Please use this identifier to cite or link to this item: https://www.arca.fiocruz.br/handle/icict/17975
Title: Size matters: Changing population structure means changing sampling requirements for schistosome populations
Authors: Barbosa, Lucio
Silva, Luciano
Blank, Walter
Reis, Mitermayer Galvão dos
Blanton, Ronald
Affilliation: Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Bahia School of Public Health and Hygiene. Salvador, BA, Brazil
Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil
CASE Western Reserve University. Cleveland, OH, USA
Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Federal University of Bahia. Salvador, BA, Brazil
CASE Western Reserve University. Cleveland, OH, USA
Abstract: Eradication of schistosomiasis is a goal for nearly all control programs today. We demonstrated how genetic markers can be used to evaluate control programs, indicate incipient resistance and perhaps predict the extinction of a local population. Our studies have been conducted by collecting parasites from all identified infections in a population to calculate individual host differentiation indices (Di) and community effective population size (Ne). Collecting all individuals and genotyping their parasites would be impractical on a large-scale, thus we sought to determine the relative error associated with different sample sizes. Using data collected in 2009 and 2012 from two villages in Bahia, Brazil, we calculated Di based on samples of different sizes. We used the R to produce 30 samples of those infected selected at random ranging from 5-50% of the total. Di was then calculated for each of these groups using SPADE. Error rates of ± 5%-10% of the true value of Di were taken as acceptable limits. Between 2009-2012 there was no difference in Di for JEN, but the increase was significant for VDR. Ne fell by 15 fold for each site. When the Di is moderate and Ne large, taking samples of 30-40% of the population was within the 10% limit 60% of the time. When the Di increased and Ne reduced, the curves were less steep, but shifted upward so that samples from JEN composed of 30% of the infected had only a 50% chance of being with 10% of the true value and in VDR, where the Di was significantly higher, only a 40% chance of being in this range. The chance of obtaining differentiation indices outside of the acceptable error range with smaller sample sizes increases when the population has undergone a bottleneck. In order to acquire the most representative results regarding population genetics of S. mansoni some characteristics such as population size, prevalence of the parasite, history of treatment in the community has be taken into account.
Keywords: Population genetics
Eradication
Sample size
Schistosoma
keywords: Genética populacional
Erradicação
Controle
Esquistossomose
Issue Date: 2016
Publisher: Sociedade Brasileira de Medicina Tropical
Citation: BARBOSA, L. et al. Size matters: Changing population structure means changing sampling requirements for schistosome populations. In: CONGRESSO DA SOCIEDADE BRASILEIRA DE MEDICINA TROPICAL, 52., Alagoas, 2016. Anais eletrônicos... Alagoas: Sociedade Brasileira de Medicina Tropical, 2016. p. 8993.
Copyright: open access
Appears in Collections:BA - IGM - Trabalhos Apresentados em Eventos

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