Loa loa

A parasitic worm causing loiasis in humans

Loa loa, commonly known as the African eye worm, is a parasitic worm that causes loiasis in humans. It is a member of the nematode family Onchocercidae.

Life Cycle

The life cycle of Loa loa involves both a human host and an insect vector. The adult worms live in the subcutaneous tissue of humans, where they can migrate through the body. Female worms release microfilariae into the bloodstream, which are then taken up by Chrysops flies, the vector, during a blood meal.

Loa loa adult worm

Inside the fly, the microfilariae develop into infective larvae over a period of 10-12 days. When the fly bites another human, the larvae are transmitted and mature into adult worms, completing the cycle.

Clinical Manifestations

Loiasis is characterized by the migration of adult worms through the subcutaneous tissues, often visible in the conjunctiva of the eye, leading to the name "eye worm." Symptoms include localized swelling known as Calabar swelling, itching, and pain. The presence of the worm in the eye can cause irritation and discomfort.

Diagnosis

Diagnosis of loiasis is typically made by identifying the microfilariae in a blood smear, usually taken during the day when the microfilariae are most active. Serological tests and imaging may also be used to detect the presence of adult worms.

Treatment

The treatment of loiasis involves the use of antiparasitic medications such as diethylcarbamazine (DEC), which is effective against both adult worms and microfilariae. Care must be taken due to potential severe reactions in patients with high microfilarial loads.

Prevention

Preventive measures include avoiding bites from the Chrysops fly by using insect repellent, wearing protective clothing, and implementing vector control strategies.

Related pages

• Loiasis
• Nematoda
• Parasitic worm
• Onchocercidae