The Prevalence of Tick-Borne Encephalitis Virus Infection Among Humans in Heilongjiang Province of China in 2020-2023.

Tick-borne encephalitis (TBE) is a serious and acute central nervous system infection caused by the tick-borne encephalitis virus (TBEV). In recent years, TBE has emerged as a growing public health threat, with cases reported across Europe, the Russian Far East, Japan and China. This study aims to assess the prevalence of TBEV infection and examine behaviours associated with an increased risk of infection among individuals who visited the Heilongjiang Red Cross Sengong General Hospital due to tick bites from 2020 to 2023. We collected blood samples and administered survey questionnaires from tick-bitten people. A total of 457 samples were screened using Nested PCR, and the detected TBEV prevalence rate was 29.54% (135/457). The symptoms of redness and swelling at the site of tick bite (42.57%), fever (28.71%) and headache (10.89%) were identified in the TBEV-positive individuals when they visited the hospital by the physician. Phylogenetic analysis of the partial E gene of TBEV revealed that the predominant strains in the region are highly virulent Far Eastern subtype. However, they do not cluster with the three established evolutionary clades of the Far Eastern type. Questionnaires data analysis identified age and first tick bite as important factors associated with TBEV infection. This study provides basic information on the epidemiology of TBEV in Heilongjiang Province in recent years and identifies that the most related risk factor of infecting TBEV is tick exposure. Further research is needed to develop effective prevention and control measures.

Chen D ，Lu Y ，Wang W ，Zhang Y ，Liu T ，Liu H ，Zhang L ，Peng X ，Lv S ，Wang Z ，Wu W ，Hou Z ... -  《-》

Tick-borne encephalitis virus (TBEV) prevalence in field-collected ticks (Ixodes ricinus) and phylogenetic, structural and virulence analysis in a TBE high-risk endemic area in southwestern Germany.

Ott D ，Ulrich K ，Ginsbach P ，Öhme R ，Bock-Hensley O ，Falk U ，Teinert M ，Lenhard T ... -  《Parasites & Vectors》

Confirmed exposure to tick-borne encephalitis virus and probable human cases of tick-borne encephalitis in Central/Northern Anatolia, Turkey.

Tick-borne encephalitis virus (TBEV) is the aetiological agent of tick-borne encephalitis (TBE), a potentially fatal central nervous system infection of humans. TBE is endemic in many areas of Europe and Asia; however, very scarce data on TBEV activity are available from Turkey. We aimed to identify TBEV exposure in healthy blood donors and the impact of TBEV in central nervous system infections in Central/Northern Anatolia. Two-thousand four hundred and fifty four sera, collected from blood donors at Ankara, Konya, Eskişehir and Zonguldak branches of the Turkish Red Crescent Middle Anatolia Regional Blood Center, were analysed for TBEV serosurveillance. Paired serum and cerebrospinal fluid samples from 108 patients with the diagnosis of aseptic meningitis/encephalitis of unknown aetiology were also evaluated to identify TBE and neuroborreliosis cases. Commercial enzyme-linked immunosorbent assays and indirect immunofluorescence tests were employed for antibody detection. Forty-seven donor samples (1.9%) were reactive for TBEV IgG. In 25 persons with IgG reactivity (53.1%), risk factors for tick-borne infections were revealed. One sample from Zonguldak province (1/198; 0.5%) in the Black Sea region of Turkey was confirmed to possess neutralizing antibodies via plaque reduction neutralization test. TBEV IgM was detected in 9.2% (8/108) of the patients. IgM was accompanied by IgG reactivity in two persons where, in one, recent history of a tick bite was also identified. Intrathecal antibody production for TBEV could not be demonstrated. No evidence for Borrelia infections could be found. Confirmed exposure to TBEV and/or an antigenically similar tick-borne flavivirus is documented for the first time in blood donors in Zonguldak in Northern Anatolia. Probable cases of TBE have also been identified from Central Anatolia. The epidemiology of TBEV activity in Turkey needs to be assessed and benefits of vaccination for general population, risk groups or travellers must be considered.

Ergünay K ，Saygan MB ，Aydoğan S ，Litzba N ，Sener B ，Lederer S ，Niedrig M ，Hasçelik G ，Us D ... -  《-》

Tick-borne encephalitis foci in northeast Italy revealed by combined virus detection in ticks, serosurvey on goats and human cases.

Alfano N ，Tagliapietra V ，Rosso F ，Ziegler U ，Arnoldi D ，Rizzoli A ... -  《Emerging Microbes & Infections》

Tick-borne encephalitis virus in arthropod vectors in the Far East of Russia.

Isolates of tick-borne encephalitis virus (TBEV) from arthropod vectors (ticks and mosquitoes) in the Amur, the Jewish Autonomous and the Sakhalin regions as well as on the Khabarovsk territory of the Far East of Russia were studied. Different proportions of four main tick species of the family Ixodidae: Ixodes persulcatus P. Schulze, 1930; Haemaphysalis concinna Koch, 1844; Haemaphysalis japonica douglasi Nuttall et Warburton, 1915 and Dermacentor silvarum Olenev, 1932 were found in forests and near settlements. RT-PCR of TBEV RNA in adult ticks collected from vegetation in 1999-2014 revealed average infection rates of 7.9 ± 0.7% in I. persulcatus, of 5.6 ± 1.0% in H. concinna, of 2.0 ± 2.0% in H. japonica, and of 1.3 ± 1.3% in D. silvarum. Viral loads varied in a range from 102 to 109 TBEV genome-equivalents per a tick with the maximal values in I. persulcatus and H. japonica. Molecular typing using reverse transcription with subsequent real time PCR with subtype-specific fluorescent probes demonstrated that the Far Eastern (FE) subtype of TBEV predominated both in mono-infections and in mixed infection with the Siberian (Sib) subtype in I. persulcatus pools. TBEV strains of the FE subtype were isolated from I. persulcatus, H. concinna and from a pool of Aedes vexans mosquitoes. Ten TBEV strains isolated from I. persulcatus from the Khabarovsk territory and the Jewish Autonomous region between 1985 and 2013 cluster with the TBEV vaccine strain Sofjin of the FE subtype isolated from human brain in 1937. A TBEV strain from H. concinna collected in the Amur region (GenBank accession number KF880803) is similar to the vaccine strain 205 isolated in 1973 from I. persulcatus collected in the Jewish Autonomous region. The TBEV strain Lazo MP36 of the FE subtype isolated from a pool of A. vexans in the Khabarovsk territory in 2014 (KT001073) differs from strains isolated from 1) I. persulcatus (including the vaccine strain 205) and H. concinna; 2) mosquitoes [strain Malishevo (KJ744034) isolated in 1978 from Aedes vexans nipponii in the Khabarovsk territory]; and 3) human brain (including the vaccine strain Sofjin). Accordingly, in the far eastern natural foci, TBEV of the prevailing FE subtype has remained stable since 1937. Both Russian vaccines against TBE based on the FE strains (Sofjin and 205) are similar to the new viral isolates and might protect against infection.

Pukhovskaya NM ，Morozova OV ，Vysochina NP ，Belozerova NB ，Bakhmetyeva SV ，Zdanovskaya NI ，Seligman SJ ，Ivanov LI ... -  《-》