Impact of precipitation on the prevalence of schistosomiasis mekongi in Lao PDR: Structural equation modelling using Earth observation satellite data

Emilie Louise Akiko Matsumoto-Takahashi; Takashi Kumagai; Kei Oyoshi; Yoshinobu Sasaki; Yousei Mizukami; Bouasy Hongvanthong; Paul T Brey; Shigeyuki Kano; Moritoshi Iwagami

doi:10.1016/j.onehlt.2023.100563

Impact of precipitation on the prevalence of schistosomiasis mekongi in Lao PDR: Structural equation modelling using Earth observation satellite data

One Health. 2023 May 11:16:100563. doi: 10.1016/j.onehlt.2023.100563. eCollection 2023 Jun.

Authors

Emilie Louise Akiko Matsumoto-Takahashi^{1

2}, Takashi Kumagai³, Kei Oyoshi⁴, Yoshinobu Sasaki⁴, Yousei Mizukami⁴, Bouasy Hongvanthong⁵, Paul T Brey⁶, Shigeyuki Kano^{1

7}, Moritoshi Iwagami^{1

7}

Affiliations

¹ Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine (NCGM), Tokyo, Japan.
² Graduate School of Public Health, St. Luke's International University, Tokyo, Japan.
³ Department of Parasitology & Tropical Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
⁴ Earth Observation Research Center (EORC), Space Technology Directorate I, Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan.
⁵ Center of Malariology, Parasitology and Entomology (CMPE), Ministry of Health, Vientiane, Lao Democratic People's Republic.
⁶ Institut Pasteur du Laos (IPL), Ministry of Health, Vientiane, Lao Democratic People's Republic.
⁷ Parasitology Laboratory, Institut Pasteur du Laos (IPL), Ministry of Health, Vientiane, Lao Democratic People's Republic.

Abstract

Increasing attention is being given to the effect of climate change on schistosomiasis, but the impact is currently unknown. As the intermediate snail host (Neotricula aperta) of Schistosoma mekongi inhabits the Mekong River, it is thought that environmental factors affecting the area of water will have an impact on the occurrence of schistosomiasis mekongi. The aim of the present study was to assess the impact of precipitation on the prevalence of human schistosomiasis mekongi using epidemiological data and Earth observation satellite data in Khong district, Champasak province, Lao PDR. Structural equation modelling (SEM) using epidemiological data and Earth observation satellite data was conducted to determine the factors associated with the number of schistosomiasis mekongi patients. As a result, SEM identified 3 significant factors independently associated with schistosomiasis mekongi: (1) a negative association with mass drug administration (MDA); (2) negative association with total precipitation per year; and (3) positive association with precipitation during the dry season. Precisely, regardless of MDA, the increase in total yearly precipitation was suggested to decrease the number of schistosomiasis patients, whereas an increase in precipitation in the dry season increased the number of schistosomiasis patients. This is probably because when total precipitation increases, the water level of the Mekong River rises, thus decreasing the density of infected larvae, cercaria, in the water, and the frequency of humans entering the river would also decrease. In contrast, when precipitation in the dry season is higher, the water level of the Mekong River also rises, which expands the snail habitant, and thus water contact between humans and the snails would also increase. The present study results suggest that increasing precipitation would impact the prevalence of schistosomiasis both positively and negatively, and precipitation should also be considered in the policy to eliminate schistosomiasis mekongi in Lao PDR.

Keywords: Climate change; Earth observation satellite; Lao PDR; Schistosoma mekongi.