In the jungle, any open wound — abrasion, puncture, avulsion, incision, or laceration — is an invitation to infection. To understand infection, and how to tell if you have one, it is helpful to understand the normal process of wound healing, or inflammation.
Underneath the clot, the process of inflammation also forms a protective barrier. After about ten to fifteen minutes, as the clotting process blocks the bleeding from the injured vessels, the body releases vasoactive amines into the wound region, and these cause the uninjured capillaries to get larger and start to leak, so that blood plasma pours into the wound area. In addition, mast cells under the skin release histamine, which attracts white blood cells out of the blood vessels into the extracellular fluid, where they help to clean the wound. Polymorphonuclear granulocytes swallow and kill bacteria; macrophages consume and destroy other debris left lying around.
But if the inflammatory process is being overwhelmed by invading bacteria, the body responds by increasing the local inflammation. It is thus excessive inflammation which, among other things, serves as a sign of a local infection.
- Pain from a wound should normally subside by the second or third day. There may be an infection if pain persists, or especially if the pain increases rather than subsides.
- Redness is usually limited to the margins of a wound, usually within a quarter inch. There may be an infection if the redness extends beyond the margins of the wound. In particular, a clear sign of infection is the presence of red streaks extending from the wound along a limb toward the body.
- Severe swelling may be a sign of infection, especially if the skin temperature increases rather than decreases over time. Increasing limitations of motion, due to swelling and pain, may also indicate an advancing infection.
- Pus is fluid filled with dead white cells. The presence of pus in a wound indicates a failure of cellular defense and confirms the presence of an infection. The pus may be whitish, green, or even reddish, depending on the infecting organism. Sometimes, but not always, there may be a foul odor.
In any injury, but especially in a wound to the foot, there is particular concern for tetanus, which is caused by Clostridium tetani, an obligate anaerobe that is especially common in soil contaminated with animal feces. All open wounds are susceptible, especially those that have been contaminated with soil. Tetanus is 100 percent fatal, and 100 percent preventable. In my opinion, wilderness leaders and jungle guides should require that all trip participants have up-to-date tetanus booster immunization. A booster shot received shortly after injury may prevent development of the disease.
In the next installment, we will discuss how to prevent and handle infected wounds in the jungle.