Effect of ingestion and waterborne routes under different shrimp densities on white spot syndrome virus susceptibility in three commercially important penaeid shrimps

Investigation into white spots in the carapace of a moribund mud crab (Scylla serrata) from a white spot syndrome virus (WSSV) positive zone in Moreton Bay, Australia

“…These were smaller than the white lesions seen grossly in the underside of the carapace; however, shrinkage during fixation and processing may explain some of this difference. In contrast, Scylla serrata from fattening pens in India that were WSSV‐infected also presented with white spots on the inner carapace surface, 15,16 but were WSSV‐PCR positive. Similarly, moribund and dead S. tranquebarica infected with WSSV displayed white spots under the carapace, while active crabs did not have such spots 17 .…”

“…A few years later, another study in India reported 90% mortality with no external signs of infection in experimentally infected S. serrata (20–50 g) fed WSSV infected shrimp tissue 14 . In contrast, two more recent studies from India have reported white spots on the inner carapace of moribund mud crabs associated with mortality rates of 11% and 90%, respectively, in captive S. serrata (500–740 g) naturally infected with WSSV 15,16 …”

“…with white spots under the carapace were from cultured crabs infected with WSSV. [15][16][17] Cultured crabs are captive and thus would be available for inspection at all stages of the moult cycle, but it is also possible that these observations suggest cultured crabs infected with WSSV are more susceptible to disease during the moulting process.…”

“…14 In contrast, two more recent studies from India have reported white spots on the inner carapace of moribund mud crabs associated with mortality rates of 11% and 90%, respectively, in captive S. serrata (500-740 g) naturally infected with WSSV. 15,16 In May 2018, a mud crab (S. serrata) was found freshly deceased in shallow water in Pumicestone Passage, northern Moreton Bay. Upon dissection, the dead crab exhibited multiple white spots under the carapace, which were grossly similar to cuticular lesions described in S. serrata and Scylla tranquebarica infected with WSSV in India.…”

“…Upon dissection, the dead crab exhibited multiple white spots under the carapace, which were grossly similar to cuticular lesions described in S. serrata and Scylla tranquebarica infected with WSSV in India. [15][16][17] Here we describe the results from an investigation into the cause of death of the S. serrata found in Pumicestone Passage.…”