Weeks of torrential rains have caused widespread flooding in low-lying areas of Bolivia such as the Amazonian region of Beni on the Brazilian border. More than 60 people have lost their lives and around 60,000 families have been made homeless.
Access to drinking water is a major problem, because dead cattle and sewage have contaminated wells and rivers. Mario Hurtado, president of the Beni Stock Raisers' Federation, estimated more than 100,000 cattle have been killed and another 500,000 animals are at risk of drowning or starvation.
An outbreak of dengue is feared once the waters have receded as the muddy expanses are the perfect breeding ground for mosquitoes. Fumigation operation are under way in Trinidad, the capital of Beni, where several cases of dengue have already been reported.
Bolivia's president Evo Morales said: "What is happening, particularly in Beni province, is something never before seen in the history of Bolivia."