Pathogenesis

There is little host reaction to the prepatent worms but once the mature female has initiated a blister (probably caused by extrusion of larvae at the anterior end) there is a marked inflammatory response against the cuticle of the entire worm, preventing its rapid removal (Figures 20.1 and 20.2). The fluid in the blister which forms at the site of emergence of the female worm is bacteriologically sterile and contains numerous larvae with white cells adhering to them. At first the cells are principally polymorphonuclear neutrophils but after a few days there are also macrophages, lymphocytes and eosinophils (there is often a high eosinophilia at this stage). The chronic response over the next few weeks, with necrosis and some vasculitis along the track of

Principles and Practice of Clinical Parasitology

Edited by Stephen Gillespie and Richard D. Pearson © 2001 John Wiley & Sons Ltd

Fig. 20.1 (A) Foot of girl with three female guinea worms emerging and being wound out on sticks in the traditional manner. Courtesy of Dr A. Tayeh. (B) Foot of child with loop of adult female guinea worm emerging from a large blister. (C) Knee of girl with female guinea worm emerging; local remedy of palm oil has been placed on the lesion and the knee has become secondarily infected. (D) Foot of child with three female guinea worms emerging. Courtesy of Dr A. Tayeh

Fig. 20.1 (A) Foot of girl with three female guinea worms emerging and being wound out on sticks in the traditional manner. Courtesy of Dr A. Tayeh. (B) Foot of child with loop of adult female guinea worm emerging from a large blister. (C) Knee of girl with female guinea worm emerging; local remedy of palm oil has been placed on the lesion and the knee has become secondarily infected. (D) Foot of child with three female guinea worms emerging. Courtesy of Dr A. Tayeh

the worm, resolves quickly once the worm is completely expelled.

Sometimes mature female worms burst in the tissues, releasing many thousands of larvae, and this results in a very large pus-filled abscess and severe cellulitis. Males and infertile females elicit a slight inflammatory reaction, followed by absorption or calcification evident on X-rays.

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