Inflammation: When someone is stung by a nettle or an insect, for example, an immediate redness appears on the skin. This represents the release of chemicals and cells which rush to the area to combat the sting. Heroin addicts with the new illness display a particularly intense inflammatory reaction at injection sites on their bodies.

Abscess: When infection remains untreated, it gathers together into a collection of pus. This in turn forms a walled-off area of infection called an abscess. It is usually a swollen, hard and painful area of soft tissue. In the present outbreak, abscesses are affecting the buttocks and other deep muscles.

Septicaemia: Literally, this translates as "infection of the bloodstream". When a severe infection overwhelms the body's first-line defences, it spreads from the initial site and enters the bloodstream. In severe cases, vital organs such as the kidneys are damaged by the now-contaminated blood and the unfortunate patient can develop organ failure. With intensive care and high-intensity treatment the person can recover. However, septicaemia still causes a high mortality rate.