Risk factors associated with white spot syndrome virus infection in a Vietnamese rice-shrimpfarming system

Diseases of Aquatic Organisms

F. Corsin¹  N. T. N. Tinh¹  N. V. Hao¹  T. T. Phi¹  K. L. Morgan¹  J. F. Turnbull¹  L. H. Phuoc¹  C. V. Mohan¹ 

关键词: White spot disease;    Aquatic epidemiology;    Risk factors;    Penaeus monodon;    Rice-shrimp farming system;   

DOI  :  10.3354/dao047001

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: White spot disease (WSD) is a pandemic disease caused by a virus commonly known as white spot syndrome virus (WSSV). Several risk factors for WSD outbreaks have been suggested. However, there have been very few studies to identify risk factorsfor WSD outbreaks in culture systems. This paper presents and discusses the risk factors for WSSV infection identified during a longitudinal observational study conducted in a Vietnamese rice-shrimp farming system. A total of 158 variables were measuredcomprising location, features of the pond, management practices, pond bottom quality, shrimp health and other animals in the pond. At the end of the study period WSSV was detected in 15 of the 24 ponds followed through the production cycle (62.5%). Onehundred and thirty-nine variables were used in univariate analyses. All the variables with a p-value ≤0.10 were used in unconditional logistic regression in a forward stepwise model. An effect of location was identified in both univariate and multivanalyses showing that ponds located in the eastern portion of the study site, closer to the sea, were more likely to test positive for WSSV by 1-step PCR at harvest. Ponds with shrimp of a smaller average size 1 mo after stocking tended to be positivefor WSSV at the end of the production cycle. Average weight at 1 mo was also highlighted in multivariate analyses when considered as either a risk factor or an outcome. Other risk factors identified in univariate analyses were earlier date of stocking anduse of commercial feed. A number of variables also appeared to be associated with a reduced risk of WSSV at harvest including the presence of dead post larvae in the batch sampled at stocking, presence of Hemigrapsus spp. crabs during the firstmonth of production, feeding vitamin premix or legumes, presence of high numbers of shrimp with bacterial infection and the presence of larger mud crabs or gobies at harvest. No associations were detected with WSSV at harvest and stocking density,presence, or number or weight of wild shrimp in the pond. The multivariate model to identify outcomes associated with WSSV infection highlighted the presence of high mortality as the main variable explaining the data. The results obtained from this studyare discussed in the context of WSD control and areas requiring further investigation are suggested.

【 授权许可】

Unknown