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
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