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BACKGROUND: The clinical presentation of dengue ranges from self-limited mild illness to severe forms, including death. African ancestry is often described as protective against dengue severity. However, in the Latin American context, African ancestry has been associated with increased mortality. This "severity paradox" has been hypothesized as resulting from confounding or heterogeneity by socioeconomic status (SES). However, few systematic analyses have been conducted to investigate the presence and nature of the disparity paradox. METHODS: We fit Bayesian hierarchical spatiotemporal models using individual-level surveillance data from Cali, Colombia (2012-2017), to assess the overall morbidity and severity burden of notified dengue. We fitted overall and ethnic-specific models to assess the presence of heterogeneity by SES across and within ethnic groups (Afro-Colombian vs. non-Afro-Colombians), conducting sensitivity analyses to account for potential underreporting. RESULTS: Our study included 65,402 dengue cases and 13,732 (21%) hospitalizations. Overall notified dengue incidence rates did not vary across ethnic groups. Severity risk was higher among Afro-Colombians (risk ratio [RR] = 1.16; 95% Credible Interval [95% CrI] = 1.08, 1.24) but after accounting for underreporting by ethnicity this association was nearly null (RR = 1.02; 95% CrI = 0.97, 1.07). Subsidized health insurance and low-SES were associated with increased overall dengue rates and severity. CONCLUSION: The paradoxically increased severity among Afro-Colombians can be attributed to differential health-seeking behaviors and reporting among Afro-Colombians. Such differential reporting can be understood as a type of intersectionality between SES, insurance scheme, and ethnicity that requires a quantitative assessment in future studies.

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The robust estimate and forecast capability of random forests (RF) has been widely recognized, however this ensemble machine learning method has not been widely used in mosquito-borne disease forecasting. In this study, two sets of RF models were developed at the national (pooled department-level data) and department level in Colombia to predict weekly dengue cases for 12-weeks ahead. A pooled national model based on artificial neural networks (ANN) was also developed and used as a comparator to the RF models. The various predictors included historic dengue cases, satellite-derived estimates for vegetation, precipitation, and air temperature, as well as population counts, income inequality, and education. Our RF model trained on the pooled national data was more accurate for department-specific weekly dengue cases estimation compared to a local model trained only on the department's data. Additionally, the forecast errors of the national RF model were smaller to those of the national pooled ANN model and were increased with the forecast horizon increasing from one-week-ahead (mean absolute error, MAE: 9.32) to 12-weeks ahead (MAE: 24.56). There was considerable variation in the relative importance of predictors dependent on forecast horizon. The environmental and meteorological predictors were relatively important for short-term dengue forecast horizons while socio-demographic predictors were relevant for longer-term forecast horizons. This study demonstrates the potential of RF in dengue forecasting with a feasible approach of using a national pooled model to forecast at finer spatial scales. Furthermore, including sociodemographic predictors is likely to be helpful in capturing longer-term dengue trends.

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BACKGROUND: Appropriate health and nutrition interventions to prevent long-term adverse effects in children are necessary before two years of age. One such intervention may include population-based deworming, recommended as of 12 months of age by the World Health Organization in soil-transmitted helminth (STH)-endemic areas; however, the benefit of deworming has been understudied in early preschool-age children. METHODOLOGY/PRINCIPAL FINDINGS: A randomized, double-blind, placebo-controlled trial was conducted to determine the effect of deworming (500 mg single-dose crushed mebendazole tablet) on growth in one-year-old children in Iquitos, Peru. Children were enrolled during their routine 12-month growth and development clinic visit and followed up at their 18 and 24-month visits. Children were randomly allocated to: Group 1: deworming at 12 months and placebo at 18 months; Group 2: placebo at 12 months and deworming at 18 months; Group 3: deworming at both 12 and 18 months; or Group 4: placebo at both 12 and 18 months (i.e. control group). The primary outcome was weight gain at the 24-month visit. An intention-to-treat approach was used. A total of 1760 children were enrolled between September 2011 and June 2012. Follow-up of 1563 children (88.8%) was completed by July 2013. STH infection was of low prevalence and predominantly light intensity in the study population. All groups gained between 1.93 and 2.05 kg on average over 12 months; the average difference in weight gain (kg) compared to placebo was: 0.05 (95% CI: -0.05, 0.17) in Group 1; -0.07 (95%CI: -0.17, 0.04) in Group 2; and 0.04 (95%CI: -0.06, 0.14) in Group 3. There was no statistically significant difference in weight gain in any of the deworming intervention groups compared to the control group. CONCLUSIONS: Overall, with one year of follow-up, no effect of deworming on growth could be detected in this population of preschool-age children. Low baseline STH prevalence and intensity and/or access to deworming drugs outside of the trial may have diluted the potential effect of the intervention. Additional research is required to overcome these challenges and to contribute to strengthening the evidence base on deworming. TRIAL REGISTRATION: ClinicalTrials.gov (NCT01314937).

