific IgG antibodies, and all positive and borderline samples were further tested for the presence of neutralizing antibodies. The seroprevalence of specific antibodies against the tick-borne encephalitis virus was calculated in both groups of subjects, and they compared. Also, the seroprevalence was analyzed in relation to sex, age, place of residence of the subjects, occupation and previous tick bite. Results: During the research period, a total of 1931 ticks were collected and determined, of which 1882 were laboratory tested using the PCR method. No tick-borne encephalitis virus RNA was detected in any sample. In the period from August 1, 2021 to October 31, 2022, no confirmed cases of tick borne encephalitis were registered on the territory of Vojvodina. The registered seroprevalence of specific antibodies to the tick-borne encephalitis virus in the group of residents of Vojvodina outside Fruška Gora is 0.20% (95% CI: 0.02 – 0.72), and in the group of residents of the Fruška Gora region it is 0.40% (95% CI: 0.01–1.02). Seroprevalence among the population of Fruška Gora is twice as high as the value of seroprevalence registered in the group of inhabitants of Vojvodina outside this region, but no statistically significant difference in seroprevalence between these two groups was determined. The highest seroprevalence of 2.94% (CI: 95% 0.07–16.39) was recorded in the age group of 80 years and older in both samples of respondants. In the group of respondents from Vojvodina outside Fruška Gora, the male/female seroprevalence ratio is 1:1 (0.20% : 0.20% (95% CI: 0.01– 1.11)), while in the population of Fruška Gora, all seropositive respondents were males, and the registered seroprevalence is 0.80% (95% CI: 0.20–2.05). Seropositive respondents were registered in places: Beočin (1.08%; 95% CI: 0.02–5.99), Beška (1.45%; 95% CI: 0.03–8.07), Čortanovci (3.57%; 95% CI: 0.09–19.90), Irig (1.92%; 95% CI: 0.04–10.71) and in the part of South Bačka District outside the Fruška Gora region (0.65%; 95% CI: 0.07–2.33). Conclusion: The population of the region of Fruška Gora and parts of the South Bačka district were more infected with the tick-borne encephalitis virus than the rest of the population of Vojvodina outside these areas. It is necessary to implement a comprehensive surveillance of viral encephalitis, based on a standardized case definition, especially in the season of the highest tick activity, with the strengthening of laboratory capacities and the introduction of new methods of laboratory testing into routine practice. It is also necessary to carry out screening of domestic and wild animals and monitoring of ticks with an examination of the prevalence of the tick-borne encephalitis virus in them.



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