TBE in Hungary

Anna Nagy, Ferenc Schneider, Eszter Mezei, András Lakos

E-CDC risk status: endemic

(data as of end 2023)

History and Current Situation

Hungarian scientists were among the pioneers in Europe as the tick-borne encephalitis virus (TBEV) was isolated in 1952, 30 years after the TBEV had been described in Russia (see chapters 3).1 However, most of their observations were published in the Hungarian language, and therefore did not become widely distributed. Between 1981 and 1997, the average annual number of TBE cases reported to authorities was around 300, and as of that year, it decreased to fewer than 20 patients per year (Figures 1, 2). It has been speculated that the decrease is a result of underreporting of TBE, following a change in the reimbursement system for payments related to serologic TBE diagnosis.2-4 However, two main arguments contradict the ‘underreporting hypothesis’:

  1. During the 5 years before 1997, a total of 1,800,000 FSME vaccine doses were sold by pharmacies (Figure 1), and this convincingly explains the observed reduction of TBE cases (total Hungarian population size is 10 million). Furthermore, after 1997, lethal TBE cases decreased in parallel with decreased incidence. If lower incidences had resulted from underreporting, then lethal cases would not have changed since the etiology of a lethal case is regularly determined by mandatory autopsy and other diagnostic tests.
  2. The incidence data from the Hungarian military are similar to that of the civilian population: no case has been reported since 2003. ‘Underreporting’5 in this context would be practically impossible. The reporting system for TBE has not changed, and a reduction of cases (most probably due to vaccination) sufficiently explains why the use of TBE serology was subsequently reduced.

Overview of TBE in Hungary

Table 1: Virus, vector, transmission of TBE in Hungary
Viral subtypes, distributionTBEV-EU6
Reservoir animalsApodemus agrarius, Apodemus flavicollis, Microtus arvalis,
Myodes glareolus6
Apodemus flavicollis, Apodemus agrarius, Myodes glareolus,
Microtus subterraneus7
Infected tick (Fig. 3)2/2485=0.08%1
6/8310≈0.07%8
40/51,746≈0.08%; the highest figure was 22/6738≈0.3% in this study9
1/17,500≈0.006%10
5/2196≈0.23%, only with PCR11
3/9616≈0.03%7
Dairy product transmissionOut of the 81 food-borne TBE cases registered between 1992 and 2011, 55.1% were male. Also, 4.4% of the total number of TBE cases were milk-borne. On average, 24.5% of people who drank infected goat milk suffered from clinical symptoms of neurologic infection.
 
Historically, only 2 TBE epidemics in Hungary were caused by cow milk.12 The largest epidemic came from a single goat (of the 75 tested animals) with 25 cases amongst 154 subjects who had consumed contaminated milk.13 In that year (2007), almost half of the total number (30/63) of registered TBE cases were of alimentary origin.
Table 2: TBE reporting and vaccine prevention in Hungary
Mandatory TBE reportingEvery physician who establishes a diagnosis of TBE must report it. Practically, these are hospital-based specialists for infectious diseases, pediatricians, internists, and neurologists.
 
Case definition: clinical symptoms of central nervous infection + presence of TBE immunoglobulin M (IgM) antibodies in serum and cerebrospinal fluid (CSF) OR TBEV-specific IgM in CSF OR isolation of infectious virus from clinical samples OR detection of TBEV RNA in clinical samples OR seroconversion and/or 4-fold specific IgG increase in a sample pair.14
Other TBE surveillanceNo
Special clinical features1.    In one study, 21% of retrospectively collected patient cases were agrarian, 16% forestry workers.8
2.    Other work has shown 12% to 16% of patients with TBE were forestry workers.9,10
3.    Similarly, another report found 10.4% of 5196 cases were forestry, 11% other agrarian workers.15
4.    Also, 2% of the 1,670 forestry workers screened for Lyme borreliosis went through TBE (Lakos, unpublished data).
5. 65% of hospitalized patients could recall a biphasic course of their TBE.16

In the same department of the Central Hospital for Infectious Diseases, during the years 1976-1980 (n=100), 27 patients showed paresis, 2 died. In 1987-1991 (n=93), only 5 patients had paresis, none of them died.17
 
