New Parasite Threatens to Wipe Out Tadpole Population

The tadpole population worldwide is vulnerable to extinction due to a deadly parasitic infection, lending further credence to the sixth mass extinction event. Frogs from six countries spanning three continents were tested in a study led by the University of Exeter and The National History Museum, UK. Tadpole were from both temperate and tropical regions, including oceanic islands, were found to have this infection. The newly discovered parasite is a type of protist — a mostly unicellular organism with its own nucleus and a distant relative of the Perkinsea. Protists are responsible for mass mortality of shellfish populations. Evidently, protists are largely found in aquatic environments.


Amphibians are one of the most threatened animal groups in the world. “In 2008, 32% were listed as threatened or extinct, and 42% were listed as in decline.” Amphibians, and frogs in particular, are known to be extremely sensitive to infectious diseases; these have often been linked to mass decline and extinctions seen in their population.


In the study, a total of 182 tadpoles representative of different families of frogs over the geographical area were examined. The infectious parasite detected in this study was found to be present primarily in the livers of tadpoles. The DNA obtained from tadpole livers was amplified and analyzed using a common laboratory technique called the polymerase chain reaction. This molecular method allows sequencing of the parasitic DNA. The sequences obtained from all the samples of tadpoles were aligned to find any repetitive patterns and were then mapped to known DNA databases to trace the ancestral origin of this unknown parasite. This exercise revealed the similarity of the protists infecting the tadpoles to the Perkinsea species. These also had very few differences from another type of protist that was recently linked to mass mortality events in tadpoles in the United States. Another notable fact in that this parasitic infection is rampant in various stages of tadpole development, not just concentrated to a single one.

Do We Want To Live in A World Without Frogs?

It is imperative that future studies address the mechanism of how the new parasite inflicts its damage, which might give a clue to curbing the outbreak. Frogs do seem to have a thumb on what could be tipping the balance of our ecosystem. We should pay more attention to what they’re trying to say.


Check out some frogs and tadpoles with SnailVR: