1.0TBE Bookhttps://tbenews.com/tbeIThttps://tbenews.com/tbe/author/brianong/rich600338<blockquote class="wp-embedded-content" data-secret="p6B6lmxtlU"><a href="https://tbenews.com/tbe/chapter-12-epidemiology-of-tbe/">Chapter 12: Epidemiology of TBE</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="https://tbenews.com/tbe/chapter-12-epidemiology-of-tbe/embed/#?secret=p6B6lmxtlU" width="600" height="338" title="“Chapter 12: Epidemiology of TBE” — TBE Book" data-secret="p6B6lmxtlU" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script> /*! This file is auto-generated */ !function(d,l){"use strict";l.querySelector&&d.addEventListener&&"undefined"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!/[^a-zA-Z0-9]/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),o=l.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),c=new RegExp("^https?:$","i"),i=0;i<o.length;i++)o[i].style.display="none";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute("style"),"height"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):"link"===t.message&&(r=new URL(s.getAttribute("src")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener("message",d.wp.receiveEmbedMessage,!1),l.addEventListener("DOMContentLoaded",function(){for(var e,t,s=l.querySelectorAll("iframe.wp-embedded-content"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute("data-secret"))||(t=Math.random().toString(36).substring(2,12),e.src+="#?secret="+t,e.setAttribute("data-secret",t)),e.contentWindow.postMessage({message:"ready",secret:t},"*")},!1)))}(window,document); //# sourceURL=https://tbenews.com/tbe/wp-includes/js/wp-embed.min.js </script> https://tbenews.com/tbe/wp-content/uploads/2017/07/Chapter-12-1-scaled.jpg25601709Chapter 12: Epidemiology of TBE Wilhelm Erber, Michael Broeker, Gerhard Dobler, Lidia Chitimia-Dobler, Heinz-Josef Schmitt Key points 1. Burden of disease and case definition Since the first description of the clinical symptoms of TBE and the detection of TBEV in Far Eastern Russia nearly a century ago,1 TBE has become the most important tick-borne viral disease across Eurasia.  To date, tick-borne encephalitis virus (TBEV) foci have been identified in Europe, Russia, through to northern and eastern Asia up to Japan. Up to 12,000 human tick-borne encephalitis (TBE) cases are registered annually from countries where the disease is reportable. However, this number likely represents an underestimate due to under-diagnosis and/or underreporting. Case fatality rates between 0.2% to 20% are reported, depending on region and perhaps on viral subtype.2 Severe long-term sequelae of TBE are well described both in children and in adults (see Chapters 8 and 9).  1.1. TBE case definition Because TBEV is present in reservoir animals in nature, eliminating or eradicating the disease is impossible. Thus TBE is an important concern for the potentially exposed individual who becomes infected, but it is also of public health relevance, as acknowledged by the World Health Organization (WHO) in all position reports from 1983 to date (2011).3-5 Moreover, TBE vaccination against TBE is on the World Health Organization’s List of Essential Medicines, the safest and most effective medicines needed in a healthcare system.6 In addition, in 2012 the European Center for Disease Prevention and Control (ECDC) decided to add TBE to the list of mandatory notifiable diseases and provided for the first time ever a uniform disease case definition (Table 1).7 Table 1: TBE case definition by the ECDC4 Clinical Criteria Any person with symptoms of inflammation of the CNS (e.g. meningitis, meningoencephalitis, encephalomyelitis, encephaloradiculitis) Laboratory Criteria Laboratory criteria for case confirmation:*At least one of the following five:– TBE specific IgM AND IgG antibodies in blood– TBE specific IgM antibodies in CSF– Sero-conversion or four-fold increase of TBE-specific antibodies in paired serum samples– Detection of TBE viral nucleic acid in a clinical specimen,– Isolation of TBE virus from clinical specimenLaboratory criteria for a probable case: Detection of TBE-specific IgM-antibodies in a unique serum sample Epidemiological Criteria Exposure to a common source (unpasteurized daily products) Case Classification 1. Possible case (Not applicable) 2. Probable case Any person meeting the clinical criteria and the laboratory criteria for a probable case OR Any person meeting the clinical criteria and with an epidemiological link 3. Confirmed case Any person meeting the clinical and laboratory criteria for case confirmation *Serological results should be interpreted according to the vaccination status and previous exposure to other flaviviral infections. Confirmed cases in such situations should be validated by serum neutralization assay or other equivalent assays. As ECDC case definition and reporting have not been universally implemented around the globe or even throughout Europe, data on the burden of disease from different countries are difficult to compare. Even if clear case definitions are provided and routinely implemented by local authorities, differences between countries exist regarding the classification of clinical diseases associated with TBEV infections. For example, Austria reports only “serologically proven hospitalized cases,” whereas the Czech Republic reports any case with “clinical and laboratory signs of aseptic meningitis / meningo-encephalitis, not necessarily associated with hospitalization and Germany reports all diagnosed (serology, virus detection) human infections, irrespective of their clinical manifestation.”8 In addition to the use of different case definitions and case classifications, there is a lack of implementation of routine diagnostics in any patients with CNS infection . This is exemplified by the Polish experience: between 2004 and 2008, only 39% of the country’s hospitals had access to TBEV-serology. Therefore, a pilot project of enhanced surveillance for TBE was implemented in 2009. Routinely testing for TBE in patients with signs of meningitis or encephalitis in the entire country doubled case numbers in 2009 compared to previous years, moreover, and additional 38 endemic districts were identified. Seven of the “new” endemic districts were located far away from previously known endemic foci, most notably in the northwest of the country.9 Finally, vaccine uptake substantially modifies the number of cases in a TBE risk area, as exemplified again by Austria, where in the last decade fewer than 100 cases are reported annually while this number, however, had been up to 700 cases annually before the introduction of a vaccination program. The 7-fold difference is easily explained by the about 84% vaccine uptake in Austria. Neighboring countries with lower vaccine uptake continue to have increasing TBE case numbers.10 It should be noted, that there are many “fever only” TBE virus infections without ZNS symptoms not being captured by the ECDC definition.11 1.2. Burden of disease: Incidence and trends A characteristic feature of TBE is that the incidence of the disease in risk areas can vary significantly from year to year. However, in addition to short-term fluctuations, there are also longer-range undulations of incidence rates recognizable in many countries (refer to Table 2 for TBE cases by country and year). Table 2: TBE cases by year and country*In China : 53% of cases are Laboratory confirmed. (source: data provided by the authors of Chapter 13, among others available upon request) Source data Figure 1: TBE disease cases (as of Table 2) from 2000-2023, polynomial trendlines added Click the image above to enlarge Click the image above to enlarge Click the image above to enlarge In Estonia for example, a country with one of the highest overall TBE incidences in Europe case numbers in the years 2005 – 2017 fluctuated between 6.2 and 18.6 with a mean incidence between 5.2 and 52.8 (see Chapter 13, Estonia). These longer-range undulations are well recognized and in synchrony in a time interval of 12-15 years in countries like Germany, Czech Republic, Slovakia, Switzerland, Austria (see Figure 1a), and similarly in Poland and Slovenia. The long-term trend, however, shows an increase in Germany, Austria, Slovakia, Switzerland and Poland, a constant trend the last 22 years in the Czech Republic and decreasing in