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

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• 作者：Pontus Lindblom ; Peter Wilhelmsson ; Linda Fryl ; Johanna Sj枚wall ; Mats Haglund ; Andreas Matussek ; Jan Ernerudh ; Sirkka Vene ; Dag Nyman ; 脜shild Andreassen ; Pia Forsberg ; Per-Eric Lindgren
• 关键词：TBEV ; Ixodes ricinus ; Clinical symptoms ; Serology ; Real-time PCR
• 刊名：Ticks and Tick-borne Diseases
• 出版年：February, 2014
• 年：2014
• 卷：5
• 期：1
• 页码：21-28
• 全文大小：847 K

文摘

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 脜land 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 脳 10²-7.7 脳 10⁶ per tick). One unvaccinated person bitten by a tick containing 7.7 脳 10⁶ TBEV copies experienced symptoms. Another unvaccinated person bitten by a tick containing 1.8 脳 10³ 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.