It just got a lot worse to be a frog living in Spain right now. Spanish frog species already combating the same deadly chytrid fungus that is wreaking havoc on amphibian populations all over the world now must also deal with a pair of lethal and fast-spreading viruses.

The viruses are part of the Ranavirus group and are often referred to as Common midwife toad virus (CMTV). Viruses of this kind have previously been found to cause declines in the UK's common frog population. However, this is the first time that a CMTV has affected a region's entire amphibian group, slaughtering frogs, salamanders, and even some of the predators that eat them.

The infection isn't pretty either.

"They hemorrhage throughout their tissues, vomit blood and pass it out through their guts, and suffer huge open ulcers," Stephen Price of University College London (UCL) told New Scientist.

He added that some CMTV infections have been seen to even cause amphibian limbs to fall off.

The gruesome mass deaths occurring in Spain recently prompted Price and his colleagues from UCL, Zoological Society of London (ZSL) and Queen Mary University of London (QMUL) in the UK, and the National Museum of Natural Sciences (MNCN-CSIC) in Madrid to launch a study of the ongoing outbreak.

Based on annual surveys across 15 locations in Picos de Europa National Park (PNPE) between 2005 and 2012, the researchers found that six amphibian species were experiencing waves of mass death from the viruses. (Scroll to read on...)

"We've identified a striking example of two viruses that are repeatedly overcoming the species barrier with catastrophic consequences," Price explained in a recent release. "This presents us with a great opportunity to understand more about the ecology and epidemiology of important multi-host pathogens."

But experts will have to work fast. According to the researchers, the viruses haven't begun to impact amphibian populations suffering from chytrid fungus infection just yet, but it's only a matter of time before threatened frog species find themselves fighting a biological war on two fronts.

"Indications are that related viruses are beginning to emerge in other locations in Europe and it's important to understand the origins and movement of these viruses to try to limit further amphibian declines," Price added.

Thankfully, the researchers have already discerned a potential genetic origin of the viruses, which could help them develop ways to fight it if drastic conservation action becomes necessary.

The study was published online in the journal Common Biology on Oct. 16.