Survival of first stage larvae (L1) of Angiostrongylus vasorum under various conditions of temperature and humidity.

This experiment has been conducted to evaluate the viability of Angiostrongylus vasorum L1 under different conditions of temperature and humidity. In order to assess the viability, fox faecal pellets containing first stage larvae (L1) were exposed to relative humidity (RH) 95% and 75%, and to different temperatures (5°C, 18°C) and at fluctuating conditions ranging from -5°C to +5°C. Moreover, larval viability under outdoor conditions in April was also observed. Survival of the larvae was strongly influenced by temperature; however, humidity did not show any significant influence on viability. In controlled condition, 100% of the larvae were found motile and active; whereas, around 14% and 19% of the larvae kept at 5°C remained viable at RH 95% and RH 75%, respectively after 78 h. All of the larvae kept at 18°C died after 66 h. In outdoor condition, larval survivability reduced to 18% after 66 h, and in fluctuation temperature viable larvae were observed in both control and experimental conditions (15%) after 78 h.