[Parasitism and corticosteronemy in rats during repeated infestations with Strongyloides ratti].

The greater the number of larvae, the lower the possibilities of superinfestation when rats are repeated exposed to contact with Strongyloides ratti larvae, once a week or every two days for periods of up to twenty-four days: super-infestations occurs only on the 2nd day (10,000 larvae), the 4th day (5,000 larvae) and the 9th day (1,000 larvae). However, superinfestation continues throughout the entire duration of the experiment (46 days) when contamination is very low (10 larvae). Although there is now superinfestations, each new contact with larvae produces a hypercorticosteronemia reaction. Thus, the immunity acquired, although it is rapidly capable of preventing the larvae from reaching adulthood, does not prevent the larvae from beginning their migration and triggering the reaction. Progressively and slowly, this cortico-adrenal reaction decreases. It no longer takes place after 3 weeks of weekly infection by 10,000 larvae of after 2 weeks of bi-daily infection by 10,000 or 5,000 larvae. The reactional hypercorticosteronemia which follows an infestation does not intensify after repeated infections, whatever their frequency or intensity.