O. volvulus is a worm that causes Onchocerciasis which has blindness as its main pathology. The worm shares a few characteristics with other filarial worms but varies in many. Ivermectin, the only safe drug against onchocerciasis is a larvicide administered once a year until the adult worm dies. This repeated administration can lead to resistance since it has been reported in animal models. Individuals co-infected with L. loa and O. volvulus also experience adverse reactions with ivermectin. An ideal drug should kill the adult worm with fewer administrations but many drugs selected on the basis of their effects on other worms have failed. To avoid this set back a direct study on O. volvulus may provide direct biological information on O. volvulus. Six biologically important enzymes were localised in paraffin embedded O. volvulus nodules using immunohistochemistry to suggest the availability of some potential targets. This book contains extensive information on filarial worms particularly O. volvulus, onchocerciasis and immunohistochemical techniques. It is therefore a useful book for researchers in parasitic diseases as well as students in medicine and allied health professions.