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Objetivos. Determinar la eficacia en dosis única del albendazol sobre las infecciones por helmintos transmitidos por el suelo (HTS) en escolares de una comunidad de la ciudad de Iquitos en Perú. Materiales y métodos. Dentro del contexto de un ensayo controlado aleatorizado realizado en una comunidad periurbana de escasos recursos, situada en Iquitos, en la Amazonía de Perú, se obtuvieron muestras de heces de escolares del quinto grado de primaria en 18 escuelas y se analizó la prevalencia y la intensidad de HTS. Un total de 1193 escolares fueron desparasitados con albendazol en dosis única (400 mg). De los 909 escolares que fueron encontrados positivos con al menos una infección por HTS, una muestra aleatoria de 385 fue seguida dos semanas más tarde, cuando se recolectó y analizó una segunda muestra de heces. Resultados. La eficacia del albendazol fue satisfactoria para las infecciones por Ascaris lumbricoides con una tasa de reducción de huevos (TRH) de 99,8%; IC 95: 99,3-100 y por anquilostomideos con una TRH de 93,6%, IC 95%: 88,2-96,6 y por Trichuris trichiura con una TRH de 72,7%, IC 95: 58,5-79,1. Conclusiones. Estos resultados son indicativos de niveles satisfactorios de eficacia y son congruentes con datos publicados sobre la eficacia del albendazol y directivas de la Organización Mundial de la Salud. Futuras investigaciones deben centrarse en mejorar la eficacia de las estrategias de tratamiento para la infección por Trichuris trichiura.

Objectives. To determine the efficacy of single-dose albendazole (400 mg) for soil-transmitted helminth infections (STH) in schoolchildren living in one community of the city of Iquitos, Perú. Materials and methods. Within the context of a randomized controlled trial performed in a peri-urban community of limited resources located in Iquitos in the Peruvian Amazon, stool specimens were collected from Grade 5 schoolchildren in 18 schools and analysed for STH prevalence and intensity. A total of 1,193 school-age children were then dewormed with single-dose albendazole (400 mg). Of the 909 children who were found positive with at least one STH infection, a random sample of 385 was followed two weeks later when a second stool specimen was collected and analyzed. Results. The efficacy of albendazole was satisfactory: for Ascaris lumbricoides , with an egg reduction rate (ERR) of 99.8%; (95% CI: 99.3-100); for hookworm, with an ERR of 93.6 %; (95% CI: 88.2-96.6) and, for Trichuris trichiura, with an ERR of 72.7 %; (95% CI: 58.5-79.1). Conclusions. These results are consistent with previous data published on the efficacy of albendazole and the directives of the World Health Organization. Future research should focus on improving the efficacy of the treatment strategies for Trichuris trichiura infection.

