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Miranda GS, Rodrigues JGM, Silva JKADO, Camelo GMA, Silva-Souza N, Neves RH, Machado-Silva JR, Negrão-Corrêa DA. New challenges for the control of human schistosomiasis: The possible impact of wild rodents in Schistosoma mansoni transmission. Acta Trop 2022; 236:106677. [PMID: 36063905 DOI: 10.1016/j.actatropica.2022.106677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 08/27/2022] [Accepted: 09/01/2022] [Indexed: 11/17/2022]
Abstract
Schistosomiasis is a neglected parasitic disease caused by digenean trematodes from the genus Schistosoma that affects millions of people worldwide. Despite efforts to control its transmission, this disease remains active within several endemic regions of Africa, Asia, and the Americas. In addition to the deficits in sanitation and educational structure, another major obstacle hindering the eradication of schistosomiasis is the ability of Schistosoma spp. to naturally infect multiple vertebrate hosts, particularly wild rodents. Due to climate change and other anthropogenic disturbances, contact between humans and wild animals has increased, and this has contributed to more frequent interactions between Schistosoma species that typically infect different hosts. This new transmission dynamic involving Schistosoma spp., humans, wild rodents, and livestock could potentially increase the frequency of Schistosoma hybridization and the establishment of new genotypes and strains. Although it is not currently possible to precisely measure how this biological phenomenon affects the epidemiology and morbidity of schistosomiasis, we speculate that these Schistosoma variants may negatively impact control strategies, treatment regimens, and disease burden in humans. In the present study, we discuss the natural infections of wild rodents with Schistosoma spp., the role of these animals as Schistosoma spp. reservoirs, and how they may select hybrids and strains of Schistosoma mansoni. We also discuss measures required to shed light on the actual role of the wild rodents Nectomys squamipes and Holochilus sciureus in the transmission and morbidity of schistosomiasis in Brazil.
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Affiliation(s)
- Guilherme Silva Miranda
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG CEP: 31270-010, 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, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG CEP: 31270-010, Brazil
| | - Jeferson Kelvin Alves de Oliveira Silva
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG CEP: 31270-010, Brazil
| | - Genil Mororó Araújo Camelo
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG CEP: 31270-010, Brazil
| | - Nêuton Silva-Souza
- Department of Chemistry and Biology, State University of Maranhão, São Luis, Brazil
| | - Renata Heisler Neves
- Department of Microbiology, Immunology and Parasitology, Faculty of Medical Sciences, Biomedical Center, University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - José Roberto Machado-Silva
- Department of Microbiology, Immunology and Parasitology, Faculty of Medical Sciences, Biomedical Center, University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Deborah Aparecida Negrão-Corrêa
- Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Campus Pampulha, Belo Horizonte, MG CEP: 31270-010, Brazil.
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Ogongo P, Nyakundi RK, Chege GK, Ochola L. The Road to Elimination: Current State of Schistosomiasis Research and Progress Towards the End Game. Front Immunol 2022; 13:846108. [PMID: 35592327 PMCID: PMC9112563 DOI: 10.3389/fimmu.2022.846108] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/21/2022] [Indexed: 12/14/2022] Open
Abstract
The new WHO Roadmap for Neglected Tropical Diseases targets the global elimination of schistosomiasis as a public health problem. To date, control strategies have focused on effective diagnostics, mass drug administration, complementary and integrative public health interventions. Non-mammalian intermediate hosts and other vertebrates promote transmission of schistosomiasis and have been utilized as experimental model systems. Experimental animal models that recapitulate schistosomiasis immunology, disease progression, and pathology observed in humans are important in testing and validation of control interventions. We discuss the pivotal value of these models in contributing to elimination of schistosomiasis. Treatment of schistosomiasis relies heavily on mass drug administration of praziquantel whose efficacy is comprised due to re-infections and experimental systems have revealed the inability to kill juvenile schistosomes. In terms of diagnosis, nonhuman primate models have demonstrated the low sensitivity of the gold standard Kato Katz smear technique. Antibody assays are valuable tools for evaluating efficacy of candidate vaccines, and sera from graded infection experiments are useful for evaluating diagnostic sensitivity of different targets. Lastly, the presence of Schistosomes can compromise the efficacy of vaccines to other infectious diseases and its elimination will benefit control programs of the other diseases. As the focus moves towards schistosomiasis elimination, it will be critical to integrate treatment, diagnostics, novel research tools such as sequencing, improved understanding of disease pathogenesis and utilization of experimental models to assist with evaluating performance of new approaches.
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Affiliation(s)
- Paul Ogongo
- Division of Experimental Medicine, Department of Medicine, University of California, San Francisco, San Francisco, CA, United States.,Department of Tropical and Infectious Diseases, Institute of Primate Research, Nairobi, Kenya
| | - Ruth K Nyakundi
- Department of Tropical and Infectious Diseases, Institute of Primate Research, Nairobi, Kenya
| | - Gerald K Chege
- Primate Unit & Delft Animal Centre, South African Medical Research Council, Cape Town, South Africa.,Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Lucy Ochola
- Department of Tropical and Infectious Diseases, Institute of Primate Research, Nairobi, Kenya.,Department of Environmental Health, School of Behavioural and Lifestyle Sciences, Faculty of Health Sciences, Nelson Mandela University, Gqeberha, South Africa
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