Filarioidea

Filarioidea

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Adult Loa loa parasite

Filarioidea is a superfamily of parasitic nematodes, commonly known as filarial worms. These worms are responsible for a group of diseases known as filariasis, which affect humans and animals. The adult worms reside in the tissues of the host, while the larvae, known as microfilariae, circulate in the bloodstream or skin.

Taxonomy

Filarioidea belongs to the order Spirurida and includes several families, the most notable being Onchocercidae. The superfamily comprises numerous genera, including Wuchereria, Brugia, Loa, and Dirofilaria.

Life Cycle

The life cycle of filarial worms involves two hosts: a definitive host, usually a mammal, and an intermediate host, typically a blood-feeding insect such as a mosquito or fly. The adult worms produce microfilariae, which are taken up by the insect vector during a blood meal. Inside the vector, the microfilariae develop into infective larvae, which are then transmitted to a new host during subsequent feedings.

Pathogenesis

Filarial worms cause disease by inducing inflammatory responses in the host. The presence of adult worms in tissues can lead to chronic conditions such as lymphatic filariasis, onchocerciasis, and loiasis.

Lymphatic Filariasis

Lymphatic filariasis is caused by Wuchereria bancrofti, Brugia malayi, and Brugia timori. It is characterized by lymphedema, elephantiasis, and hydrocele.

Onchocerciasis

Onchocerciasis, also known as river blindness, is caused by Onchocerca volvulus. It leads to severe itching, skin changes, and visual impairment.

Loiasis

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Loa loa microfilaria in blood smear

Loiasis is caused by Loa loa, the African eye worm. It is characterized by the migration of adult worms across the subcutaneous tissues and the conjunctiva of the eye.

Diagnosis

Diagnosis of filarial infections is typically made by detecting microfilariae in blood or skin samples. Serological tests and molecular techniques such as PCR are also used to identify specific species.

Treatment

Treatment of filariasis involves the use of antiparasitic drugs such as ivermectin, diethylcarbamazine, and albendazole. These medications target the microfilariae and, in some cases, the adult worms.

Prevention

Preventive measures include vector control, use of insect repellents, and mass drug administration programs to reduce the prevalence of infection in endemic areas.

Related Pages

• Nematode
• Parasitic disease
• Vector (epidemiology)