Infectivity of Strongyloides venezuelensis is influenced by variations in temperature and time of culture.

The present research investigated the influence of temperature and time of larvae culture on the infectivity of Strongyloides venezuelensis. Mice were infected s.c. with 1500 larvae of S. venezuelensis maintained at 28°C for three days of culture (dc), 28°C for seven dc or 18°C for seven dc. On days 1, 3, 5, 7, 14 and 21 post-infection the animals were sacrificed and cell numbers in the blood, peritoneal cavity fluid (PCF), broncoalveolar fluid (BALF), cytokines, immunoglobulins, number of parasites and eggs/g of feces were quantified. Results demonstrated an increase in eosinophils and mononuclear cells in the blood, PCF and BALF of infected mice. Larvae at 28°C/3dc induced earlier eosinophils in the PCF and BALF as opposed to larvae at 28°C/7dc and 18°C/7dc. Larvae at 28°C/7dc induced higher synthesis of IL-4, IL-5 and IL-10 on days 5 and 7 post-infection. Larvae at 28°C/3dc in culture induced higher synthesis of IL-12 than larvae of seven dc, but time in culture induced better synthesis of IFN-γ after larval migration had ceased and only adult worms were present. Larvae at 28°C/3dc in culture induced higher synthesis of IgG and IgG1 and expelled less female parasites than larvae cultivated for seven days. In conclusion, it was observed that the infectivity of S. venezuelensis is influenced by variations in temperature and time of culture.