Hookworm Infection
Conditions
Keywords
Hookworm, Allergy, Vaccine, Skin Test, Immediate-type hypersensitivity to Na-ASP-2 hookworm antigen
Brief 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.
Interventions
BIOLOGICALNa-ASP-2 Skin Test Reagent
Na-ASP-2 Hookworm Skin Test Reagent, 1-1000 mcg/mL solution
Sponsors
Albert B. Sabin Vaccine Institute
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
DIAGNOSTIC
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 45 Years
Healthy volunteers
Yes
Inclusion criteria
* Males and females between 6 and 45 years of age, inclusive, at the time of consenting to the parent study. * Age greater than or equal to 18 years at the time of signing the supplemental informed consent document for the skin test procedure (parent study). * Willingness to participate in the study as evidenced by signing the informed consent or assent document.
Exclusion criteria
* Inability to correctly answer all questions on the informed consent comprehension questionnaire. * Attends school or works full-time outside of the study area. * Behavioral, cognitive, or psychiatric disease that in the opinion of the investigator affects the ability of the volunteer to understand and cooperate with the study protocol. * Other condition that in the opinion of the investigator would jeopardize the safety or rights of a volunteer to participate in the trial or would render the subject unable to comply with the protocol. * Pregnancy as determined by a positive urine hCG test (if female). * Use of corticosteroids (excluding topical or nasal) or immunosuppressive drugs within 30 days of planned skin test application. * Extensive dermatitis precluding skin testing. * Current use of a beta blocker (oral or topical) or anti-histamine medication. A volunteer may participate in the study if they agree to withhold use of an anti-histamine for at least 5 days prior to application of the skin test. * Use of a tricyclic anti-depressant within the past month.
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Size of Wheal Diameter at Site of Skin Test Application, Measured 15 Minutes After Injection | 15 minutes after skin test application |
Secondary
| Measure | Time frame |
|---|---|
| Anti-Na-ASP-2 IgE Antibody Level on Day of Skin Test Reaction | Upon skin testing |
Countries
Brazil
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Na-ASP-2 Hookworm Antigen Skin Test All participants will be skin tested with Na-ASP-2 skin test reagent (1000 mcg/ml recombinant Na-ASP-2) applied to their arms, using both the prick-puncture and intradermal techniques. | 87 |
| Total | 87 |
Baseline characteristics
| Characteristic | Na-ASP-2 Hookworm Antigen Skin Test |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 87 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 87 Participants |
| Region of Enrollment Brazil | 87 Participants |
| Sex: Female, Male Female | 48 Participants |
| Sex: Female, Male Male | 39 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | — / — |
| other Total, other adverse events | 0 / 87 |
| serious Total, serious adverse events | 0 / 87 |
Outcome results
Primary
Size of Wheal Diameter at Site of Skin Test Application, Measured 15 Minutes After Injection
Time frame: 15 minutes after skin test application
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Na-ASP-2 Hookworm Antigen Skin Test | Size of Wheal Diameter at Site of Skin Test Application, Measured 15 Minutes After Injection | 3.5 cm |
Secondary
Anti-Na-ASP-2 IgE Antibody Level on Day of Skin Test Reaction
Time frame: Upon skin testing
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Na-ASP-2 Hookworm Antigen Skin Test | Anti-Na-ASP-2 IgE Antibody Level on Day of Skin Test Reaction | 1.89 kU/L |