No abstract

A sheep herd from which contaminated cheese was produced, causing 21 cases of alimentary tick-borne encephalitis (TBE) in human beings, was tested serologically for the presence of specific antibodies against both the TBE virus (TBEV) and Anaplasma phagocytophilum, the cause of tick-borne fever (TBF) in ruminants, and compared with three other herds variously exposed to tick bites but without any TBE history. Virus-neutralisation (VN) with the TBEV strain Hypr and CV-1 cells was used in TBE tests, and indirect immunofluorescence assay (IFA) with neutrophils from goats experimentally infected with A. phagocytophilum was used for TBF testing. In 13 sheep from the incriminated herd (N =41), VN titres ranging from 1/4 to 1/128 traced previous TBE infection and all sheep had elevated titres of A. phagocytophilum antibodies ranging from 1/80 to 1/5120 in IFA, whereas two other herds (N = 8 and 9) were seronegative for TBEV and had significantly lower levels of A. phagocytophilum antibodies, corresponding to a lesser challenge from TBF. A control herd (N = 10) that was grazed on tick-free meadows in north Norway was completely seronegative. The respective distributions of positive titres of A. phagocytophilum and TBEV antibodies in the incriminated herd were not mutually random; the animals with higher anti-A. phagocytophilum titres tended to have lower anti-TBEV titres and vice versa (Spearman correlation coeff. =-0.86, p< or =0.01). The authors hypothesize that the immunosuppressive effect of TBF co-infection in sheep could be a contributory cause of TBE-virus contamination of milk, an aspect of TBE epidemiology that has not been considered thus far.

We report West Nile virus infection of the central nervous system in a 69-year-old man, residing in North Moravia (Czech Republic), who visited the USA from 6 July to 31 August 2002. He developed fever with fatigue at the end of his US stay, and was hospitalized in Ostrava after his return on 3 September with fever (up to 39.5 degrees Celsius), fatigue, anorexia, moderate laryngotracheitis, dizziness, insomnia, blurred speech, and a marked bradypsychism. EEG demonstrated a slow bifrontal theta-delta activity, and CT of the brain a slight hydrocephalus. A significant increase of antibodies neutralizing West Nile virus was detected between the first (1:16) and second (1:256) blood serum sample. The patient recovered gradually and was released from hospital on 16 September. This is the first recorded human case of West Nile fever (WNF) imported to the Czech Republic. Nine similar cases of WNF import from the USA have already been reported in other European countries - France, Denmark, the Netherlands, and Germany.

During the period 2000-2003, patients hospitalized for suspected tick-borne encephalitis in the Czech Republic were screened for possible A. phagocytophilum co-infection. Blood samples taken at admission were tested for the presence of A. phagocytophilum DNA by nested PCR using a modified target sequence as an internal control, and sera were tested for the presence of antibodies by indirect immunofluorescence and western blotting methods using cell-culture-derived antigens. To verify the assay specificity, a set of 45 sera of Patagonian residents served as a non-tick-exposed control group, and a set of 14 B. henselae-positive sera was used to check cross-reactivity. Of 809 patients hospitalized, 80 (9.9%) showed IgG antibodies reactive to A. phagocytophilum at > or =80 (reciprocal dilution factor) and 50 (6.2%) at > or =160; two (0.2%) patients showed elevated IgM titers of 40. No full blood obtained from 162 patients tested positive in PCR when false negativity was excluded. During hospitalization, the diagnosis of tick-borne encephalitis was confirmed in 536 patients, 57 (10.6%) of whom had anti-A. phagocytophilum IgG antibodies reactive at > or =80 and 41 (7.6%) at > or =160, which did not differ significantly from the whole set (P = 0.66/0.30), the maximum IgG titer registered was 5120, and no IgM titer reached the 40 cut-off. Available paired sera from 189 tick-borne encephalitis patients showed no significant shifts, but one case of slight seroconversion (IgG shift from < 80 to 320) was detected in one of the non-tick-borne encephalitis patients. The sex of the patient showed no significance for the prevalence of A. phagocytophilum antibodies; however, the seropositive patients were older on average than those who were seronegative (43.5 +/- 15.9 vs. 37.9 +/- 18.3 years, P = 0.05). Clinical manifestation of the disease did not differ noticeably between patients with and without A. phagocytophilumreactive antibodies, except for fever duration, which was significantly longer in patients with titers > or =1280. Overall, A. phagocytophilum co-infection did not seem to be a frequent and/or significant complication of tick-borne encephalitis acquired in the Czech Republic.