White spot syndrome virus (WSSV) prevalence in wild and aquaculture crustacean populations from Mozambique, assessed by molecular diagnosis

Abstract

White spot syndrome virus (WSSV) is still one of the most dangerous viral pathogens in crustacean aquaculture since its first identification in 1992, especially for tropical and subtropical countries. In Mozambique, WSSV was first detected in 2011 in cultured shrimp after mass mortality of shrimp in ponds. To control the virus, disease surveillance is the most recommended approach. The aim of this study was to report WSSV infection in crustaceans from wild stock and farms in Mozambique. Frozen and fresh samples of pleopods, larvae, and muscle from shrimp and crabs collected in seven provinces of Mozambique between 2011 and 2013, and in 2018, were tested for WSSV using the commercial IQ2000™ kit. A total of 946 out of 3480 tested samples were WSSV positive and it corresponds to a total prevalence of 27.2% in crustaceans. The infection rate was 31.6% (723samples) in wild shrimps, 21.8% (152) in wild crabs, and 14.4% (71) in aquaculture shrimps. The positivity infection rate varied within the sampling provinces. The highest infection rate was reported in Gaza (61.43%) followed by Inhambane and Zambezia (45.79 and 40%, respectively). The lowest prevalence of WSSV was reported in Cabo Delgado (2.99%). This study demonstrated the presence of WSSV in Mozambique in high prevalence in both wildlife and aquaculture crustaceans, demonstrating the need for constant monitoring and implementation of preventive measures to decrease the rates of positive infectivity both in the wild and aquaculture crustaceans.