Parasite evolution and impact in action: assessing the importance of hybrid schistosomes in Africa

In Africa there are two main species of human schistosome, Schistosoma haematobium and Schistosoma mansoni that give rise to urogenital schistosomiasis and intestinal schistosomiasis, respectively. Each schistosome species is a waterborne parasite firmly tied to certain species of freshwater gastropod snails. Infections with schistosomes can start very early in life and, depending on the transmission setting, exposure to these blood flukes is an unavoidable risk of daily life. In addition to these schistosome species, there are several others that infect a variety of wild and/or domesticated mammals. Species of the latter are significant scourges of livestock health and food security yet are not given sufficient veterinary attention. A recently appreciated feature of the reproductive biology of all schistosomes is their capacity for cross-specific interaction, which may, or may not, lead onto the formation of viable hybrids. These saltatory steps in evolution can be between either closely- or distantly-related forms. Heterosis, or hybrid vigour, is a peculiar feature to hybrid schistosomes that may raise their ability to cause disease or expand their range to areas where their parental species cannot. Effective methods used to control such hybrids needs a detailed One Health appraisal. As our understanding of schistosome hybridisation is incomplete, Professor Stothard will give an introductory overview of this scientific meeting’s objectives, a brief outline of critical knowledge gaps with a few considered pointers for subsequent general discussion and deliberation.

Professor J Russell Stothard

Liverpool School of Tropical Medicine

Professor J Russell Stothard

Liverpool School of Tropical Medicine

Professor Stothard is a medical parasitologist with focus on helminth and protist parasites grouped within the neglected tropical diseases. His specialist expertise is in the evolution, epidemiology and control of schistosomiasis having undertaken many multidisciplinary studies from schistosome characterisation to snail ecology. In so doing, he has advanced our understanding of natural transmission cycles of key species of schistosome and their freshwater intermediate snail hosts. Such knowledge typically underpins scientific guidance to better tailor future disease control strategies and specific intersectoral interventions. His research has been translated into several international policy changes, presenting, co-chairing and chairing several expert committees of the World Health Organisation.

If you would like to submit an abstract, please contact the Scientific Programmes team. 

The advancement in molecular methods allowed to study phenomena like hybridisation and introgression at a very detailed level. This resulted in the demonstration of hybridisation between schistosome species in the field, in diverse ecological settings and involving different species combinations. In this talk, Tine Huyse will present some of the first studies on the molecular detection of schistosome hybrids in Africa, and how they evolved over time. Both clinical studies and epidemiological field studies will be presented, with a final reflection on opportunities and challenges. 

Dr Tine Huyse

Royal Museum for Central Africa, Belgium

Dr Tine Huyse

Royal Museum for Central Africa, Belgium

Tine Huyse works at the Royal Museum for Central Africa as a senior biologist. She previously worked as a postdoctoral fellow at the University of Leuven, the Tropical Institute of Medicine in Antwerp, and the Natural History Museum in London. She is also the scientific commissioner of the zone Landscapes and Biodiversity in the permanent exhibition of the museum.

Her main research interests include the molecular epidemiology of neglected tropical diseases including schistosomiasis and fasciolosis, which affect millions of people and animals worldwide. She studies the anthropogenic and environmental impact on disease transmission and has a special interest in hybridisation between human and animal parasites. A One Health approach is therefore necessary. To this end, she developed new markers and molecular assays with her team to rapidly detect pathogen infections in blood, stool and intermediate snail host samples (xenomonitoring). Next-generation-sequencing technologies on field and museum samples are applied to increase the amount of genomic information in order to reconstruct parasite transmission dynamics. Also the impact of the snail microbiome and parasite co-infections on disease transmission is studied.

Finally, in order to tackle complex wicked problems like schistosomiasis, a citizen science approach has been set up, where local community members are involved both in snail monitoring and community-led awareness campaigns.

If you would like to submit and abstract, please contact the Scientific Programmes team. 

