What does soil-transmitted helminth elimination look like? Results from a targeted molecular detection survey in Japan.
Adolescent
Ancylostoma
/ genetics
Ancylostomiasis
/ parasitology
Animals
Ascariasis
/ parasitology
Ascaris lumbricoides
/ genetics
Child
Child, Preschool
Feces
/ parasitology
Female
Helminths
Humans
Hygiene
Japan
Male
Necator americanus
/ genetics
Necatoriasis
/ parasitology
Soil
/ parasitology
Surveys and Questionnaires
Trichuriasis
/ parasitology
Trichuris
/ genetics
Ancylostoma duodenale
Ascaris lumbricoides
Multi-parallel real-time PCR
Necator americanus
STH
Soil-transmitted helminth
Targeted prevalence survey
Trichuris trichiura
WASH
Journal
Parasites & vectors
ISSN: 1756-3305
Titre abrégé: Parasit Vectors
Pays: England
ID NLM: 101462774
Informations de publication
Date de publication:
08 Jan 2020
08 Jan 2020
Historique:
received:
08
09
2019
accepted:
30
12
2019
entrez:
10
1
2020
pubmed:
10
1
2020
medline:
30
5
2020
Statut:
epublish
Résumé
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. 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. Among the 682 children, no positive samples were identified, and participants reported high standards of WASH. 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.
Sections du résumé
BACKGROUND
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
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
RESULTS
Among the 682 children, no positive samples were identified, and participants reported high standards of WASH.
CONCLUSIONS
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.
Identifiants
pubmed: 31915050
doi: 10.1186/s13071-019-3875-z
pii: 10.1186/s13071-019-3875-z
pmc: PMC6950881
doi:
Substances chimiques
Soil
0
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
6Subventions
Organisme : Bill and Melinda Gates Foundation
ID : OPP1129535
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