TBE in Romania

Lidia Chitimia-Dobler, Adriana Hristea, Wilhelm Erber and Tamara Vuković-Janković

E-CDC risk status: endemic

(no new data available as of May 2023)

History and current situation

Based on an epidemiological survey performed,1 human TBEV neuroinfections may have an endemic emergent course, and natural foci are in full territorial expansion. Identified risk areas are Tulcea district, Transylvania, at the base of the Carpathian Mountains and the Transylvanian Alps.2,3 TBE has been a notifiable disease since 1996. Surveillance of TBE is not done at the country level, only regionally in some counties (northern/central/western part, close to Hungary). The passive surveillance system was implemented in 2008. However, there is no regular screening and the relative risk of contracting this disease is unknown. In 1999, an outbreak of TBE in humans was recorded with a total of at least 38 human cases.4 The probable cause of the outbreak was goat milk and raw goat milk products. Subsequent studies to detect TBEV in ticks in the affected regions resulted in a non-specified number of TBEV isolates, which were described as belonging to the European subtype of TBEV. A publication of the neighboring Republic of Moldova described the existence of the Far-eastern subtype of TBEV just at the border to Romania.5

In 2001–2006, an epidemiological survey of TBEV infection in 1,669 individuals from 11 Transylvanian counties showed a seroprevalence rate in the general population of 0.6%; higher rates were found in at-risk populations: 5.8% in those living around natural foci and up to 41.5% in those with known occupational risks.1,6

In 2008, a seroprevalence study was published testing 5,063 sera from humans and 2,336 sera from animals derived from a total of 20 counties all over Romania during the years 1985 to 1993. The overall seroprevalence rate was found to be 6.5% for humans and 10.0% for animals with ranges from 0% to 19.4% for individual counties. The testing was done using hemagglutination inhibition testing without further confirmation by neutralization test.7 A recent prevalence antibody study published in 2017 which studied, by serum neutralization test, 519 sheep samples from 5 Romanian counties, provided a total seroprevalence rate of 15.2% with ranges from 2.0% to 27.7%. The data are summed up in Table 3.

During an unpublished study from 2011–2012, a total of 6,548 nymphs and 853 adult ticks of the species Ixodes ricinus from the Romanian counties Alba, Cluj, Ilfov, Mures and Sibiu, including the region of outbreak in 1999, were tested by real time-RT-PCR. All ticks were found to be negative. Testing of 74 sheep sera by TBEV neutralization test gave 6/60 (10%) sera from sheep from Sibiu county, while all other sera were found negative.7 In the same study the goat flock which presumably caused the milk-borne outbreak in 1999 in the county of Sibiu, was serologically tested by neutralization test. 10/10 (100%) goats of the flock showed positive antibody titers for TBEV.7

In the period between 2006–2015 the studies undertaken showed that the most frequent species of tick in Romania is I. ricinus. Three Romanian counties were selected as ticks sampling sites (Sibiu, Tulcea and Giurgiu), collected from vegetation, livestock and reptiles. Specific RNAs from TBEV were detected (3’ UTR-genomic region) in <1% of I. ricinus pools.8 A seroprevalence study tested 1,116 sera collected from humans in 15 localities from 10 counties. The overall seroprevalence was 0.62% (7/1,116). All positive sera were from one single locality from Sibiu county with 4.9% prevalence for the county and 9.7% for that site.9

Overview of TBE in Romania

Table 1: Virus, vector, transmission of TBE in Romania
Viral subtypes, distribution European subtype; possibly Far-Eastern subtype (?)1,5
Reservoir animals No data
Infected tick species (%) I. ricinus – estimated prevalence of TBE virus <1%8
Dairy product transmission Outbreak in 1999 in Sibiu county with at least 38 human cases4

Table 2: TBE reporting and vaccine prevention in Romania
Mandatory TBE reporting Since 2008
Other TBE-surveillance No data
Special clinical features No data
Available vaccines FSME-IMMUN
Vaccination recommendations and reimbursement No national TBE vaccination policy and/or recommendations implemented
Vaccine uptake by age group/ risk group/ general population Unknown
Name, address/website of TBE National Reference Center Centrul de Prevenire si Control a Bolilor Transmisibile, Bucarest; https://cnscbt.ro/

Table 3: Seroprevalence rates against TBEV in humans and animals in different counties of Romania



Figure 2: TBEV-isolation and TBE cases in Romania

Source: European Centre for Disease Prevention and Control. Epidemiological situation of tick-borne encephalitis in the European Union and European Free Trade Association countries. Stockholm: ECDC; 2012.

Contact

Lidia Chitimia-Dobler
lydiachitimia@gmail.com

Authors

Lidia Chitimia-Dobler, Adriana Hristea, Wilhelm Erber and Tamara Vuković-Janković

Citation

Chitimia-Dobler L, Hristea A, Erber W, Vuković-Janković T. TBE in Romania. Chapter 13. In: Dobler G, Erber W, Bröker M, Chitimia-Dobler L, Schmitt HJ, eds. The TBE Book. 7th ed. Singapore: Global Health Press; 2024. doi: 10.33442/26613980_13-26-7

References

  1. Molnar GB, Perseca T, Feder A, Pacuraru D, Marialaki E, Cojan A. Epidemiological assessment of morbidity and natural foci of TBE-CEE virus infection in Transylvania. Rev Med Chir Soc Med Nat Iasi. 2008;112:471-7. doi: 10.3201/eid2312.170166
  2. Kollaritsch H, et al. Background document on vaccines and vaccination against tick–borne encephalitis. Geneva, WHO Strategic Advisory Group of Experts on Immunization. Accessed 17 May 2024. http://www.who.int/immunization/ sage/6_TBE_backgr_18_Mar_net_apr_2011.pdf
  3. Süss J. Tick-borne encephalitis in Europe and beyond–the epidemiological situation as of 2007. Euro Surveill. 2008;13 (26). pii:18916.
  4. Ionescu L, Alexse A, Ceianu C, et al. Investigation methods used for identifying the presence of tick-borne encephalitis virus (TBEV) in vector arthropods. Lucr Stiin Med Vet. 2009;17(9):288-93.
  5. Ponomareva EP, Mikryukova TP, Gori AV, et al. Detection of Far-Eastern subtype of tick-borne encephalitis viral RNA in ticks collected in the Republic of Moldova. J Vector Borne Dis. 2015;52:334-6.
  6. Ionescu L, Necsulescu M, Alexse A, et al. Infection with tick-borne encephalitis virus in Romania (in Romanian). Rev Rom Med Vet. 2008;3:69-79.
  7. Kahl O, Chitimia-Dobler L, Süss J. Unpublished data.
  8. Vladimirescu A, Dumitrescu G, Ionescu L, et al. Real-Time PCR studies regarding the Borrelia burgdorferi, Francisella tularensis, tick-borne encephalitis virus (TBEV) and crimeean congo hemorrhagic fever virus (CCHFv) occurrence in the Romanian ticks. Int J Infect Dis. 2016;45S:193.
  9. Panciu AM, Cheran CA, Militaru ED, Rîciu CD, Hristea A. Serosurvey of tick-borne encephalitis virus infection in Romania. Pathogens. 2024;13:231. doi:10.3390/pathogens13030231
  10. Salat J, Mihalca AD, Mihaiu M, Modrý D, Ruzek D. Tick-borne encephalitis in sheep, Romania. Emerg. Infect. Dis. 2017;23:2065–7. doi:10.3201/eid2312.170166

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