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Andrus PS, Stothard JR, Wade CM. Seasonal patterns of Schistosoma mansoni infection within Biomphalaria snails at the Ugandan shorelines of Lake Albert and Lake Victoria. PLoS Negl Trop Dis 2023; 17:e0011506. [PMID: 37578945 PMCID: PMC10424865 DOI: 10.1371/journal.pntd.0011506] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 07/06/2023] [Indexed: 08/16/2023] Open
Abstract
Intestinal schistosomiasis is hyperendemic in many sub-Saharan African countries. In Uganda, it is endemic at both Lake Albert (LA) and Lake Victoria (LV) and caused by S. mansoni that uses Biomphalaria snails as obligatory intermediate snail hosts. To shed light on local patterns of infection, we utilised two PCR-based methods to detect S. mansoni within Biomphalaria spp. as collected at the Ugandan shorelines of Lake Albert and Lake Victoria from 2009-2010. Overall, at our Lake Albert sites, the mean infection prevalence was 12.5% (15 of 120 snails), while at our Lake Victoria sites the prevalence was 5% (3 of 60 snails). At our Lake Albert sites, the highest infection prevalence of 13.3% (8 of 60 snails) was at Walukuba, while at our Lake Victoria sites, the highest infection prevalence of 10% (2 of 20 snails) was at Lwanika. Three species of Biomphalaria, B. pfeifferi, B. stanleyi and B. sudanica, were identified at our Lake Albert collection sites, while only a single species, B. choanomphala, was identified at our Lake Victoria collection sites. Biomphalaria stanleyi (2 of 20 snails; 15%) had the highest infection prevalence, followed by B. sudanica (5 of 60 snails; 13.3%), B. pfeifferi (4 of 40 snails; 10%) and B. choanomphala (3 of 60 snails; 5%). Of the Biomphalaria species identified, B. choanomphala had the highest haplotype (gene) diversity score, followed by B. stanleyi, B. sudanica and B. pfeifferi. Sites with a higher mean prevalence of S. mansoni infection had higher intra-species haplotype diversity scores than sites with a lower mean prevalence. The wet seasons (LA: 13.3%; LV: 8.7%) had a consistently higher mean infection prevalence of S. mansoni than the dry seasons (LA: 9.5%; LV: 5%) for all species and all sites tested at both Lake Albert (n = 480) and Lake Victoria (n = 320), though the difference was not statistically significant.
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Affiliation(s)
- Peter S. Andrus
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - J. Russell Stothard
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Christopher M. Wade
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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Miranda GS, Rodrigues JGM, Resende SD, Camelo GMA, Silva JKADO, Dos Santos JCR, Silva-Souza N, Pereira FB, Furtado LFV, Rabelo ÉML, Negrão-Corrêa D. From field to laboratory: isolation, genetic assessment, and parasitological behavior of Schistosoma mansoni obtained from naturally infected wild rodent Holochilus sciureus (Rodentia, Cricetidae), collected in Northeastern Brazil. Parasitol Res 2023; 122:395-411. [PMID: 36534238 DOI: 10.1007/s00436-022-07710-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 10/27/2022] [Indexed: 12/23/2022]
Abstract
Wild rodent species are naturally infected by Schistosoma mansoni; however, the genetic characterization of the parasite, its parasitological features, and its role in human schistosomiasis are poorly understood. In this study, we isolated and characterized Schistosoma from naturally infected Holochilus sciureus, called HS strain, collected from a schistosomiasis endemic region in Maranhão State, Brazil. To isolate the parasite, miracidia obtained from the livers of H. sciureus were used to infect Biomphalaria glabrata of sympatric (called SB) and allopatric (called BH) strains, and the produced cercariae were subcutaneously inoculated into hamsters and/or BALB/c mice. Parasitological kinetics in experimentally infected hosts were evaluated, and the tRNACys-12S (referred to as 16S herein) and cox 1 regions of mtDNA from isolated worms were amplified and sequenced. Only miracidia obtained from infected mice, but not from hamsters, were capable of infecting B. glabrata, allowing maintenance of the isolated parasite. Cox1 and 16S mtDNA sequences showed 100% similarity with S. mansoni, and phylogenetic analysis showed that the HS strain of S. mansoni forms an assemblage with isolates from America and Kenya, confirming the conspecificity. Experimental infection of B. glabrata SB with S. mansoni HS resulted in two peaks of cercariae shedding at 45 and 70 days post-infection (dpi) and caused higher mortality than in B. glabrata BH. The worm recovery rate in mice was approximately 13%, and the peak of egg elimination occurred at the 10th week post-infection. Therefore, S. mansoni obtained from H. sciureus was successfully isolated, genetically characterized, and maintained in mice, allowing further study of this schistosome strain.
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Affiliation(s)
- Guilherme Silva Miranda
- Department of Parasitology, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG, CEP: 31.270-010, Brazil
- Department of Biology, Federal Institute of Education, Science and Technology of Maranhão, São Raimundo das Mangabeiras, Brazil
| | - João Gustavo Mendes Rodrigues
- Department of Parasitology, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG, CEP: 31.270-010, Brazil
| | - Samira Diniz Resende
- Department of Parasitology, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG, CEP: 31.270-010, Brazil
| | - Genil Mororó Araújo Camelo
- Department of Parasitology, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG, CEP: 31.270-010, Brazil
| | | | - Jose Carlos Reis Dos Santos
- Department of Parasitology, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG, CEP: 31.270-010, Brazil
| | - Nêuton Silva-Souza
- Department of Chemistry and Biology, State University of Maranhão, São Luís, Brazil
| | - Felipe Bisaggio Pereira
- Department of Parasitology, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG, CEP: 31.270-010, Brazil
| | - Luis Fernando Viana Furtado
- Department of Clinical and Toxicological Analysis, Federal University of Minas Gerais, Av. Antonio Carlos 6627, Campus Pampulha, MG, Belo Horizonte, Brazil
| | - Élida Mara Leite Rabelo
- Department of Parasitology, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG, CEP: 31.270-010, Brazil
| | - Deborah Negrão-Corrêa
- Department of Parasitology, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG, CEP: 31.270-010, Brazil.
