LONDON—The hardest part of a journey is often the last mile. Twenty-five years after health workers started a campaign to rid the world of the guinea worm, cases have been reduced by over 99%. But the 1800 or so that still occur annually pose a threat to worldwide eradication efforts and will be the hardest and most expensive to address.
At a press conference here today, the United Kingdom's international development minister, Stephen O'Brien, announced that the government will be donating about £20 million ($31 million) over 4 years to finish the eradication effort, led by the Carter Center in Atlanta—provided others donors come forward with the remaining £40 million needed.
If it succeeds, the campaign would make guinea worm only the second human disease to be eradicated—after smallpox—and the first to disappear through behavioral change instead of a vaccine. The parasite, once abundant across Africa and South Asia, is now confined to only four countries. Mali, Ethiopia, and the newly independent South Sudan—which accounts for 98% of cases—have not yet interrupted its transmission; and to the disappointment of eradication leaders, a few isolated cases also occurred last year in Chad, which had previously been declared worm-free.
The guinea worm is spread when people ingest its larvae through contaminated drinking water; the larvae incubate inside the human host and emerge painfully through the skin as fully grown, 1-meter-long worms a year later. Speaking at the conference, former U.S. President Jimmy Carter, who at 87 still spearheads the campaign, recalled the first time he observed a worm emerging from a young woman's breast. The woman's excruciating pain "brought tears to my eyes," he said.
Since the worm can grow only inside the human body, it could be eliminated entirely if no new infections occurred. Simple behavioral changes such as filtering drinking water and discouraging people with an emerging worm from walking into ponds and lakes have reduced cases of guinea worm from 3.5 million in 1986 to 1797 in 2010. But finishing the job has been difficult, and the original deadline of 1995 has been moved back several times.
Among the problems, Carter said, is that Africans often resist the idea that local, sacred ponds are dangerous. War and unrest have caused major setbacks as well—although negotiations led by Carter resulted in an interruption in the Sudanese civil war in 1995 that allowed the campaign to go forward. Surveillance remains the most difficult challenge. Health workers have canvassed 23,600 villages in Africa to teach people about prevention and distribute water filters, but most of the remaining cases occur in remote, isolated locales. "It's easier to spot a wildfire than a smoldering twig," World Health Organization Director-General Margaret Chan said at this morning's conference.
The Carter Center's current goal is eradication worldwide—defined as three consecutive years of no reported cases—by 2015. The £20 million from the U.K. government, which O'Brien said is the first of many new contributions to neglected tropical diseases that the United Kingdom plans to make, is one-third of the amount Carter says is needed. The money will go toward providing health education and training, digging clean wells, and providing tools such as water filters and larvicide to communities.
Chan called on others to follow suit. It has been difficult to keep up attention and funding for the disease because it's not usually fatal, she said: "For most of the world, this is an invisible worm. Out of sight, out of mind, living in remote areas beyond the end of the road." Holding Carter's hand, she thanked him and the U.K. government for their "do-good spirit in this time of austerity."
Correction: The number of cases of guinea worm was 3.5 million in 1986, not 1996.