Pests, insects, and vector-borne diseases
Poor housing structures, including cracks in roofs, floors, walls and eaves, as well as a lack of window and door screening, increase risks of vector-borne diseases carried by pests and insects. Most notable are malaria and dengue, as well as leishmaniasis, carried by sandflies, and Chagas, which is transmitted by crawling triatomine insects.
Climate change, deforestation and urbanization also have exacerbated the risk of transmission of dengue, malaria, tick-borne encephalitis, Lyme disease, and Chagas, in many parts of the world. Lack of adequate water infrastructure, drainage or sewage disposal can also increase transmission of malaria and dengue fever, providing breeding grounds near and around homes.
Pests in temperate areas, such as mites and cockroaches, have been shown to trigger allergic reactions in people. It is estimated that some 10-20% of the population is potentially allergic to dust mites. In addition to housing design, excess moisture and poor ventilation increase the risks of exposure to mites and other allergens.