Guinea worm: inching towards eradication

In 1986, there were an estimated 3.6 million cases of Guinea worm disease per year in 21 countries in Africa and Asia. Today, the parasitic disease is close to eradication. In 2017, there were only 30 cases in Chad and Ethiopia. In the first three months of 2018, there were only 3 human cases in one country, Chad.

Former US President Jimmy Carter's foundation in 1986 led an international campaign against Guinea worm. Nearly 80 million cases have been averted due to the campaign. Guinea worm would be the first human parasitic disease to be eradicated and only the second disease after smallpox to be eliminated. It would also be the first disease to be eradicated without the use of a vaccine or medicine.

The life cycle of the parasite begins when humans drink unfiltered water from ponds or stagnant water sources containing microscopic copepods (water fleas) infected with larvae. Once ingested, the copepods die and release the larvae into the digestive tract, where they mature and mate. Males die but females grow to about 60-100 centimeters (2-3 feet) long and as wide as a spaghetti noodle.

The female worm usually exits from the leg or foot after about one year inside the body. The blister is painful. Attempts to clean or sooth the pain of the blister in ponds or other water sources lead to the release of millions of immature larvae into the water. Copepods then consume first-stage larvae. The larvae develop in the copepods until they are again consumed by humans.

There is no drug or treatment for Guinea worm. The worm is usually removed a couple centimeters per day over the course of weeks using gauze or a stick. The process is debilitating and can lead to secondary bacterial infections. The disease prevents people from taking care of themselves, working, attending school or farming for extended periods.

Guinea worm has largely been stopped through community programs to educate and change behavior. Simple education such as teaching people to drink filtered water and preventing infected people from entering water have limited the spread of the disease.

Guinea worm disease remains endemic in South Sudan, Mali, Chad and Ethiopia. In 2017, there were only 30 isolated cases in 20 villages in two countries, Chad and Ethiopia.

Infected dogs were first discovered in Chad in 2012, raising concern about animal transmission even though they are not the natural host of Guinea worm. Dogs in fishing villages in Chad are believed to have acquired the disease by eating raw fish and guts carrying Guinea worm larvae. Interventions and education with locals have brought down infection rates since the problem developed.