Sand flea (Tunga spp.) infections in humans and domestic animals: state of the art

Abstract

Tungiasis is a parasitic disease of humans and animals caused by fleas (Siphonaptera) belonging to the genus Tunga. Two species, Tunga penetrans (L.) and Tunga trimamillata, out of 10 described to date, are known to affect man or domestic animals; the other eight are exclusive to a few species of wild mammals. Tunga penetrans and T. trimamillata originated from Latin America, although the first species is also found in sub-Saharan Africa (between 20 degrees N and 25 degrees S). Hundreds of millions of people are at risk of infection in more than 70 nations, mostly in developing countries. The second species has been reported only in Ecuador and Peru. Males and non-fertilized females of Tunga are haematophagous ectoparasites; pregnant females penetrate the skin where, following dilatation of the abdomen, they increase enormously in size (neosomy) and cause inflammatory and ulcerative processes of varying severity. The importance of Tunga infection in humans concerns its frequent localization in the foot, which sometimes causes very serious difficulty in walking, thereby reducing the subject's ability to work and necessitating medical and surgical intervention. Tungiasis in domestic animals can be responsible for economic losses resulting from flea-induced lesions and secondary infections. Because tungiasis represents a serious problem for tropical public health and because of the recent description of a new species (Tunga trimamillata), it seems appropriate to review current knowledge of the morphology, molecular taxonomy, epidemiology, pathology, treatment and control of sand fleas of the genus Tunga.

Topographic Distribution of the Sand Flea Tunga penetrans in Wistar Rats and Humans in Two Endemic Areas in Brazil

“…Virtually any domestic or sylvatic mammal stepping with its feet or resting for some time on the ground can become infested. 11,12,18 It is usually assumed that female sand fleas penetrate the epidermis at the site where skin has come into contact with the soil for a protracted period of time. However, inhabitants of endemic areas frequently have observed adult sand fleas running on uncovered body parts such as the legs or the arms.…”

“…[13][14][15][16][17][18][19][20] In human tungiasis, more than 97% of all embedded sand fleas are located at the feet. 16 However, at the feet, embedded sand fleas are heterogeneously distributed, with the periungual areas, the heels, and the lateral rim of the foot being predilection sites.…”

An Ectopic Case of Tunga spp. Infection in Peru

“…2,8,13 It was first mentioned by the Spanish chronicler Fernandez de Oviedo y Valdes in 1526 and then, by numerous chroniclers, explorers, and travelers to Central and South American countries in the following centuries.…”

“…17 The most common ectopic topography appears on the hands, although it has been observed on the thigh, elbow, breast, inguinal areas, gluteal region, trunk, abdomen, face, eyelid, testes, penis, pubis, and wrist. 2,5,9,18,19 Our case is the first human tungiasis located on the knee, an unusual area.…”

“…Two species, Tunga penetrans (Linnaeus) and Tunga trimamillata (Pampiglione and others), cause human tungiasis; infection by the latter has been reported only in Ecuador and Peru. 1,2 In Peru, the sand flea is also termed nigua (from the Arawak) or pique (from the Quechua), and it most commonly affects individuals living in poverty-stricken villages or suburban areas. The most vulnerable are those who walk barefoot or wear sandals, and tungiasis affects the lower extremities of the victims.…”