Ancient fossils reveal rise in parasitic infections due to climate change

January 12, 2015
(A) Whole specimen from sample 154 with shallow pits; (B) Partial specimen from sample 154 with deep pits; (C) Partial specimen from sample 157 displaying pits on multiple growth layers; and (D) Incipient steinkern from sample 162 displaying pits preserved as positive relief on lower half of specimen. Credit: John Warren Huntley

When seeking clues about the future effects of possible climate change, sometimes scientists look to the past. Now, a paleobiologist from the University of Missouri has found indications of a greater risk of parasitic infection due to climate change in ancient mollusk fossils. His study of clams from the Holocene Epoch (that began 11,700 years ago) indicates that current sea level rise may mimic the same conditions that led to an upsurge in parasitic trematodes, or flatworms, he found from that time. He cautions that an outbreak in human infections from a related group of parasitic worms could occur and advises that communities use the information to prepare for possible human health risks.

Trematodes are internal parasites that affect mollusks and other invertebrates inhabiting estuarine environments, which are the coastal bodies of brackish water that connect rivers and the open sea. John Huntley, assistant professor of geological sciences in the College of Arts and Science at MU, studied prehistoric collected from the Pearl River Delta in China for clues about how the clams were affected by changes caused from global warming and the resulting surge in parasites.

"Because they have soft bodies, trematodes do not leave body fossils," Huntley said. "However, infected clam shells develop oval-shaped pits where the clam grew around the parasite in order to keep it out; the prevalence of these pits and their makeup provide clues to how the clams adapted to fight trematodes. When compared to documented rises in more than 9,300 years ago, we found that we currently are creating conditions for an increase in trematodes in present-day estuarine environments. This could have harmful implications for both animal and human health, including many of the world's fisheries."

Modern-day trematodes will first infest mollusks like clams and snails, which are eaten by shore birds and mammals including humans. Symptoms of infection in humans range from liver and gall bladder inflammation to chest pain, fever, and brain inflammation. The infections can be fatal. At least 56 million people globally suffer from one or more foodborne trematode infections, according to the World Health Organization.

Huntley and his team compared these findings to those from his previous study on clams found in the Adriatic Sea. Using data that includes highly detailed descriptions of climate change and radiocarbon dating Huntley noticed a rising prevalence of pits in the clam shells, indicating a higher prevalence of the parasites during times of in both the fossils from China and Italy.

The estuarine clam Potamocorbula amurensis displaying the characteristic oval-shaped pits with raised rims induced by parasitic trematode worms. Credit: John Warren Huntley

"By comparing the results we have from the Adriatic and our new study in China, we're able to determine that it perhaps might not be a coincidence, but rather a general phenomenon," Huntley said. "While predicting the future is a difficult game, we think we can use the correspondence between the parasitic prevalence and past to give us a good road map for the changes we need to make."

Explore further: Clam found to be over 500 years old

More information: "A complete Holocene record of trematode-bivalve infection and implications for the response of parasitism to climate change," PNAS, www.pnas.org/content/111/51/18150.full.pdf+html

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9 comments

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Shootist
3.4 / 5 (5) Jan 12, 2015
Fact: The climate changes.
orti
1.8 / 5 (10) Jan 12, 2015
Get your free grant money if you can work "climate change" into the wording.
aksdad
1.9 / 5 (9) Jan 12, 2015
When compared to documented rises in sea level more than 9,300 years ago, we found that we currently are creating conditions for an increase in trematodes in present-day estuarine environments

If the paleoclimate record is accurate, sea level rise around 9,000 years ago averaged 13 to 15 mm per year.

http://www.giss.n...nitz_10/

The current rate of sea level rise is about 2.8 to 3.2 mm per year, less than 1/4th the ancient rate.

http://sealevel.colorado.edu/

It's difficult to see any similarities. Back then, sea levels increased by 1.5 meters (59 inches) a century. In the last 100 years they increased less than 0.2 meters (~7 inches).

As for humans "creating conditions for an increase"; so far there is no evidence that human emissions contributed anything other than an insignificant amount to the warming--and sea level rise--that occurred in the last 100 years.
pandora4real
3.3 / 5 (6) Jan 12, 2015
Hey, you spambots keep wasting your time with the same feckless arguments. The Cruz Wolf is at NASA's door, y'all are now a clear and present threat, and it's time to shut down the social media accounts, forget the insipid comments, and roll up our sleeves.
greenonions
4.5 / 5 (8) Jan 12, 2015
Many thanks to aksdad for a very interesting link to GISS. I assume that you read the whole page - and wonder if you are in agreement. Here is a short quote - "But the temperature rise of the last few decades is unprecedented within the past millennium. More disconcertingly, within the last 10-15 years, meltwater from glaciers and ice sheets accounts for two thirds to nearly four fifths of the total observed rise in sea level (which includes ocean thermal expansion)"
teslaberry
1.7 / 5 (6) Jan 12, 2015
the only parasites i see are those researchers conducting blatantly bullshit research on nsf funded dime.
alfie_null
5 / 5 (6) Jan 13, 2015
. . . As for humans "creating conditions for an increase"; so far there is no evidence that human emissions contributed anything other than an insignificant amount to the warming--and sea level rise--that occurred in the last 100 years.

A team of researchers whose credentials I can vet publish in a refereed journal. Then some anonymous guy hiding behind the pseudonym 'aksdad' tells me they are all wrong and he is right. Then dingleberry-picks a bunch of stats and flings them at me.
jyro
1 / 5 (4) Jan 13, 2015
Cooking food kills worms, since the beginning of Earth 4 billion years ago the climate has continuously changed.
nevermark
3.7 / 5 (3) Jan 19, 2015
Get your free grant money if you can work "climate change" into the wording.


the only parasites i see are those researchers conducting blatantly bullshit research on nsf funded dime.


How distressing when science (funded by thousands of organizations around the world) doesn't produce the conclusions you want to hear. Let's call them names.

...since the beginning of Earth 4 billion years ago the climate has continuously changed.


Obviously climate is always changing but it is always changing differently. The specific types and causes of change are worth understanding.

...so far there is no evidence that human emissions contributed anything...


Even the oil companies disagree with you.

Can a real scientifically based skeptic help these poor lost deniers find their way?

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