A SERIES | Diseases on the Brink

Articles in this series examine diseases that hover on the brink of eradication, and the daunting obstacles that doctors and scientists face to finish the job. A final article will report on the challenges of campaigns that try to offer prevention of a number of diseases at once.

PART ONE: POLIO The polio campaign threatens to become a costly display of all that can conspire against efforts to eliminate a disease.

PART TWO: GUINEA WORM Guinea worm, which has plagued untold generations, is poised to become the first disease since smallpox to be pushed into oblivion.

PART THREE: TRACHOMA The World Health Organization estimates that 70 million people are infected with trachoma, and two million are blind because of it.

PART FOUR: FILARIASIS Health experts hope to eliminate lymphatic filariasis, which causes lymph nodes to swell, within a generation.

PART FIVE: MEASLES Mothers in Nepal are foot soldiers in the global fight to slash the number of children who die from complications of measles.

PART SIX: THE IODINE SOLUTION Kazakhstan's iodized salt campaign is an example of how a still- developing country can achieve a remarkable public health success.

PART SEVEN: TROUBLED COORDINATION Campaigns that included some combination of measles shots, polio drops, deworming pills, vitamin A and nets were carried out in nine African countries this year.