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3
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Mulindwa J, Namulondo J, Kitibwa A, Nassuuna J, Nyangiri OA, Kimuda MP, Boobo A, Nerima B, Busingye F, Candia R, Namukuta A, Ssenyonga R, Ukumu N, Ajal P, Adriko M, Noyes H, de Dood CJ, Corstjens PLAM, van Dam GJ, Elliott AM, Matovu E. High prevalence of Schistosoma mansoni infection and stunting among school age children in communities along the Albert-Nile, Northern Uganda: A cross sectional study. PLoS Negl Trop Dis 2022; 16:e0010570. [PMID: 35895705 PMCID: PMC9359559 DOI: 10.1371/journal.pntd.0010570] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/08/2022] [Accepted: 06/08/2022] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Knowing the prevalence of schistosomiasis is key to informing programmes to control and eliminate the disease as a public health problem. It is also important to understand the impact of infection on child growth and development in order to allocate appropriate resources and effort to the control of the disease. METHODS We conducted a survey to estimate the prevalence of schistosomiasis among school aged children in villages along the Albert-Nile shore line in the district of Pakwach, North Western Uganda. A total of 914 children aged between 10-15 years were screened for Schistosoma mansoni using the POC-CCA and Kato Katz (KK) techniques. The infection intensities were assessed by POC-CCA and KK as well as CAA tests. The KK intensities were also correlated with POC-CCA and with CAA intensity. Anthropometric measurements were also taken and multivariate analysis was carried out to investigate their association with infection status. RESULTS The prevalence of schistosomiasis using the POC-CCA diagnostic test was estimated at 85% (95% CI: 83-87), being highest amongst children living closer to the Albert-Nile shoreline. Visual scoring of the POC-CCA results was more sensitive than the Kato Katz test and was positively correlated with the quantified infection intensities by the CAA test. The majority of the children were underweight (BMI<18.5), and most notably, boys had significantly lower height for age (stunting) than girls in the same age range (p < 0.0001), but this was not directly associated with S. mansoni infection. CONCLUSION High prevalence of S. mansoni infection in the region calls for more frequent mass drug administration with praziquantel. We observed high levels of stunting which was not associated with schistosomiasis. There is a need for improved nutrition among the children in the area.
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Affiliation(s)
- Julius Mulindwa
- Department of Biochemistry and Sports Sciences, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Joyce Namulondo
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Anna Kitibwa
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Jacent Nassuuna
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Oscar Asanya Nyangiri
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Magambo Phillip Kimuda
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Alex Boobo
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Barbara Nerima
- Department of Biochemistry and Sports Sciences, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Fred Busingye
- Vector Borne & NTD Control Division, Ministry of Health, Kampala, Uganda
| | - Rowel Candia
- Vector Borne & NTD Control Division, Ministry of Health, Kampala, Uganda
| | - Annet Namukuta
- Vector Borne & NTD Control Division, Ministry of Health, Kampala, Uganda
| | - Ronald Ssenyonga
- Department of Epidemiology and Biostatistics, School of Public Health, Makerere University, Kampala, Uganda
| | - Noah Ukumu
- Pakwach District Local Government, District Health Office, Pakwach, Uganda
| | - Paul Ajal
- Pakwach District Local Government, District Health Office, Pakwach, Uganda
| | - Moses Adriko
- Vector Borne & NTD Control Division, Ministry of Health, Kampala, Uganda
| | - Harry Noyes
- Centre for Genomic Research, University of Liverpool, Liverpool, United Kingdom
| | - Claudia J. de Dood
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Paul L. A. M. Corstjens
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Govert J. van Dam
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | - Alison M. Elliott
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Enock Matovu
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
- * E-mail:
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Mutuku MW, Laidemitt MR, Spaan JM, Mwangi IN, Ochanda H, Steinauer ML, Loker ES, Mkoji GM. Comparative Vectorial Competence of Biomphalaria sudanica and Biomphalaria choanomphala, Snail Hosts of Schistosoma mansoni, From Transmission Hotspots In Lake Victoria, Western Kenya. J Parasitol 2021; 107:349-357. [PMID: 33906231 DOI: 10.1645/20-138] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Schistosoma mansoni, which causes human intestinal schistosomiasis, continues to be a major public health concern in the Lake Victoria basin in western Kenya, with Biomphalaria sudanica (a shoreline inhabiting snail) and Biomphalaria choanomphala (a deep-water snail) playing roles in transmission. A recent study showed that B. sudanica was abundantly present near all study villages on the lakeshore, but B. choanomphala was significantly more abundant near villages known to be persistent transmission hotspots. The present study investigated the relative compatibility of B. sudanica and B. choanomphala with S. mansoni. A reciprocal cross-infection experiment used young adult F1 generation B. sudanica and B. choanomphala that were exposed to either 1, 5, or 10 sympatric or allopatric human-derived S. mansoni miracidia. Three weeks post-exposure (PE) and weekly thereafter, the snails were counted and screened for schistosome cercariae, and at 7 wk PE, total cercariae shed during a 2 hr period by each infected snail was determined. Pre-patent periods for S. mansoni in both B. sudanica and B. choanomphala were similar, and most snails in all exposure combinations started shedding cercariae 5 wk PE. Prevalences were significantly higher in B. choanomphala (12.2-80.9%) than in B. sudanica (5.2-18.6%) at each dose, regardless of whether miracidia were of an allopatric or a sympatric source (P < 0.0001). Overall, the odds of a snail becoming infected with 5 or 10 miracidia were significantly higher than the odds of being infected with 1 miracidium, (P < 0.0001), and fewer cercariae were produced by snails exposed to single as compared to 5 or 10 miracidia. On average, B. choanomphala produced more cercariae ( = 458, SD = 414) than B. sudanica ( = 238, SD = 208) (P < 0.0001). These results suggest that B. choanomphala is more compatible with S. mansoni than B. sudanica. Though B. choanomphala can be found in shallow shoreline waters, it is, for the most part, a deeper-water taxon. Because dredging is a relatively inefficient means of sampling, B. choanomphala is likely underestimated with respect to its population size, the number of S. mansoni-positive snails, and its role in maintaining transmission.
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Affiliation(s)
- Martin W Mutuku
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya.,School of Biological Sciences, College of Biological and Physical Sciences, University of Nairobi, Nairobi, Kenya
| | - Martina R Laidemitt
- Center for Evolutionary and Theoretical Immunology, Parasitology Division, Museum of Southwestern Biology, Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Johannie M Spaan
- Department of Basic Medical Sciences, Western University of Health Sciences, Lebanon, Oregon 97355
| | - Ibrahim N Mwangi
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Horace Ochanda
- School of Biological Sciences, College of Biological and Physical Sciences, University of Nairobi, Nairobi, Kenya
| | - Michelle L Steinauer
- Department of Basic Medical Sciences, Western University of Health Sciences, Lebanon, Oregon 97355
| | - Eric S Loker
- Center for Evolutionary and Theoretical Immunology, Parasitology Division, Museum of Southwestern Biology, Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131
| | - Gerald M Mkoji
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
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5
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Habib MR, Lv S, Rollinson D, Zhou XN. Invasion and Dispersal of Biomphalaria Species: Increased Vigilance Needed to Prevent the Introduction and Spread of Schistosomiasis. Front Med (Lausanne) 2021; 8:614797. [PMID: 33644096 PMCID: PMC7902764 DOI: 10.3389/fmed.2021.614797] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 01/06/2021] [Indexed: 11/13/2022] Open
Abstract
Biological invasion is a matter of great concern from both public health and biodiversity perspectives. Some invasive snail species may trigger disease emergence by acting as intermediate hosts. The geographic distribution of Schistosoma mansoni depends on the presence of susceptible species of Biomphalaria freshwater snails that support the parasite's transformation into infective stages. Biomphalaria spp. have shown strong local and global dispersal capacities that may increase due to the global warming phenomenon and increases in the development of agricultural and water projects. Should intermediate hosts become established in new areas then this will create potential transmission foci. Examples of snail invasions that have had an impact on schistosomiasis transmission include the introduction of Biomphalaria tenagophila to Congo and B. glabrata to Egypt. The current spread of B. straminea in China is causing concern and needs to be monitored closely. An understanding of the mode of invasion and distribution of these snails as well as their experimental susceptibility to S. mansoni will predict the potential spread of schistosomiasis. Here we review the invasion patterns of Biomphalaria snails and factors that control their distribution and the impact that invasion may have on intestinal schistosomiasis transmission. In addition, we propose some possible surveillance responses for optimum control strategies and interventions. Whenever possible, swift action should be taken to contain any new occurrence of these intermediate snail hosts.