We have known that distinct Schistosoma species are capable of hybridisation since the 1950s, but it was not until 2009 and the discovery of hybrids between S. haematobium and S. bovis in humans that there were fears of zoonotic urogenital bilharziasis. Then, the interest in these hybrids has grown since their emergence in Europe in 2013. One major question is the zoonotic capacity of these hybrids. The various studies from the laboratory to the field are not consensual. The aim of this presentation will be to review the evidence for and against the zoonotic nature of urogenital bilharziasis. A number of avenues will also be explored to shed light on this issue.

Professor Jerome Boissier

Université de Perpignan, France

Professor Jerome Boissier

Université de Perpignan, France

Professor Jerome Boissier is interested in the ecology, evolution and transmission of mesenteric and urogenital schistosomiasis. For more than 10 years, he has been interested in the sexuality of these parasites, successively tackling themes linked to the sex-ratio bias, the pairing system and then sexual determinism. Today, his work focuses more on the field and on factors linked to transmission. On the pathogen side, Professor Boissier is interested in hybridisation phenomenon, particularly in the Haematobium group, through functional biology approaches and field surveys. On the host side, he is interested in the potential role of animals in transmission and the importance of the genetic background of patients in the development of severe forms of the disease.

If you would like to submit an abstract, please contact the Scientific Programmes team. 

Across Africa, human schistosomiasis is caused by four Schistosoma species (S. mansoni, S. haematobium, S. guineensis and S. intercalatum) coexisting alongside with several species associated with animals (eg S. bovis and S. curassoni). Three of these four human schistosome-species occur in Cameroon: S. haematobium and S. mansoni are widely distributed across the country, whereas S. guineensis has a very restricted distribution. Our studies on interactions between these schistosome species have revolutionised general understanding by demonstrating: the existence of a choice of mate in mixed infections, the mating competition between species, the competitive exclusion, the heterosis, and the introgressive hybridisation. The increasing reports of hybrids between human and animal schistosome species in several parts of Africa are very worrisome. These multispecies interactions and hybridisations have significant impacts on schistosome epidemiology, transmission and disease control, with several under-appreciated factors. Our current research on hybrid schistosomes will contribute to elucidate gaps in knowledge of interactions between human and animal schistosome species in Cameroon, especially within the S. haematobium group. Louis-Albert Tchuem Tchuenté will present some of our major findings and provide an overview of our ongoing SHIS-CAM research project on species hybridisation and interactions in schistosomes in Cameroon, within the context of One Health.

Louis-Albert Tchuem Tchuenté

University of Yaoundé I, Cameroon

Louis-Albert Tchuem Tchuenté

University of Yaoundé I, Cameroon

Louis-Albert Tchuem Tchuenté is Professor of Parasitology, founding Director of the research Centre for Schistosomiasis & Parasitology, and Coordinator of the National Programme for the Control of Schistosomiasis and Intestinal Helminthiasis. He has extensive expertise in the ecology, epidemiology, biology and control of Neglected Tropical Diseases, with focus on schistosomiasis and soil-transmitted helminthiasis. Through his scientific discoveries, he contributed to a better knowledge of the reproductive biology of schistosomes. His work was a significant step to elucidate the relationships of different schistosome species and to demonstrate the occurrence of mating competitions and their impact on the dynamics of natural transmission of schistosomiasis. He provided strategic direction and built high political commitments for the control of schistosomiasis, with significant achievements. He is a member of committees of several organisations, including the World Health Organisation. He received several awards and distinctions, including the dignity of Commander of the National Order of Valour of Cameroon.

If you would like to submit an abstract, please contact the Scientific Programmes team. 

Schistosomiasis remains a pressing public health concern in Malawi, compounded by the emergence of hybrid species between Schistosoma. haematobium (human-specific) and Schistosoma matthaei (animal specific). These hybrids, identified in recent studies under the Hybridization in Urogenital Schistosomiasis (HUGS) project, were confirmed in 7% of the communities in Mangochi and Nsanje districts. These hybrids exhibit atypical egg shedding patterns, complicating traditional diagnosis and treatment while raising concerns about potential drug resistance and increased morbidity, particularly among women experiencing Female Genital Schistosomiasis (FGS), highlighting the need for molecular diagnostic tools to accurately identify infections.

