Prevalence of Hookworm Infection and Community Preparedness for Hookworm Vaccine Trials in Endemic Areas of Brazil
Condition: Hookworm Infection
MeSH terms: Infections; Communicable Diseases; Hookworm Infections; Ancylostomiasis
Study type: Interventional

Summary: 
      Na-ASP-2 is a protein expressed during the larval stage of the N. americanus hookworm life
      cycle. In a clinical study in previously hookworm-infected adults in Brazil, this protein
      induced urticarial reactions (rash) in a subset of volunteers. The clinical trial component
      of this study involves skin testing for immediate-type hypersensitivity to the Na-ASP-2
      Antigen. Both prick-puncture and intradermal tests will be applied.
    

Detailed description: 
      The clinical testing of the Na-ASP-2 Skin Test Reagent to detect Immediate-type
      hypersensitivity to the Na-ASP-2 hookworm antigen will be conducted as part of a larger,
      on-going observational study of the prevalence and intensity of hookworm infection currently
      underway in Brazil. Eligible adult participants (ages 18-45 years) in this observational
      study will be invited to undergo the skin testing procedure. Skin testing will only be
      performed if they agree and sign the supplemental informed consent form for this skin testing
      procedure.

        -  Study site: Americaninhas Vaccine Center, Americaninhas, Minas Gerais, Brazil

        -  Number of participants to be skin tested: approximately 150 adults

        -  Duration of the skin testing procedures: up to 1 month; each participant will undergo
           skin testing and a follow-up blood collection 21+/-7 days after skin testing.

        -  Each participant will have both skin prick-puncture and intradermal skin tests applied
           on the same study day. The prick-puncture and intradermal tests will be applied
           sequentially to the volar aspects of the participant's forearms:

             1. Skin prick-puncture: three different concentrations of Na-ASP-2 solution (10, 100,
                and 1000 μg/mL) will be applied sequentially in duplicate, to the left forearm.

             2. Intradermal: one concentration of Na-ASP-2 (100 μg/mL) will be injected, in
                duplicate, to the right forearm.

             3. Allergen diluent and histamine solutions will be utilized as the negative and
                positive controls, respectively, for both the skin prick-puncture and intradermal
                tests.

             4. Participants will be observed in the study clinic for at least 30 minutes following
                application of the skin tests, and will be examined 2 and 7 days following skin
                testing.

             5. Sizes of the wheal and erythema reactions for each application will be recorded and
                graded in comparison to the histamine positive control reaction.

        -  Each participant will have blood collected via venipuncture (a maximum of 25 mL)
           immediately prior to application of the skin tests, and between 2 and 4 weeks after skin
           testing, in order to measure antibodies (particularly IgG and IgE) to Na-ASP-2 using an
           ELISA procedure.
    

Intervention name(s): Na-ASP-2 Skin Test Reagent
Intervention type(s): Biological
Intervention description(s): Na-ASP-2 Hookworm Skin Test Reagent, 1-1000 mcg/mL solution
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: Hookworm; Allergy; Vaccine; Skin Test; Immediate-type hypersensitivity to Na-ASP-2 hookworm antigen