Wednesday, February 1, 2023
| Country, y (reference) | Total FB-TBE cases | No. FB-TBE/TBE cases (%)† |
|---|---|---|
| Slovakia[5,14,15] | 177 | |
| 1993 | 7/NA | |
| 2012 | 15/32 (46.88) | |
| 2013 | 5/157 (3.18) | |
| 2014 | 11/115 (9.57) | |
| 2015 | 14/80 (17.50) | |
| 2016 | 65/169 (38.46) | |
| 2009–2016 | 60 additional cases not included in mentioned outbreaks‡ | |
| Czech Republic[3,16] | 65 | |
| 1994 | 1/617 (0.16) | |
| 1997 | 2/415 (0.48) | |
| 1998 | 1/422 (0.24) | |
| 1999 | 28/489 (5.73) | |
| 2002 | 5/647 (0.77) | |
| 2003 | 6/606 (0.99) | |
| 2004 | 2/507 (0.39) | |
| 2005 | 8/643 (1.24) | |
| 2007 | 8/546 (1.47) | |
| 2008 | 4/631 (0.63) | |
| Poland[17,18] | 52 | |
| 1995 | 48/NA | |
| 2017 | 4/196 (2.04) | |
| Hungary[10,19] | 42 | |
| 2007 | 31/69 (44.93) | |
| 2011 | 11/43 (25.58) | |
| Estonia[8,20] | 28 | |
| 2005 | 27/164 (16.46) | |
| 2019 | 1/82 (1.22) | |
| Germany[21,22] | 16 | |
| 2016 | 2/348 (0.57) | |
| 2017 | 14/485 (2.89) | |
| Croatia[23,24] | 14 | |
| 2015 | 9/26 (34.62) | |
| 2019 | 5/13 (38.46) | |
| Austria[9,25] | 8 | |
| 1989 | 2/NA | |
| 2008 | 6/86 (6.98) | |
| Russia[6] | 5 | |
| 1991 | 5/NA | |
| Slovenia[26] | 3 | |
| 2012 | 3/164 (1.83) |
Table 1. Foodborne and nonfoodborne TBE cases, Europe, 1980–2021*
*FB-TBE, foodborne tick-borne encephalitis; NA not available; TBE, tick-borne encephalitis.
†Number of TBE cases are from European Centre for Disease Prevention and Control annual report[2] and other reports[27,28].
‡From [14].
| Country (reference) | No. confirmed cases | No. CNS invasive disease | CNS invasive disease type | Blood serology | CSF serology |
|---|---|---|---|---|---|
| Austria[9] | 6 | 4 | 4 ME cases | Positive IgG and IgM | Borderline IgM, positive IgG; borderline IgM, borderline IgG; positive IgM, positive IgG; positive IgM, borderline IgG |
| Croatia[23] | 7 | 6 proven, 7 symptomatic | 5 meningitis cases, 1 ME case; 1 case with fever and headache but LP not performed | Positive IgG and IgM | 6 patients had CSF pleocytosis but negative IgG and IgM |
| Czech Republic[16] | 1 | 1 | ME, myelitis | Positive IgM | CSF pleocytosis |
| Estonia[20] | 1 | 1 | ME | Positive IgM and IgG | positive serology |
| Germany[22] | 2 | 2 | ME in both cases | Positive IgG and IgM | Positive IgG and IgM |
| Hungary[10] | 25 | 2 confirmed; 25 with neurologic symptoms but LP only performed on 3 | Positive IgG and IgM | Positive IgG in 2 of 3 CSF samples | |
| Hungary[19] | 7 | 4 | 4 confirmed ME cases | In all 7 confirmed cases, positive IgM in blood or CSF | |
| Poland[18] | 35 | 15 | Positive IgM and IgG | Positive serology for 15 patients with neuroinfection | |
| Poland[29] | 4 | 4 | 4 meningitis cases | 2 had elevated IgG and IgM. 1 had only elevated IgM. The fourth wasn't examined | All 4 had elevated IgG and IgM |
| Slovakia[15] | 2 | 1 | Positive IgM | Positive IgM | |
| 43 | 12 | Positive IgM and IgG | 12 patients with IgM and IgG in CSF | ||
| Slovenia[26] | 3 | 1 | 2 cases with symptoms of ME but LP only performed on 1 | Positive IgG and IgM | CSF pleocytosis |
Table 2. Neuroinvasive disease reported in cases of foodborne tick-borne encephalitis, Europe, 1980–2021*
*CNS, central nervous system; CSF, cerebrospinal fluid; LP, lumbar puncture; ME, meningoencephalitis.
