PARC CADEAU 2, Haiti — Along this arid strip of borderland, the river brings life. Its languid waters are used to cook the food, quench the thirst and bathe the bodies of thousands of Haitian migrants who have poured onto its banks from the Dominican Republic, fleeing threats of violence and deportation.

These days, the river also brings death. Horrid sanitation has led to a cholera outbreak in the camps, infecting and killing people who spilled over the border in recent months in hopes of finding refuge here.

Nearly 3,000 people have arrived in the makeshift camps since the spring, leaving the Dominican Republic by force or by fear after its government began a crackdown on illegal migrants. Some, born in the Dominican Republic but unable to prove it, cannot even speak French or Creole, Haiti’s main languages, showing how wide a net the Dominican government has cast.

Haitian officials have done almost nothing to support them. The population is scattered across the drought-racked southwest border, mostly barren plains. Families of eight sleep in tents fashioned from sticks and cardboard. They drink river water, struggle to find food, and make do without toilets or medical attention.