Prevalence and fragmented populations of submicroscopic Plasmodium vivax in Vanuatu from 2017 to 2019

Abstract

Vanuatu had experienced a remarkable decrease in malaria since the mid-2000s but transmission hotspots remained on several islands. We conducted cross-sectional surveys in known hotspots on seven islands between 2017 and 2019. Among 6,943 participants we found low prevalence of exclusively submicroscopic Plasmodium vivax infections on Epi (4.3%; 95% CI 3.0–6.0%), Malekula (4.8%; 95% CI 4.0-5.7%), Santo (6.5%; 95% CI 5.3–7.7%), Maewo (0.4%; 95% CI 0.1–1.2%), and Vanua Lava (1.2%; 95% CI 0.5–2.8%). Regression analysis revealed significant association between P. vivax infections and age (OR = 1.07, p = 0.007) and enlarged spleen (OR = 5.36, p < 0.001) among 2,407 children ≤ 12 years. Microsatellite genotyping of 53 P. vivax samples showed that parasites on Epi had lower heterozygosity ( H E = 0.173) and haplotype diversity ( h = 0.731) than those on Malekula ( H E = 0.638; h = 0.990) and Santo ( H E = 0.751; h = 0.984). P. vivax effective population size estimates on Epi were an order-of-magnitude smaller than those on Malekula and Santo. Significant genetic differentiation (F ST = 0.018–0.138, p < 0.01) and apparent population structure were observed among these three islands. P. vivax populations had shown evidence of fragmentation at the island level in Vanuatu by 2019.

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BibTeX

@article{chan2026prevalence,
  title = {{Prevalence and fragmented populations of submicroscopic Plasmodium vivax in Vanuatu from 2017 to 2019}},
  author = {Chim W. Chan and Wataru Kagaya and Morris Kalkoa and James Yaviong and Harry Iata and Kalo Kalkoa and George Taleo and Akira Kaneko},
  journal = {Scientific Reports},
  year = {2026},
  month = oct,
  doi = {10.1038/s41598-026-76607-5},
  url = {https://www.nature.com/articles/s41598-026-76607-5},
  note = {CC BY 4.0},
}

RIS

TY  - JOUR
TI  - Prevalence and fragmented populations of submicroscopic Plasmodium vivax in Vanuatu from 2017 to 2019
AU  - Chim W. Chan
AU  - Wataru Kagaya
AU  - Morris Kalkoa
AU  - James Yaviong
AU  - Harry Iata
AU  - Kalo Kalkoa
AU  - George Taleo
AU  - Akira Kaneko
PY  - 2026
DA  - 2026/10/22
JO  - Scientific Reports
DO  - 10.1038/s41598-026-76607-5
UR  - https://www.nature.com/articles/s41598-026-76607-5
AB  - Vanuatu had experienced a remarkable decrease in malaria since the mid-2000s but transmission hotspots remained on several islands. We conducted cross-sectional surveys in known hotspots on seven islands between 2017 and 2019. Among 6,943 participants we found low prevalence of exclusively submicroscopic Plasmodium vivax infections on Epi (4.3%; 95% CI 3.0–6.0%), Malekula (4.8%; 95% CI 4.0-5.7%), Santo (6.5%; 95% CI 5.3–7.7%), Maewo (0.4%; 95% CI 0.1–1.2%), and Vanua Lava (1.2%; 95% CI 0.5–2.8%). Regression analysis revealed significant association between P. vivax infections and age (OR = 1.07, p = 0.007) and enlarged spleen (OR = 5.36, p < 0.001) among 2,407 children ≤ 12 years. Microsatellite genotyping of 53 P. vivax samples showed that parasites on Epi had lower heterozygosity ( H E = 0.173) and haplotype diversity ( h = 0.731) than those on Malekula ( H E = 0.638; h = 0.990) and Santo ( H E = 0.751; h = 0.984). P. vivax effective population size estimates on Epi were an order-of-magnitude smaller than those on Malekula and Santo. Significant genetic differentiation (F ST = 0.018–0.138, p < 0.01) and apparent population structure were observed among these three islands. P. vivax populations had shown evidence of fragmentation at the island level in Vanuatu by 2019.
SN  - 2045-2322
ER  -

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