weighted weekly) of the infected shrimp was only 10–40% that of
the non-infected shrimp. Mortality attributed to EHP infection was
variable, with farm reports of a daily mortality of approximately 1–
2%. No significant mortality from EHP-infection has been reported
in a laboratory bioassay (Tangprasittipap et al., 2013), this may be
related to the short duration (7-day) of the bioassay. Severe infections
by EHP can increase the susceptibility for other bacterial
infections. We have found, in some cases, EHP infections were
accompanied by opportunistic infections of Vibrio spp. (named
septic hepatopancreatic necrosis, SHPN), and this could result in
increased mortalities.