Civil unrest is making it harder to contain a new outbreak of cholera in Haiti just as other diseases threaten to ignite new health crises, the Pan American Health Organisation says.

The Caribbean country had confirmed 18 deaths from cholera as of October 9, with hundreds of potential cases being studied, PAHO said, after authorities announced the disease's surprise return earlier this month.

Haiti has been suffering a worsening humanitarian crisis amid protests against the government of interim Prime Minister Ariel Henry as blockades shut a critical fuel terminal since last month, bringing much of the country to a halt.

"The ongoing civil unrest and precarious security situation in the country hinder efforts to contain and control this outbreak," PAHO director Dr Carissa F. Etienne said, adding that "these same situations also continue to impact other health priorities," including maternal health, malaria, HIV, tuberculosis and routine vaccinations.

About 41 per cent of Haitian children are vaccinated against measles and 51 per cent are fully vaccinated against polio, Etienne told journalists.

"This is well way below recommended levels, leaving Haiti at high risks of further outbreaks," Etienne said.

PAHO considers Haiti one of four countries in the Americas at "very high risk" of polio transmission, along with neighbouring Dominican Republic as well as Brazil and Peru.

Thirty-two cases of cholera had been confirmed as of October 9, with more than 260 suspected cases still awaiting confirmation in the area surrounding Port-au-Prince, Etienne said, adding that nearly one quarter of these cases are among children between the ages of one and four.

PAHO sees the risk from the cholera outbreak as "moderate" for the rest of the Americas and "minimum" at a global level, with the greatest risk facing other departments in Haiti not yet affected, as well as the Dominican Republic, PAHO official Dr Sylvain Aldighieri said.

Haiti previously suffered an outbreak of cholera in 2010 when United Nations peacekeepers dumped infected sewage in a river, leading officials to apologise for the spread that killed thousands.