Epidemiology of Polyparasitism in Coastal Kenya: Determinants, Interactions and Health Effects of Plasmodium Species and Schistosoma Haematoubium Infections

Concurrent infections with multiple parasites are common in human populations inhabiting tropical regions of the world. Although morbidities associated with single parasite infections are well-established, much less is known about the risk factors for co-infection, the epidemiological and biological associations among parasite species, or the related health effects of polyparasitism. This cross-sectional study of Plasmodium species and Schistosoma haematobium co-infections among people in a rural village of coastal Kenya was conducted to address some of these questions. Predictors of polyparasitic infections were identified within the social, environmental and spatial context of households. The relative importance of individual- versus household-level factors in predicting parasite infection also was examined using multi-level modeling techniques, thereby providing insights into mechanisms by which socio-economic position (SEP) and other factors might influence disease risk. In addition, evidence for biologically meaningful associations between parasites was evaluated after adjustment for household clustering of individuals. Finally, potential synergistic relationships between these infections and their effects on anemia and stunting in children were assessed. Results revealed a heavy burden of parasitic infection in this population, especially in children. Intense Plasmodium species and S. haematobium infections were found to cluster in a subset of children with suggestions of synergistic effects on anemia and stunting. Determinants of heavy infections were age-specific and included household SEP. Individual-level characteristics explained much more of the household-level variation in infection than did household-level variables. Finally, analyses of species-specific Plasmodium infections demonstrated fewer co-infections that expected by chance, suggesting the presence of cross-species interaction. This research highlights the unacceptable burden of parasitic disease in tropical regions of the world, and suggests that integrated control efforts which consider multiple infections, and which are targeted at school-aged children, should maximize disease reduction under resource-limited conditions.Ph.D.Epidemiological ScienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/63645/1/lflorey_1.pd

Feeding tree preference of Yellow-bellied Sapsuckers, Sphyrapicus varius varius, based on tree species and size, at UMBS, Chebogyan County, lower northern Michigan.

This study examined the frequency of sapwells on different species of trees at the University of Michigan Biological Station, Cheboygan County, Michigan (45 33'30.370""N,84 40'27.516""W;T37N,R3W,Sec.33), in order to show species and size specific preferences of Yellow-bellied Sapsuckers (Sphyrapicus varius varius) for sap trees. Four 20 m by 20 m quadrats were selected randomly from points along two crossing transect lines that intersected at the nest tree. In these quadrats, trees with a diameter at brease height (dbh) over 20 cm were censused and presence or absence of sapwells, indicating sapsucker feeding, was recorded. Results suggested that sapsuckers preferred Scotch pines (Pinus sylvestris) as feeding trees but no preferences for tree sizes were revealed. These results contribute to the morass of findings on sapsucker feeding preferences. These studies suggest that feeding preferences vary based on many factors including tree species, tree size, sap flow, sap sucrose content, location, season and the availability of other food sources. Examining Yellow-bellied Sapsucker feeding tree preference highlights the interconnectedness of ecosystems.http://deepblue.lib.umich.edu/bitstream/2027.42/54725/1/3166.pdfDescription of 3166.pdf : Access restricted to on-site users at the U-M Biological Station

Impact evaluation of malaria control interventions on morbidity and all-cause child mortality in Mali, 2000–2012

