Tick-borne encephalitis in Sweden in relation to aseptic meningo-encephalitis of other etiology: a prospective study of clinical course and outcome

Abstract

A total of 149 patients with clinical symptoms of acute viral meningo-encephalitis were enrolled in this study from June 1991 to December 1993. Tick-borne encephalitis (TBE) was diagnosed in 85 of the 149 patients (males 54%, median age 42 years (range 15-78)). The initial clinical appearance of TBE was classified as mild (mainly meningeal; (n = 47), moderate (n = 31) or severe (n = 7), more or less encephalitic. The most common acute symptoms of encephalitis were ataxia (26%), altered consciousness (20%), decreased concentration or memory (9%), irritable response to light and sound (28%), tremor (9%) and dysphasia (9%). Spinal nerve paralysis (11%) occurred in all three clinical stages and did not correlate with the severity or duration of encephalitis. The duration of hospitalisation, the time on the sick-list and the time to recovery were significantly longer in TBE patients. All patients survived, but many patients with TBE suffered an extended period of neurological dysfunction. Of patients with TBE 80% (68/85) showed persisting symptoms of CNS dysfunction on follow-up at week 6, compared with 55% (35/64) of the patients with aseptic meningitis of other aetiology. The corresponding figures after 1 year were 40% (33/83) and 20% (13/64). One year after TBE 13 (28%) patients with initially mild, meningeal symptoms had decreased memory and decreased concentration capacity, dysphasia or ataxia. Spinal nerve paralysis persisted after 1 year in 5 of 9 patients with TBE. In conclusion, TBE in Sweden is associated with a significant morbidity and a post-TBE syndrome existed after 1 year in more than one third of the patients.

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

“…It has been found that as much as 46 % of patients may suffer from postencephalitic symptoms (Haglund et al, 1996;Günther et al, 1997;Kaiser, 1999;Mickiene et al, 2002;Kaiser, 2011). The TBE virus (TBEV) belonging to the genus Flavivirus is a positive-sense single stranded RNA virus transmitted by ticks of the species Ixodes.…”

Autonomic and peripheral nervous system function in acute tick‐borne encephalitis

“…It has long been recognized that about 10% of patients with TBE suffer from spinal nerve paralysis, which usually persists after recovery (Gunther et al. 1997; Schellinger et al. 2000).…”

“…Hence, it has been speculated that paralysis of spinal nerves might be a separate entity distinguished from the more common and obvious CNS manifestations (Gunther et al. 1997). Pathological evidence supporting this notion is lacking.…”

“…Long‐lasting and disabling sequelae occur in up to 50% of survivors (Gunther et al. 1997; Haglund et al. 1996; Kaiser 2011).…”

Tick-Borne Encephalitis Virus: A General Overview

“…However, due to differences in seroprevalence rates in Europe and in Russia, the higher morbidity of Eastern TBE forms could, at least partly, be the result of selective notification of mainly severe cases (Süss, 2003). In contrast to the forms mentioned above, infections caused by European strains typically take a biphasic course in 72-87% of patients (Kaiser, 1999;Günther et al, 1997;Holzmann, 2003): After a short incubation period (usually 7-14 days, with extremes of 4-28 days), the first (viremic) phase presents as an uncharacteristic influenza-like illness lasting 2-4 days (range 1-8 days) with fever, malaise, headache, myalgia, gastrointestinal symptoms, leukocytopenia, thrombocytopenia and elevated liver enzymes as frequent symptoms. This is often followed by a symptom-free interval of about one week (range 1-33 days) before the second phase.…”