A 79-year-old man with arterial hypertension and chronic venous ulcers on both shins, fell ill acutely with diarrhea, fatigue and sleepiness in midsummer 2013. After a week, diarrhea stopped, but he became febrile up to 38.5°C and was no longer able to walk independently due to general weakness. As a beekeeper he had been exposed to ticks in the past but could not remember having had a tick bite during the preceding few months. At admission to hospital on day 8 of his illness, he was lethargic, disoriented, but without signs of meningeal irritation. His blood pressure was 133/83 mmHg, heart rate 99/min, breathing rate 30/min and axillary temperature 38.9°C. Routine laboratory blood tests revealed normal blood cell count, mild hyponatremia (Na 129; normal 135-145 mmol/l), and slightly elevated concentrations of C-reactive protein (32 mg/l; normal 0-5 mg/l), liver enzymes (aspartate aminotransferase 0.73; normal ≤0.58 μkat/l, gamma-glutamyl transpeptidase 1.12 μkat/l; normal ≤0.92 μkat/l) and creatinine (101 μmol/l; normal 44-97 μmol/l). CSF examination yielded elevated protein concentration (1.31 g/l; normal 0.15-0.45 g/l), but normal leukocyte count (3 × 10
6/l; normal ≤5 × 10
6/l) and glucose concentration. In the following days the patient remained febrile up to 39.4°C. On day 10, tremor of hands and tongue appeared and his mental status deteriorated to somnolence. Computed tomography of the brain showed only mild periventricular leukopathy. Repeated CSF analyses on day 14 and 23 revealed elevated protein concentrations (1.23, and 2.02 g/l, respectively), but still no pleocytosis (CSF leukocyte count 1, and 2 × 10
6/l, respectively). PCR analyses of CSF for the presence of TBEV on day 8 and 23 were negative as were for HSV 1, HSV 2, VZV, and enteroviruses. Based on serological results the patient did not have Lyme neuroborreliosis. However, serum IgM and IgG antibodies to TBEV were demonstrated using enzyme linked immunosorbent assay - ELISA (Enzygnost Anti-TBE/FSME Virus IgG, IgM; Siemens, Marburg, Germany) (Table
1). The follow-up levels of specific serum antibodies and the avidity of specific serum IgG (12.7%, 15.4%, and 51.6% on day 14, 21, and 65, respectively) indicated recent infection with TBEV. In addition, demonstration of intrathecal production of anti-TBEV IgM and IgG verified CNS infection with TBEV (Table
1). From day 14 the patient was no longer febrile and his mental and physical status progressively improved. Hospitalization was prolonged because of hospital acquired pneumonia which was treated with amoxicillin/clavulanate. At transfer to a nursing facility on day 32 the patient was afebrile, completely oriented, feeble, but without focal neurological deficit. Routine laboratory test results were unremarkable.
Table 1
Enzyme linked immunosorbent assay findings
Day 14 | 1.473 | 78.4 | 0.601 | 53.7 | NA | NA |
Day 23 | 1.133 | 130 | 0.676 | 89.7 | 48.6 | 40.2 |