Abstract Background Major investments have been made since 2001, with intensification of malaria control interventions after 2006. Interventions included free distribution of insecticide-treated nets (ITN) to pregnant women and children under 5 years old, the introduction of artemisinin combination therapy (ACT) for malaria treatment, and indoor residual spraying of insecticides. Funders include the Government of Mali, the Global Fund to Fight AIDS, Tuberculosis and Malaria, and the US President’s Malaria Initiative. Methods Data from nationally representative household surveys conducted from 2000 to 2015 was used to performed the trend analysis for malaria intervention coverage, prevalence of morbidities among children under 5 years old [parasitemia and severe anaemia (< 8 g/dl)], and all-cause mortality of children under 5 (ACCM). Prevalence of contextual factors likely to contribute to ACCM were also assessed. The impact of these interventions was assessed on malaria morbidity and mortality using a plausibility argument. With the assumption that malaria contributes significantly to under-five mortality in settings with high malaria transmission, associations between malaria control interventions and all-cause under-five mortality (ACCM) were assessed taking into account other contextual factors related to child survival. Results Intervention coverage improved significantly from 2006 to 2012. Household ownership of ITN increased from 49% in 2006 to 84% in 2012. ITN use also increased over the same period, from 26% in 2006 to 69% in 2012 among children under 5 and from 28% in 2006 to 73% in 2012 among pregnant women. The coverage of intermittent preventive treatment in pregnancy (IPTp) using two or more doses of SP increased from 10% in 2006 to 29% in 2012. In 2010, 23% of febrile children under 5 received ACT, as opposed to 19% in 2012. The prevalence of Plasmodium falciparum infection increased from 2010 (38.6%) to 2012 (51.6%), followed by a decrease in 2015 (35.8%). The prevalence of severe anaemia decreased from 2010 (26.3%) to 2012 (20.6%) and continued to decline in 2015 (19.9%). An impressive decline in ACCM was observed, from 225 in 1997–2001 to 192 in 2002–2006 and 95 in 2008–2012. Changes in contextual factors such as climate, socio-economic, nutrition, and coverage of maternal and child health interventions over the evaluation period did not favour reductions in ACCM, and are therefore unlikely to explain the observed results. Conclusions Taken as a whole, the evidence supports the conclusion that malaria control interventions substantially contributed to the observed decline in ACCM in Mali from 2000 to 2012, even in the context of continued high prevalence of parasitaemia explained by contextual factors such as climate change and political instability

A renewed focus on preventing malaria in pregnancy

Abstract While much progress has been achieved globally in the fight against malaria, the significant financial investments made to date have not translated into scaled-up malaria in pregnancy (MiP) prevention efforts. Mothers and newborns remain at risk, and now is the time to refocus efforts. Against the backdrop of a new global health architecture embodied by the principles of Every Women, Every Child and driven by the work of the H6 Partnership, Global Financing Facility, strong bilaterals and key financiers, there is a new and timely juncture to advocate for MiP. Recent updates in the WHO Recommendations on Antenatal Care for a Positive Pregnancy Experience present an opportunity to strengthen MiP as a core maternal and child health issue and position MiP prevention as a priority

Impact of Malaria Control on Mortality and Anemia among Tanzanian Children Less than Five Years of Age, 1999-2010.

Mainland Tanzania scaled up multiple malaria control interventions between 1999 and 2010. We evaluated whether, and to what extent, reductions in all-cause under-five child mortality (U5CM) tracked with malaria control intensification during this period.Four nationally representative household surveys permitted trend analysis for malaria intervention coverage, severe anemia (hemoglobin <8 g/dL) prevalence (SAP) among children 6-59 months, and U5CM rates stratified by background characteristics, age, and malaria endemicity. Prevalence of contextual factors (e.g., vaccination, nutrition) likely to influence U5CM were also assessed. Population attributable risk percentage (PAR%) estimates for malaria interventions and contextual factors that changed over time were used to estimate magnitude of impact on U5CM.Household ownership of insecticide-treated nets (ITNs) rose from near zero in 1999 to 64% (95% CI, 61.7-65.2) in 2010. Intermittent preventive treatment of malaria in pregnancy reached 26% (95% CI, 23.6-28.0) by 2010. Sulfadoxine-pyrimethamine replaced chloroquine in 2002 and artemisinin-based combination therapy was introduced in 2007. SAP among children 6-59 months declined 50% between 2005 (11.1%; 95% CI, 10.0-12.3%) and 2010 (5.5%; 95% CI, 4.7-6.4%) and U5CM declined by 45% between baseline (1995-9) and endpoint (2005-9), from 148 to 81 deaths/1000 live births, respectively. Mortality declined 55% among children 1-23 months of age in higher malaria endemicity areas. A large reduction in U5CM was attributable to ITNs (PAR% = 11) with other malaria interventions adding further gains. Multiple contextual factors also contributed to survival gains.Marked declines in U5CM occurred in Tanzania between 1999 and 2010 with high impact from ITNs and ACTs. High-risk children (1-24 months of age in high malaria endemicity) experienced the greatest declines in mortality and SAP. Malaria control should remain a policy priority to sustain and further accelerate progress in child survival

