Modelagem geoestatística da infecção por Ascaris lumbricoides

Abstract

The following study intends to model the spatial distribution of ascariasis, through the use of geoprocessing and geostatistic analysis. The database used in the study was taken from the PAISQUA project, including a coproparasitologic and domiciliary survey, conducted in 19 selected census tracts of Rio de Janeiro State, Brazil, randomly selecting a group of 1,550 children aged 1 to 9 years old plotting them in their respective domicile's centroids. Risk maps of Ascaris lumbricoides were generated by indicator kriging. The estimated and observed values from the cross-validation were compared using a ROC curve. An isotropic spherical semivariogram model with a range of 30m and nugget effect of 50% was employed in ordinary indicator kriging to create a map of probability of A. lumbricoides infection. The area under the ROC curve indicated a significant global accuracy. The occurrence of disease could be estimated in the study area, and a risk map was elaborated through the use ordinary kriging. The spatial statistics analysis has proven itself adequate for predicting the occurrence of ascariasis, unrestricted to the regions political boundaries.

<i>Ascaris lumbricoides</i>: A Review of Its Epidemiology and Relationship to Other Infections

“…The set of environmental, social and behavioral predictors of elevated Ascaris egg output are not always consistent across studies, but crowding [18][19][20] , poor education of mothers [18,[20][21][22] , open defecation [20,22] , inadequate water supply [18][19][20] , poverty [18,20,[22][23][24][25] , poor nutritional status [24,26,27] , use of human biosolids for fertilizers and irrigation [16] , geophagy [12] , not washing hands before eating [25] , pig ownership or livestock breeding [20,25,28] , and consumption of raw pork and raw water plants [25] are often reported, depending on the population under consideration (preschool chil-9 dren, schoolchildren, migrant women, street vendors, entire communities).…”

FREQUÊNCIA DE PARASITOSES INTESTINAIS: um estudo com crianças de uma creche de Santa Cruz do Sul - RS

“…Abossie e Seid, 34 36 estas duas variáveis também influenciam na aquisição de parasitoses, pois um pequeno número de peças na casa acarreta em um convívio de um maior número de pessoas, num menor espaço físico e quanto mais pessoas convivendo juntas, acompanhado de hábitos de higiene inadequados, também aumenta a possibilidade de aquisição de infecções parasitárias. Estudo realizado por Abera et al, 37 em Tilili, na Etiópia, revela que há associação significativa entre o tamanho da família e a presença de parasitoses, sendo que a chance de ser infectado com parasitas gastrointestinais para crianças de uma família de 7 membros foi maior do que uma família com 3 membros (odds ratio: 1,85).…”

Jack knifing for semivariogram validation

“…More details about the process can be found in Journel and huiJBreGts (1978). There are some reports in the literature with some applications of the cross validation technique but using only the one-to-one graph of measured versus estimated values (Fortes et al, 2004;Mello et al, 2005;Mello et al, 2008). In this paper, six different jack knifing parameters are examined as criteria for judging the performance of semivariogram models, neighborhood of estimation and geostatistical hypothesis.…”

“…This procedure is successively repeated for every measured value and at the end it is possible to calculate errors using measured, estimated and estimation variance values whose values must remain within some specified statistical limits. This technique is also known as a cross validation or "leave-one-out" and has been used in some different applications (schechtMan and WanG, 2004;Fortes et al, 2004;Zhu et al, 2008, Mello et al, 2008, pires and strieder, 2006. The objective of this study was to show the use of the jack knifing technique to validate geostatistical hypothesis and semivariogram models.…”