Abstract
Ticks are the most important vectors of human pathogens, leading to increased public health burdens worldwide. Tick-borne pathogens include viruses (e.g. tick-borne encephalitis and Powassan); bacteria, such as the causative agents of Lyme disease, spotted fever rickettsiosis and human anaplasmosis; and malaria-like protozoan parasites causing babesiosis. Tick-borne diseases are emerging due to the geographical expansion of their tick vectors, especially in the northern hemisphere. Two examples of this phenomenon are Ixodes scapularis and Amblyomma americanum, which have expanded their ranges in the USA in recent decades and are responsible for the continuous emergence of Lyme disease and human ehrlichiosis, respectively. This phenomenon is also occurring worldwide and is reflected by the increasing number of tick-borne encephalitis and haemorrhagic fever cases in Europe and Asia. In this review, we provide a concise synopsis of the most medically important tick-borne pathogen worldwide, with a particular emphasis on emerging public health threats.