There were an estimated 3.5 million cases of Guinea worm disease in Africa and Asia in 1986 but in 2013 that figure has fallen to 148.

The good news comes from the Carter Center, founded in 1982 by ex-US president Jimmy Carter and his wife Rosalynn in partnership with Emory University. Provisional numbers show that cases of the tropical disease were also well down (73%) on the 2012 figure.

Guinea worm disease (also known as dracunculiasis) is contracted when people consume water contaminated with Guinea worm larvae. After a year, a metre-long worm slowly emerges from the body through a painful blister in the skin.

The Carter Centre notes that in the absence of a vaccine or medical treatment, the disease is being wiped out mainly through teaching people to filter all drinking water and preventing contamination by keeping anyone with an emerging worm from entering water sources.

In 1991, when the number of endemic villages reached its peak, there were 23,735 villages in 21 countries in Africa and Asia reporting Guinea worm disease. In 2013, there were only 63 in four countries, all in Africa - South Sudan (113 cases ) Chad (14), Mali (11) and Ethiopia (7).

President Carter said the centre and its partners, which include the Bill & Melinda Gates Foundation and the UK's Department for International Development, "remain committed to ending the devastating suffering caused by Guinea worm disease, recognising that the final cases of any eradication campaign are the most challenging and most expensive to eliminate".