The international medical charity, known by its French acronym MSF, said it was concerned the new outbreak in the war-torn country could spread and become out of control.
Cholera is a bacterial infection of the small intestine that can cause severe diarrhoea and dehydration. It can lead to death if left untreated.
More than 2,000 cases of cholera have been reported since April 27, the World Health Organisation (WHO) said.
This is the second wave of cholera-associated deaths in a year in Yemen, where more than 8 million people lack access to drinking water and sanitation.
A Saudi-led coalition has been battling Shiite Houthi rebels in Yemen since March 2015, in a war that has killed more than 10,000 civilians.
The country's health system and civilian infrastructure are collapsing after two years of conflict.
WHO said last month that fewer than 45 per cent of health facilities in Yemen were now fully functioning, and that the flow of "essential medicines" had fallen by nearly 70 per cent.
The United Nations said a child aged under five dies of preventable causes every 10 minutes in Yemen, and has called Yemen "the largest humanitarian crisis in the world".
Some 17 million people lack adequate food, and one third of the country's provinces are on the brink of famine.
The UN says 18.8 million people need humanitarian or protection assistance in Yemen, the Arab world's poorest country.