{"version":"1.0","provider_name":"TBE Book","provider_url":"https:\/\/tbenews.com\/tbe","author_name":"IT","author_url":"https:\/\/tbenews.com\/tbe\/author\/brianong\/","title":"Chapter 9: TBE in adults - TBE Book","type":"rich","width":600,"height":338,"html":"<blockquote class=\"wp-embedded-content\" data-secret=\"MclUsfcdUI\"><a href=\"https:\/\/tbenews.com\/tbe\/chapter-9-tbe-in-adults\/\">Chapter 9: TBE in adults<\/a><\/blockquote><iframe sandbox=\"allow-scripts\" security=\"restricted\" src=\"https:\/\/tbenews.com\/tbe\/chapter-9-tbe-in-adults\/embed\/#?secret=MclUsfcdUI\" width=\"600\" height=\"338\" title=\"&#8220;Chapter 9: TBE in adults&#8221; &#8212; TBE Book\" data-secret=\"MclUsfcdUI\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\" class=\"wp-embedded-content\"><\/iframe><script>\n\/*! This file is auto-generated *\/\n!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);\n\/\/# sourceURL=https:\/\/tbenews.com\/tbe\/wp-includes\/js\/wp-embed.min.js\n<\/script>\n","thumbnail_url":"https:\/\/tbenews.com\/tbe\/wp-content\/uploads\/2024\/06\/Chapter-9-TBE-IN-ADULT-scaled.jpg","thumbnail_width":2560,"thumbnail_height":1837,"description":"Chapter 9:TBE in adults Johann Sellner, Petra Bogovic, Joanna Zajkowska Key points Introduction Tick-borne encephalitis (TBE) encompasses various diseases caused by infection with the TBE virus (TBEV). TBEV is a positive-strand RNA virus in the genus Flaviviridae, which is primarily transmitted by infected ticks (primarily genus Ixodes) and occasionally by consuming unpasteurized dairy products from infected ruminants.1 Among the several viral subtypes of TBEV, the European subtype (TBEV-Eur) is predominantly found in Europe. Siberian (TBEV-Sib) and Far Eastern (TBEV-FE) are additional prominent subtypes. An overall increase in TBE cases in the European Union (EU)\/European Economic Area (EEA) was observed between 2012 and 2020, according to the European Centre for Disease Control (ECDC).2 In 2021, there was a slight decrease of cases compared to 2020. The drivers of the rising incidence remain unclear.3 For 2021, 22 EU\/EEA countries reported 2,949 confirmed cases, with Czechia (n=589), Sweden (n=533), and Germany (n=417) as the front runners. The notification rate was highest in Lithuania (13.1 cases per 100,000 population), followed by Latvia (11.7) and Estonia (6.2). Among the confirmed cases in which information for vaccination was available, 93.2% were not vaccinated against TBE. There is a seasonal pattern for occurrence. In 2021, 90% of confirmed cases occurred between June and November in the EU\/EEA, with July being the month with the highest number of reported cases.2 The clinical manifestation of TBE depends on the virulence of the pathogen and the immune status of the host. The majority of the infected people remain asymptomatic or suffer from a self-limiting febrile illness. Some patients develop neurological and neuropsychiatric disturbances caused by meningitis, encephalitis, myelitis, radiculitis, or combinations thereof.4 Cases of nervous system manifestation are more frequently reported among men (male-to-female ratio 1.5:1) and in the age group 45\u201364 years.2 Mortality of TBE caused by TBEV-Eu is in the range of 0.5-2%. Involvement of the nervous system is associated with long-term sequelae in almost every second survivor.5 Clinical course and long-term outcome vary by TBE virus subtype, although some of the reported differences could be related to access to medical care or testing or methodologic biases.6 Preventive strategies include vaccination and avoiding tick bites; no antiviral medication has been approved. Risk factors Ecological variables TBEV transmission is affected by place, time, and tick population density. However, infection rates in TBE virus\u2013endemic areas are inconsistent, which impedes risk assessments.6 People with outdoor occupations, e.g., farmers, forestry workers, and training in forested areas, are at increased risk for contracting TBE. The risk for TBEV infection for an individual traveler is greatly affected by their itinerary and activities. Among the ECDC cases of 2021, only 1.6% were associated with travel.2 Most infections result from tick bites acquired in forested areas while bicycling, birdwatching, camping, fishing, hiking, or collecting berries, flowers, or mushrooms.6 In contrast, the risk is negligible for people who remain in urban or unforested areas and do not consume unpasteurized dairy products. Epidemiological data from different European countries demonstrate that the incidence of TBE is higher in older adults than in younger age groups. More than half of the patients are \u226550 years of age.7-9 Both a decline in adaptive and innate immunity and changed lifestyle habits may contribute to this observation.10 This age distribution is also present among TBE cases in vaccinated people.11 Risk factors for severe or protracted course The most endangered groups for severe clinical manifestation are older adults.12-15 Immunosuppression is another risk factor for unfavorable outcomes. The case fatality rate for TBE is higher in these patient groups.16 A report on a cluster of TBE in organ transplant recipients underscores the association between host immune suppression and fatal outcomes.17 Whether vaccination breakthrough TBE is associated with more severe disease is a matter of investigation.18 A recent study reported that a severe disease course was associated with a low serum TBEV-specific IgG antibody response at the time of onset of the neurologic phase of the disease.19 Another factor that may result in a more severe clinical picture of TBE is the relatively rare occurrence of co-infection with other tick-borne pathogens like Borrelia burgdorferi, Anaplasma phagocytopilum, Rickettsia spp. or Listeria monocytogenes.20,21 Host genetic risk factors Clinical and epidemiological data indicate that human susceptibility to clinical TBEV infection greatly varies according to age and gender. Mouse models of TBE corroborate that genetic control influences the clinical course of TBE. In this regard, sufficient neutralizing antibody response might be crucial for preventing host fatality. In addition, high expression of various cytokines\/chemokines during TBE can mediate immunopathology and be associated with a more severe course of infection and increased fatality.22 Genetic polymorphisms and immune signatures that may predispose to TBEV infection and its severity are covered in the following sections. The CCR5 plays a crucial role in leukocyte migration and attraction. In human immunodeficiency virus (HIV) infections, the CCR5\u039432 mutation is crucial for invading CD4 cells by HIV particles with a CCR5 tropism.23 In mouse models for flaviviral infections, homozygote CCR5-deficient (-\/-) mice died in almost 100% of all infections with West Nile virus (WNV), whereas CCR5 (-\/+) heterozygote mice, and homozygote mice with a wildtype CCR5 receptor, had a significantly lower mortality rate.22 These observations from animal studies could be corroborated during a WNV outbreak by identifying the CCR5\u039432 mutation as a strong predictor for a severe clinical disease course in humans. Following the epidemiological results from WNV research, a potential effect of the CCR5\u039432 mutation on TBE was investigated. A clinical study from Lithuania analyzed the incidence of the CCR5\u039432 mutation in different patient populations and found individuals homozygous for CCR5\u039432 only among patients with TBE.24 Moreover, the CCR5\u039432 allele prevalence also increased with the clinical severity of the disease. In another study by this author group, the prevalence of CCR5\u039432 homozygotes was higher in children (2.5%), in adults with severe TBE (1.9%), and in the combined cohort of TBE patients (2.3%) than in controls (0%).25&nbsp;In a Polish study, the blood expression of CCR5 neither differed between the groups nor did it change in the course"}