Tiny Menace

It’s summer time, and hungry ticks are lying in wait for victims, including trail runners.

What these six or eight-legged* critters don’t know is that they have themselves been hijacked. Their passengers came on board when they drank their first blood from a rodent or bird.

The hijackers include bacteria in the Rickettsia and Borrelia families. These organisms are tiny (Rickettsia is 0.8-2μm in length and Borrelia 5-25μm) and travel from the tick’s digestive system into its salivary glands. When the tick punctures your skin, it introduces the bacteria contained in its saliva into your bloodstream.

The distinctly coiled bacteria (called spirochetes) burrow into the endothelial cells which line your blood vessels. They consume these cells’ mitochondria, and eventually become so numerous that the host cells burst and the toxins within are released. These poisons are what cause the symptoms of African tick bite fever (from ) and).