Post-Mass Drug Administration Serological Assessment of Lymphatic Filariasis and Onchocerciasis in Plateau State, Nigeria Open Access

Castor, Rebecca (Spring 2020)

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Nigeria bears the highest burden in Africa for lymphatic filariasis (LF) and onchocerciasis, two vector-transmitted filarial diseases caused by Wuchereria bancrofti and Onchocerca volvulus, respectively. This study compared results of a novel Ov16/Wb123 biplex rapid antibody test with laboratory‐based ELISA for anti-Ov16 and anti-Wb123 antibodies and LF circulating filarial antigen (CFA) by immunochromatographic card test (ICT) during post-treatment surveillance for LF in 3 local government areas (LGAs) of Plateau State, Nigeria. From April to May 2016, finger-prick blood samples were collected from consenting individuals in school-based Transmission Assessment Surveys (TAS) of first and second year primary school children (approximately 6-7 years old) and community-wide household surveys of individuals >2 years of age in each LGA. Rapid tests (Ov16/Wb123 biplex and ICT) were conducted in the field; dried blood spots (DBS) were prepared for laboratory-based ELISA testing. A total of 6,854 individuals (median age: 7 range: 2-95) had matched demographic data and valid results from all laboratory tests. Overall prevalence estimates for LF CFA, and Wb123 by ELISA and biplex test were 0.13% (95% upper confidence limit [uCL]: 0.23), 1.75% (95% uCL: 2.03), and 0.13% (95% uCL: 0.23), respectively. CFA prevalence generally increased with age, whereas Wb123 prevalence by both ELISA and Biplex tended to be highest in children 5-9 and in the oldest age groups. Of the 9 samples positive for CFA by ICT, only one was positive for Wb123 antibody biplex positive and none were Wb123 ELISA positive. None of the 120 individuals positive by Wb123 ELISA were positive by Wb123 biplex or for CFA by ICT. Overall prevalence estimates for Ov16 by ELISA and biplex were 0.01% (95% uCL: 0.07) and 0.03% (95% uCL: 0.09), respectively. All Ov16-positive individuals were at least 50 years old. Compared to ELISA, the biplex rapid antibody test demonstrated good performance for Ov16, but poorer performance for Wb123. This study strongly suggests that transmission interruption of both diseases has been achieved in the study areas and provides important data on the age distribution of Wb123 and Ov16 in low transmission settings.

Table of Contents

Chapter I: Background 1

Lymphatic filariasis 2

History 3

Biology and Pathology 4

Diagnostic Tests 5

Global Elimination Program 9

Post Treatment Surveillance 12

Onchocerciasis 14

History 15

Biology and Pathology 15

Diagnostic Tests 17

Onchocerciasis Control Programs 18

Post-Treatment Surveillance 19

Chapter II: Manuscript 21

Introduction 22

Methods 25

Survey Design 25

Data Collection 26

Ethical Approval 28

Data Analysis 28

Results 29

Survey Demographics 29

Coverage of Lymphatic Filariasis Control Measures 30

Lymphatic filariasis and Onchocerciasis Descriptive Analysis 30

Household Risk Factor Analysis 33

Discussion 35

Tables and Figures 39

Chapter III: Summary, Public Health Implications, and Future Directions 54

Summary 55

Future Public Health Implications 56

Future Directions 56

References 57

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