Lymphatic filariasis is caused by threadlike worms that live in and cause damage to the lymphatic system. The disease is transmitted by mosquitoes that pick up the microfilariae when they bite infected humans; the microfilariae develop into the infective larval stage and then are injected into another person during a bite. The most common filarial species is Wuchereria bancrofti, but Brugia malayi and Brugia timri cause the infection in Asia. It takes several mosquito bites over many months to cause the infection. People living in tropical and subtropical settings are at the greatest risk for the infection.

Nonfilarial elephantiasis is thought to be caused by contact with irritant soils associated with volcanic activity. Chemicals from the soil are transmitted through the soles of the feet and then travel to the lymphatic system, blocking proper drainage. Other causes of nonfilarial elephantiasis include certain sexually transmitted infections (e.g., lymphogranuloma venereum), tuberculosis, leishmaniasis, recurring streptococcal infections, and leprosy. In some cases, no cause can be identified (idiopathic).

Complications of elephantiasis include secondary skin infection. The disease may take years to manifest, and many people never acquire outward clinical manifestations. However, studies have now disclosed that such victims, who appear healthy, actually have hidden lymphatic pathology and kidney damage as well. The debilitating consequences of elephantiasis may cause personal and socioeconomic hardships. Obstruction of blood vessels in the affected extremity may lead to gangrene.