Tick borne encephalitis is the most frequent vector-transmitted infectious disease of the central nervous system in Europe and Asia. The disease caused by European subtype of tick borne encephalitis virus has typically a biphasic clinical course with the second phase presenting as meningitis, meningoencephalitis, or meningoencephalomyelitis. Cerebrospinal fluid pleocytosis is considered a condition sine qua non for the diagnosis of neurologic involvement in tick borne encephalitis, which in routine clinical practice is confirmed by demonstration of serum IgM and IgG antibodies to tick borne encephalitis virus. Here we present a patient from Slovenia, an area highly endemic for tick borne encephalitis, with encephalitis but without cerebrospinal fluid pleocytosis in whom tick borne encephalitis virus infection of the central nervous system was demonstrated. Cerebrospinal fluid pleocytosis is not mandatory in encephalitis caused by tick borne encephalitis virus. In daily clinical practice, in patients with neurologic symptoms/signs compatible with tick borne encephalitis and the risk of exposure to ticks in a tick borne encephalitis endemic region, the search for central nervous system infection with tick borne encephalitis virus is warranted despite the lack of cerebrospinal fluid pleocytosis.

In this retrospective cohort study of patients with tick-borne encephalitis (TBE), the clinical outcome in relation to co-infection with B. burgdorferi sensu lato (s.l.) and, specifically, the effect of antibiotic treatment on clinical outcome in patients with TBE who were seropositive for borreliae but who did not fulfil clinical or microbiologic criteria for proven co-infection, were assessed at a single university medical center in Slovenia, a country where TBE and Lyme borreliosis are endemic with high incidence. Among 684 patients enrolled during a seven-year period from 2007 through 2013, 382 (55.8%) had TBE alone, 62 (9.1%) had proven co-infection with borreliae and 240 (35.1%) had possible co-infection. The severity of acute illness was similar in all the groups. The odds for incomplete recovery decreased during a 12-month follow-up but were higher in women, older patients, and in those with more severe acute illness. Incomplete recovery was not associated with either proven (odds ratio (OR) 1.21, 95% confidence interval (CI) 0.49–2.95; p = 0.670) or possible co-infection (OR 0.95, 95% CI 0.55–1.65; p = 0.853). Among patients with possible co-infection, older patients were more likely to be prescribed antibiotics, but the odds for incomplete recovery were similar in those who received antibiotics and those who did not (OR 0.82, 95% CI 0.36–1.87; p = 0.630), suggesting that routine antibiotic treatment in patients with TBE and possible co-infection may not be warranted.

Doxycycline is one of the recommended antibiotics for treating erythema migrans (EM). Since EM predominantly occurs during summer, the potential of doxycycline to induce photosensitivity is of concern. In studies on the efficacy of doxycycline for treating relatively small numbers of patients with EM, the reported frequency of photosensitivity has varied from none to 15%. The aim of this study was to elucidate the frequency and clinical symptoms of doxycycline-induced photosensitivity in a large cohort of patients with EM treated in a single medical centre. Prospectively collected data on adverse events were analysed in adult patients with EM treated with doxycycline 100 mg twice daily for 10–15 days. Photosensitivity reactions ranging from itching and burning sensations to transient mild erythema of sun-exposed skin were documented in 16/858 (1.9, 95% CI 1.1–3.0%) patients and appeared from June to October with highest frequency in July. These adverse events were more frequent in patients treated for 14 or 15 days (16/750 [2.1%]; 95% CI 1.2–3.4%) than in those treated for 10 days (0/108 [0%]; 95% CI 0.0–3.4%); however, the difference was not significant (P = 0.24). Women were more often affected than men (13/475 [2.7%], 95% CI 1.5–4.6% versus 3/383 [0.8%], 95% CI 0.2–2.3%; P = 0.04). Of the 16 patients who developed photosensitivity, 13 did not adhere to the recommendation to avoid sun exposure. None of the patients had any long-term sequelae of photosensitivity. Photosensitivity reactions in adult patients with EM treated with doxycycline 100 mg twice daily for 10–15 days occurred rarely, were not severe, and had no long-term sequelae. Registered at http://clinicaltrials.gov , Identifiers NCT00910715, May 28th 2009, NCT01163994, July 13th 2010 and NCT03584919, June 19th 2018 retrospectively registered.