Micronutrients and Leptospirosis: A Review of the Current Evidence

<div><p>Background</p><p>Leptospirosis is one of the most widespread zoonoses and represents a major threat to human health. Due to the high burden of disease, limitations in diagnostics, and limited coverage and availability of effective human and veterinary vaccines, leptospirosis remains an important neglected zoonotic disease. Improved surveillance and identification of modifiable risk factors for leptospirosis are urgently needed to inform preventive interventions and reduce the risk and severity of <i>Leptospira</i> infection.</p><p>Methodology/Principal Findings</p><p>This review was conducted to examine the evidence that links micronutrient status and <i>Leptospira</i> infection. A total of 56 studies were included in this review: 28 in vitro, 17 animal, and 11 observational human studies. Findings indicated that <i>Leptospira</i> infection is associated with higher iron and calcium concentrations and hypomagnesemia.</p><p>Conclusions/Significance</p><p>Few prospective studies and no randomized trials have been conducted to date to examine the potential role of micronutrients in <i>Leptospira</i> infection. The limited literature in this area constrains our ability to make specific recommendations; however, the roles of iron, calcium, and magnesium in leptospirosis represent important areas for future research. The role of micronutrients in leptospirosis risk and severity needs to be elucidated in larger prospective human studies to inform public health interventions.</p></div

Search strategy: A diagrammatic representation of the retrieval strategy used for identifying and selecting studies for inclusion in the final analysis.

<p>Search strategy: A diagrammatic representation of the retrieval strategy used for identifying and selecting studies for inclusion in the final analysis.</p

Social-ecological factors and preventive actions decrease the risk of dengue infection at the household-level: Results from a prospective dengue surveillance study in Machala, Ecuador

<div><p>Background</p><p>In Ecuador, dengue virus (DENV) infections transmitted by the <i>Aedes aegypti</i> mosquito are among the greatest public health concerns in urban coastal communities. Community- and household-level vector control is the principal means of controlling disease outbreaks. This study aimed to assess the impact of knowledge, attitudes, and practices (KAPs) and social-ecological factors on the presence or absence of DENV infections in the household.</p><p>Methods</p><p>In 2014 and 2015, individuals with DENV infections from sentinel clinics in Machala, Ecuador, were invited to participate in the study, as well as members of their household and members of four neighboring households located within 200 meters. We conducted diagnostic testing for DENV on all study participants; we surveyed heads of households (HOHs) regarding demographics, housing conditions and KAPs. We compared KAPs and social-ecological factors between households with (n = 139) versus without (n = 80) DENV infections, using bivariate analyses and multivariate logistic regression models with and without interactions.</p><p>Results</p><p>Significant risk factors in multivariate models included proximity to abandoned properties, interruptions in piped water, and shaded patios (p<0.05). Significant protective factors included the use of mosquito bed nets, fumigation inside the home, and piped water inside the home (p<0.05). In bivariate analyses (but not multivariate modeling), DENV infections were positively associated with HOHs who were male, employed, and of younger age than households without infections (p<0.05). DENV infections were not associated with knowledge, attitude, or reported barriers to prevention activities.</p><p>Discussion</p><p>Specific actions that can be considered to decrease the risk of DENV infections in the household include targeting vector control in highly shaded properties, fumigating inside the home, and use of mosquito bed nets. Community-level interventions include cleanup of abandoned properties, daily garbage collection, and reliable piped water inside houses. These findings can inform interventions to reduce the risk of other diseases transmitted by the <i>Ae</i>. <i>aegypti</i> mosquito, such as chikungunya and Zika fever.</p></div

A map of the study site and distribution of study households.

<p>(A) Location of Ecuador in the Americas (B) location of the city of Machala, El Oro Province, Ecuador, (C) and the distribution of households surveyed in this study. Household locations were aggregated to the neighborhood level for de-identification. Some clusters (5 households) have been disaggregated across block boundaries. This figure was created in ArcGIS version 10.3.1 (ESRI, 2016) using shape files from the GADM database of Global Administrative Areas, version 2.8, freely available at <a href="http://gadm.org" target="_blank">gadm.org</a>. Streets are derived from data available at the OpenStreetMap project (<a href="http://openstreetmap.org" target="_blank">openstreetmap.org</a>) for the municipality of Machala, El Oro, Ecuador. Neighborhood polygons were manually digitized by AMSI, and the shape file data are available upon request to the authors.</p

Multivariate logistic regression model of predictors of acute or recent DENV infections in the household.

<p>Multivariate logistic regression model of predictors of acute or recent DENV infections in the household.</p

Characteristics of cities where collections were performed.

Population data rounded from [17]. Arboviral transmission data from [16].</p

KAPs in households with versus without acute or recent DENV infections.

<p>KAPs in households with versus without acute or recent DENV infections.</p

Social-ecological factors in households with versus without acute or recent DENV infections.

<p>Social-ecological factors in households with versus without acute or recent DENV infections.</p

Total number of pools of adult male and female <i>Ae</i>. <i>aegypti</i> tested (and positive for ZIKV) for each city and year.

Total number of pools of adult male and female Ae. aegypti tested (and positive for ZIKV) for each city and year.</p

Number of dengue and Zika cases in Ecuador, 2015–2022.

Number of dengue and Zika cases in Ecuador, 2015–2022.</p