Is an isolated initial phase of a tick-borne encephalitis a common event?

Clinical and Laboratory Characteristics and Outcome of Illness Caused by Tick-Borne Encephalitis Virus without Central Nervous System Involvement

Illness progressed to encephalitis in 84% of patients within 18 days after defervescence.

Information on febrile illness caused by tick-borne encephalitis virus (TBEV) without central nervous system involvement is limited. We characterized 98 patients who had TBEV RNA in their blood but no central nervous system involvement at the time of evaluation. Median duration of illness was 7 days; 37 (38%) patients were hospitalized. The most frequent findings were malaise or fatigue (98%), fever (97%), headache (86%), and myalgias (54%); common laboratory findings were leukopenia (88%), thrombocytopenia (59%), and abnormal liver test results (63%). During the illness, blood leukocyte counts tended to improve, whereas thrombocytopenia and liver enzymes tended to deteriorate. At the time of positive PCR findings, 0/98 patients had serum IgG TBEV and 7 serum IgM TBEV; all patients later seroconverted. Viral RNA load was higher in patients with more severe illness but did not differ substantially in relation to several other factors. Illness progressed to tick-borne encephalitis in 84% of patients within 18 days after defervescence.

Cost-effectiveness of tick-borne encephalitis vaccination in Slovenian adults

BACKGROUND

Slovenia is an endemic country with a high incidence rate of tick-borne encephalitis (TBE) and low vaccination coverage. TBE causes high costs for the health care insurances as well as the society due to hospitalization and frequent long term or permanent neurological sequelae. Vaccination is effective and a safe prophylaxis against TBE.

OBJECTIVE

The purpose of this study was to evaluate the incremental cost-effectiveness ratio (ICER) between vaccination and no vaccination in Slovenia. The results are shown as cost per quality-adjusted life year (QALY) gained from the view of the health care payer and the society.

METHODS

Based on the natural course of the disease, the Markov model was used for comparing the economic and health outcomes of vaccinated and unvaccinated groups from 18 to 80 years of age.

RESULTS

The incremental cost-effectiveness ratio from the current Slovenian vaccination programme for FSME-Immun(®) compared to no vaccination amounts to € 15,128 per QALY gained and for Encepur(®) € 20,099 per QALY gained from the view of the health care payer. From the view of the society vaccination is cost saving, mainly due to avoiding the high indirect costs.

CONCLUSIONS

According to the cost-effectiveness threshold as proposed by the Slovenian Health Council, the current Slovenian vaccination programme against TBE is cost-effective from the health care payer's perspective and also economical from the society's perspective.

Benefit of detecting tick-borne encephalitis viremia in the first phase of illness

In Switzerland, reports of tick-borne encephalitis virus (TBEV) infections to the Federal Office of Public Health have increased by 100% in 2005 compared to the annual mean from 1999 to 2004. This might be partly due to unspecificity in serological testing. In order to make diagnostics more specific and to improve patient management, we recommend to consider the first phase of the biphasic course of TBE, that can be suspected in a trias of tick bite, followed by a feverish illness associated with thrombocytopenia and/or leucocytopenia. In this phase, detection of viremia by TBEV-specific polymerase chain reaction assay (PCR) will enable diagnosis as well as prediction of the second phase of TBEV infection, developing in the majority of patients. Circumstances suggesting detection of TBE viremia are exemplified by two case reports.

Tick-borne encephalitis--pathogenesis, clinical course and long-term follow-up

The prospective studies available today confirm the experience gained from several retrospective studies that TBE is a disease with a severe acute clinical course and considerable long-term morbidity. A defined post-encephalitic TBE syndrome exists, causing long-lasting morbidity that often affects the quality of life and sometimes also forces the individual to a change in life-style. The sequelae render high costs for individual patients and the society. Three clinical courses may be identified: one with complete recovery within 2 months, occurring in approximately one fourth of patients, one with protracted, mainly cognitive dysfunction, and one with persisting spinal nerve paralysis with or without other post-encephalitic symptoms. Up to 46% of patients are left with permanent sequelae at long-time follow-up, the most commonly reported residuals being various cognitive or neuropsychiatric complaints, balance disorders, headache, dysphasia, hearing defects, and spinal paralysis. This knowledge enhances the need for continued local epidemiological surveillance of TBE to form a basis for vaccination policies. Even though knowledge of the clinical course of TBE has improved in recent years, there are still several aspects of this disease that warrant further studies. These comprise the clinical picture and prognosis in children, an evaluation of different rehabilitation strategies, and an improved understanding of pathogenic mechanisms to permit the development of antiviral or, maybe more probable, immune modulatory treatment strategies.