TRH and infection: The LD50 for RIMD2210633 was 10,000 CFU per larvae while the LD50 dose for EXE 04/2018 was 1000 CFU per larvae when the experiment was carried out at 37 °C indicating that VP 04/2018 was more virulent than the reference strain even without the presence of known virulence genes (tdh and trh) needed for human infection.