A role of polychaetes in transmission of white spot syndrome virus in shrimp ponds?

White spot disease (WSD) is caused by white spot syndrome virus (WSSV) (Nimaviridae). WSSV emerged in the early-to-mid 1990s in Southeast Asia and became panzoonotic since. The disease can be mitigated by introducing rigorous sanitation protocols, proper pond management, use of specific pathogen-free shrimp and by early diagnosis followed by eradication. The virus is transmitted horizontally by healthy individuals predating on diseased ones, via feeding on detritus or by intake of WSSV-contaminated water. WSSV can also be transmitted vertically via broodstock. The virus infects a wide range of crustaceans beyond the penaeids such as crabs and crayfish, and these co-inhabitants of ponds form a reservoir of WSSV for disease transmission to penaeids. Much less knowledge is there on the potential of resident benthic organisms as vectors for WSSV. A literature survey indicates that WSSV is present in a number of non-crustacean invertebrates, which sometimes vector the disease to penaeid shrimp. Dendronereis spp. is a most ubiquitous resident annelid in shrimp ponds and used as food source for shrimp. We showed that WSSV replicates in Dendronereis spp. and can be transmitted from this polychaete to penaeid shrimp. Furthermore there appears to be a positive correlation between the past incidence of WSD in ponds and the occurrence of WSSV in resident Dendronereis spp, whereas there is no correlation with other pond parameters. We hypothesize that Dendronereis spp., as a replicative host for WSSV, may serve as a reservoir for WSSV and may be associated with the persistence of this virus in pond systems.