Onchocerca volvulus

On·cho·cer·ca vol·'vu·lus

the blinding nodular worm, a species that causes onchocerciasis.

Onchocerca volvulus

A species of Onchocerca, a parasitic worm that is transmitted to people by the bite of black flies of the genus Simulium. Tiny, threadlike offspring of the worm migrate to the skin and eyes and produce inflammatory reactions that result in skin swellings and river blindness. The inflammation produced by the parasites may be mediated by a bacterium, Wolbachia, which in turn infests the parasitic worm.

See also: Onchocerca

Onchocerca

a genus of nematode parasites in the family Onchocercidae. They are important as causes of onchocercosis. Their life cycles depend on the carriage of larval microfilariae by a variety of insects, chiefly mosquitoes, black flies and midges (families Simuliidae and Ceratopogonidae). The microfilariae are found in the lymph and connective tissue spaces of the skin. Called also Wehrdikmansia.

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Onchocerca armillata

the microfilariae are found in the skin of the hump, withers, neck, dewlap and umbilicus and the adults in the aorta of cattle, buffalo, sheep, goats and donkeys.

Onchocerca bohmi

see elaeophorabohmi.

Onchocerca cebei

found in nodules on the brisket and the lateral aspects of the hindlimbs of buffalo. Called also O. sweetae.

Onchocerca cervicalis

found in the ligamentum nuchae of the horse and mule. The microfilariae are commonest in the area of the linea alba. Etiologically related to the occurrence of fistulous withers, poll evil, equine conjunctivitis and possibly equine recurrent ophthalmitis.

Onchocerca cervipedis

found in the subcutaneous tissues of the neck and limbs of deer.

Onchocerca dukei

adults are found in nodules in subcutaneous and perimuscular sites in cattle, mostly in the thorax, abdomen, diaphragm and thighs.

Onchocerca flexuosa

occurs in deer.

Onchocerca garmsi

parasites of deer.

Onchocerca gibsoni

found in nodules under the skin of the brisket or the lateral aspect of the hindlimbs of Bos taurus and Bos indicus cattle.

Onchocerca gutturosa

found in cattle and buffalo in the ligamentum nuchae, on the scapular cartilage and in the hip, shoulder and stifle areas.

Onchocerca lienalis

found in the gastrosplenic ligament, on the capsule of the spleen and above the xiphisternum in cattle.

Onchocerca ochengi

found in cattle, in nodules in cutaneous and subcutaneous sites on the udder, scrotum and flanks.

Onchocerca raillieti

adult worms are found in the ligamentum nuchae, in subcutaneous cysts on the penis and in perimuscular connective tissue of donkeys.

Onchocerca reticulata

a parasite of horses, mules and donkeys. Adult worms are found in the connective tissue of flexor tendons and suspensory ligament of the fetlock, mostly in the forelimb.

Onchocerca rugosicauda

found in the subcutaneous fascia in the shoulders and back of roe deer.

Onchocerca sweetae

see O. cebei (above).

Onchocerca synceri

found in subcutaneous tissues in African buffalo.

Onchocerca tarsicola

a parasite of deer.

Onchocerca tubingensis

a parasite of deer.

Onchocerca volvulus

causes dermatitis and ocular disease in humans.