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BACKGROUND: To control soil-transmitted helminth (STH) infections, the World Health Organization recommends school-based deworming programs with a health hygiene education component. The effect of such health hygiene interventions, however, has not been adequately studied. The objective of the present study was to determine the effectiveness of a health hygiene education intervention on the occurrence of STH re-infection four months post-de-worming. METHODOLOGY/PRINCIPAL FINDINGS: An open-label pair-matched cluster-randomized trial was conducted in Grade 5 schoolchildren of 18 primary schools (9 intervention and 9 control) in the Peruvian Amazon. Baseline assessment included interview with a pre-tested questionnaire and collection of single stool specimens that were examined using the single Kato-Katz thick smear. All schoolchildren were then treated with single-dose albendazole (400 mg). Schoolchildren in intervention schools then received 1) an initial one hour in-class activity on health hygiene and sanitation and 30-minute refresher activities every two weeks over four months; and 2) a half-day workshop for teachers and principals, while children in control schools did not. Four months later, STH infection was re-assessed in all schools by laboratory technologists blinded to intervention status. From April 21-October 20, 2010, a total of 1,089 schoolchildren (518 and 571 from intervention and control schools, respectively) participated in this study. Intervention children scored significantly higher on all aspects of a test of STH-related knowledge compared with control children (aOR = 18·4; 95% CI: 12·7 to 26·6). The intensity of Ascaris lumbricoides infection at follow-up was statistically significantly lower (by 58%) in children in intervention schools compared with children in control schools (aIRR = 0·42; 95% CI = 0·21 to 0·85). No significant changes in hookworm or Trichuris trichiura intensity were observed. CONCLUSIONS/SIGNIFICANCE: A school-based health hygiene education intervention was effective in increasing STH knowledge and in reducing Ascaris lumbricoides infection. The benefits of school-based periodic deworming programs are likely to be enhanced when a sustained health hygiene education intervention is integrated into school curricula.

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BACKGROUND: Evidence from randomized controlled trials has shown that delayed cord-clamping is beneficial to infant iron status. The role of maternal anaemia in this relationship, however, has not been established. OBJECTIVE: To determine the effect of maternal anaemia at delivery on the association between timing of umbilical cord-clamping and infant anaemia at 4 and 8 months of age. METHODS: A cohort of pregnant women admitted to the labour room of Hospital Iquitos (Iquitos, Peru) and their newborns were recruited into the study during two time periods (18 May to 3 June and 6-20 July 2009). Between the two recruitment periods, the hospital's policy changed from early to delayed umbilical cord-clamping. Maternal haemoglobin levels were measured before delivery, and the time between delivery and cord-clamping was recorded at delivery for the entire cohort. Mother-infant pairs were followed-up at 4 (n = 207) and 8 months (n = 184) post partum. Infant haemoglobin levels were measured at follow-up visits. Data were analysed using logistic regression models. RESULTS: The prevalence of maternal anaemia (Hb <11.0 g/dl) at delivery was 22%. Infant haemoglobin levels at 4 and 8 months of age were 10.4 g/dl and 10.3 g/dl, respectively. Infant haemoglobin levels did not differ significantly between infants born to anaemic mothers and those born to non-anaemic mothers at either 4 or 8 months of age. However, the association between the timing of cord-clamping and infant anaemia was modified by the mother's anaemia status. Significant benefits of delayed cord-clamping in preventing anaemia were found in infants born to anaemic mothers at both 4 months (aOR = 0.59, 95% CI 0.36-0.99) and 8 months (aOR = 0.38, 95% CI 0.19-0.76) of age. CONCLUSION: The study contributes additional evidence in support of delayed cord-clamping. This intervention is likely to have most public health impact in areas with a high prevalence of anaemia during pregnancy.

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OBJECTIVES: To determine the efficacy of single-dose albendazole (400 mg) for soil-transmitted helminth infections (STH) in schoolchildren living in one community of the city of Iquitos, Perú. MATERIALS AND METHODS: Within the context of a randomized controlled trial performed in a peri-urban community of limited resources located in Iquitos in the Peruvian Amazon, stool specimens were collected from Grade 5 schoolchildren in 18 schools and analysed for STH prevalence and intensity. A total of 1,193 school-age children were then dewormed with single-dose albendazole (400 mg). Of the 909 children who were found positive with at least one STH infection, a random sample of 385 was followed two weeks later when a second stool specimen was collected and analyzed. RESULTS: The efficacy of albendazole was satisfactory: for Ascaris lumbricoides , with an egg reduction rate (ERR) of 99.8%; (95% CI: 99.3-100); for hookworm, with an ERR of 93.6 %; (95% CI: 88.2-96.6) and, for Trichuris trichiura, with an ERR of 72.7 %; (95% CI: 58.5-79.1). CONCLUSIONS: These results are consistent with previous data published on the efficacy of albendazole and the directives of the World Health Organization. Future research should focus on improving the efficacy of the treatment strategies for Trichuris trichiura infection.