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Affiliation(s)
- Mohamed R. Habib
- Medical Malacology Laboratory, Theodor Bilharz Research Institute, Giza, Egypt
- National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention, Shanghai, China
- Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China
| | - Shan Lv
- National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention, Shanghai, China
- Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China
- National Center for International Research on Tropical Diseases, Shanghai, China
- WHO Collaborating Center on Tropical Diseases, Shanghai, China
- School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - David Rollinson
- Department of Life Sciences, Natural History Museum, London, United Kingdom
| | - Xiao-Nong Zhou
- National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention, Shanghai, China
- Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China
- National Center for International Research on Tropical Diseases, Shanghai, China
- WHO Collaborating Center on Tropical Diseases, Shanghai, China
- School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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6
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Outa JO, Sattmann H, Köhsler M, Walochnik J, Jirsa F. Diversity of digenean trematode larvae in snails from Lake Victoria, Kenya: First reports and bioindicative aspects. Acta Trop 2020; 206:105437. [PMID: 32151590 DOI: 10.1016/j.actatropica.2020.105437] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/24/2020] [Accepted: 03/05/2020] [Indexed: 10/24/2022]
Abstract
This study investigated the occurrence of digenean trematode larvae in snails from the Kenyan part of Lake Victoria. The survey included caenogastropod snails that have received less focus in parasitological studies in Africa: their trematodes are largely unknown. Out of 1145 snail specimens, 149 (13.0%) were infected with Digenea. The highest prevalence (P) was recorded in Melanoides tuberculata (64.5%), followed by Pila ovata (15.4%), Radix natalensis (9.5%), Bulinus ugandae (9.1%), Bellamya unicolor (8.9%), Biomphalaria pfeifferi (7.3%) and Biomphalaria sudanica (4.4%). Morphological and molecular analyses revealed 17 digenean species. Contrary to reports of low diversity of Digenea in caenogastropods, P. ovata harboured 8 species - at least twice as many as in each of the pulmonates. The following taxa are reported for the first time in the Lake Victoria region: Haplorchis pumilio, Thapariella prudhoei, Nudacotyle sp., Renicola sp. and Bolbophorus sp. An unknown cercaria belonging to the genus Haematoloechus is reported from P. ovata: a xiphidiocercaria possessing a long sword-shaped stylet (47-71 µm) which does not match any available literature records. From this study, H. pumilio from M. tuberculata (P = 69.4%), Fasciola gigantica from R. natalensis (P = 1.9%) and Bolbophorus sp. from Bu. ugandae (P = 4.6%) are species of veterinary or medical importance. Snails from the study site with little direct anthropogenic influence had the highest prevalence and diversity of digenean larvae, indicating that environmental conditions influence trematode occurrence.
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7
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Koopman JP, Egesa M, Wajja A, Adriko M, Nassuuna J, Nkurunungi G, Driciru E, van Willigen G, Cose S, Yazdanbakhsh M, Kaleebu P, Kabatereine N, Tukahebwa E, Roestenberg M, Elliott AM. Risk assessment for the implementation of controlled human Schistosoma mansoni infection trials in Uganda. AAS Open Res 2020; 2:17. [PMID: 31819922 PMCID: PMC6901351 DOI: 10.12688/aasopenres.12972.2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/06/2019] [Indexed: 11/20/2022] Open
Abstract
Schistosomiasis is a parasitic infection highly prevalent in sub-Saharan Africa, and a significant cause of morbidity; it is a priority for vaccine development. A controlled human infection model for
Schistosoma mansoni (CHI-S) with potential to accelerate vaccine development has been developed among naïve volunteers in the Netherlands. Because responses both to infections and candidate vaccines are likely to differ between endemic and non-endemic settings, we propose to establish a CHI-S in Uganda where
Schistosoma mansoni is endemic. As part of a “road-map” to this goal, we have undertaken a risk assessment. We identified risks related to importing of laboratory vector snails and schistosome strains from the Netherlands to Uganda; exposure to natural infection in endemic settings concurrently with CHI-S studies, and unfamiliarity of the community with the nature, risks and rationale for CHI. Mitigating strategies are proposed. With careful implementation of the latter, we believe that CHI-S can be implemented safely in Uganda. Our reflections are presented here to promote feedback and discussion.
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Affiliation(s)
- Jan Pieter Koopman
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Moses Egesa
- Uganda Virus Research Institute, Entebbe, Uganda
| | - Anne Wajja
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Moses Adriko
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda
| | - Jacent Nassuuna
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Gyaviira Nkurunungi
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Emmanuella Driciru
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Gijsbert van Willigen
- Department of Health, Safety and the Environment, Leiden University Medical Center, Leiden, The Netherlands
| | - Stephen Cose
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda.,Clinical Research Department, London School of Hygiene & Tropical Medicine, London, UK
| | - Maria Yazdanbakhsh
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Pontiano Kaleebu
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | | | - Edridah Tukahebwa
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda
| | - Meta Roestenberg
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Alison M Elliott
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda.,Clinical Research Department, London School of Hygiene & Tropical Medicine, London, UK
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8
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Fuss A, Mazigo HD, Mueller A. Malacological survey to identify transmission sites for intestinal schistosomiasis on Ijinga Island, Mwanza, north-western Tanzania. Acta Trop 2020; 203:105289. [PMID: 31837312 DOI: 10.1016/j.actatropica.2019.105289] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 11/28/2019] [Accepted: 12/03/2019] [Indexed: 12/18/2022]
Abstract
The role of malacological surveys to identify potential transmission sites for schistosomiasis control in this era of mass drug administration have received little attention. In that context, the present study was conducted to determine the abundance, identity and disease transmission potential of intermediate host snails for intestinal schistosomiasis on Ijinga Island, north-western Tanzania. A cross-sectional malacological study was conducted between February and March 2016 on Ijinga Island, Lake Victoria, north-western Tanzania. Snails were collected at points where humans are in frequent contact with water using a standardized scooping technique and have been identified using shell morphological features. The Schistosoma infection status of the collected snails was determined by using real-time Polymerase Chain Reaction (real-time PCR). A total number of 4,888 snails were putatively identified as Biomphalaria species. A random sample of 788 snails underwent molecular analyses for Schistosoma infection. Overall, 279 (35.4%) of Biomphalaria species were identified to be infected with parasites of the lateral spined S. mansoni group. The findings confirm that Biomphalaria species collected in areas with high human water contacts are infected with Schistosoma and that there is a likeliness of local risk for schistosomiasis transmission at most water contact points around Ijinga Island.
