Multi-host transmission dynamics of Schistosoma japonicum in Samar province, the Philippines.

<h4>Background</h4>Among the 6.7 million people living in areas of the Philippines where infection with Schistosoma japonicum is considered endemic, even within small geographical areas levels of infection vary considerably. In general, the ecological drivers of this variability are not...

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Autores principales:	Steven Riley, Hélène Carabin, Patrick Bélisle, Lawrence Joseph, Veronica Tallo, Ernesto Balolong, A Lee Willingham, Tomas J Fernandez, Ryan O'Neal Gonzales, Remigio Olveda, Stephen T McGarvey
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2008
Materias:	Medicine R
Acceso en línea:	https://doaj.org/article/e3047ab1a8524011afb244fc2f15cc1e
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spelling	oai:doaj.org-article:e3047ab1a8524011afb244fc2f15cc1e2021-11-25T05:37:08ZMulti-host transmission dynamics of Schistosoma japonicum in Samar province, the Philippines.1549-12771549-167610.1371/journal.pmed.0050018https://doaj.org/article/e3047ab1a8524011afb244fc2f15cc1e2008-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/18215106/?tool=EBIhttps://doaj.org/toc/1549-1277https://doaj.org/toc/1549-1676<h4>Background</h4>Among the 6.7 million people living in areas of the Philippines where infection with Schistosoma japonicum is considered endemic, even within small geographical areas levels of infection vary considerably. In general, the ecological drivers of this variability are not well described. Unlike other schistosomes, S. japonicum is known to infect several mammalian hosts. However, the relative contribution of different hosts to the transmission cycle is not well understood. Here, we characterize the transmission dynamics of S. japonicum using data from an extensive field study and a mathematical transmission model.<h4>Methods and findings</h4>In this study, stool samples were obtained from 5,623 humans and 5,899 potential nonhuman mammalian hosts in 50 villages in the Province of Samar, the Philippines. These data, with variable numbers of samples per individual, were adjusted for known specificities and sensitivities of the measurement techniques before being used to estimate the parameters of a mathematical transmission model, under the assumption that the dynamic transmission processes of infection and recovery were in a steady state in each village. The model was structured to allow variable rates of transmission from different mammals (humans, dogs, cats, pigs, domesticated water buffalo, and rats) to snails and from snails to mammals. First, we held transmission parameters constant for all villages and found that no combination of mammalian population size and prevalence of infectivity could explain the observed variability in prevalence of infection between villages. We then allowed either the underlying rate of transmission (a) from snails to mammals or (b) from mammals to snails to vary by village. Our data provided substantially more support for model structure (a) than for model structure (b). Fitted values for the village-level transmission intensity from snails to mammals appeared to be strongly spatially correlated, which is consistent with results from descriptive hierarchical analyses.<h4>Conclusions</h4>Our results suggest that the process of acquiring mammalian S. japonicum infection is more important in explaining differences in prevalence of infection between villages than the process of snails becoming infected. Also, the contribution from water buffaloes to human S. japonicum infection in the Philippines is less important than has been recently observed for bovines in China. These findings have implications for the prioritization of mitigating interventions against S. japonicum transmission.Steven RileyHélène CarabinPatrick BélisleLawrence JosephVeronica TalloErnesto BalolongA Lee WillinghamTomas J FernandezRyan O'Neal GonzalesRemigio OlvedaStephen T McGarveyPublic Library of Science (PLoS)articleMedicineRENPLoS Medicine, Vol 5, Iss 1, p e18 (2008)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R
spellingShingle	Medicine R Steven Riley Hélène Carabin Patrick Bélisle Lawrence Joseph Veronica Tallo Ernesto Balolong A Lee Willingham Tomas J Fernandez Ryan O'Neal Gonzales Remigio Olveda Stephen T McGarvey Multi-host transmission dynamics of Schistosoma japonicum in Samar province, the Philippines.
description	<h4>Background</h4>Among the 6.7 million people living in areas of the Philippines where infection with Schistosoma japonicum is considered endemic, even within small geographical areas levels of infection vary considerably. In general, the ecological drivers of this variability are not well described. Unlike other schistosomes, S. japonicum is known to infect several mammalian hosts. However, the relative contribution of different hosts to the transmission cycle is not well understood. Here, we characterize the transmission dynamics of S. japonicum using data from an extensive field study and a mathematical transmission model.<h4>Methods and findings</h4>In this study, stool samples were obtained from 5,623 humans and 5,899 potential nonhuman mammalian hosts in 50 villages in the Province of Samar, the Philippines. These data, with variable numbers of samples per individual, were adjusted for known specificities and sensitivities of the measurement techniques before being used to estimate the parameters of a mathematical transmission model, under the assumption that the dynamic transmission processes of infection and recovery were in a steady state in each village. The model was structured to allow variable rates of transmission from different mammals (humans, dogs, cats, pigs, domesticated water buffalo, and rats) to snails and from snails to mammals. First, we held transmission parameters constant for all villages and found that no combination of mammalian population size and prevalence of infectivity could explain the observed variability in prevalence of infection between villages. We then allowed either the underlying rate of transmission (a) from snails to mammals or (b) from mammals to snails to vary by village. Our data provided substantially more support for model structure (a) than for model structure (b). Fitted values for the village-level transmission intensity from snails to mammals appeared to be strongly spatially correlated, which is consistent with results from descriptive hierarchical analyses.<h4>Conclusions</h4>Our results suggest that the process of acquiring mammalian S. japonicum infection is more important in explaining differences in prevalence of infection between villages than the process of snails becoming infected. Also, the contribution from water buffaloes to human S. japonicum infection in the Philippines is less important than has been recently observed for bovines in China. These findings have implications for the prioritization of mitigating interventions against S. japonicum transmission.
format	article
author	Steven Riley Hélène Carabin Patrick Bélisle Lawrence Joseph Veronica Tallo Ernesto Balolong A Lee Willingham Tomas J Fernandez Ryan O'Neal Gonzales Remigio Olveda Stephen T McGarvey
author_facet	Steven Riley Hélène Carabin Patrick Bélisle Lawrence Joseph Veronica Tallo Ernesto Balolong A Lee Willingham Tomas J Fernandez Ryan O'Neal Gonzales Remigio Olveda Stephen T McGarvey
author_sort	Steven Riley
title	Multi-host transmission dynamics of Schistosoma japonicum in Samar province, the Philippines.
title_short	Multi-host transmission dynamics of Schistosoma japonicum in Samar province, the Philippines.
title_full	Multi-host transmission dynamics of Schistosoma japonicum in Samar province, the Philippines.
title_fullStr	Multi-host transmission dynamics of Schistosoma japonicum in Samar province, the Philippines.
title_full_unstemmed	Multi-host transmission dynamics of Schistosoma japonicum in Samar province, the Philippines.
title_sort	multi-host transmission dynamics of schistosoma japonicum in samar province, the philippines.
publisher	Public Library of Science (PLoS)
publishDate	2008
url	https://doaj.org/article/e3047ab1a8524011afb244fc2f15cc1e
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Multi-host transmission dynamics of Schistosoma japonicum in Samar province, the Philippines.

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