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OBJECTIVE: To assess the effectiveness of a hospital policy change toward delayed cord clamping on infant hemoglobin (Hb) levels and anemia status at 4 and 8 months of age. METHODS: A cohort of Peruvian mothers and infants, originating from a pre/post study investigating a change in hospital policy from early to delayed cord clamping, was followed until 8 months postpartum. Infant hemoglobin levels and anemia status were measured at 4 and 8 months postpartum. RESULTS: Following the hospital policy change, adjusted mean infant Hb levels improved by 0.89 gdl(-1) [95% confidence interval (95% CI) 0.57-1.22] and anemia was significantly reduced (aOR = 0.38; 95% CI 0.19-0.78) at 8 months postpartum. CONCLUSIONS: A hospital policy change toward delayed cord clamping is effective in improving Hb levels and the anemia status of 8-month-old infants. Prior to scaling-up this intervention, issues related to training, monitoring, safety, additional long-term benefits and specific local conditions should be investigated.

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OBJECTIVE: To investigate the effect of a two-component intervention to change hospital practice with regard to the timing of umbilical cord clamping. METHODS: A pre-/post-study design was used to measure the effect of a two-component intervention on mean time to clamp the umbilical cord. The study took place at Hospital Iquitos "César Garayar García" in Iquitos, Peru. A total of 224 women were recruited from the hospital labor room: 112 pre-intervention, from 18 May-3 June 2009, and 112 post-intervention, from 6-20 July 2009. The intervention consisted of 1) a "best practice" three-day training workshop on birthing, and 2) a hospital directive. All deliveries were observed and the time between delivery of the first shoulder and clamping of the umbilical cord was measured with a digital stopwatch. RESULTS: The mean time between delivery and cord clamping before the intervention was 56.8 seconds (95% confidence interval [CI]: 51.0, 62.7). This increased to 169.8 seconds (95% CI: 153.8, 185.8) following the intervention. The difference in mean time to clamp remained significant in multivariate analyses (ß adjusted = 113.2 seconds, 95% CI: 96.6, 129.9). CONCLUSIONS: Hospital policy and practice can be successfully changed from early to delayed umbilical cord clamping using a simple, two-component intervention.

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OBJECTIVE: To investigate the effect of a two-component intervention to change hospital practice with regard to the timing of umbilical cord clamping. METHODS: A pre-/post-study design was used to measure the effect of a two-component intervention on mean time to clamp the umbilical cord. The study took place at Hospital Iquitos "César Garayar García" in Iquitos, Peru. A total of 224 women were recruited from the hospital labor room: 112 pre-intervention, from 18 May-3 June 2009, and 112 post-intervention, from 6-20 July 2009. The intervention consisted of 1) a "best practice" three-day training workshop on birthing, and 2) a hospital directive. All deliveries were observed and the time between delivery of the first shoulder and clamping of the umbilical cord was measured with a digital stopwatch. RESULTS: The mean time between delivery and cord clamping before the intervention was 56.8 seconds (95 percent confidence interval [CI]: 51.0, 62.7). This increased to 169.8 seconds (95 percent CI: 153.8, 185.8) following the intervention. The difference in mean time to clamp remained significant in multivariate analyses (βadjusted = 113.2 seconds, 95 percent CI: 96.6, 129.9). CONCLUSIONS: Hospital policy and practice can be successfully changed from early to delayed umbilical cord clamping using a simple, two-component intervention.

OBJETIVO: Investigar el efecto de una intervención de dos componentes para modificar la práctica hospitalaria respecto del momento en que se practica el pinzamiento del cordón umbilical. MÉTODOS: Se empleó un estudio con diseño antes-después para medir el efecto de una intervención de dos componentes sobre el tiempo medio de pinzamiento del cordón umbilical. El estudio se llevó a cabo en el Hospital Iquitos "César Garayar Gar-cía" en Iquitos (Perú). Se incluyeron en total 224 mujeres atendidas en la sala de trabajo de parto del hospital: 112 antes de la intervención, entre el 18 de mayo y el 3 de junio del 2009, y 112 después de la intervención, entre el 6 y el 20 de julio del 2009. La intervención consistió en: 1) un taller de capacitación sobre las "mejores prácticas" en la atención del parto, de 3 días de duración y 2) una directiva del hospital. Se observaron todos los partos y se midió el tiempo entre la salida del hombro anterior y el pinzamiento del cordón umbilical con un cronómetro digital. RESULTADOS: El tiempo medio entre el parto y el pinzamiento del cordón antes de la intervención fue de 56,8 segundos (intervalo de confianza [IC] de 95 por cento: 51,0-62,7), y aumentó a 169,8 segundos (IC 95 por cento: 153,8-185,8) después de la intervención. La diferencia en el tiempo medio hasta el pinzamiento siguió siendo significativa en los análisis multivariados (βajustado = 113,2 segundos, IC 95 por cento: 96,6-129,9). CONCLUSIONES: Es posible cambiar las normas y las prácticas hospitalarias de pinzamiento del cordón umbilical de precoz a tardío mediante una intervención sencilla de dos componentes.