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Mutuku MW, Laidemitt MR, Beechler BR, Mwangi IN, Otiato FO, Agola EL, Ochanda H, Kamel B, Mkoji GM, Steinauer ML, Loker ES. A Search for Snail-Related Answers to Explain Differences in Response of Schistosoma mansoni to Praziquantel Treatment among Responding and Persistent Hotspot Villages along the Kenyan Shore of Lake Victoria. Am J Trop Med Hyg 2020; 101:65-77. [PMID: 31162012 PMCID: PMC6609173 DOI: 10.4269/ajtmh.19-0089] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Following a 4-year annual praziquantel (PZQ) treatment campaign, the resulting prevalence of Schistosoma mansoni was seen to differ among individual villages along the Kenyan shore of Lake Victoria. We have investigated possible inherent differences in snail-related aspects of transmission among such 10 villages, including six persistent hotspot (PHS) villages (≤ 30% reduction in prevalence following repeated treatments) located along the west-facing shore of the lake and four PZQ-responding (RESP) villages (> 30% prevalence reduction following repeated treatment) along the Winam Gulf. When taking into account all sampling sites, times, and water hyacinth presence/absence, shoreline-associated Biomphalaria sudanica from PHS and RESP villages did not differ in relative abundance or prevalence of S. mansoni infection. Water hyacinth intrusions were associated with increased B. sudanica abundance. The deeper water snail Biomphalaria choanomphala was significantly more abundant in the PHS villages, and prevalence of S. mansoni among villages both before and after control was positively correlated with B. choanomphala abundance. Worm recoveries from sentinel mice did not differ between PHS and RESP villages, and abundance of non-schistosome trematode species was not associated with S. mansoni abundance. Biomphalaria choanomphala provides an alternative, deepwater mode of transmission that may favor greater persistence of S. mansoni in PHS villages. As we found evidence for ongoing S. mansoni transmission in all 10 villages, we conclude that conditions conducive for transmission and reinfection occur ubiquitously. This argues for an integrated, basin-wide plan for schistosomiasis control to counteract rapid reinfections facilitated by large snail populations and movements of infected people around the lake.
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Affiliation(s)
- Martin W Mutuku
- School of Biological Sciences, College of Biological and Physical Sciences, University of Nairobi, Nairobi, Kenya.,Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Martina R Laidemitt
- Department of Biology, Center for Evolutionary and Theoretical Immunology, Museum of Southwestern Biology, Parasitology Division, University of New Mexico, Albuquerque, New Mexico
| | - Brianna R Beechler
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon
| | - Ibrahim N Mwangi
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Fredrick O Otiato
- Influenza Surveillance Program, Centers for Disease Control and Prevention, Nairobi, Kenya
| | - Eric L Agola
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Horace Ochanda
- School of Biological Sciences, College of Biological and Physical Sciences, University of Nairobi, Nairobi, Kenya
| | - Bishoy Kamel
- Department of Biology, Center for Evolutionary and Theoretical Immunology, Museum of Southwestern Biology, Parasitology Division, University of New Mexico, Albuquerque, New Mexico
| | - Gerald M Mkoji
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Michelle L Steinauer
- Department of Basic Medical Sciences, Western University of Health Sciences, Lebanon, Oregon
| | - Eric S Loker
- Department of Biology, Center for Evolutionary and Theoretical Immunology, Museum of Southwestern Biology, Parasitology Division, University of New Mexico, Albuquerque, New Mexico
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10
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Koopman JP, Egesa M, Wajja A, Adriko M, Nassuuna J, Nkurunungi G, Driciru E, van Willigen G, Cose S, Yazdanbakhsh M, Kaleebu P, Kabatereine N, Tukahebwa E, Roestenberg M, Elliott AM. Risk assessment for the implementation of controlled human Schistosoma mansoni infection trials in Uganda. AAS Open Res 2019; 2:17. [PMID: 31819922 PMCID: PMC6901351 DOI: 10.12688/aasopenres.12972.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/06/2019] [Indexed: 08/05/2023] Open
Abstract
Schistosomiasis is a parasitic infection highly prevalent in sub-Saharan Africa, and a significant cause of morbidity; it is a priority for vaccine development. A controlled human infection model for Schistosoma mansoni (CHI-S) with potential to accelerate vaccine development has been developed among naïve volunteers in the Netherlands. Because responses both to infections and candidate vaccines are likely to differ between endemic and non-endemic settings, we propose to establish a CHI-S in Uganda where Schistosoma mansoni is endemic. As part of a "road-map" to this goal, we have undertaken a risk assessment. We identified risks related to importing of laboratory vector snails and schistosome strains from the Netherlands to Uganda; exposure to natural infection in endemic settings concurrently with CHI-S studies, and unfamiliarity of the community with the nature, risks and rationale for CHI. Mitigating strategies are proposed. With careful implementation of the latter, we believe that CHI-S can be implemented safely in Uganda. Our reflections are presented here to promote feedback and discussion.
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Affiliation(s)
- Jan Pieter Koopman
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Moses Egesa
- Uganda Virus Research Institute, Entebbe, Uganda
| | - Anne Wajja
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Moses Adriko
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda
| | - Jacent Nassuuna
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Gyaviira Nkurunungi
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Emmanuella Driciru
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Gijsbert van Willigen
- Department of Health, Safety and the Environment, Leiden University Medical Center, Leiden, The Netherlands
| | - Stephen Cose
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, UK
| | - Maria Yazdanbakhsh
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Pontiano Kaleebu
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | | | - Edridah Tukahebwa
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda
| | - Meta Roestenberg
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Alison M. Elliott
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, UK
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11
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Adriko M, Tinkitina B, Tukahebw EM, Standley CJ, Stothard JR, Kabatereine NB. The epidemiology of schistosomiasis in Lango region Uganda 60 years after Schwetz 1951: Can schistosomiasis be eliminated through mass drug administration without other supportive control measures? Acta Trop 2018; 185:412-418. [PMID: 29935144 DOI: 10.1016/j.actatropica.2018.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 05/31/2018] [Accepted: 06/11/2018] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Lango region is the only known endemic region for urinary and intestinal schistosomiasis in Uganda. Although there has been no significant improvement in sanitation and safe water supply in the region over years, the endemicity and prevalence of Schistosoma haematobium, in particular, have declined, perhaps due to yearly mass treatment campaigns implemented since 2003. METHODS We report the epidemiology of Urinary and Intestinal schistosomiasis in Lango since 1951-2011 determined through Microscopic examinations for S. mansoni and S. haematobium respectively. A retrospective data review from 195 to 2011 was done to establish the prevalence over the years in the region. We performed Poisson regression analysis to observe trends in epidemiology before and after control was initiated in 2002. In addition, malacological surveys were undertaken in 2007 to assess local transmission potential. FINDINGS Contrary to earlier records, S. haematobium was low and confined to a few putative foci, with declined in infections from 28.2% in 1951 to 2.48% by 2011. Although this decline can be attributed to control, this was already much lower in 1967 than 1951, long before control interventions began suggesting that environmental changes may have made the habitat less suitable for the transmission of S. haematobium. Compared to the historical records S. mansoni prevalence first increased up immediately before control interventions in 2003, significantly declined (p=<0.001) until 2007. However, in 2007 and 2011 declined insignificant, (p = 0.656). No snail has ever been isolated shedding S. haematobium cercariae but many Bulinus snail spp. were found shedding S. bovis cercariae. CONCLUSION This suggests that a combination of environmental and mass treatment has had a significant impact on transmission in Lango region.
