Most emerging infectious disease (diseases that are new in the human population) come from animals.  Viruses constantly circulate in their animal hosts and occasionally spillover into other species, including humans.  In a new study published in the journal Nature, Olival and colleagues report that bats are the number one mammal implicated in a possible future spillover of zoonotic disease.  This comes as  little surprise, as bats have already been suspect number one in some of the most recent headline-grabbing human outbreaks (Ebola, SARS, rabies, etc).  This new study also highlights South America as potentially being the breeding ground for as-yet-unidentified zoonotic viruses – and the most likely place for a new spillover event.

Why bats?  They are very unique in the mammal world – being the only one who can fly.  They have large geographical home ranges, huge variations in body temperature (flying hot and sleeping cold), and super immune systems that we are just starting to understand.  Another concerning aspect is the bat – human relationship.  Olival et al highlight that one of the most important factors in whether or not a spillover will occur is mammal sympatry (two different species of mammals living in the same area and frequently encountering each other).  As humans continue to encroach on the home range of wild animals, not only do we encounter them, but we also encounter their viruses.

The United States Agency for International Development (USAID) Emerging Pandemic Threats program has partnered with UC Davis to create the PREDICT project.  PREDICT uses international sampling and surveillance program to monitor zoonotic diseases and will hopefully stop the next zoonotic outbreak before it happens.  They have a neat interactive map here.