Onchocerciasis (River Blindness)

Amanda Kramer

WHAT IS RIVER BLINDNESS?

A neglected tropical diseased caused by the worm Onchocerca volvulus and

carried by Simulium blackflies that can result in skin damage and blindness.

DISTRIBUTION

25 million people infected

300,000 blind800,000 with visual impairment

No reported deaths

99% of cases in sub-Saharan Africa

Yemen and Americas also affected

LIFE CYCLE OF ONCHOCERCUS VOLVULUS

RELEASE OF WOLBACHIA CAUSES SYMPTOMS

SYMPTOMS

Skin nodules

Leopard SkinBlindness

DIAGNOSIS

• Skin snip• Removal and testing of nodules• Antibody tests in development

TREATMENTIvermectin

Primary Treatment

DeoxycyclineSecondary Treatment

• Binds to glutamate-gated chloride channel• Hyperpolarizes nerve and muscle cells• Kills larvae

• Antibiotic protein synthesis inhibitor• Kills Wolbachia, a necessary symbiotic

bacteria

PREVENTION

• Anti-insect measures• Covering clothing• Screens• Insect repellent

• IVM treatment

REFERENCES• Brattig NW, Rathjens U, Ernst M, Geisinger F, Renz A, Tischendorf F. 2000. Lipopolysaccharide-like molecules derived from Wolbachia endobacteria of the filaria Onchocerca

volvulus are candidate mediators in the sequence of inflammatory and anti-inflammatory responses of human monocytes. Microbes and Infection 2: 1147-1157.

• Center for Disease Control, "Parasites - Onchocerciasis (alson known as River Blindness)." Last modified May 21, 2013. Accessed March 16, 2014. http://www.cdc.gov/parasites/onchocerciasis/.

• Convit J, Schuler H, Borges R, Olivero V, Dominguez-Vasquez A, Frontado H, Grillet M. 2013. Interruption of Onchocerca volvulus transmission in Northern Venezuela. Parasites and Vectors 6: 289.

• Langworthy NG, Renz A, Mackenstedt U, Henkle-Duhrsen K, Bronsvoort MB, Tanya VN, Donnelly MJ, Trees AJ. 2000. Macrofilaricidal activity of tetracycline against the filarial nematode Onchocerca ochengi: elimination of Wolbachia precedes worm death and suggests a dependent relationship. Proc R Soc Lond 267: 1063-1069.

• Osei-Atweneboaan MY, Boakye DA, Awadzi K, Gyapong JO, Prichard RK. 2012. Genotypic analysis of B-tubulin in Oncocerca volvulus from communities and individuals showing poor parasitological response to ivermectin treatment. International Journal for Parasitology: Drugs and Drug Resistance 2: 20-28.

• Stanford Human Biology, "Mechanism of Action." Accessed March 16, 2014. http://www.stanford.edu/class/humbio103/ParaSites2005/Ivermectin/mechanism of action.htm.

• Wikipedia, "Onchocerciasis." Last modified March 20, 2014. Accessed March 16, 2014. http://en.wikipedia.org/wiki/Onchocerciasis.

• Wilson MD, Osei-Atweneboana M, Boakye DA, Osei-Akoto I, Obuobi E, Wiafe C, Kiszewski A. 2013. Efficacy of DEET and non-DEET-based insect repellents against bites of Similium damnosum vectors of onchocerciasis. Medical and Veterinary Entomology 27: 226-231.

• World Health Organization, "Onchocerciasis." Last modified March 2014. Accessed March 16, 2014. http://www.who.int/mediacentre/factsheets/fs374/en/.

• World Health Organization, "Onchocerciasis (river blindness) disease information." Last modified 2014. Accessed March 16, 2014. http://www.who.int/blindness/partnerships/onchocerciasis_disease_information/en/.