Recent studies have revealed that parasitic nematodes, which infect over a billion individuals worldwide, harbor viruses that might clarify the reasons some of these infections lead to severe diseases.
A research project from the Liverpool School of Tropical Medicine (LSTM) applied advanced bioinformatics techniques to identify 91 RNA viruses across 28 species of parasitic nematodes, covering 70% of those known to infect humans and animals. While many of these infections are either symptomless or mild, some can result in serious, life-altering conditions.
Nematode worms are the most numerous animals on Earth, found on every continent. Various species can infect humans as well as essential livestock and crops. Yet, in many instances, scientists are still unclear about how certain nematodes lead to specific diseases.
This new research, published in Nature Microbiology, paves the way for further exploration into whether these newly found viruses—only five of which were documented before—could be linked to numerous chronic and debilitating diseases. If such associations can be established, it might lead to the development of more effective treatments in the future.
Mark Taylor, a Professor of Parasitology at LSTM, expressed: “This discovery is incredibly promising and could reshape our understanding of the millions of infections triggered by parasitic nematodes. The presence of an RNA virus in any organism is noteworthy, as these viruses are recognized disease agents. When these worms residing in our bodies release these viruses, they disseminate through the bloodstream and tissues, triggering an immune reaction.”
“This prompts us to consider whether some diseases attributed to these parasites might actually be influenced by the virus rather than the nematode itself.”
Some parasitic nematodes, like hookworms and whipworms, can lead to intense abdominal pain, bloody diarrhea, stunted growth, and anemia. Infection with filarial worms can result in disfiguring conditions such as lymphoedema or “elephantiasis,” and onchocerciasis, also known as “river blindness,” which causes vision loss and skin ailments.
The researchers propose that the recently discovered viruses might be implicated in several of these health issues. For instance, Onchocerciasis-Associated Epilepsy (OAE), which affects children and teens in Sub-Saharan Africa, has recently been linked to onchocerciasis. However, the underlying reason for the neurological symptoms—such as uncontrollable head nodding, marked growth delays, and mental health challenges—remains unclear.
Among the viruses identified in the parasites responsible for onchocerciasis is a rhabdovirus, a type associated with rabies. The authors suggest that if this virus infects or damages human neurological tissues, it could explain the manifestations of OAE.
To fully understand the variety and implications of viruses residing in parasitic nematodes, further investigation is necessary, particularly regarding their effects on nematode biology and their potential role as disease drivers in both humans and animals.
The significant finding of these previously hidden widespread viruses originated with Dr. Shannon Quek, a Postdoctoral Research Associate at LSTM and the study’s lead author. She initially used similar data mining techniques to uncover viruses in mosquitoes that spread disease before shifting her focus to nematodes.
Dr. Quek, hailing from Indonesia—a nation significantly affected by parasitic nematodes—remarked: “As a child, I witnessed many individuals suffering from these diseases and dealt with dengue fever multiple times. This sparked my interest in tropical illnesses. Diseases caused by parasitic nematodes are often chronic and lifelong, profoundly affecting individuals’ quality of life, economic productivity, and mental well-being.”
“There is considerable research on the microbiomes of mosquitoes and how the bacteria within them can inhibit the transmission of viruses, potentially reducing vector-borne diseases like dengue. This interaction between organisms within the same host led me to ponder—what else resides within parasitic nematodes? Following my discovery, this will now become a primary focus of our research.”
