Insights from experience in the treatment of tick-borne bacterial coinfections with tick-borne encephalitis

Over the last decades, new knowledge has been accumulated on the worldwide spread of mixed tick-borne infections of different nature (viral, bacterial, protozoal), new pathogen species have been discovered, and it has been shown that individual ticks are infected with several pathogens simultaneously. This information has changed the ideas about the etiological landscape of diseases, which can develop by ixodid tick bites that led to the understanding that this practical problem requires comprehensive studies on the prevention, diagnosis, and treatment of these diseases. At present, there is an urgent need to develop unified approaches to the treatment of the mixed tick-borne infections of viral and bacterial nature. Simultaneous administration of specific drugs against both viral (tick-borne encephalitis virus) and bacterial pathogens (Borrelia spp., Rickettsia spp., Ehrlichia spp., Anaplasma phagocytophilum, and others) is required. This, however, is hampered by the scarcity of antivirals and the side effects of certain antibiotics, which can suppress the patient's immunity and possess a neurotoxic effect, aggravating the viral disease (in particular, tick-borne encephalitis). Thus, since the therapeutic approaches to tick-borne infections of viral and bacterial nature are fundamentally different, these coinfections present a major practical challenge for modern health care in affected regions. This chapter provides information on the spread of tick-borne encephalitis virus and the most significant bacterial pathogens in the world. It highlights Russian, European, and American recommendations for the treatment of tick-borne infections of viral and bacterial nature, as well as experimental studies on the effect of antibiotics on the acute and chronic course of tick-borne encephalitis. © 2022 Elsevier Inc.