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Affiliation(s)
- M Adriko
- Vector Control Division, Ministry of Health, P.O. Box 1661, Plot 15 Bombo Road, Kampala, Uganda; Uganda Institute of Allied Health & Management Science (UIAHMS), School of Medical Entomology and Parasitology, P.O. Box 1661, Kampala, Uganda.
| | - B Tinkitina
- Vector Control Division, Ministry of Health, P.O. Box 1661, Plot 15 Bombo Road, Kampala, Uganda
| | - E M Tukahebw
- Vector Control Division, Ministry of Health, P.O. Box 1661, Plot 15 Bombo Road, Kampala, Uganda
| | - C J Standley
- Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - J R Stothard
- Parasitology Department, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - N B Kabatereine
- Uganda Institute of Allied Health & Management Science (UIAHMS), School of Medical Entomology and Parasitology, P.O. Box 1661, Kampala, Uganda; Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
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12
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Elliott AM, Roestenberg M, Wajja A, Opio C, Angumya F, Adriko M, Egesa M, Gitome S, Mfutso-Bengo J, Bejon P, Kapulu M, Seager Z, Lutalo T, Nazziwa WB, Muwumuza A, Yazdanbakhsh M, Kaleebu P, Kabatereine N, Tukahebwa E. Ethical and scientific considerations on the establishment of a controlled human infection model for schistosomiasis in Uganda: report of a stakeholders' meeting held in Entebbe, Uganda. AAS Open Res 2018; 1:2. [PMID: 30714021 PMCID: PMC6358001 DOI: 10.12688/aasopenres.12841.2] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2018] [Indexed: 02/02/2023] Open
Abstract
Controlled human infection (CHI) models are gaining recognition as an approach to accelerating vaccine development, for use in both non-endemic and endemic populations: they can facilitate identification of the most promising candidate vaccines for further trials and advance understanding of protective immunity. Helminths present a continuing health burden in sub-Saharan Africa. Vaccine development for these complex organisms is particularly challenging, partly because protective responses are akin to mechanisms of allergy. A CHI model for Schistosoma mansoni (CHI-S) has been developed at Leiden University Medical Centre, the Netherlands. However, responses to schistosome infections, and candidate vaccines, are likely to be different among people from endemic settings compared to schistosome-naïve Dutch volunteers. Furthermore, among volunteers from endemic regions who have acquired immune responses through prior exposure, schistosome challenge can be used to define responses associated with clinical protection, and thus to guide vaccine development. To explore the possibility of establishing the CHI-S in Uganda, a Stakeholders' Meeting was held in Entebbe in 2017. Regulators, community members, researchers and policy-makers discussed implementation challenges and recommended preparatory steps: risk assessment; development of infrastructure and technical capacity to produce the infectious challenge material in Uganda; community engagement from Parliamentary to grass-roots level; pilot studies to establish approaches to assuring fully informed consent and true voluntariness, and strategies for selection of volunteers who can avoid natural infection during the 12-week CHI-S; the building of regulatory capacity; and the development of study protocols and a product dossier in close consultation with ethical and regulatory partners. It was recommended that, on completion, the protocol and product dossier be reviewed for approval in a joint meeting combining ethical, regulatory and environment management authorities. Most importantly, representatives of schistosomiasis-affected communities emphasised the urgent need for an effective vaccine and urged the research community not to delay in the development process.
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Affiliation(s)
- Alison M. Elliott
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, Entebbe, P.O. Box 49, Uganda,
| | - Meta Roestenberg
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Anne Wajja
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, Entebbe, P.O. Box 49, Uganda
| | - Christopher Opio
- Department of Medicine, College of Health Sciences, Makerere University, Kampala, P.O. Box 7072, Uganda
| | - Francis Angumya
- Department of Medicine, College of Health Sciences, Makerere University, Kampala, P.O. Box 7072, Uganda
| | - Moses Adriko
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda
| | - Moses Egesa
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, Entebbe, P.O. Box 49, Uganda,Department of Medical Microbiology, School of Biomedical Sciences, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Serah Gitome
- Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
| | - Joseph Mfutso-Bengo
- Centre for Bioethics for Eastern and Southern Africa, School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Tom Lutalo
- Uganda Virus Research Institute, Entebbe, Uganda
| | | | | | - Maria Yazdanbakhsh
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Pontiano Kaleebu
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, Entebbe, P.O. Box 49, Uganda,Uganda Virus Research Institute, Entebbe, Uganda
| | - Narcis Kabatereine
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda,Schistosomiasis Control Initiative, Faculty of Medicine, School of Public Health, Imperial College London, London, UK
| | - Edridah Tukahebwa
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda
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13
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Elliott AM, Roestenberg M, Wajja A, Opio C, Angumya F, Adriko M, Egesa M, Gitome S, Mfutso-Bengo J, Bejon P, Kapulu M, Seager Z, Lutalo T, Nazziwa WB, Muwumuza A, Yazdanbakhsh M, Kaleebu P, Kabatereine N, Tukahebwa E. Ethical and scientific considerations on the establishment of a controlled human infection model for schistosomiasis in Uganda: report of a stakeholders' meeting held in Entebbe, Uganda. AAS Open Res 2018; 1:2. [PMID: 30714021 PMCID: PMC6358001 DOI: 10.12688/aasopenres.12841.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Controlled human infection (CHI) models are gaining recognition as an approach to accelerating vaccine development, for use in both non-endemic and endemic populations: they can facilitate identification of the most promising candidate vaccines for further trials and advance understanding of protective immunity. Helminths present a continuing health burden in sub-Saharan Africa. Vaccine development for these complex organisms is particularly challenging, partly because protective responses are akin to mechanisms of allergy. A CHI model for Schistosoma mansoni (CHI-S) has been developed at Leiden University Medical Centre, the Netherlands. However, responses to schistosome infections, and candidate vaccines, are likely to be different among people from endemic settings compared to schistosome-naïve Dutch volunteers. Furthermore, among volunteers from endemic regions who have acquired immune responses through prior exposure, schistosome challenge can be used to define responses associated with clinical protection, and thus to guide vaccine development. To explore the possibility of establishing the CHI-S in Uganda, a Stakeholders' Meeting was held in Entebbe in 2017. Regulators, community members, researchers and policy-makers discussed implementation challenges and recommended preparatory steps: risk assessment; development of infrastructure and technical capacity to produce the infectious challenge material in Uganda; community engagement from Parliamentary to grass-roots level; pilot studies to establish approaches to assuring fully informed consent and true voluntariness, and strategies for selection of volunteers who can avoid natural infection during the 12-week CHI-S; the building of regulatory capacity; and the development of study protocols and a product dossier in close consultation with ethical and regulatory partners. It was recommended that, on completion, the protocol and product dossier be reviewed for approval in a joint meeting combining ethical, regulatory and environment management authorities. Most importantly, representatives of schistosomiasis-affected communities emphasised the urgent need for an effective vaccine and urged the research community not to delay in the development process.
