Five healthy volunteers will be repeatedly exposed to L3 Necator americanus larvae after which two skin biopsies will be taken. Three of the volunteers will be treated two weeks after each infection after which the study will end after 13 weeks. Two of the volunteers will retain the infection for up to two years and will be asked to donate stool samples.

Five volunteers will be exposed to 50 Necator americanus L3 larvae, after which they will be treated with a curative regimen of albendazole after two weeks. Then, they will be inoculated with a lower dose of 10 L3 larvae concentrated on one spot, followed by two skin biopsies (one at the inoculation site, the other one serving as a negative control). Subsequently, participants will be treated with albendazole at week 5, except for the participants who have volunteered to become chronic donors. For chronic donors, patency of infection will be assessed and infections repeated (max dose 50 L3 larvae at one time) until egg outputs are >1500 eggs per gram (epg) at the start of the donor phase. If necessary, top-up inoculations can be performed in the donor phase as well when the egg-output is too low for the requested experiments.

Inclusion Criteria:

In order to be eligible to participate in this study, a subject must meet all of the following criteria:

1. Subject is aged ≥ 18 and ≤ 45 years and in good health.
2. Subject has adequate understanding of the procedures of the study and agrees to abide strictly thereby.
3. Subject is able to communicate well with the investigator, is available to attend all study visits.
4. Subject agrees to refrain from blood donation to Sanquin or for other purposes throughout the study period.
5. Subject agrees to refrain from travel to a hookworm endemic area during the course of the trial.
6. Subject has signed informed consent (note: there are different informed consent forms for group A- and B participants).

Additional inclusion criteria for group B participants:

1. Agrees to remain infected and to commit to study procedures and rules
2. Agrees to refrain from blood donation to Sanquin or for other purposes throughout the study period.
3. Agrees to refrain from travel to a hookworm endemic area during the course of the trial.
4. Minimum egg output of 1500 epg at the start of the donor phase.
5. Does not meet any of the criteria for withdrawal outlined in section 8.4.

Exclusion Criteria:

A potential subject who meets any of the following criteria will be excluded from participation in this study:

1. Any history, or evidence at screening, of clinically significant symptoms, physical signs or abnormal laboratory values suggestive of systemic conditions, such as cardiovascular, pulmonary, renal, hepatic, neurological, dermatological, endocrine, malignant, haematological, infectious, immune-deficient, psychiatric and other disorders, which could compromise the health of the volunteer during the study or interfere with the interpretation of the study results. These include, but are not limited to, any of the following:

   • positive HIV, HBV or HCV screening tests;
   • the use of immune modifying drugs within three months prior to study onset (inhaled and topical corticosteroids and oral anti-histamines exempted) or expected use of such during the study period;
   • having one of the following laboratory abnormalities: ferritine <10ug/L, transferrine <2.04g/L or Hb <6.5 mmol/L for females or <7.5 mmol/L for males.
   • history of malignancy of any organ system (other than localised basal cell carcinoma of the skin), treated or untreated, within the past 5 years;
   • any history of treatment for severe psychiatric disease by a psychiatrist in the past year;
   • history of drug or alcohol abuse interfering with normal social function in the period of one year prior to study onset;
   • inflammatory bowel syndrome;
   • regular constipation, resulting in bowel movements less than three times per week.

2. Known hypersensitivity to or contra-indications for use of albendazole, including comedication known to interact with albendazole metabolism (e.g. carbamazepine, phenobarbital, phenytoin, cimetidine, theophylline, dexamethasone).

3. Known allergy to amphotericin B or gentamicin.

4. For female subjects: positive urine pregnancy test at screening

5. Positive faecal qPCR for hookworm at screening, any known history of hookworm infection or treatment for hookworm infection.

6. Being an employee or student of the study team.

7. Current or past scars, tattoos, or other disruptions of skin integrity at the intended site of larval application.

8. increased risk of complications after skin biopsy (e.g. use of anticoagulants, immunosuppressive medication or having tattoo's in the biopsy region).

9. Any condition or situation that could influence the independent consent of participant (e.g. being a direct colleague or family member of study personnel).

10. Any other condition or situation that would, in the opinion of the investigator, place the participant at an unacceptable risk of injury or render the participant unable to meet the requirements of the protocol or would compromise the integrity of the data.

Additional exclusion criteria for group B participants:

1. For female subjects: pregnancy as determined by positive urine hCG measured before stool donation.
2. Having one of the following laboratory abnormalities: ferritin <10ug/L, transferrin <2.04g/L or Hb <7.0mmol/L for females or <8.0mmol/L for males.
3. Positive HIV, HBV or HCV screening tests before donation.