A geospatial analysis of local intermediate snail host distributions provides insight into schistosomiasis risk within under-sampled areas of southern Lake Malawi

Reed, Amber L., Alharbi, Mohammad, Makaula, Peter, Condemine, Charlotte, Hesketh, Josie, Archer, John, Jones, Sam, Kayuni, Sekeleghe, Musaya, Janelisa, Stanton, Michelle ORCID: https://orcid.org/0000-0002-1754-4894, Stothard, Russell ORCID: https://orcid.org/0000-0002-9370-3420, Fronterre, Claudio and Jewell, Christopher (2024) 'A geospatial analysis of local intermediate snail host distributions provides insight into schistosomiasis risk within under-sampled areas of southern Lake Malawi'. Parasites & Vectors, Vol 17, Issue 1, e272.

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Abstract

Background: Along the southern shoreline of Lake Malawi, the incidence of schistosomiasis is increasing with snails of the genera Bulinus and Biomphalaria transmitting urogenital and intestinal schistosomiasis, respectively. Since the underlying distribution of snails is partially known, often being focal, developing pragmatic spatial models that interpolate snail information across under-sampled regions is required to understand and assess current and future risk of schistosomiasis.
Methods: A secondary geospatial analysis of recently collected malacological and environmental survey data was undertaken. Using a Bayesian Poisson latent Gaussian process model, abundance data were fitted for Bulinus and Biomphalaria. Interpolating the abundance of snails along the shoreline (given their relative distance along the shoreline) was achieved by smoothing, using extracted environmental rainfall, land surface temperature (LST), evapotranspiration, normalised difference vegetation index (NDVI) and soil type covariate data for all predicted locations. Our adopted model used a combination of two-dimensional (2D) and one dimensional (1D) mapping.
Results: A significant association between normalised difference vegetation index (NDVI) and abundance of Bulinus spp. was detected (log risk ratio − 0.83, 95% CrI − 1.57, − 0.09). A qualitatively similar association was found between NDVI and Biomphalaria sp. but was not statistically significant (log risk ratio − 1.42, 95% CrI − 3.09, 0.10). Analyses of all other environmental data were considered non-significant.
Conclusions: The spatial range in which interpolation of snail distributions is possible appears < 10km owing to fine-scale biotic and abiotic heterogeneities. The forthcoming challenge is to refine geospatial sampling frameworks with future opportunities to map schistosomiasis within actual or predicted snail distributions. In so doing, this would better reveal local environmental transmission possibilities.

Item Type:	Article
Subjects:	QX Parasitology > QX 20 Research (General) QX Parasitology > Helminths. Annelida > QX 355 Schistosoma WC Communicable Diseases > Tropical and Parasitic Diseases > WC 810 Schistosomiasis
Faculty: Department:	Biological Sciences > Department of Tropical Disease Biology Biological Sciences > Vector Biology Department
Digital Object Identifer (DOI):	https://doi.org/10.1186/s13071-024-06353-y
SWORD Depositor:	JISC Pubrouter
Depositing User:	JISC Pubrouter
Date Deposited:	04 Jul 2024 14:45
Last Modified:	04 Jul 2024 14:45
URI:	https://archive.lstmed.ac.uk/id/eprint/24837

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