The United Nations has reported at least 10 new fatalities due to a cholera outbreak among Somali refugees in the world’s largest refugee camp in Kenya.

Officials with the UN refugee agency, the UNHCR, said on Saturday over 1,000 more Somali refugees have fallen ill as a result of the latest outbreak, which began in November 2015 in the Dadaab camp in northeastern Kenya.

The camp is home to nearly 350,000 refugees from neighboring Somalia, said UNHCR official Osman Yussuf Ahmed.

“The most important thing is hygiene,” Ahmed said while elaborating on efforts by aid workers to spray chlorine across the camp and distribute soap among the refugees.

“We are not leaving anything to chance,” he added.

The cholera virus is commonly transmitted through contaminated drinking water, and causes severe diarrhea. The current outbreak has reportedly been exacerbated by weeks of heavy rains in Kenya.

The ill-fated refugees sheltered in the Dadaab camp have come in waves to Kenya from neighboring Somalia since 1991, as their largely lawless country is struggling with a bloody civil war as well as famine.