Problems and solutions with the design and execution of an epidemiological study of white spot disease in black tiger shrimp (Penaeus monodon) in Vietnam

Corsin, F.; Phi, Thi Thuy Ngan; Phuoc, Le Hong; Tình, Nguyễn Thị; Hảo, Nguyễn Văn; Mohan, C. V.; Turnbull, James; Morgan, K. L.

doi:10.1016/s0167-5877(01)00265-3

Cited by 17 publications

(7 citation statements)

References 12 publications

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“…Continuous independent variables from WSSV positive and negative ponds were compared by ANOVA when the data were normally distributed and the variance was homogeneous (Bartlett's test at 5% significance level), or by Kruskal-Wallis test for other data (Epi Info 6.04b, Dean et al 1996). Median and quartiles were used as cut-off points to categorise variables.…”

Section: Methodsmentioning

confidence: 99%

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

Corsin¹,

Turnbull²,

Hảo³

et al. 2001

Dis. Aquat. Org.

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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 factors for 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 measured comprising 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%). One hundred and thirtynine 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 multivariate analyses 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 positive for 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 and use 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 first month 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 study are discussed in the context of WSD control and areas requiring further investigation are suggested.KEY WORDS: White spot disease · Aquatic epidemiology · Risk factors · Penaeus monodon · Rice-shrimp farming systemResale or republication not permitted without written consent of the publisher

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Section: Methodsmentioning

confidence: 99%

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

Corsin¹,

Turnbull²,

Hảo³

et al. 2001

Dis. Aquat. Org.

Self Cite

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“…Patent WSD results in rapid, high mortalities, affecting up to 100% of the exposed stock within 3-10 days of initial signs (Lightner, 1996). Numerous authors have described the epidemiology of the disease in individual farms, farm clusters and geographic regions (Lotz, 1997;Corsin et al, 2002) while others have detailed the prevailing practice of so-called 'emergency harvest' as a mechanism to prevent total crop loss following initial discovery of diseased animals (Turnbull et al, 2005). Overall, despite almost two decades since its discovery, WSD is still considered the most significant known pathogen impacting the sustainability and growth of the global penaeid shrimp farming industry (Stentiford et al, 2009(Stentiford et al, , 2010Lightner, 2011).…”

Section: Introductionmentioning

confidence: 99%

Susceptibility to infection and pathogenicity of White Spot Disease (WSD) in non-model crustacean host taxa from temperate regions

Bateman

Tew

French

et al. 2012

Journal of Invertebrate Pathology

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“…Also, it is unclear where WSSV originated and how it subsequently spread to other regions in Vietnam from the original introduction site(s). Epidemiological studies have been faced with numerous design and execution problems, making it difficult to infer WSSV spread based on farmer reports of shrimp health and screening ponds for WSSV (Corsin et al, 2002). Finding suitable methods to identify and discriminate WSSV strains -and infer their origin -is therefore important for WSSV forensics and epidemiology.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of white spot syndrome virus variable DNA loci as molecular markers of virus spread at intermediate spatiotemporal scales

Dieu

Marks

Zwart

et al. 2010

Journal of General Virology

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Variable genomic loci have been employed in a number of molecular epidemiology studies of white spot syndrome virus (WSSV), but it is unknown which loci are suitable molecular markers for determining WSSV spread on different spatiotemporal scales. Although previous work suggests that multiple introductions of WSSV occurred in central Vietnam, it is largely uncertain how WSSV was introduced and subsequently spread. Here, we evaluate five variable WSSV DNA loci as markers of virus spread on an intermediate (i.e. regional) scale, and develop a detailed and statistically supported model for the spread of WSSV. The genotypes of 17 WSSV isolates from along the coast of Vietnam -nine of which were newly characterized in this study -were analysed to obtain sufficient samples on an intermediate scale and to allow statistical analysis. Only the ORF23/24 variable region is an appropriate marker on this scale, as geographically proximate isolates show similar deletion sizes. The ORF14/15 variable region and variablenumber tandem repeat (VNTR) loci are not useful as markers on this scale. ORF14/15 may be suitable for studying larger spatiotemporal scales, whereas VNTR loci are probably suitable for smaller scales. For ORF23/24, there is a clear pattern in the spatial distribution of WSSV: the smallest genomic deletions are found in central Vietnam, and larger deletions are found in the south and the north. WSSV genomic deletions tend to increase over time with virus spread in cultured shrimp, and our data are therefore congruent with the hypothesis that WSSV was introduced in central Vietnam and then radiated out.

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Problems and solutions with the design and execution of an epidemiological study of white spot disease in black tiger shrimp (Penaeus monodon) in Vietnam

Cited by 17 publications

References 12 publications

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

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

Susceptibility to infection and pathogenicity of White Spot Disease (WSD) in non-model crustacean host taxa from temperate regions

Evaluation of white spot syndrome virus variable DNA loci as molecular markers of virus spread at intermediate spatiotemporal scales

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