World Health Day, Apr. 7, was launched in 1948 by the World Health Organization, the United Nations agency devoted to international public health. It is the world's highest health policy setting body and is composed of health ministers from its 194 member states.
World Health Day is seen as an opportunity to draw worldwide attention to a subject of major importance to global health each year. Many of the yearly themes have focused on environmental aspects of health, including: urbanization and health: make cities healthier (2010 and 1996); protecting health from the adverse effects of climate change (2008); shape the future of life: healthy environments for children (2003).
This year World Health Day focuses on diseases that are carried from person to person by mosquitoes, ticks, sandflies, and other tiny organisms. Environmental challenges like urbanization and climate change are causing such diseases - for example, malaria and dengue fever - to show up in places where they were previously unknown.
The tiny organisms that carry the pathogens and parasites that cause these diseases are called vectors, and the diseases are known as "vector-borne." They are most commonly found in tropical areas and places where access to safe drinking water and sanitation systems is problematic.
But because of global travel and climate change, these diseases are spreading to more temperate areas including the U.S. USA Today reports that valley fever, a disease caused by a soil fungus, is sharply on the rise in California and the Southwest.
"Valley Fever is one of multiple diseases experts say are spreading in part because of climate change," says the USA Today report.
"They include a brain-eating amoeba showing up in northern lakes that were once too cold to harbor it and several illnesses carried by ticks whose range is increasing."