In Zimbabwe, nurses at Harare's Parirenyatwa public hospital, the city's biggest, say that since November there have been no H.I.V. test kits - in a nation where one in four people is H.I.V.-positive. Two physicians said in separate interviews recently that in the space of six months last year, half of Harare's kidney-dialysis patients died, all because the government did not spend its scarce foreign currency to buy catheters for blood-cleansing equipment.