Infectious Disease Compendium

Onchocerca volvulus

Microbiology

A tissue nematode.

Epidemiologic Risks

Sub Sahara Africa. Spread by the black fly bite. Also found in Central and South America, there by way of the slave trade.

Syndromes

Onchocerciasis aka River Blindness. Part if not all of the inflammation in the eye may be due to a bacteria, a symbiont, called Wolbachia found in the gut of the worm.

Mostly causes itchy skin lesions and nodules.

Maybe the Nodding disease through molecular mimicry.

Make the diagnosis with skin biopsy.

Treatment

Ivermectin 150 microgram/kg once, repeat q 3 to 6 months, although resistance is increasing (PubMed). Moxidectin is in the pipeline for future therapy.

Doxycycline for 4-6 weeks to kill the Wolbachia bacteria that live in adult worms results in lower microfilarial loads in the host, and may kill the adult worms, due to the symbiotic relationship between Wolbachia and the worm. doxycycline treatment requires daily dosing for at least four to six weeks

Treatment with diethylcarbamazine can cause the Mazzotti reaction: fever, urticaria, swollen/ tender lymph nodes, tachycardia, hypotension, arthralgias, edema, and abdominal pain that occurs within seven days of treatment and can be fatal.

Notes

Good review here (PubMed).

Last update: 05/05/18