CASES WITHOUT BORDERS KWA'AL, Nigeria - The pond was about the size of a school swimming pool, except it was surrounded by dry mud pocked with hundreds of hoofprints. A herd of goats was at one edge, drinking and defecating in the same spot. The sun was going down behind a thorn tree, backlighting 50 naked boys splashing one another in the warm dusk. Where a colonialist romantic would have seen a landscape of native innocence, I saw a horror movie: there were worms in the brown water invisibly digging right through the boys' skin. Kwa'al is a market village...