Chasing the Worm

by Michelle Lodge

This article was published Sept. 22, 2009 by the British Medical Journal 2009;339:b3892.

New cases of guinea worm disease in southern Sudan have recently fallen from 20 000 a year to an estimated 1500, and doctors are hoping that the disease will become the second in history to be eliminated.

Any observer of guinea worm disease, or dracunculiasis, will tell you that this waterborne parasitic disease should be simple to eradicate. After all, no vaccinations or costly drugs are needed, the disease cannot be passed from one person to another, and the wounds that the worm itself causes on a patient's body are handled effectively with what you would use for a scraped knee: clean water, antiseptic, gauze, and an antibacterial ointment.

But eradication of the nematode, Dracunculus medinensis, requires that most slippery of ingredients: a change in human behaviour. In fact it requires two changes, one of which is particularly difficult to effect because of the parasite's wily ways.

The life cycle of the worm begins when a person drinks water infected with its larvae (see box). So the first change that health campaigners are pursuing is to persuade people to filter their water before drinking it.

Then over the course of a year the larvae mature and grow into long, spaghetti-like white worms that live in the body's subcutaneous and intramuscular tissues. When the female worms are ready to emerge and lay their eggs, they ingeniously cause such blistering of the skin and such a fiery pain that the host naturally seeks out cool water for relief, thus enabling the worm to lay its eggs in water and continue its life cycle.

Life cycle of the guinea worm

The adaptable guinea worm begins life as an independent larva in a pool of stagnant water after its mother, emerging from the body of a person with guinea worm disease, has sprayed her cloud of eggs. Tiny freshwater fleas, or copepods, then ingest the larvae or eggs.

The larvae require 10 to 14 days of development inside the copepods before becoming infective to humans. Once a person drinks water infested with larvae-bearing copepods, the flea's shell disintegrates on contact with digestive juices, and the larvae are released. From there the parasites make their way into the small intestines, from which they bore through the intestinal wall into the abdominal cavity. Eventually they mate. The male dies, and the impregnated female matures to be a slender white worm of up to 1 m long.

After living in the body for a year the pregnant guinea worm is ready to lay her eggs in water. In preparation she burrows through the patient's skin, usually in the lower extremities, forming a painful blister from which she emerges. Patients can have several guinea worms living in their bodies at once, compounding the suffering. To relieve the fiery agony caused by the worm, a patient may seek the coolness of water. This water then becomes recontaminated with larvae, and the cycle is repeated.

To interrupt the cycle health campaigners have to effect the second change: to try to persuade the parasite's human prey to refrain from going into ponds, rivers, or other communal bathing areas when they have a guinea worm emerging from their bodies.

As any public health doctor knows, old habits die hard. Moreover, those working to eradicate the disease in Sudan, the worst affected country, have several other major problems to contend with, namely the after effects of a 20 year civil war, ongoing violence, a mobile and illiterate population, and a vast underdeveloped land.

Sudan is one of six remaining countries where the disease, which can make it impossible for those infected to walk, work, or care for a family, still exists; the others are Ghana, Ethiopia, Mali, Niger, and Nigeria, although transmission seems to have been arrested this year in Niger and Nigeria.

"In principle, a 14 month period is good enough to result in zero cases, provided that all guinea worm cases that occur during this period are fully contained," said Gautam Biswas, of the World Health Organization, who surveyed regions in southern Sudan in June. "This is a challenging task but is still doable."

Today provisional figures indicate that just over 1500 indigenous cases exist in southern Sudan, a big fall from the more than 20 000 indigenous cases reported three years ago. Several players have contributed to this success, the most important probably being the government of the autonomous region of Southern Sudan.

Its project, the Southern Sudan guinea worm eradication programme, is an immense operation of 14 000 people, made up of village volunteers and an army of experts. Its programme director, Makoy Samuel Yibi Logora, reports directly to the health minister.

But another important player is the Carter Center, an Atlanta based foundation set up by the former US president Jimmy Carter and his wife, Rosalyn, which underwrites the project with the help of donors and partners such as the US Centers for Disease Control and Prevention in Atlanta and WHO. The foundation took on the eradication of guinea worm disease as one of its goals in the 1980s after the Carters encountered a young Ghanaian woman with a worm emerging from her swollen breast. At that time about 3.5 million cases thrived in 20 African and Asian nations.

Fund raising has shored up the programme with tens of millions of US dollars since its inception. In December, for instance, the Bill and Melinda Gates Foundation and the United Kingdom's Department for International Development pledged a combined $55m (£34m; {euro}38m) for the Carter Center led guinea worm programme. Of that amount $32m from the Gates Foundation must be matched one to one with the centre's fund raising.