The zoonotic potential of hybrids broadens the transmission reservoir, incorporating livestock and intensifying risks in communities dependent on shared water sources for domestic and livelihood activities. This heightened human-animal interface complicates control efforts, particularly in endemic areas where water contact is unavoidable. This presentation delves into findings from the HUGS project, addressing the clinical and zoonotic challenges posed by hybrid schistosomes. It advocates for a One Health approach, integrating human and animal health sectors to enhance diagnostic capacity, develop tailored treatment protocols, and promote community awareness (and involvement in preventive and control) initiatives. These strategies are vital for mitigating the public health burden of hybrid schistosomiasis and advancing Malawi’s efforts toward sustainable disease control.

Professor Janelisa Musaya

Kamuzu University of Health Sciences, Malawi

Professor Janelisa Musaya

Kamuzu University of Health Sciences, Malawi

Janelisa Musaya is a Professor of Immuno-parasitology at the Kamuzu University of Health Sciences (KUHeS) and interim Deputy Director of the Malawi Liverpool Wellcome Research Programme (MLW). With over 19 years of experience in research, teaching, and mentorship, she specialises in neglected tropical diseases (NTDs), focusing on trypanosomiasis and schistosomiasis. Professor Musaya holds a PhD in Immunoparasitology from the University of Malawi, alongside master’s degrees in Epidemiology and Research Ethics. Her ground-breaking research has mapped tsetse fly distribution, identified genetic factors influencing trypanosomiasis outcomes, and uncovered hybrid schistosome species in Malawi. She leads a dynamic international research team, mentoring master’s and PhD students while collaborating with experts from over 15 countries. Passionate about community engagement, she develops innovative, locally relevant approaches to disease control, including improving mass drug administration campaigns. Her dedication to building research capacity and fostering equitable health policies continues to shape the fight against NTDs and improve health outcomes in Malawi

If you would like to submit an abstract, please contact the Scientific Programmes team. 

Genital schistosomiasis (GS) remains an ignored consequence of urogenital schistosomiasis in the genital system of men and women. However, this is not fully described in infections caused by hybrid schistosomes. Among the research studies conducted on GS, we described a Hybridisation of UroGenital Schistosomiasis (HUGS) longitudinal sub-study on male and female genital schistosomiasis (MGS and FGS) caused by hybrids, conducted in Southern Malawi.

Following demographic, health and socio-economic data collection, urine, cervicovaginal fluid, swabs and semen samples were collected and analysed to determine schistosome infection. Samples also underwent molecular analysis to detect human, zoonotic and hybrid schistosomes. Colposcopy and histopathology were also conducted while other associated infections (Human papilloma virus (HPV) and sexually transmitted infections (STIs) were also screened.

Dr Sekeleghe Kayuni

Malawi Liverpool Wellcome Clinical Research Programme, Malawi

Dr Sekeleghe Kayuni

Malawi Liverpool Wellcome Clinical Research Programme, Malawi

Seke is a medical doctor and parasitologist from Malawi who holds a Bachelor of Medicine, Bachelor of Surgery from University of Malawi, Diploma in Tropical Medicine and Hygiene from Royal College of Physicians in London, MSc in Tropical Medicine and International Health from University of London, and PhD in Tropical Medicine at University of Liverpool.

His expertise is in Tropical Medicine, especially neglected tropical diseases (NTDs). He has conducted several research studies on genital schistosomiasis (GS), a prevalent schistosomiasis complication in men and women in endemic areas; on community interventions for schistosomiasis and geohelminths management; and currently on a NIHR-Wellcome “Hybridization of urogenital schistosomiasis (HUGS) in Malawi”. 

He also has 20 years’ experience in clinical practice, leadership and management of large facilities in Malawi’s health facilities, treating over 2,000 patients monthly. He’s a Lecturer in Parasitology at Liverpool School of Tropical Medicine and London School of Hygiene and Tropical Medicine.

