Nav: Home

Bloodsucker discovered: First North American medicinal leech described in over 40 years

August 15, 2019

Freshwater wetlands from Georgia to New York are home to a previously unrecognized species of medicinal leech, according to scientists at the Smithsonian's National Museum of National History. The new species, named Macrobdella mimicus, was first identified from specimens collected in southern Maryland, prompting a search through marshes and museum collections that ultimately revealed that the leech has long occupied a range that stretches throughout the Piedmont region of the eastern United States, between the Appalachian Mountains and the Atlantic Coast.

An international team of museum scientists led by Anna Phillips, the museum's curator of parasitic worms, describe the new species in the Aug. 15 issue of the Journal of Parasitology. "We found a new species of medicinal leech less than 50 miles from the National Museum of Natural History--one of the world's largest libraries of biodiversity," Phillips said. "A discovery like this makes clear just how much diversity is out there remaining to be discovered and documented, even right under scientists' noses."

Leeches are parasitic worms, many of which feed on the blood of their hosts. In the 1700s and 1800s, physicians used leeches to treat a wide range of ailments, believing that by ridding a patient's body of bad blood, the parasites could cure headaches, fevers and other conditions. Any leech that readily feeds on humans is considered a medicinal leech, although in North America most leeches used for bloodletting were imported from Europe, leaving native species relatively undisturbed.

Phillips and her colleagues have been exploring the diversity of medicinal leeches in North America for years. When she returned to the museum from a 2015 field expedition with several orange-spotted, olive-green leech specimens she had collected from a Maryland swamp, she and her team assumed they belonged to a familiar species called M. decora, a leech that is thought to live throughout a large swath of the northern United States. But DNA sequencing revealed otherwise.

Examining the specimens' genomes at key regions used for species identification, Ricardo Salas-Montiel, a graduate student at the National Autonomous University of Mexico, found significant differences from the DNA of M. decora. The molecular discrepancy was surprising, but when the scientists took a closer look at the newly collected leeches, they found a physical difference that distinguished them from M. decora, as well. Like M. decora, the new leeches have multiple reproductive pores along the bottom of their bodies, known as gonopores and accessory pores. In the new leeches, the gonorpores and accessory pores were located in a different position relative to each other.

A subsequent field outing led to the team finding more leeches from South Carolina that shared the same accessory pore positioning. "Then we sequenced [their DNA], and they all came out more closely related to the leeches we had found in Maryland than to anything else known to science," Phillips said.

Phillips quickly retrieved dozens of North American leeches stored in the Smithsonian's parasite collection and examined their accessory pores. "All of a sudden, I started finding these things everywhere," she said. Leeches with the unique pore positioning had been found in locations from northern Georgia to Long Island and preserved in the museum's collection for years. The oldest, Phillips said, dated back to 1937.

From there, Phillips expanded her search, scouring parasite collections at the North Carolina Museum of Natural Sciences and the Virginia Museum of Natural History, pinpointing additional places where the leech had been found in the past. She and her team also found fresh specimens in Georgia and North Carolina and used DNA sequencing to confirm their close relationship to the others.

Each specimen added to the team's understanding of the leech's history in the region and its geographical range. Their molecular, geographical and morphological data suggest the M. mimicus occupies a sliver of the eastern United States that is nestled between the ranges of two other medicinal leech species, Phillips said. The historical record from the museums' collections, with specimens spanning 63 years, adds another critical layer of information, confirming that the species was not recently introduced to the area and does not represent a newly evolved species. "It's been here this whole time," she said. "We just hadn't looked at it in this new way."
-end-
Funding for this research was provided by the Smithsonian, the National Autonomous University of Mexico, the Natural Sciences and Engineering Research Council of Canada, the Royal Ontario Museum and the Olle Engkvist Byggmästare Foundation in Sweden.

Smithsonian

Related Science Articles:

75 science societies urge the education department to base Title IX sexual harassment regulations on evidence and science
The American Educational Research Association (AERA) and the American Association for the Advancement of Science (AAAS) today led 75 scientific societies in submitting comments on the US Department of Education's proposed changes to Title IX regulations.
Science/Science Careers' survey ranks top biotech, biopharma, and pharma employers
The Science and Science Careers' 2018 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.
Science in the palm of your hand: How citizen science transforms passive learners
Citizen science projects can engage even children who previously were not interested in science.
Applied science may yield more translational research publications than basic science
While translational research can happen at any stage of the research process, a recent investigation of behavioral and social science research awards granted by the NIH between 2008 and 2014 revealed that applied science yielded a higher volume of translational research publications than basic science, according to a study published May 9, 2018 in the open-access journal PLOS ONE by Xueying Han from the Science and Technology Policy Institute, USA, and colleagues.
Prominent academics, including Salk's Thomas Albright, call for more science in forensic science
Six scientists who recently served on the National Commission on Forensic Science are calling on the scientific community at large to advocate for increased research and financial support of forensic science as well as the introduction of empirical testing requirements to ensure the validity of outcomes.
World Science Forum 2017 Jordan issues Science for Peace Declaration
On behalf of the coordinating organizations responsible for delivering the World Science Forum Jordan, the concluding Science for Peace Declaration issued at the Dead Sea represents a global call for action to science and society to build a future that promises greater equality, security and opportunity for all, and in which science plays an increasingly prominent role as an enabler of fair and sustainable development.
PETA science group promotes animal-free science at society of toxicology conference
The PETA International Science Consortium Ltd. is presenting two posters on animal-free methods for testing inhalation toxicity at the 56th annual Society of Toxicology (SOT) meeting March 12 to 16, 2017, in Baltimore, Maryland.
Citizen Science in the Digital Age: Rhetoric, Science and Public Engagement
James Wynn's timely investigation highlights scientific studies grounded in publicly gathered data and probes the rhetoric these studies employ.
Science/Science Careers' survey ranks top biotech, pharma, and biopharma employers
The Science and Science Careers' 2016 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.
Three natural science professors win TJ Park Science Fellowship
Professor Jung-Min Kee (Department of Chemistry, UNIST), Professor Kyudong Choi (Department of Mathematical Sciences, UNIST), and Professor Kwanpyo Kim (Department of Physics, UNIST) are the recipients of the Cheong-Am (TJ Park) Science Fellowship of the year 2016.
More Science News and Science Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.