Identification of tick-borne encephalitis virus in ticks collected in southeastern Hungary.

Tick-borne encephalitis virus (TBEV) is an arthropod-borne viral pathogen causing infections in Europe and is responsible for most arbovirus central nervous system infections in Hungary. Assessing the TBEV prevalence in ticks through detection of genomic RNA is a broadly accepted approach to estimate the transmission risk from a tick bite. For this purpose, 2731 ticks were collected from the neighboring area of the town of Dévaványa, located in southeastern Hungary, which is considered a low-risk-transmission area for TBEV. Altogether, 2300 ticks were collected from the vegetation, while 431 were collected from rodents. Samples were pooled and then screened for TBEV with a newly designed semi-nested RT-PCR (RT-snPCR) targeting the NS1 genomic region. PCR results were confirmed by direct sequencing of the second round amplicons. Among the 3 different collected tick species (Ixodes ricinus, Haemaphysalis concinna, Dermacentor marginatus), I. ricinus was the only species that tested positive for TBEV. TBEV-positive ticks were collected from small mammals or from the vegetation. One nymphal pool and 4 larval pools tested positive for TBEV. The only positive nymphal pool was unfed and came from vegetation, while ticks of the 4 positive larval pools were collected from rodents. Minimal TBEV prevalence in ticks was 0.08% for unfed nymphs and 0.78% for feeding larvae. Our results indicate that further long-term investigations on the occurrence of TBEV are needed to better describe the geographic distribution and the prevalence of infected ticks in Hungary.

Pintér R ，Madai M ，Vadkerti E ，Németh V ，Oldal M ，Kemenesi G ，Dallos B ，Gyuranecz M ，Kiss G ，Bányai K ，Jakab F ... -  《-》

Molecular detection of severe fever with thrombocytopenia syndrome and tick-borne encephalitis viruses in ixodid ticks collected from vegetation, Republic of Korea, 2014.

Ticks play an important role in transmission of arboviruses responsible for emerging infectious diseases, and have a significant impact on human, veterinary, and wildlife health. In the Republic of Korea (ROK), little is known about information regarding the presence of tick-borne viruses and their vectors. A total of 21,158 ticks belonging to 3 genera and 6 species collected at 6 provinces and 4 metropolitan areas in the ROK from March to October 2014 were assayed for selected tick-borne pathogens. Haemaphysalis longicornis (n=17,570) was the most numerously collected, followed by Haemaphysalis flava (n=3317), Ixodes nipponensis (n=249), Amblyomma testudinarium (n=11), Haemaphysalis phasiana (n=8), and Ixodes turdus (n=3). Ticks were pooled (adults 1-5, nymphs 1-30, and larvae 1-50) and tested by one-step reverse transcription polymerase chain reaction (RT-PCR) or nested RT-PCR for the detection of severe fever with thrombocytopenia virus (SFTSV), tick-borne encephalitis virus (TBEV), Powassan virus (POWV), Omsk hemorrhagic fever virus (OHFV), and Langat virus (LGTV). The overall maximum likelihood estimation (MLE) [estimated numbers of viral RNA positive ticks/1000 ticks] for SFTSV and TBEV was 0.95 and 0.43, respectively, while, all pools were negative for POWV, OHFV, and LGTV. The purpose of this study was to determine the prevalence of SFTSV, TBEV, POWV, OHFV, and LGTV in ixodid ticks collected from vegetation in the ROK to aid our understanding of the epidemiology of tick-borne viral diseases. Results from this study emphasize the need for continuous tick-based arbovirus surveillance to monitor the emergence of tick-borne diseases in the ROK.

Yun SM ，Lee YJ ，Choi W ，Kim HC ，Chong ST ，Chang KS ，Coburn JM ，Klein TA ，Lee WJ ... -  《-》

Prevalence of tick-borne encephalitis virus in Ixodes ricinus and Dermacentor reticulatus ticks collected from the Lublin region (eastern Poland).

A total of 875 nymphal and adult Ixodes ricinus ticks and 148 adult Dermacentor reticulatus ticks were collected by flagging lower vegetation in the Lublin region (eastern Poland) and examined for the presence of RNA of tick-borne encephalitis virus (TBEV) by nested RT-PCR. The minimum infection rate of I. ricinus ticks with TBEV amounted to 1.6% while the infection rate of D. reticulatus ticks was 10.8%. The results suggest that D. reticulatus may be a potential vector of TBEV in Central Europe.

Wójcik-Fatla A ，Cisak E ，Zając V ，Zwoliński J ，Dutkiewicz J ... -  《-》

Risk of exposure to ticks (Ixodidae) and the prevalence of tick-borne encephalitis virus (TBEV) in ticks in Southern Poland.

The article presents the results of the first study on seasonal activity of ticks and prevalence of tick-borne encephalitis virus (TBEV) in nymphs from the Silesian Province (Southern Poland). Previous studies on the prevalence of TBEV in ticks in Poland have been conducted mostly in northern and eastern regions, but none in the Silesian Province itself. The aims of this study were to analyse the seasonal variation in tick populations and compare TBEV prevalence in nymphs from different geographical locations in the Silesia. A total of 5160 questing Ixodes ricinus ticks were collected by the flagging method from 23 localities in southern Poland in 2010. Micro-climatic parameters (air temperature and humidity) were measured in order to estimate their influence on tick population. The highest tick activity was recorded in spring and was positively correlated with relative air humidity (RH). TBEV in the Silesian Province was analysed in 1750 nymphs and an overall prevalence was 0.11% (2 pools out of 175 analysed). The results of this study show that TBEV pool prevalence in nymphs is low in accordance with the low number of TBE cases reported within the region.

Cuber P ，Andreassen Å ，Vainio K ，Asman M ，Dudman S ，Szilman P ，Szilman E ，Ottesen P ，Ånestad G ，Cieśla-Nobis S ，Solarz K ... -  《-》

Tick-borne encephalitis virus in ticks detached from humans and follow-up of serological and clinical response.

The risk of tick-borne encephalitis virus (TBEV) infection after a tick bite remains largely unknown. To address this, we investigated the presence of TBEV in ticks detached from humans in an attempt to relate viral copy number, TBEV subtype, and tick feeding time with the serological and clinical response of the tick-bitten participants. Ticks, blood samples, and questionnaires were collected from tick-bitten humans at 34 primary health care centers in Sweden and in the Åland Islands (Finland). A total of 2167 ticks was received from 1886 persons in 2008-2009. Using a multiplex quantitative real-time PCR, 5 TBEV-infected ticks were found (overall prevalence 0.23%, copy range <4×10(2)-7.7×10(6)per tick). One unvaccinated person bitten by a tick containing 7.7×10(6) TBEV copies experienced symptoms. Another unvaccinated person bitten by a tick containing 1.8×10(3) TBEV copies developed neither symptoms nor TBEV antibodies. The remaining 3 persons were protected by vaccination. In contrast, despite lack of TBEV in the detached ticks, 2 persons developed antibodies against TBEV, one of whom reported symptoms. Overall, a low risk of TBEV infection was observed, and too few persons got bitten by TBEV-infected ticks to draw certain conclusions regarding the clinical outcome in relation to the duration of the blood meal and virus copy number. However, this study indicates that an antibody response may develop without clinical symptoms, that a bite by an infected tick not always leads to an antibody response or clinical symptoms, and a possible correlation between virus load and tick feeding time.

Lindblom P ，Wilhelmsson P ，Fryland L ，Sjöwall J ，Haglund M ，Matussek A ，Ernerudh J ，Vene S ，Nyman D ，Andreassen A ，Forsberg P ，Lindgren PE ... -  《-》