Tunga penetrans: a type of burrowing flea that has also been referred to as the chigger flea, sand flea, chigoe, jigger, nigua, pigue, or le bicho de pe. It causes an infestation of humans known as tungiasis. Tunga penetrans is found in tropical and subtropical regions of the world, including Mexico to South America, the West Indies and Africa. The fleas live in sandy climates, including beaches, stables and farms. Humans are infected when pregnant females burrow into the skin. This stage is usually painless. Later, itching and irritation develop as the females develop fully. The inflammation may be severe and lead to ulcer formation. When the lesions occur in the feet, the affected person may have difficulty walking. Secondary bacterial infections are a known complication of tungiasis.