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Hasegawa M, Pilotte N, Kikuchi M, Means AR, Papaiakovou M, Gonzalez AM, Maasch JRMA, Ikuno H, Sunahara T, Ásbjörnsdóttir KH, Walson JL, Williams SA, Hamano S. What does soil-transmitted helminth elimination look like? Results from a targeted molecular detection survey in Japan. Parasit Vectors 2020; 13:6. [PMID: 31915050 PMCID: PMC6950881 DOI: 10.1186/s13071-019-3875-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 12/30/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Japan is one of the few countries believed to have eliminated soil-transmitted helminths (STHs). In 1949, the national prevalence of Ascaris lumbricoides was 62.9%, which decreased to 0.6% in 1973 due to improvements in infrastructure, socioeconomic status, and the implementation of national STH control measures. The Parasitosis Prevention Law ended in 1994 and population-level screening ceased in Japan; therefore, current transmission status of STH in Japan is not well characterized. Sporadic cases of STH infections continue to be reported, raising the possibility of a larger-scale recrudescence of STH infections. Given that traditional microscopic detection methods are not sensitive to low-intensity STH infections, we conducted targeted prevalence surveys using sensitive PCR-based assays to evaluate the current STH-transmission status and to describe epidemiological characteristics of areas of Japan believed to have achieved historical elimination of STHs. METHODS Stool samples were collected from 682 preschool- and school-aged children from six localities of Japan with previously high prevalence of STH. Caregivers of participants completed a questionnaire to ascertain access to water, sanitation and hygiene (WASH), and potential exposures to environmental contamination. For fecal testing, multi-parallel real-time PCR assays were used to detect infections of Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale and Trichuris trichiura. RESULTS Among the 682 children, no positive samples were identified, and participants reported high standards of WASH. CONCLUSIONS To our knowledge, this is the first STH-surveillance study in Japan to use sensitive molecular techniques for STH detection. The results suggest that recrudescence of STH infections has not occurred, and that declines in prevalence have been sustained in the sampled areas. These findings suggest that reductions in prevalence below the elimination thresholds, suggestive of transmission interruption, are possible. Additionally, this study provides circumstantial evidence that multi-parallel real-time PCR methods are applicable for evaluating elimination status in areas where STH prevalence is extremely low.
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Affiliation(s)
- Mitsuko Hasegawa
- Department of Parasitology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Doctoral Leadership Program, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
- The Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts USA
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts USA
| | - Mihoko Kikuchi
- Doctoral Leadership Program, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
- The Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Arianna R. Means
- Department of Global Health, University of Washington, Seattle, Washington USA
- Department of Life Sciences, Natural History Museum, London, UK
| | - Marina Papaiakovou
- Department of Biological Sciences, Smith College, Northampton, Massachusetts USA
- Department of Life Sciences, Natural History Museum, London, UK
| | - Andrew M. Gonzalez
- Department of Biological Sciences, Smith College, Northampton, Massachusetts USA
| | | | - Hiroshi Ikuno
- Department of Bacteriology, BML, Inc, Saitama, Japan
| | - Toshihiko Sunahara
- The Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Department of Vector Ecology and Environment, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | | | - Judd L. Walson
- Department of Global Health, University of Washington, Seattle, Washington USA
- Department of Life Sciences, Natural History Museum, London, UK
- Departments of Medicine (Infectious Disease), Pediatrics and Epidemiology, University of Washington, Seattle, Washington USA
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts USA
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts USA
| | - Shinjiro Hamano
- Department of Parasitology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Doctoral Leadership Program, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
- The Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - the DeWorm3 Project Team
- Department of Parasitology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Doctoral Leadership Program, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
- The Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Department of Biological Sciences, Smith College, Northampton, Massachusetts USA
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts USA
- Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Department of Global Health, University of Washington, Seattle, Washington USA
- Department of Life Sciences, Natural History Museum, London, UK
- Department of Bacteriology, BML, Inc, Saitama, Japan
- Department of Vector Ecology and Environment, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
- Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington USA
- Departments of Medicine (Infectious Disease), Pediatrics and Epidemiology, University of Washington, Seattle, Washington USA
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