Antigen-positive children as possible microfoci of transmission of lymphatic filariasis in low-prevalence areas of Haiti Public

Abstract

Lymphatic filariasis (LF) is a filarial infection associated with severe morbidity that is endemic in over 80 countries, including Haiti. Yet, LF is one of a handful of infectious diseases said to be nearing global elimination. Many populations endemic for LF have seen decreased prevalence over the last decade as availability and use of mass drug treatment has increased. In progression towards global elimination, the World Health Organization recommends that any area with prevalence greater than or equal to 1% should receive mass drug administration (MDA) for at least five consecutive rounds in order to interrupt transmission. It is believed, though not proven, that areas of low-prevalence pose little risk for continued transmission of LF. Five low-prevalence communes identified in the original nation-wide mapping of Haiti in 2001 were utilized in this study: Grand Goâve, Hinche, Moron, St. Louis de Sud and Thomazeau. An initial evaluation of schoolchildren was performed in each commune to help identify antigen-positive children, who could be indicators of transmission within their communities and act as focal points for the subsequent community survey. Two case definitions were employed to identify these sources: index cases (antigen-positive) and antigen-positive ELISA-based autochthonous (AEA) cases (confirmed infections known to be locally acquired). Global Positioning System coordinates and immunochromatographic tests were collected on approximately 1,600 persons of all ages in the five communes. The likelihood of antigen-positive cases being in proximity to index and AEA cases was evaluated using multivariate regression techniques and Bernoulli cluster analyses. Community surveys revealed higher antigen prevalence in three of the five communes than was observed in the original mapping effort. Regression techniques identified a statistically significant increased likelihood of being antigen-positive when living within 20 meters of either index or AEA cases when controlling for age, gender, and commune and spatial clustering of antigen-positive cases was observed in some, but not all communes. Such results indicate that localized transmission was occurring, even in low-prevalence settings. These results suggest that more robust surveillance may be needed in order to detect and extinguish lingering sources of transmission.

Table of Contents

CHAPTER 1: BACKGROUND AND LITERATURE REVIEW................1
CHAPTER 2: MANUSCRIPT..................................................14
ABSTRACT:.....................................................................15
INTRODUCTION:...............................................................16
METHODS:......................................................................20
RESULTS:.......................................................................25
DISCUSSION:................................................................. 28
CONCLUSIONS:................................................................35
TABLES AND FIGURES:......................................................38
CHAPTER 3: IMPLICATIONS................................................51
CHAPTER 4: EXPANDED ANALYSIS.......................................55
NARRATIVE:....................................................................56
TABLES:.........................................................................60
APPENDICES:...................................................................68
APPENDIX I: BACKGROUND AND LITERATURE REVIEW...............69
APPENDIX II: MANUSCRIPT.................................................70
REFERENCES....................................................................98

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Subfield / Discipline	Global Epidemiology - MPH & MSPH
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health
Mot-clé	lymphatic filariasis, low-prevalence, microfoci, spatial-clustering
Committee Chair / Thesis Advisor	Sullivan, Kevin M, Emory University
Committee Members	Lammie, Patrick, CDC
Partnering Agencies	CDC

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