How will global climate change affect the prevalence of tropical diseases? In general, warmer temperatures will expand the areas in which these diseases are endemic. However, if households can take actions to protect themselves from disease—such as purchasing bednets or insecticidal sprays—then economic factors may greatly mitigate the effects of climate change. These actions are costly, however, and particularly in poor countries, many households face borrowing constraints. A model of disease transmission combining the household's objectives and constraints shows that a temperature increase of 3°C will induce modest changes in disease prevalence and output. These effects can be mitigated by improvements in the efficacy of disease prevention.