Impact evaluation of malaria control interventions on morbidity and all-cause child mortality in Rwanda, 2000-2010

The impressive decline in child mortality that occurred in Rwanda from 1996-2000 to 2006-2010 coincided with a period of rapid increase of malaria control interventions such as indoor residual spraying (IRS); insecticide-treated net (ITN) distribution and use, and improved malaria case management. The impact of these interventions was examined through ecological correlation analysis, and robust decomposition analysis of contextual factors on all-cause child mortality. Child mortality fell 61% during the evaluation period and prevalence of severe anemia in children 6-23 months declined 71% between 2005 and 2010. These changes in malaria morbidity and mortality occurred concurrently with a substantial increase in vector control activities. ITN use increased among children under five, from 4% to 70%. The IRS program began in 2007 and covered 1.3 million people in the highest burden districts by 2010. At the same time, diagnosis and treatment with an effective antimalarial expanded nationally, and included making services available to children under the age of 5 at the community level. The percentage of children under 5 who sought care for a fever increased from 26% in 2000 to 48% in 2010. Multivariable models of the change in child mortality between 2000 and 2010 using nationally representative data reveal the importance of increasing ITN ownership in explaining the observed mortality declines. Taken as a whole, the evidence supports the conclusion that malaria control interventions contributed to the observed decline in child mortality in Rwanda from 2000 to 2010, even in a context of improving socioeconomic, maternal, and child health conditions

Measuring malaria diagnosis and treatment coverage in population-based surveys: a recall validation study in Mali among caregivers of febrile children under 5 years

Abstract Background Nationally-representative household surveys are the standard approach to monitor access to and treatment with artemisinin-based combination therapy (ACT) among children under 5 years (U5), however these indicators are dependent on caregivers’ recall of the treatment received. Methods A prospective case–control study was performed in Mali to validate caregivers’ recall of treatment received by U5s when seeking care for fever from rural and urban public health facilities, community health workers and urban private facilities. Clinician-recorded consultation details were the gold standard. Consenting caregivers were followed-up for interview at home within 2 weeks using standard questions from Demographic and Health Surveys and Malaria Indicator Surveys. Results Among 1602 caregivers, sensitivity of recalling that the child received a finger/heel prick was 91.5%, with specificity 85.7%. Caregivers’ recall of a positive malaria test result had sensitivity 96.2% with specificity 59.7%. Irrespective of diagnostic test result, the sensitivity and specificity of caregivers’ recalling a malaria diagnosis made by the health worker were 74.3% and 74.9%, respectively. Caregivers’ recall of ACT being given had sensitivity of 43.2% and specificity 90.2%, while recall that any anti-malarial was given had sensitivity 59.0% and specificity 82.7%. Correcting caregivers’ response of treatment received using a combination of a visual aid with photographs of common drugs for fever, prescription documents and retained packaging changed ACT recall sensitivity and specificity to 91.5% and 71.1%, respectively. Conclusions These findings indicate that caregivers’ responses during household surveys are valid when assessing if a child received a finger/heel prick during a consultation in the previous 2 weeks, and if the malaria test result was positive. Recall of ACT treatment received by U5s was poor when based on interview response only, but was substantially improved when incorporating visual aids, prescriptions and drug packaging review

Trends in 5-year estimates of all-cause neonatal, infant, and under-five year mortality rates in Mainland Tanzania, 1990–2010.

<p>Footnote: Each rate presented as the mid-point of the five-year interval it reflects (e.g., 2010 survey, measuring mortality 2005–2009, was plotted at 2007). Mortality among children 1–59 months of age declined 54% between 1999 and 2010 (from 111 to 57 deaths per 1000 live births) compared to the 45% relative decline for the traditional 0–59 month age group described in text.</p

Conceptual framework for constructing an adequacy and plausibility assessment to support the Mainland Tanzania malaria impact evaluation.

<p>Conceptual framework for constructing an adequacy and plausibility assessment to support the Mainland Tanzania malaria impact evaluation.</p

Severe anemia prevalence and all-cause mortality (deaths per 1000 live births) according to age group (A) and (B) and malaria endemicity (C) and (D), respectively.

<p>Severe anemia prevalence and all-cause mortality (deaths per 1000 live births) according to age group (A) and (B) and malaria endemicity (C) and (D), respectively.</p