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Affiliation(s)
- Alison M. Elliott
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, Entebbe, P.O. Box 49, Uganda,
| | - Meta Roestenberg
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Anne Wajja
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, Entebbe, P.O. Box 49, Uganda
| | - Christopher Opio
- Department of Medicine, College of Health Sciences, Makerere University, Kampala, P.O. Box 7072, Uganda
| | - Francis Angumya
- Department of Medicine, College of Health Sciences, Makerere University, Kampala, P.O. Box 7072, Uganda
| | - Moses Adriko
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda
| | - Moses Egesa
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, Entebbe, P.O. Box 49, Uganda,Department of Medical Microbiology, School of Biomedical Sciences, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Serah Gitome
- Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
| | - Joseph Mfutso-Bengo
- Centre for Bioethics for Eastern and Southern Africa, School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Tom Lutalo
- Uganda Virus Research Institute, Entebbe, Uganda
| | | | | | - Maria Yazdanbakhsh
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Pontiano Kaleebu
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, Entebbe, P.O. Box 49, Uganda,Uganda Virus Research Institute, Entebbe, Uganda
| | - Narcis Kabatereine
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda,Schistosomiasis Control Initiative, Faculty of Medicine, School of Public Health, Imperial College London, London, UK
| | - Edridah Tukahebwa
- Vector Control Division, Ministry of Health of Uganda, Kampala, Uganda
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14
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Zhang SM, Bu L, Laidemitt MR, Lu L, Mutuku MW, Mkoji GM, Loker ES. Complete mitochondrial and rDNA complex sequences of important vector species of Biomphalaria, obligatory hosts of the human-infecting blood fluke, Schistosoma mansoni. Sci Rep 2018; 8:7341. [PMID: 29743617 PMCID: PMC5943310 DOI: 10.1038/s41598-018-25463-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/16/2018] [Indexed: 01/24/2023] Open
Abstract
Using high throughput Illumina sequencing technology, we determined complete sequences for the mitochondrial genome (mitogenome) and nuclear ribosomal DNA (rDNA) complex for three African freshwater snail taxa within the genus Biomphalaria, B. pfeifferi, B. sudanica and B. choanomphala, and for two laboratory strains of B. glabrata originating from the Neotropics. Biomphalaria snails are obligate vectors of the blood fluke Schistosoma mansoni, a major etiologic agent of human intestinal schistosomiasis. Our data show that mitogenomes from African and Neotropical Biomphalaria are highly conserved. With respect to rDNA, the two internal transcribed spacers (ITS1 and 2) were found to be highly variable whereas the three ribosomal RNA genes (28S, 5.8S and 18S rRNA) exhibited no or very limited variation. Our analyses reveal that the two taxa inhabiting Lake Victoria, B. sudanica and B. choanomphala, are very similar to one another relative to the similarity either shows to B. pfeifferi or B. glabrata. This new sequence information may prove useful for developing new markers for snail identification, environmental detection/monitoring purposes or for tracking epidemiology and snail dependencies of S. mansoni in endemic areas. It also provides new information pertinent to still unresolved questions in Biomphalaria systematics and nomenclature.
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Affiliation(s)
- Si-Ming Zhang
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerqu, NM, 87131, USA.
| | - Lijing Bu
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerqu, NM, 87131, USA
| | - Martina R Laidemitt
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerqu, NM, 87131, USA
| | - Lijun Lu
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerqu, NM, 87131, USA
| | - Martin W Mutuku
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box, 54840-00200, Nairobi, Kenya
| | - Gerald M Mkoji
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box, 54840-00200, Nairobi, Kenya
| | - Eric S Loker
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerqu, NM, 87131, USA.,Parasitology Division, Museum of Southwestern Biology, University of New Mexico, Albuquerque, 87131, USA
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15
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Mutuku MW, Lu L, Otiato FO, Mwangi IN, Kinuthia JM, Maina GM, Laidemitt MR, Lelo EA, Ochanda H, Loker ES, Mkoji GM. A Comparison of Kenyan Biomphalaria pfeifferi and B. Sudanica as Vectors for Schistosoma mansoni, Including a Discussion of the Need to Better Understand the Effects of Snail Breeding Systems on Transmission. J Parasitol 2017; 103:669-676. [PMID: 28708450 DOI: 10.1645/17-72] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024] Open
Abstract
In Kenya, schistosomes infect an estimated 6 million people with >30 million people at risk of infection. We compared compatibility with, and ability to support and perpetuate, Schistosoma mansoni of Biomphalaria pfeifferi and Biomphalaria sudanica, 2 prominent freshwater snail species involved in schistosomiasis transmission in Kenya. Field-derived B. pfeifferi (from a stream in Mwea, central Kenya) and B. sudanica (from Nawa, Lake Victoria, in western Kenya) were exposed to S. mansoni miracidia isolated from fecal samples of naturally infected humans from Mwea or Nawa. Juvenile (<6 mm shell diameter), young adult (6-9 mm), and adult snails (>9 mm) were each exposed to a single miracidium. Schistosoma mansoni developed faster and consistently had higher infection rates (39.6-80.7%) in B. pfeifferi than in B. sudanica (2.4-21.5%), regardless of the source of S. mansoni or the size of the snails used. Schistosoma mansoni from Nawa produced higher infection rates in both B. pfeifferi and B. sudanica than did S. mansoni from Mwea. Mean daily cercariae production was greater for B. pfeifferi exposed to sympatric than allopatric S. mansoni (583-1,686 vs. 392-1,232), and mean daily cercariae production among B. sudanica were consistently low (50-590) with no significant differences between sympatric or allopatric combinations. Both non-miracidia-exposed and miracidia-exposed B. pfeifferi had higher mortality rates than for B. sudanica, but mean survival time of shedding snails (9.3-13.7 wk) did not differ significantly between the 2 species. A small proportion (1.5%) of the cercariae shedding B. pfeifferi survived up to 40 wk post-exposure. Biomphalaria pfeifferi was more likely to become infected and to shed more cercariae than B. sudanica, suggesting that the risk per individual snail of perpetuating transmission in Kenyan streams or lacustrine habitats may differ considerably. High infection rates exhibited by the preferential self-fertilizing B. pfeifferi relative to the out-crossing B. sudanica point to the need to investigate further the role of host breeding systems in influencing transmission of schistosomiasis by snail hosts.
