Doctors worldwide are becoming concerned about the increasing prevalence of ticks. These are tiny, blood-sucking bugs that carry germs from one host to another. Their bites can pass on serious health problems like Lyme disease. The Centers for Disease Control and Prevention (CDC) in the USA has reported a dramatic upswing in tick activity. It said thirty-one million Americans are bitten by ticks annually, and that the number of cases is increasing year by year. Biology professor Vett Lloyd said: "Tick populations are expanding geographically because we're changing the climate." The UK's 'Guardian' newspaper reported that cases of Lyme disease rose over 20 per cent between 2024 and 2025.

Ticks are arachnids — they are related to spiders. They have oval, flat bodies and eight legs. After they fill themselves with blood, their bodies become spherical. They range in size from the size of a poppy seed to an apple seed. They latch on to animals and humans by sinking their mouthparts into the skin of their victims. Their mouthparts pierce the skin and drink blood for days. Their saliva contains a mild anaesthetic. This numbs the bite area, so people often do not feel anything. The CDC offers advice for avoiding tick bites. It recommends wearing insect repellents that contain the ingredient DEET. It also advises wearing long-sleeved shirts, long pants and closed shoes.