The chigoe flea or jigger (Tunga penetrans) is a parasitic insect found in most tropical and sub-tropical climates. In Brazil, the parasite is referred to as a foot bug. At 1 mm long, the chigoe flea is the smallest known flea. Breeding female chigoes burrow into exposed skin on the feet of mammals and remain there for two weeks while developing eggs, sometimes causing intense irritation. After this point, the skin lesion looks like a 5- to 10-mm blister with a central black dot, which are the flea's exposed hind legs, respiratory spiracles and reproductive organs. If the flea is left within the skin, infection and/or other dangerous complications can occur, although they are relatively rare.
The parasitic flea lives in soil and sand, and feeds intermittently on warm-blooded hosts, such as humans, cattle, sheep, dogs, mice, and other animals. To reproduce, the female flea burrows head-first into the host's skin, often leaving the tip of its abdomen visible through an orifice in a skin lesion. This orifice allows the chigoe flea to breathe and defecate while feeding on blood vessels. In the next two weeks, its abdomen swells with up to several dozen eggs, which it releases to fall to the ground when ready to hatch. The flea then dies and is sloughed off with the host's skin.
Infections are almost always on the foot of the host. During the first day or two of infection, the host may feel an itching or irritation which then passes as the area around the flea calluses and becomes insensitive. Depending on the exact site, this can cause sensations ranging from mild irritation to serious discomfort.
The occurrence of lesions on the toes, between them, on the soles can be easily explained because most of the victims are poor and walk barefoot or wear cheap floppies. Because the front part of the feet (toes) hit the ground first, the fleas have more opportunity to latch on there. They also get trapped between the toes, or under the soles when the victims stand still. More lesions on the hands are seen in children because they play in the sand or dusty ground. Other common sites of infestation are the buttocks and the genital area and this can be explained by the habit of sitting on bare ground.
In order to help eradicate the jiggers parasite government officials visit schools and afflicated children are requested to sit with their feet in bowls of potassium permanganate. (see photos). If repeated often enough the parasite should die.
If the floors of classrooms are screeded and the children wear shoes then the problem will not appear.