A team of 40 Cuban doctors on Wednesday joined international aid experts in Guyana to help fight the threat of disease following floods that killed at least six people and forced tens of thousands from their homes.

The Cubans were deployed in rural communities, some of which were still swamped by stagnant, polluted water more than two weeks after the worst floods in the South American nation’s history, government officials said.

Cuba’s Communist government sent the doctors in response to an appeal from Guyana’s president, Bharrat Jagdeo.

The floods, caused by torrential rains, killed at least six people and affected nearly 300,000 - almost one quarter of the population. The worst-hit areas were the capital, Georgetown, and surrounding areas on the Atlantic Coast, which have been declared disaster zones by the government.

Jagdeo appealed to the international community to send aid and medical assistance. Officials said they were worried contaminated water, insects and rodents could spread fatal diseases.

“We have to make sure there is no epidemic of any sort. I think that with this support from abroad and from the donor community we will be able to take care of the health effort and strengthen it,” Jagdeo told reporters late Tuesday.

Experts from the Pan American Health Organization, the World Health Organization, the U.S. Agency for International Development and other agencies were working with local officials to help contain the disease threat.

The European Union, the United States, Venezuela, Brazil, Canada, China and Russia have all sent aid shipments or teams to Guyana in response to the government appeal.

United Nations experts were assessing the damage caused by the floods to decide what more aid might be needed.