Disease is a physical abnormality that causes problems and would then be classified as a pathology. Medicine attempts to cure disease.
Types of diseases
Hosts of the most important diseases
Diseases may be spread by animals (e.g. Mosquito-borne diseases, schistosomiasis (a helminth worm carried by snails), ...) or by microorganisms (which are called pathogens when they spread disease), especially through poor hygiene, and poor sanitation (see water-borne diseases.
Improving the health of local people
Poor nutrition and unhealthy living conditions (often due to poverty) increase susceptibility to disease. This applies to both environmental diseases such as respiratory illnesses, and those caused by pathogens, which can more successfully attack when a person's immune system is weak).
Cures can be simple. The lack of hygiene education is a factor that can easily be adressed.