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Affiliation(s)
- Martin W Mutuku
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Lijun Lu
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Fredrick O Otiato
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Ibrahim N Mwangi
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Joseph M Kinuthia
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Geoffrey M Maina
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Martina R Laidemitt
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Eric A Lelo
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Horace Ochanda
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Eric S Loker
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Gerald M Mkoji
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
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16
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Bakuza JS, Gillespie R, Nkwengulila G, Adam A, Kilbride E, Mable BK. Assessing S. mansoni prevalence in Biomphalaria snails in the Gombe ecosystem of western Tanzania: the importance of DNA sequence data for clarifying species identification. Parasit Vectors 2017; 10:584. [PMID: 29169384 PMCID: PMC5701381 DOI: 10.1186/s13071-017-2525-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 11/06/2017] [Indexed: 01/10/2023] Open
Abstract
Background Snails are essential for the transmission and maintenance of schistosomiasis in endemic areas, as they serve as intermediate hosts for schistosome parasites. A clear understanding of the snail species present, their local distribution and infection status is therefore a prerequisite for effective control of schistosomiasis. The purpose of this study was to establish the infection status and distribution of Schistosoma mansoni in snails in the Gombe area along the shores of Lake Tanganyika in western Tanzania, using both detection of cercarial shedding and molecular approaches. Methods Snails were collected from streams located close to human settlements in Gombe National Park, as well as from nearby villages (Kiziba, Mtanga, Mwamgongo and Bugamba) and the largest town in the region (Kigoma). Snails were individually exposed to light to induce shedding of schistosome larvae, which were examined using a compound light microscope. Additionally, the internal transcribed spacer (ITS) region of the ribosomal RNA gene cluster was simultaneously amplified in both snails and their trematodes using a single polymerase chain reaction (PCR) and sequenced to confirm species identification. Results Snails morphologically identified as Biomphalaria pfeifferi were present in all streams except at Mtanga but their distribution was patchy in both time and space. Sequencing of PCR products indicated that not all snails were B. pfeifferi. None of the snails from Gombe or Bugamba shed schistosome larvae, while larvae were shed at all other sites. Overall, an infection prevalence of only 12% was observed in snails based on cercarial shedding. While 47% of the snails were PCR-positive for the 500 bp ITS fragment, which was predicted to indicate infection with S. mansoni, sequence data demonstrated that these bands are not species-specific and can be amplified from other trematode infections. In addition, a 1000 bp band was amplified in 14% of samples, which was identified as a trematode in the family Derogenidae. Conclusions The results support the previous assumption that B. pfeifferi snails may be involved in transmitting schistosomiasis in the area but suggest that the community structure of both snails and trematodes may be more complicated than previously thought. This emphasises the importance of confirming species identifications using sequencing, rather than relying only on PCR-based diagnostics or cercarial shedding. Electronic supplementary material The online version of this article (10.1186/s13071-017-2525-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jared S Bakuza
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK. .,Department of Biological Sciences, Dar es Salaam University College of Education, Dar es Salaam, Tanzania.
| | - Robert Gillespie
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Gamba Nkwengulila
- Department of Zoology and Wildlife Conservation, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Aileen Adam
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Elizabeth Kilbride
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Barbara K Mable
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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Stanton MC, Adriko M, Arinaitwe M, Howell A, Davies J, Allison G, LaCourse EJ, Muheki E, Kabatereine NB, Stothard JR. Intestinal schistosomiasis in Uganda at high altitude (>1400 m): malacological and epidemiological surveys on Mount Elgon and in Fort Portal crater lakes reveal extra preventive chemotherapy needs. Infect Dis Poverty 2017; 6:34. [PMID: 28162096 PMCID: PMC5292801 DOI: 10.1186/s40249-017-0248-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 01/19/2017] [Indexed: 01/24/2023] Open
Abstract
Background Intestinal schistosomiasis is of public health importance in Uganda but communities living above 1400 m are not targeted for control as natural transmission is thought unlikely. To assess altitudinal boundaries and at-risk populations, conjoint malacological and epidemiological surveys were undertaken on Mount Elgon (1139 m–3937 m), in Fort Portal crater lakes and in the Rwenzori Mountains (1123 m–4050 m). Methods Seventy freshwater habitats [Mount Elgon (37), Fort Portal crater lakes (23), Rwenzori Mountains (8) and Lake Albert (2)] were inspected for Biomphalaria species. Water temperature, pH and conductivity were recorded. A parasitological examination of 756 schoolchildren [Mount Elgon (300), Fort Portal crater lakes (456)] by faecal microscopy of duplicate Kato-Katz smears from two consecutive stool samples was bolstered by antigen (urine-CCA dipstick) and antibody (SEA-ELISA) diagnostic assays. Results Biomphalaria spp. was found up to 1951 m on Mount Elgon and 1567 m in the Fort Portal crater lakes. Although no snail from Mount Elgon shed cercariae, molecular analysis judged 7.1% of snails sampled at altitudes above 1400 m as having DNA of Schistosoma mansoni; in Fort Portal crater lakes three snails shed schistosome cercariae. Prevalence of intestinal schistosomiasis as measured in schoolchildren by Kato-Katz (Mount Elgon = 5.3% v. Fort Portal crater lakes = 10.7%), CCA urine-dipsticks (18.3% v. 34.4%) and SEA-ELISA (42.3% v. 63.7%) showed negative associations with increasing altitude with some evidence of infection up to 2000 m. Conclusions Contrary to expectations, these surveys clearly show that natural transmission of intestinal schistosomiasis occurs above 1400 m, possibly extending up to 2000 m. Using spatial epidemiological predictions, this now places some extra six million people at-risk, denoting an expansion of preventive chemotherapy needs in Uganda. Electronic supplementary material The online version of this article (doi:10.1186/s40249-017-0248-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michelle C Stanton
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Moses Adriko
- Vector Control Division, Ministry of Health, Kampala, P.O. Box 1661, Uganda
| | - Moses Arinaitwe
- Vector Control Division, Ministry of Health, Kampala, P.O. Box 1661, Uganda
| | - Alison Howell
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Juliet Davies
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Gillian Allison
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - E James LaCourse
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Edridah Muheki
- Vector Control Division, Ministry of Health, Kampala, P.O. Box 1661, Uganda
| | - Narcis B Kabatereine
- Vector Control Division, Ministry of Health, Kampala, P.O. Box 1661, Uganda.,Schistosomiasis Control Initiative, Imperial College London, London, W2 1PG, UK
| | - J Russell Stothard
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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A centenary of Robert T. Leiper's lasting legacy on schistosomiasis and a COUNTDOWN on control of neglected tropical diseases. Parasitology 2016; 144:1602-1612. [PMID: 27363810 PMCID: PMC5964474 DOI: 10.1017/s0031182016000998] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Part of Robert T. Leiper's (1881–1969) lasting legacy in medical helminthology is grounded on his pioneering work on schistosomiasis (Bilharzia). Having undertaken many expeditions to the tropics, his fascination with parasite life cycles typically allowed him to devise simple preventive measures that curtailed transmission. Building on his formative work with others in Africa and Asia, and again in Egypt in 1915, he elucidated the life cycles of African schistosomes. His mandate, then commissioned by the British War Office, was to prevent and break transmission of this disease in British troops. This he did by raising standing orders based on simple water hygiene measures. Whilst feasible in military camp settings, today their routine implementation is sadly out of reach for millions of Africans living in poverty. Whilst we celebrate the centenary of Leiper's research we draw attention to some of his lesser known colleagues, then focus on schistosomiasis in Uganda discussing why expanded access to treatment with praziquantel is needed now. Looking to WHO 2020 targets for neglected tropical diseases, we introduce COUNTDOWN, an implementation research consortium funded by DFID, UK, which fosters the scale-up of interventions and confirm the current relevance of Leiper's original research.
