Ticks are obligate blood-sucking arthropods, which can feed on mammals, birds, reptiles and amphibians. Ticks are reservoirs for various pathogens which they transmit to both humans and animals. The tick-borne diseases induced by these pathogens are not only harmful to human and animal health, but also cause significant economic losses to livestock farmers. Research on ticks is, therefore, both medically and economically important. This paper reviews previous research on the diversity of tick-borne pathogens, tick-pathogen-host interaction mechanisms, tick-borne disease prevention and control, tick symbiont diversity, function and the mechanisms underlying tick-symbiont interactions. An increase in the amount of research on ticks and technological advances has resulted in an obvious improvement in the quality of  research and information available on these pests. These results can not only reveal more of the biology of ticks, but also help the prevention and control of tick-borne diseases.