Press release

Allschwil, Switzerland, 19 June 2025

Researchers from the Swiss Tropical and Public Health Institute (Swiss TPH) and

partners have discovered a new parasitic worm species named Trichuris incognita in

Côte d’Ivoire during a Swiss TPH-led clinical trial. The discovery has significant

implications for drug development and diagnostics, as the species is visually

indistinguishable from known whipworms yet much less responsive to standard

treatment. The discovery is now formally recognised through the official handover of

preserved specimens to the Natural History Museum in Basel, in accordance with

international scientific naming protocols.

Whipworm infections affect approximately 500 million people worldwide, predominantly in

children in low- and middle-income countries. These infections, caused by the parasitic worm

Trichuris trichiura, can lead to significant health issues including abdominal pain, diarrhoea, and

anaemia. Until now, it was assumed that all human whipworm infections were due to this single

species.

However, researchers from the Swiss Tropical and Public Health Institute (Swiss TPH), in

collaboration with partners in Côte d'Ivoire and the University of Calgary, Canada, have

identified a previously unknown species infecting humans. This discovery was made during a

clinical trial in Côte d'Ivoire where standard treatments with albendazole and ivermectin showed

lower efficacy compared to results in Lao PDR and Tanzania.

As the species looks exactly the same as Trichuris trichiura under the microscope, researchers

first suspected drug resistance. Genome analysis then revealed that patients were infected with

a different until then unknown species. The new species was named Trichuris incognita by the

research team in reference to its ability to remain unnoticed until now.

Major implications for drug development

“This discovery has major implications for how we treat parasitic worm infections globally,” said

Jennifer Keiser, Head of the Helminth Drug Development unit at Swiss TPH and Professor of

Neglected Tropical Diseases at the University of Basel. “It is possible that patients in many

regions have been infected with Trichuris incognita, while our best available treatment – the

combination of albendazole and ivermectin – is not effective against it. The discovery further

underscores the urgent need for new therapies against these neglected tropical diseases.”

Keiser is hopeful that the new drug emodepside, which showed very promising results in recent

clinical trials, may prove effective against Trichuris Incognita. Further studies will be necessary

to confirm its efficacy. Swiss TPH is currently collaborating with Bayer to further develop

emodepside.

Unknown global distribution

The new species has been confirmed primarily in Côte d'Ivoire. Its global distribution remains

unknown, as comprehensive DNA sampling is still needed from other endemic regions. “For

Côte d'Ivoire, this discovery is crucial,” said Jean Coulibaly, researcher at the Centre Suisse de

Recherches Scientifiques en Côte d’Ivoire. “This finding could change how we control whipworm

infections across the country – and globally.”

Official hand-over to the Museum of Natural History Basel

Today, Swiss TPH officially handed over male and female specimens of Trichuris incognita,

preserved in ethanol, to the Museum of Natural History in Basel. This step is part of the formal

process required by the International Code of Zoological Nomenclature to register the species.

“We are proud to archive the name-bearing type of Trichuris incognita as an invaluable part of

our scientific collections,” said Christian Kropf, Head of Life Sciences at the Natural History

Museum Basel. “Our collections are curated at highest standards and are available for study to

all who are interested in exploring the diversity of life on our planet.”

Importance of next-generation sequencing

The breakthrough was made possible thanks to next-generation sequencing technologies,

which allowed researchers to construct the whole genome of the parasite. The discovery also

highlights the growing importance of next generation sequencing technologies in parasitology

and diagnostics, enabling scientists to detect hidden species that traditional methods like

microscopy fail to discover.

“It’s incredibly exciting to be part of this discovery,” said Max Bär, who proved the existence of

Trichuris incognita in his PhD thesis. “This worm may look just like other species from the same

genus under the microscope, but its genetic makeup is slightly different. And this tiny difference

has considerable implications for global health.”

Media contacts at Swiss TPH:

• Layla Hasler, Communications, Swiss TPH, communications@swisstph.ch, +41 61 284

83 49

• Jennifer Keiser, Head of the «Helminth Drug Development» unit, Swiss TPH,

jennifer.keiser@swisstph.ch, +41 61 284 82 18

Media contact at Natural History Museum Basel

• Katrin Huber, Public Relations, katrin.huber@bs.ch, +41 61 266 55 19

Swiss TPH – Excellence in Global Health

The Swiss Tropical and Public Health Institute (Swiss TPH) is a world-leading institute in global health with a particular

focus on low- and middle-income countries. Associated with the University of Basel, Swiss TPH combines research,

education and services at local, national and international level. Around 1,000 staff and students from 96 nations work

at Swiss TPH focusing on climate change, environment and health, infectious and non-communicable diseases, societal and cultural context and health systems and policies.

www.swisstph.ch