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Lu L, Zhang SM, Mutuku MW, Mkoji GM, Loker ES. Relative compatibility of Schistosoma mansoni with Biomphalaria sudanica and B. pfeifferi from Kenya as assessed by PCR amplification of the S. mansoni ND5 gene in conjunction with traditional methods. Parasit Vectors 2016; 9:166. [PMID: 27000855 PMCID: PMC4802880 DOI: 10.1186/s13071-016-1457-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/16/2016] [Indexed: 12/02/2022] Open
Abstract
Background Schistosoma mansoni is hosted by several species of Biomphalaria spp. snails in Africa. We were interested in determining if there were differences in compatibility of S. mansoni with Biomphalaria sudanica from Lake Victoria, or with B. pfeifferi from streams and smaller water bodies in Kenya. Does this parasite develop with equal efficiency in both snail species, and does this have implications for transmission in different habitat types? Methods Primers for PCR amplification of the S. mansoni ND5 gene were designed and tested for sensitivity and specificity. We exposed laboratory-reared B. sudanica and field-derived B. pfeifferi to single miracidium infections and at 1, 2, 4, 8, 16 and 24 days post-exposure (dpe), snails were extracted for the PCR assay. Snails were also shed for cercariae and/or dissected prior to extraction. Additionally, B. sudanica and B. pfeifferi were collected from field locations and tested with the PCR assay. Results The ND5 PCR assay was sensitive (>0.1 fg S. mansoni genomic DNA) and allowed S. mansoni to be differentiated from other relevant schistosome species or snails. The number of PCR positive snails at 1–4 dpe was higher for B. pfeifferi than for B. sudanica, but not significantly so (P = 0.052). From 8–24 dpe, more B. pfeifferi harbored successfully developing parasites (positive by both dissection and PCR) than did B. sudanica (P = 0.008). At 40 dpe, more B. pfeifferi than B. sudanica shed cercariae or harbored dissection positive/PCR positive infections (P < 0.001). Both immature and failed (dissection negative but PCR positive) S. mansoni infections could also be detected in naturally infected snails of both species. Conclusions The PCR assay detected S. mansoni infections in snails exposed to one miracidium for one day. Both B. sudanica and B. pfeifferi supported full development of S. mansoni, but B. pfeifferi was more compatible, with significantly more dissection positive/PCR positive or shedding infections, and significantly fewer failed infections (dissection negative/PCR positive). This highlights the relatively lower compatibility of B. sudanica with S. mansoni, and suggests the factors responsible for incompatibility and how they might affect transmission of S. mansoni in habitats like Lake Victoria deserve additional study.
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Affiliation(s)
- Lijun Lu
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, 87131, USA.
| | - Si-Ming Zhang
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, 87131, USA
| | - Martin W Mutuku
- Center for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Gerald M Mkoji
- Center for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Eric S Loker
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, 87131, USA.,Parasitology Division, Museum of Southwestern Biology, University of New Mexico, Albuquerque, 87131, USA
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Environmental epidemiology of intestinal schistosomiasis in Uganda: population dynamics of biomphalaria (gastropoda: planorbidae) in Lake Albert and Lake Victoria with observations on natural infections with digenetic trematodes. BIOMED RESEARCH INTERNATIONAL 2015; 2015:717261. [PMID: 25705680 PMCID: PMC4331394 DOI: 10.1155/2015/717261] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 06/16/2014] [Accepted: 09/30/2014] [Indexed: 01/29/2023]
Abstract
This study documented the population dynamics of Biomphalaria and associated natural infections with digenetic trematodes, along the shores of Lake Albert and Lake Victoria, recording local physicochemical factors. Over a two-and-a-half-year study period with monthly sampling, physicochemical factors were measured at 12 survey sites and all freshwater snails were collected. Retained Biomphalaria were subsequently monitored in laboratory aquaria for shedding trematode cercariae, which were classified as either human infective (Schistosoma mansoni) or nonhuman infective. The population dynamics of Biomphalaria differed by location and by lake and had positive relationship with pH (P < 0.001) in both lakes and negative relationship with conductivity (P = 0.04) in Lake Albert. Of the Biomphalaria collected in Lake Albert (N = 6,183), 8.9% were infected with digenetic trematodes of which 15.8% were shedding S. mansoni cercariae and 84.2% with nonhuman infective cercariae. In Lake Victoria, 2.1% of collected Biomphalaria (N = 13,172) were infected with digenetic trematodes with 13.9% shedding S. mansoni cercariae, 85.7% shedding nonhuman infective cercariae, and 0.4% of infected snails shedding both types of cercariae. Upon morphological identification, species of Biomphalaria infected included B. sudanica, B. pfeifferi, and B. stanleyi in Lake Albert and B. sudanica, B. pfeifferi, and B. choanomphala in Lake Victoria. The study found the physicochemical factors that influenced Biomphalaria population and infections. The number and extent of snails shedding S. mansoni cercariae illustrate the high risk of transmission within these lake settings. For better control of this disease, greater effort should be placed on reducing environmental contamination by improvement of local water sanitation and hygiene.
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Abou-El-Naga IF. Meta-analysis indicates lack of local adaptation of Schistosoma mansoni to Biomphalaria alexandrina in Egypt. Parasitol Res 2014; 113:1185-94. [DOI: 10.1007/s00436-014-3756-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 01/03/2014] [Indexed: 01/09/2023]
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Abstract
In May 2012, the World Health Assembly passed resolution WHA 65.21, calling upon member states to intensify schistosomiasis control and, wherever possible, to attempt transmission interruption and initiate interventions towards local elimination. It is now clear that CONTRAST--a multidisciplinary alliance to optimize schistosomiasis control and transmission surveillance in sub-Saharan Africa--was ahead of the game. Indeed, launched in October 2006, this 4-year project funded by the European Commission made important contributions for sustainable schistosomiasis control in the selected African countries through innovation, validation and application of new tools and locally adapted intervention strategies complementary to preventive chemotherapy. Moreover, CONTRAST articulated a research agenda for schistosomiasis elimination, framed by 10 key questions. Here, we provide a rationale for CONTRAST and discuss its overarching goal, the interrelated objectives, establishment and running of a research node network across Africa, partnership configuration and modus operandi of the project. A collection of 25 articles is presented that are grouped into five main themes: molecular, biological, spatial, social and cross-cutting issues pertaining to the epidemiology and control of schistosomiasis. We summarize key achievements made by CONTRAST, many of which are featured in this special issue of Acta Tropica. Together with an independent view put forth by an eminent schistosomiasis researcher, the current piece provides an umbrella for the 25-article collection, including current gaps and remaining research needs. Finally, post-CONTRAST initiatives are discussed and a speculative viewpoint is given on how schistosomiasis control/elimination will have evolved over the next several years.
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