From 1985 to 2008, the death rate from TBE in Hungary was 29/3987 (0.73%).18 However, in an earlier period from 1977 to 1996, the fatality rate was higher – 43/5196 (0.83%). Most of the fatal cases were male (85%), while the proportion of male patients in the total TBE population was 70%.15
Available vaccinesFSME Immune Inject is a vaccine available for public use since 1992; another vaccine, Encepur, launched in 1995. Previously, between 1977 and 1990, some 150,000 doses were distributed for the at-risk population. It has to be mentioned, that TBE vaccination in Austria at the same time showed a field effectiveness 79.4%-100% after the second dose and 97.3%-100% after the third dose26) From 1990 to 2017, 6 million doses were sold. (The Hungarian population is 10 million).
Vaccination recommendations and reimbursementWhen FSME Immune Inject was first available in Hungary in the early 1990s, the reimbursement rate was 95%; the pharmacy price was 59 HUF (€ 0.20). After a gradual decrease, the reimbursement was cancelled for the FSME and Encepur vaccines in 2008 and 2012, respectively. The present price is around 13,000 HUF (€ 40). For occupationally exposed workers, vaccination has been mandatory at the employers’ expense since 1999.20
Vaccine uptake by age group/risk group/general populationNot available
Name, address/website of TBE National Reference CenterNational Center for Public Health and Pharmacy, National Reference Laboratory for Viral Zoonoses, Budapest, Hungary [https://www.nnk.gov.hu/].

Figure 1: Gender distribution of TBE cases and the sold number of doses of TBE vaccines

The data of TBE cases in this graph originated from the National Reference Laboratory for Viral Zoonoses and from the Department of Epidemiological and Vaccination Surveillance of the National Center for Public Health and Pharmacy. The data for 1998 is missing, an estimation is plotted in the graph. No reliable information on the number of vaccine doses sold in 1995 could be found; estimated information was used. (The number of vaccine doses sold is not available from 2018.)


Figure 2: Burden of TBE in Hungary from 1981 to 202324,25. Age distribution and the number of the tested patients

The data of TBE cases in this graph originated from the National Reference Laboratory for Viral Zoonoses and from the Department of Epidemiological and Vaccination Surveillance of the National Center for Public Health and Pharmacy. The number of TBE cases decreased dramatically after a mass vaccination campaign from 1992 to 1995. The Hungarian population is approximately 10 million, so the incidence for 100 cases is 1/100,000. A West Nile virus epidemic resulted in 225 WNV infections in 2018 (https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2019.24.28.1900038). That was the reason for the striking elevation of the requested TBE serological tests (number of tested patients). The elevated number of tests coincided with the elevated number of verified TBE cases.

Source data
YearFemaleMale<1 year1–14 years15–24 years25–59 years>60 yearsUnknown ageTotal TBE casesSold vaccine dosesSamples tested (IgG)
19817920701843192258286N/A 2113
1982102244032552073220346N/A 2241
19836016301637144215223N/A 2595
1984130297043672624411427N/A 3074
19855817502824155251233N/A 2456
198612326003349267331383N/A 3486
19876814901730138302217N/A 4157
19886414901324139352213N/A 3215
19896521901958166392284N/A 3016
19905417401937132382228232512809
19911091900283718048629936,7203823
19925713301931115241190400,0002301
19939124803053205429339650,0002737
19946519902443153404264450,0002488
19957416001832147343234200,0002875
19966318301050144348246161,7172168
19972874061759173102136,3942168
199819550818417074125,8432000
19992148065478369184,5551649
20001935047403054172,615988
20011837067357055153,9412036
2002245606134516080154,1651379
20033678051173250114171,1511315
2004236601023479089163,3471428
20051440025389054215,238927
20062136034428057349,206467
200726370474210063274,396750
20081342045433055271,0921636
20092446059506070288,6291527
20101535039308050221,0951154
20111726053305043233,5791003
201211330172610044229,7941095
201313400243512053146,5181099
2014922035203031150,507840
2015321012156024132,878855
2016415012160019177,064958
2017412013111016157,6871050
20181022042197032N/A1814
2019612001143018N/A830
2020414000135018N/A578
2021240013206N/A553
20221019050195029N/A597
20231014012165024N/A719

Figure 3: TBEV-isolation and TBE cases in Hungary

Map of Hungary showing human TBE incidence (ECDC, 2017).22 TBEV isolation sites are marked by circle (Fornosi, 1954),1 six-pointed stars (Molnár, 1979),23 five-pointed stars (Gerzsenyi, 1980 and 1985),9,10 four-pointed star (Pintér, 2013),11 and three-pointed star (Zöldi, 2015).7 A map with more detailed incidence data21 can be downloaded from https://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20128.

Contact

Anna Nagy
nagy.anna@nngyk.gov.hu

Authors

Anna Nagy, Ferenc Schneider, Eszter Mezei, András Lakos

Citation

Nagy A, Schneider F, Mezei E, Lakos A. TBE in Hungary. 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_13-14-7

References

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