If you would like to submit an abstract, please contact the Scientific Programmes team. 

Urogenital schistosomiasis is a disease caused mainly by the human parasite, Schistosoma haematobium. The downstream manifestations of the disease, particularly pertaining to the genital track, can be disabling and often go unrecognised, as they are confounded by symptoms commonly related to sexually transmitted diseases. The sexual and reproductive life of the disease sufferers can be affected with an increase in infertility, ectopic pregnancies and abnormal pain and bleeding. An upsurge in advocacy efforts has increased the global interest and recognition of female and male genital schistosomiasis (FGS/MGS) as some of the most neglected genital disorders. Modern diagnostic approaches are refining burden of disease estimates and new questions are emerging on the potential impact of schistosome hybrids and animal species on disease manifestations and respond to treatment. Professor Bustinduy will give an introductory overview of both FGS/MGS and the different diagnostic and treatment strategies available with a special emphasis on gaps in knowledge and potential novel research approaches considering zoonotic species and hybrids.

Professor Amaya L Bustinduy

London School of Hygiene & Tropical Medicine

Professor Amaya L Bustinduy

London School of Hygiene & Tropical Medicine

Professor Bustinduy trained in paediatrics and infectious diseases in the US and started working on helminthic infections, and their impact on child health in Coastal Kenya in 2009. She is foremost a field clinical epidemiologist and has investigated a broad range of disease manifestations in children and young women related to neglected tropical parasitic diseases (NTD), namely schistosomiasis and giardiasis. Other work has included PK/PD driven drug trials (praziquantel) in preschool children in Uganda and PK modelling in pregnant women with schistosomiasis in the Philippines. She is interested in community-based diagnosis of female genital schistosomiasis, validating diagnostic tools at the point-of-care and its integrations with cervical cancer, STIs and HIV diagnosis and access to care. She heads the Schistosomiasis Clinical Research Group at the London School of Hygiene & Tropical Medicine and works as a paediatric infectious diseases’ consultant in the UK NHS. She leads on field related studies in Uganda, Malawi and Zambia. She is a member in several expert committees of the World Health Organisation.

If you would like to submit an abstract, please contact the Scientific Programmes team. 

Inter-species Schistosoma hybrids blur the lines between human and animal African schistosomiasis, creating worrying scenarios of animal reservoirs of human infections and the occurrence of zoonotic species, all of which could severely compromise schistosomiasis control efforts.

Molecular and genomic tools have been instrumental in uncovering the different hybrid forms in multiple geographical areas. However, gaps remain in our understanding of the evolutionary history of these hybrid forms, their impact on human and animal health and moreover what further research is needed to fully understand the extent of the permeability of the pre- and post-zygotic barriers that are either maintaining or dissolving species integrity.

This presentation will take a step back to look at the African Schistosoma species in terms of their taxonomic status, whilst discussing the opportunities they encounter to enable inter-species mixing / hybridisation, together with the potential outcomes. I will also discuss the biases we observe within the different Schistosoma hybridisation systems now identified in Africa, how best to interpret these so that we better understand what inter-species hybridisation may mean in terms of human schistosomiasis control and elimination in Africa.

Dr Bonnie Webster

Natural History Museum, UK

Dr Bonnie Webster

Natural History Museum, UK

Bonnie Webster is a parasitologist at the Natural History Museum in London, specialising in the study of schistosomiasis, a neglected tropical disease caused by Schistosoma flatworms. Her research combines molecular biology, epidemiology, and parasitology to inform and advance global schistosomiasis control strategies. She works both in the lab and in field settings across endemic regions to improve diagnostic tools and understand parasite transmission dynamics.

A significant focus of her work is on integrating genomic and molecular tools, such as qPCR and population genomics, to track genetic changes in Schistosoma populations and identify reservoirs of infection. By studying the biology and evolution of Schistosoma species and their snail hosts, she provides insights critical for improving control programs. Additionally, she collaborates with international partners, contribute to WHO expert committees, and support capacity-building efforts in low-resource settings to drive progress towards eliminating schistosomiasis globally.