Predictive Factors of Households Positive for Lymphatic Filariasis after TAS-2/3 in Burkina Faso, Haiti, and Nepal Open Access

Lopes da Rosa-Spiegler, Jessica (Fall 2021)

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Lymphatic Filariasis (LF) is a vector-borne parasitic disease. In 2000, the World Health Organization (WHO) launched the Global Programme to Eliminate Lymphatic Filariasis (GPELF). Under WHO guidance, endemic countries implemented multiple rounds of mass drug administration (MDA) to interrupt LF transmission across their communities. The goal is to reduce transmission to a level where transmission is no longer sustainable, eventually resulting in eliminating LF as a public health problem. After several years of MDA, a surveillance program called Transmission Assessment Survey (TAS) is repeated 3 times, spanning 4-6 years. TAS-1 is used to determine when MDA can be stopped. Subsequently, TAS-2 and TAS-3 are used to monitor and evaluate that LF prevalence has not exceeded the threshold in the absence of chemotherapeutic intervention. Despite passing TAS benchmarks, many countries are finding LF- positive children who would have lived the majority of their lives during MDA. LF-positive children indicate that transmission is on-going, albeit at low levels. Some regions have failed TAS- 2 or TAS-3, indicating that interpretation of previous TAS results did not consider the full meaning of persistent LF-positive children at levels below the threshold. There is concern that isolated TAS-cases represent transmission "hotspots" or micro-foci. It is possible that TAS methodology is not sensitive enough, nor has enough predictive value, to consistently spotlight areas of focal transmission. If focal transmission is not detected, recrudescence of LF could occur. TAS-2/3 follow-up studies investigate the epidemiology associated with TAS-cases in regions that have passed TAS. This thesis seeks to determine if LF-positive children identified during TAS are indicators of "hotspots" in their communities. Specifically, the hypothesis tested is that households of TAS-cases are located within micro-foci with other households that have LF- positive individuals. The question tested is whether distance to the TAS-case household affects the likelihood that another household has at least one LF-positive member. logistical regression analysis on a sample population from Burkina Faso, Haiti and Nepal indicated that distance did not affect the likelihood that a household is LF-positive. However, the analysis yielded other predictive factors that could be applied to better surveille LF during TAS-2/3 follow-up.

Table of Contents

Chapter 1: Introduction 1

I. Introduction and Rational 1

II. Problem Statement 3

III. Theoretical Framework 4

IV. Purpose Statement 6

V. Research Question 7

VI. Significance 7

VII. Definition of Terms 8

Chapter 2: Review of Literature 12

I. Intervention 12

II. Diagnosis 13

III. Transmission Assessment Survey (TAS) 14

IV. LF Cases after MDA Years 16

Chapter 3: Methods 23

I. Introduction 23

II. Population and Sample 23

III. Research Design 26

IV. Instruments 27

V. Procedures 27

VI. Data Analysis 29

Chapter 4: Results 32

I. Description of Index-Community Households 32

II. Multi-Country Logistic Regression of Distance on CFA-Positivity 33

III. Logistic Regression of Distance on CFA-Positivity by Country 35

IV. Exploratory Analysis Including Index-Households 37

V. Exploratory Analysis of Households in Index and Neighbor Communities 38

Chapter 5: Discussion 57

I. Summary 57

II. Discussion of key Results 58

III. Limitations and Strengths 65

IV. Implications 67

V. Recommendations 68

VI. Conclusion 69

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