Here is the study: http://www.science.org/doi/10.1126/science.adg0344

A deadly pandemic has decimated bats in North America — and that has ultimately had harmful effects on humans, including higher rates of infant mortality, according to a new study.

The research is part of growing evidence that humans rely on the animal and plant species around them, and are harmed when those species decline or go extinct.

White-nose syndrome is a deadly fungal disease that kills an average of 70 per cent of bats it infects, and has been spreading to new areas since it was first reported on the continent in 2006.

[…]

Ecologists know that bats play a crucial role in eating up and controlling insect pests.

Because of that, Eyal Frank, an environmental economist at the University of Chicago, decided to look at what happened when white-nose syndrome spread into new counties in the eastern U.S., decimating bat populations.

He found that farmers responded to the resulting insect outbreaks by increasing their pesticide use 31 per cent. Pesticides are toxic, and often associated with human health impacts such as increases in infant deaths.

Frank found that infant mortality went up eight per cent after the arrival of white-nose syndrome in a county, according to his study published today in the journal Science.

[…]

The study shows how interactions between species such as bats and insects stabilize the ecosystems that other species rely on, including humans, who can be harmed when those species disappear, Frank said.

“These ecosystems are very complex systems with many interactions between species, and we do not fully understand what to expect or what will happen when we allow one species to fall below some viable population level or to go extinct,” said Frank, who had previously linked the deaths of half a million people in India to the collapse of local vulture populations due to accidental poisoning.