Filarioidea

Filarioidea is a superfamily of nematodes within the order Spirurida that includes numerous parasitic species affecting humans and other vertebrates. Members are typically slender, threadlike worms that inhabit lymphatic vessels, subcutaneous tissues, or serous cavities. Adults are usually dioecious, and females often produce microfilariae, which may circulate in the bloodstream, migrate through tissues, or reside in skin depending on the species.

The life cycle of Filarioidea generally involves an intermediate arthropod vector, such as mosquitoes, blackflies, or biting midges. In the vertebrate host, adult worms release microfilariae that are taken up by a feeding vector. Within the vector, microfilariae develop to the third larval stage (L3), which is transmitted to a new host during the vector’s bite. The larvae then mature into adults, completing the cycle. Pathology arises from both adult worms and microfilariae, often through lymphatic obstruction, inflammatory responses, and tissue damage in eyes or skin.

Medically and veterinary important genera include Wuchereria and Brugia (causing lymphatic filariasis), Loa loa (loiasis), Onchocerca (onchocerciasis or river blindness), Dirofilaria (heartworm in dogs and other animals), and Mansonella species. Disease manifestations range from lymphatic dysfunction and elephantiasis to ocular lesions and subcutaneous nodules, depending on the species and tissue tropism.

Diagnosis relies on identifying microfilariae in blood, skin snips, or nodules, supplemented by serology or molecular methods. Control efforts focus on mass drug administration, vector control, and preventive therapies in animals. Filarioidea represent a group of endoparasitic nematodes with significant implications for human and animal health, distribution largely in tropical and subtropical regions.