Spontaneous Antigenemia in Loiasis

Study Overview
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Brief Summary
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This prospective study will enroll and follow 60 loiasis patients with high worm burden to monitor the spontaneous release of filarial antigen in peripheral blood. This study will define the cross-reactive antigen profile of persons with spontaneous loiasis antigenemia, and determine whether it varies with time.

Detailed Description
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Global efforts to eradicate lymphatic filariasis (LF) depend on rapid diagnostic tests (RDTs) that detect Wuchereria bancrofti circulating filarial antigen but these tests are unreliable in African nations where Loa loa is co-endemic because they yield false-positive results in some individuals with loiasis. The goals of this project are to define the cross-reactive antigen profile of persons with spontaneous antigenemia, how it varies over time, and to determine which L. loa antigens in cross-reactive sera best distinguish loiasis cross-reactivity from LF. This prospective study will prospectively enroll 50 adults who presented with cross-reactive antigenemia at screening and 10 negative controls. Participants will followed for one year and tested every three months for persistence of antigenemia.

Official Title
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Spontaneous Antigenemia in Loiasis, A Study of the Loiasis Antigens Responsible for Cross-reactivity in the Rapid Diagnostic Test for Lymphatic Filariasis

Conditions
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Loiasis, Lymphatic Filariasis

Intervention / Treatment
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* Other: No intervention


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ability to give informed consent Loiasis Mf count > 20,000 Mf/mL Resident of study area No evidence of severe or systemic comorbidities Consent to storage of blood samples for future study Exclusion Criteria: Subject plans to move from the study area during subsequent 12 months

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Cross-reactive loiasis<br>This cohort will prospectively enroll 50 adults (age 18+) with cross-reactive antigenemia based on a positive filariasis test strip (FTS) and L. loa Mf counts >20,000 Mf/mL. | Other: No intervention<br>* Patients in these cohorts will not be given anti-filariasis therapies because these drugs are not approved for use in patients with high worm burdens (>20,000 Mf/mL)<br>|
| non-cross-reactive loiasis<br>This cohort will prospectively enroll 10 adults (age 18+) with a negative filariasis test strip (FTS) and L. loa Mf counts >20,000 Mf/mL. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| prevalence of specific cross-reactive L. loa antigens at baseline | Prevalence of filariasis test strip (FTS) positive individuals at screening. Cross-reactive proteins in plasma will be identified by mass-spectrometry to identify a cross-reactive biomarker | 1 day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Recurrence of cross-reactive antigenemia | To determine if the same antigens are present at each follow up | quarterly for 1 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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diagnostics, cross-reactivity