Exploring Poverty-Related Risk Factors for Leprosy Transmission in a Highly Endemic Area of Brazil: Focus on Helminth Co-Infections and Micronutrients Público
Dennison, Cori (Spring 2019)
Abstract
Background: Although cases of leprosy have decreased over the past 20 years, there are still many obstacles to control the infection, especially in areas of hyperendemicity such as northeast Minas Gerais (MG), Brazil. Studies have shown that leprosy, as well as helminth infections, are associated with poverty. We hypothesized that in areas with higher rates of leprosy, helminth infections and micronutrient deficiencies are risk factors for continued leprosy transmission due to effects on the immune response leading to acquisition and spread of Mycobacterium leprae. Methods:This hypothesis was examined through a case-control study in Minas Gerais, Brazil. Participants were enrolled either as newly diagnosed cases or as one of two types of controls: household contacts and negative controls. Data were collected through surveys, clinical data, and stool specimens for helminth diagnosis and blood for micronutrient analyses. Analysis was conducted through univariate analysis,Chi-square testing, adjusted odds ratios and ultimately logistic regression controlling for socioeconomic status and micronutrient status.Results: This study recruited 75 cases and 148 controls. Schistosomiasis infection was found in 11.8% of cases and 5.2% of controls. When looking at micronutrient deficiencies, 21.7% of cases and 10.4% of controls had vitamin D deficiency. Multibacillary infection was the prominent classification identified (73.3%) with the majority having no disabilities associated with infection (60.0%). Themajority of cases in this study had at least primary education (71.4%) and lower income (92.0%). On multivariate analyses, cases were more likely to have schistosomiasis infection when compared to all controls (aOR = 3.60; 95% CI [1.06, 12.10]) and an even higher likelihood when compared to just household contacts (aOR = 6.56; 95% CI [1.16, 36.94]). When looking at micronutrient results, cases were more likely to have vitamin D deficiency compared to both control groups (aOR = 4.81; 95% CI [1.24, 18.72]). Conclusions: Through this case-control study we saw associations between schistosomiasis and vitamin D deficiency with leprosy. These results show the importance and relationship between co-infections and micronutrient deficiencies in the continued transmission of leprosy infection in endemic areas. Additionally, these associations could lead to potential combined control efforts in endemic areas for both schistosomiasis and leprosy infections.
Table of Contents
Chapter 1: Introduction……………………………………………... 1-2
Chapter 2: Literature Review……………………………………….. 3-9
Leprosy Immunology…………………………………..………... 3-4
Undernutrition and Leprosy………………………………..…… 4-5
Poverty Related Risk Factors and Leprosy……………………… 5-6
Schistosomiasis and Leprosy……………………………….…… 7-8
Study Relevance………………………………………………… 8-9
Chapter 3: Manuscript……………………………………………. 10-23
Abstract………………………………………………………. 10-11
Introduction……………………………...…………………... 11-15
Methods……………………………………………………… 15-19
Results………………………………………………………... 19-23
Discussion……………………………………………………. 20-24
Chapter 4: Implications and Recommendations....…………..….. 24-25
References………………………………………………………… 26-28
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