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The World Health Organization recommends deworming of children aged 12-24 months in highly endemic areas. Our research objectives were to: 1) examine prevalence patterns of helminth infection in early childhood; 2) assess the association between helminth infection and socio-demographic characteristics; and 3) examine the effect of the intensity of helminth infection on stunting and anemia. A survey of children (7-9 and 12-14 months) living in Belén (Peru) was undertaken between July 2007 and February 2008. A questionnaire was administered to obtain socio-demographic characteristics, blood and stool samples were collected, and length-for-age Z scores were calculated. The Kato-Katz method was used to determine the prevalence and intensity of Ascaris, Trichuris, and hookworm infections. Of 370 participating children, 349 had parasitological results. Infections first appeared in children at 8 months of age. The prevalence of any helminth infection increased linearly to approximately 37.0% (95%CI: 24.3-51.3%) by 14 months of age. Multivariate analysis showed that age, female sex, and residing in the floodplain were significant determinants of helminth infection. Among infected children, moderate-to-heavy infection of any helminth was associated with stunting (ßadjusted=-0.84; 95%CI: -1.48, -0.20). These results support the implementation of deworming programs aimed at young children in highly endemic areas.

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Self-reports are commonly used to ascertain malaria prevalence in epidemiological studies conducted in settings where laboratory diagnosis is impractical. Most studies, however, do not use self-report per se, but indirect report, where one respondent provides responses for all household members. Studies also vary in terms of the time frame used for this ascertainment. The aim of our research was to determine the validity of self-report and indirect report in ascertaining malaria prevalence over six, eighteen and thirty-month time periods. Reports of malaria episodes collected through interviewer-administered questionnaires (193 self-reports, 614 indirect reports) were compared to microscopy-confirmed cases (principally Plasmodium vivax) registered at a government-run health post in the Peruvian Amazon. Test parameters were estimated using a Bayesian latent class approach for imperfect gold standards. Logistic regression analyses were performed to explore determinants associated with accurate responses. Malaria self-report for the thirty-month period prevalence had the highest sensitivity (91.0%). Specificity was maximized when malaria prevalence was measured over the last six months for both self-report (91.6%) and indirect report (96.7%). Accuracy was highest for the six-month period prevalence in both self-report (91.3%) and indirect report (96.4%). Respondents who were female, had more education, or who provided a report on behalf of a child ≤ 12 years of age, were generally more accurate. Both self-report and indirect report provides accurate estimates of malaria prevalence, especially over shorter periods of time. The choice between self-report and indirect report should ultimately depend on the research question and the target study population.

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BACKGROUND: The contribution made by fish ponds (pisciculture) to malaria transmission in the Peruvian Amazon remains to be confirmed. Recent entomological evidence indicates that Anopheles darlingi, the main malaria vector in the region, is frequently found in fish ponds along the Iquitos-Nauta road (Loreto, Peru). The aim of this study was to quantify the effect of fish pond density on malaria occurrence. METHODS: A retrospective 30-month cohort study was conducted in eight communities along the Iquitos-Nauta road. Malaria incidence was ascertained from malaria registries of the local health post, which consist of data from both active and passive surveillance (247 cases). Fish pond density was measured using an interpreted satellite image and information on potential confounders was collected through interviewer-administered questionnaires. RESULTS: A total of 1018 individuals from 234 eligible households (90% of the 259 total number of households in the study area) provided complete information on exposures and outcome. Fish pond density was found to be a significant predictor of malaria occurrence (aOR=1.23; 95% CI: 1.09-1.38). CONCLUSION: The association between fish pond density and malaria suggests that fish ponds contribute to malaria transmission in the region. These results have important implications for the prevention and control of malaria and the development of pisciculture as an important economic activity in Amazonia and beyond.

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