| Country (reference) | Year | No. persons exposed | Clinical attack rate, % | Source of dairy products |
|---|---|---|---|---|
| Slovakia[5] | 1993 | 7 | 100 | Goat |
| Poland[18] | 1995 | 63 | 76.2 | Goat |
| Hungary[10] | 2007 | 154 | 20.1 | Goat |
| Austria[9] | 2008 | 7 | 57.1 | Goat and cow |
| Hungary[19] | 2011 | 103 | 10.7 | Cow |
| Slovenia[26] | 2012 | 4 | 75 | Goat |
| Croatia[23] | 2015 | 10 | 90 | Goat |
| Germany[22] | 2016 | 32 | 6.3 | Goat |
| Slovakia[15] | 2016 | 500 | 8.8 | Sheep |
| Germany[21] | 2017 | 27 | 51.9 | Goat |
Table 3. Attack rates for foodborne tick-borne encephalitis, Europe, 1980–2021
Physicians - maximum of 1.00 AMA PRA Category 1 Credit(s)™
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This activity is intended for infectious disease clinicians, public health officials, internists, neurologists, and other clinicians caring for patients with or at risk for foodborne tick-borne encephalitis.
The goal of this activity is for learners to be better able to describe cases of alimentary-transmitted TBE in Europe in the last 4 decades, including estimated attack rate, epidemiological and clinical characteristics, and clinical and public health implications, based on a systematic review and meta-analysis of 410 cases.
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Tick-borne encephalitis (TBE) is a viral infection of the central nervous system that occurs in many parts of Europe and Asia. Humans mainly acquire TBE through tick bites, but TBE occasionally is contracted through consuming unpasteurized milk products from viremic livestock. We describe cases of TBE acquired through alimentary transmission in Europe during the past 4 decades. We conducted a systematic review and meta-analysis of 410 foodborne TBE cases, mostly from a region in central and eastern Europe. Most cases were reported during the warmer months (April–August) and were associated with ingesting unpasteurized dairy products from goats. The median incubation period was short, 3.5 days, and neuroinvasive disease was common (38.9%). The clinical attack rate was 14% (95% CI 12%–16%), and we noted major heterogeneity. Vaccination programs and public awareness campaigns could reduce the number of persons affected by this potentially severe disease.
Tick-borne encephalitis (TBE) is a viral infection of the central nervous system (CNS) caused by tick-borne encephalitis virus (TBEV). TBE occurs mainly in eastern, central, and northern Europe and in northern China, Mongolia, and Russia[1]. Although vaccination can effectively prevent TBE, >3,000 cases were reported in Europe in 2019, and case-fatality was 0.7%[2]. However, many mild and subclinical infections probably remain undiagnosed.
Humans acquire TBE mainly via tick bites, but TBEV can occasionally be transmitted through consumption of unpasteurized milk products from viremic livestock. The largest known outbreak of foodborne TBE (FB-TBE) occurred in 1954 in what was then Czechoslovakia, when TBE developed in >600 persons infected via TBEV-contaminated milk from cows and goats[3]. During that period, the disease was termed biphasic milk fever. During the past 4 decades, repeated smaller outbreaks have been reported in association with TBEV transmission via contaminated milk in various countries in Europe and in Russia[3–10].
Despite the role of food as a transmission route, FB-TBE has not been systematically described until recently. Two recent published reviews summarized published reports[11,12], but those studies did not include meta-analysis of published data. We systematically describe cases of alimentary TBEV transmission in Europe during the past 4 decades, estimate the attack rate of FB-TBE, and describe the epidemiologic and clinical characteristics of FB-TBE.
