This project will be test the effect of probiotics on occupational allergic sensitization, respiratory symptoms and bronchial hyperresponsiveness in workers or students that develop respiratory symptoms exposed to laboratory animals, i.e., small rodents.

INTRODUCTION: The objective of the present project is to test the effect of probiotics on occupational allergic sensitization, respiratory symptoms and bronchial hyperresponsiveness in workers or students exposed to laboratory animals, i.e., small rodents.

Furthermore, our study aims to determine changes in immunological patterns with the use of probiotics in adulthood, which could prevent allergic sensitization and allergic diseases.

Probiotics have been used as treatment in various allergic diseases, especially as prevention of child atopic dermatitis by using them during pregnancy, or for neonates and infants.

STUDY DESIGN AND METHODS: This will be a randomized controlled trial involving laboratory animal workers and students exposed to rats, mice, hamsters, guinea pigs or rabbits. Subjects will be recruited in the laboratories of the University of S. Paulo and State University of Campinas (Unicamp). Exposed subjects will be randomly allocated to two groups: treatment and placebo. Both groups will be followed up for two years. Subjects will be evaluated at baseline, after one year and after two years.

Treatment: the intervention group will receive once daily capsules containing 109 CFU of Lactobacillus rhamnosus HN001, Lactobacillus paracasei Lpc-37 and Bifidobacterium animalis ssp. Lactis HN019 and the control group will receive once daily similar capsules containing placebo.

Procedures: blood sampling for blood cell counts, measurement of total IgE levels, specific immunoglobulin E (IgE) for rats, mice, hamsters, guinea pigs and rabbits; stool samples to test for parasites and for probiotic bacteria; skin prick test for animal allergens and common allergens, i.e. cockroaches, house dust mites, cats, dogs and mixed fungi; spirometry; and evaluation of bronchial responsiveness by bronchial challenge tests if the participant develop respiratory symptoms.

At the end of two years, changes in sensitization, bronchial responsiveness or symptoms in the treatment group compared to the placebo group will be considered the effect of probiotics.

Data analysis: group results will be compared by the chi-squared test regarding the prevalence of sensitization and other categorical variables. For continuous variables such as IgE levels, comparisons will be made by Student's t test. These analyses will be performed at the 1- and 2-year time points.

Inclusion Criteria:

• Older than 18 years, both sexes, ability to read, understand and to decide on protocol consenting.
• Participants should be healthy
• Animal handling for research purposes as part of regular activities as a worker or student.
• Planning to continue this activity for the next 2 years.

Exclusion Criteria:

• Previous laboratory animal handling for 15 days or longer. This exposure may have sensitized or selected people that are not susceptible to sensitizations.
• Sensitization to any laboratory animal (rat, mouse, hamster, guinea pig or rabbit).
• Allergic diseases that interfere with the evaluation of study variables.
• Using immunosuppressive drugs (ex: methotrexate, cyclosporine, leflunomide) or corticosteroids in immunosuppressive doses (e.g.: prednisone doses of 1.0 mg/kg/day or more).
• Cancer or treatment of neoplasia.
• Having diseases that cause immunosuppression such as diabetes, AIDS, renal failure, heart failure or other organ failure.
• Pregnancy, breastfeeding, or not willing to take necessary precautions to avoid a pregnancy during the study.
• Use of other probiotic products during the study.