Researchers from the Wellcome Sanger Institute, the University of Copenhagen and others report that they have performed the largest genomic analysis to date of whipworm Trichuris trichiura. Scientists say their study “Genomics of Ancient and Modern Populations Trichuris trichiura,” Posted in Nature Communicationprovides a global set of genetic data on which to base new methods of disease control.
Using genomic data to create a transmission map and ongoing analysis of the worm’s genetic makeup can help track factors such as drug resistance and predict how the parasite might continue to spread in the future. , helping to inform public health decisions, the scientists add.
Trichocephalosis is a neglected tropical disease estimated to affect up to 500 million people worldwide. It is caused by T.trichiura and is most commonly found in tropical and subtropical regions. However, parasite eggs found in fossilized remains have shown that the whipworm was once distributed worldwide, with evidence of this in Europe and other sites in North America where infections are rare.
Chronic parasitic infections can cause a range of debilitating gastrointestinal problems, nutritional deficiencies, and delays in physical and cognitive development, especially in children. The majority of these cases are treated with a group of drugs, which have varying levels of effectiveness, and there are few alternative treatments available.
The research generated whole genome DNA sequencing data from modern worms taken from human and primate hosts. These recent samples were obtained from several different regions, including countries in Africa, Central America, Asia, and Europe.
These were compared with ancient samples obtained from archaeological dig sites, the oldest of which date back a thousand years, mainly from Viking settlements in Denmark, as well as sites in the Netherlands and Lithuania. These samples are the oldest helminth samples from which whole genome sequencing data have been generated, and are suggested to be the oldest eukaryotic pathogens, providing unique insight into parasites of the human past.
Comparison of recent past and recent parasite data
Comparison of genetic data of past and recent parasites from around the world has shown how geographically distributed parasite populations are related and the likely influence of human migration in the global spread of modern parasites.
Data from researchers can be used to inform pest management strategies, with the broader goal of reducing the spread of disease. This data could also be used to help track parasite response to new and existing treatments, as resistance to current therapies is a barrier to current drugs that may be on the rise.
Through their analysis, the team provides further support that this worm is specific to humans, baboons and possibly other primates. Therefore, measures to try to stop the spread of T.trichiura will have to take this into account as only treating humans might miss the worms found in other primates in some areas.
“We describe the continent-wide genetic structure between whipworms infecting humans and baboons versus those infecting other primates,” the researchers write. “Demographic analyzes of admixtures and populations support a stepwise distribution of genetic variation that is highest in Uganda, consistent with an African origin and later translocation with human migration.
“Finally, genome-wide analyzes between human samples and between human and non-human primate samples reveal local regions of genetic differentiation between geographically distinct populations. These data provide insight into zoonotic reservoirs of infectious viruses for humans. T.trichiura and support future efforts towards implementing genomic epidemiology of this globally important helminth.
“Trichocephalosis can cause debilitating symptoms and have a huge impact on the development of children in areas where it is prevalent, which is why it is crucial that we find new ways to prevent infections and treat this disease,” said Martin Jensen Søe, PhD. , previously at the University of Copenhagen and co-first author of the study. “One of the main lessons from our research is that some primates can also carry the disease-causing parasite, so it is important to take this into account when planning measures to stop the spread of the disease. Trichuris trichiura.”