How climate change affects parasites and disease spread

Though hosts might expand their geographical range due to global warming, the parasites do not always follow suit, says a study on how climate change affects parasites.

The evidence from this study suggests that perceived fallout from global warming - in terms of the fears of the spread of infectious disease associated with global warming induced range expansions - is not as foregone a conclusion as many may think.

"Invasive species escape parasites for several reasons," said Ryan Hechinger, an associate professor at University of California, Santa Barbara in the US.

"Many parasites do not come with the invader to begin with - they miss the boat," Hechinger added.

Many parasites that accompany their invasive host do not persist because the parasites, many of which live part of their life cycle in different hosts, no longer have access to the environments or other hosts required to complete their life cycle, he added.

And a species that expands its range by moving into an adjoining area may also escape its parasite, the findings showed.

The researchers studied Kellet's whelk, a large marine snail whose historical biogeographical range starts at mid-Baja California waters in the south to Point Conception in the north.

At least for marine parasites such as the ones that live in the Kellet's whelk, the evidence indicates that range expansion for the host does not mean the same for its parasites, the researchers said.

The study appeared in the Journal of Biogeography.