Once that goal has been met the Carter Center, WHO, and the remaining affected countries will have $87m to finish the job. Most of that will go to efforts in Southern Sudan.

"We are fighting the worm, one case at a time," said Ernesto Ruiz-Tiben, the Carter Center's director of the programme, acknowledging the labour intensive effort needed to avert or treat even one case of the disease.

Apart from trying to effect behaviour change, the programme also aims to treat the water with Abate, a larvicide that is not toxic to humans and animals, but this has to be done within 10 days of the eggs' release.

Despite the recent fighting in parts of the region, Dr Ruiz-Tiben said that the civil disruption has not hindered the progress of the eradication programme. Bismarck Swangin, a communications officer for Unicef in Juba, said that the conflicts over the past month have not been in areas where the disease is endemic. But he added that the fighting has severely curtailed the borehole well programme in the affected states, which can lead to other illnesses, such as cholera.

After the comprehensive peace agreement signed between Khartoum and the south in 2005, and which set up a temporary autonomous government in Juba, more aid organisations have built compounds in Southern Sudan. But they are ever vigilant about violence that still breaks out over livestock theft and grazing rights.

Yibi Logora, the director of the project in Southern Sudan, has been working on his country's guinea worm problem since 1995. He notes the encouraging progress-an 80% drop in cases-yet adds that "the postwar challenges have been massive." Among them are the scant supply of clean water; lack of infrastructure, such as paved roads and healthcare facilities; landmine scares, intertribal fighting and population displacement; and the nomadic nature of its people, many of whom are pastoralists who perpetually move their herds of goats and cattle in search of food and water.

The land and weather can impede success as well. Treating guinea worm disease in Southern Sudan requires regular travel on rough terrain to thousands of villages (the region has 17 000 such settlements) in an area the size of Austria and Switzerland combined. When the rains come, dry river beds swell and flood with raging currents, and the region's dampened black sand causes vehicles to spin out of control.

During the rainy period, which coincides with the disease transmission season (typically April to September), workers in the field often have to sit out the foul weather before resuming their work.

To tackle the latest cases of guinea worm in the area, the programme has opened three case containment centres this year in the Eastern Equatoria state and is considering adding others. Patients stay voluntarily at these centres and may have visitors and family members to live with them. Twice daily the centre's nurses treat the patient's wounds. In addition, patients are served three hot meals a day and receive health education.

Several times a day the centres broadcast an upbeat guinea worm disease song. The staff also teach patients how to counsel neighbours on ways to avoid the disease, with pictures on a cloth flip chart. These reinforce the essential messages of persuading people not to go into communal water sources and to place cloth filters over the mouths of the plastic jerry cans typically used by women to collect family drinking water. They also encourage people to suck through a pipe filter when drinking water. These filters can be worn on a string or beaded necklace.

Critical to the success of the case containment centres, and the project itself, are the village volunteers, who often refer new cases for treatment. The volunteers are highly motivated. Nakura Agata, of Morvangilimo, one of the volunteer army, told the BMJ, one scorching afternoon in June, "A lot of my relatives, including one of my daughters, have had the worm this year. It hurts me to see them in pain. As a volunteer I can help them."

Milestones in Eradication of Guinea Worm Disease

1986 The Carter Center sets the eradication of guinea worm disease as a goal

1993 Pakistan becomes the first country where transmission is stopped

1994 Kenya is the first African nation in which transmission is stopped

1996 Transmission is stopped in India

1997 Transmission is stopped in Cameroon, Senegal, and Yemen

1998 Transmission is stopped in Chad

2001 Transmission is stopped in Central African Republic

2003 Transmission is stopped in Uganda

2004 Transmission is stopped in Benin and Mauritania

2005 The comprehensive peace agreement is signed in Sudan, ending the major north-south civil war and separating the two regions politically for six years

2006 Transmission is stopped in Burkina Faso, Côte d'Ivoire, and Togo

2008 The Bill and Melinda Gates Foundation and the UK Department for International Development pledge $55m to the guinea worm eradication programme led by the Carter Center, with the option of matching $32m from the Gates Foundation one to one with funds raised by the centre

2009 Geneva Declaration sets the year for stopping transmission worldwide; transmission is halted in Niger and Nigeria (to be verified in spring 2010)

The Carter Center contributed to the cost of Michelle Lodge's trip to Southern Sudan.
Michelle Lodge is a New York based writer.