It supports processes that we all often take for granted, such as air quality, climate regulation, water purification, parasite and disease control, pollination and the prevention of erosion.

UNESCO: Message by UNESCO Director-General Irina Bokova

This monitored children for growth development and the number of times they had a diarrhoea-related disease or parasite infection.

BBC: Less brainpower hits stunted youth

But if a non-native parasite is carrying a disease, the new hosts may not be able to withstand it, says Lovett.

CNN: Unwelcome visitors cause havoc for bees

It also warns that disease and parasite transmission and climate change may give the invading European hare an edge over our native species.

BBC: Irish hare under threat from 'European brown' hare

The parasite that causes the disease has been wily enough to evade eradication attempts in the past--from the Rockefeller Foundation's efforts in the early 1900s, to the World Health Organization in the 1950s.

FORBES: Magazine Article

In recent years, problems have fouled acquaculture's reputation: pollution from waste runoff, high disease and parasite rates due to a high density of fish and the uptake of industrial chemicals harmful to humans have combined to make fish less healthy to eat.

FORBES: Magazine Article

The cause of Chagas disease is the parasite Trypanosoma cruzi, which is transmitted to humans from a bite from an insect known as the triatomine bug.

CNN: Chagas disease

It's a disease caused by a parasite that migrates from host to host via mosquito.

NPR: Altered Mosquitoes May Save Humans From Malaria

The curious life cycle of the parasite, called plasmodium, is one of the reasons why the disease has proved so difficult to control.

BBC: Venom to arm mosquito against malaria

Another practical point is that the type of malarial parasite used in this and many other experiments is not actually one that causes human disease.

ECONOMIST: Recruiting mosquitoes to fight malaria