Sanchez-Zazueta Edgar, Martínez-Cordero Francisco Javier, Chávez-Sánchez María Cristina, Montoya-Rodríguez Leobardo
Laboratory of Aquaculture Economics and Foresight, Centro de Investigación en Alimentación y Desarrollo (CIAD), A.C., Mazatlán Unit Av. Sábalo Cerritos s/n, Estero del Yugo, A.P. 711, Mazatlán, Sinaloa, C.P. 82100, Mexico.
Laboratory of Aquaculture Economics and Foresight, Centro de Investigación en Alimentación y Desarrollo (CIAD), A.C., Mazatlán Unit Av. Sábalo Cerritos s/n, Estero del Yugo, A.P. 711, Mazatlán, Sinaloa, C.P. 82100, Mexico.
Prev Vet Med. 2017 Oct 1;146:27-33. doi: 10.1016/j.prevetmed.2017.07.015. Epub 2017 Jul 26.
This quantitative risk assessment provided an analytical framework to estimate white spot syndrome virus (WSSV) transmission risks in the following different scenarios: (1) partial harvest from rearing ponds and (2) post-harvest transportation, assuming that the introduction of contaminated water with viral particles into shrimp culture ponds is the main source of viral transmission risk. Probabilities of infecting shrimp with waterborne WSSV were obtained by approaching the functional form that best fits (likelihood ratio test) published data on the dose-response relationship for WSSV orally inoculated through water into shrimp. Expert opinion defined the ranges for the following uncertain factors: (1) the concentrations of WSSV in the water spilled from the vehicles transporting the infected shrimp, (2) the total volume of these spills, and (3) the dilution into culture ponds. Multiple scenarios were analysed, starting with a viral load (VL) of 1×10mL in the contaminated water spilled that reached the culture pond, whose probability of infection of an individual shrimp (P) was negligible (1.7×10). Increasing the VL to 1×10mL and 1×10mL yielded results into very low (P=5.3×10) and high risk (P=1.6×10) categories, respectively. Furthermore, different pond stocking density (SD) scenarios (20 and 30 post-larvae [PL]/m) were evaluated, and the probability of infection of at least one out of the total number of shrimp exposed (P) was derived; for the scenarios with a low VL (1×10mL), the P remained at a negligible risk level (P, 2.4×10 to 1.8×10). For most of the scenarios with the moderate VL (1×10mL), the P scaled up to a low risk category (P, 1.1×10 to 5.6×10), whereas for the scenarios with a high VL (1×10mL), the risk levels were high (P, 2.3×10 to 3.5×10) or very high (P, 1.1×10 to 1.6×10) depending on the volume of contaminated water spilled in the culture pond (VCWSCP, 4 or 20L). In the sensitivity analysis, for a SD of 30 PL/m, it was shown that starting with a VL of 1×10mL and a VCWSCP of 12L, the P was moderate (1.05×10). This was the threshold for greater risks, given the increase in either the VCWSCP or VL. These findings supported recommendations to prevent WSSV spread through more controlled transportation and partial harvesting practices.
这种定量风险评估提供了一个分析框架，用于估计在以下不同情况下白斑综合征病毒（WSSV）的传播风险：（1）养殖池塘的部分收获和（2）收获后的运输，假设含有病毒颗粒的受污染水进入对虾养殖池塘是病毒传播风险的主要来源。通过拟合最符合（似然比检验）已发表的关于通过水口服接种WSSV到对虾的剂量反应关系数据的函数形式，获得了通过水传播的WSSV感染对虾的概率。专家意见确定了以下不确定因素的范围：（1）运输受感染对虾的车辆溢出水中WSSV的浓度，（2）这些溢出物的总体积，以及（3）在养殖池塘中的稀释情况。分析了多种情况，从溢出到养殖池塘的受污染水中病毒载量（VL）为1×10/mL开始，此时单个对虾被感染的概率（P）可忽略不计（1.7×10）。将VL增加到1×10/mL和1×10/mL分别产生了极低（P = 5.3×10）和高风险（P = 1.6×10）类别。此外，评估了不同的池塘放养密度（SD）情况（20和30尾仔虾[PL]/m），并得出了暴露的对虾总数中至少有一只被感染的概率（P）；对于低VL（1×10/mL）的情况，P保持在可忽略不计的风险水平（P，2.4×10至1.8×10）。对于大多数中等VL（1×10/mL）的情况，P上升到低风险类别（P，1.1×10至5.6×10），而对于高VL（1×10/mL）的情况，根据养殖池塘中溢出的受污染水的体积（VCWSCP，4或20L），风险水平为高（P，2.3×10至3.5×10）或非常高（P，1.1×10至1.6×10）。在敏感性分析中，对于30 PL/m的SD，结果表明从1×10/mL的VL和12L的VCWSCP开始，P为中等（1.05×10）。鉴于VCWSCP或VL的增加，这是更高风险的阈值。这些发现支持了通过更可控的运输和部分收获做法来防止WSSV传播的建议。
