Modeling the West Nile virus transfusion transmission risk in a nonoutbreak country associated with traveling donors

Abstract

Background: West Nile virus (WNV) is a mosquito-borne virus and transfusion transmission (TT) has been demonstrated. The European Union and neighboring countries experience an annual transmission season. Study Design and Methods: We developed a novel probabilistic model to estimate the WNV TT risk in Australia attributable to returned donors who had travelled to the European Union and neighboring countries during the 2018. We estimated weekly WNV TT risks in Australia for each outbreak country and the cumulative risk for all countries. Results: Highest mean weekly TT risk in Australia attributable to donors returning from a specific outbreak country was 1 in 23.3 million (plausible range, 16.8-41.9 million) donations during Week 39 in Croatia. Highest mean weekly cumulative TT risk was 1 in 8.5 million donations (plausible range, 5.1-17.8 million) during Week 35. Conclusions: The estimated TT risk in Australia attributable to returning donors from the European Union and neighboring countries in 2018 was very small, and additional risk mitigation strategies were not indicated. In the context of such low TT risks, a simpler but effective approach would be to monitor the number of weekly reported West Nile fever cases and implement risk modeling only when the reported cases reached a predefined number or trigger point.

West Nile virus transfusion‐transmission risk in Australia associated with a seasonal outbreak in the United States

“…In this study, we have modified a previously published risk model 14 to estimate the WNV TT risk in Australia associated with WNV outbreaks in the US. Our results demonstrate that the estimated WNV TT risk in Australia associated with the 2018 transmission season in the US was very small.…”

“…A third, and simpler, strategy to manage the WNV TT risk in Australia associated with outbreaks in the US would be to remove current restrictions on donors returning from the US and perform ongoing surveillance with a predefined number of total reported WNND disease cases in the US, based on a predefined level of risk in Australia, as a trigger for implementing risk modeling in Australia 14,22 …”

“…A third, and simpler, strategy to manage the WNV TT risk in Australia associated with outbreaks in the US would be to remove current restrictions on donors returning from the US and perform ongoing surveillance with a predefined number of total reported WNND disease cases in the US, based on a predefined level of risk in Australia, as a trigger for implementing risk modeling in Australia. 14,22 While the reported number of WNV RNA-positive blood donors could be used as a measure of the total number of WNV infections, we believe that the reported number of neuroinvasive cases would be a more reliable measure. Individuals with neuroinvasive disease are very likely to seek medical intervention.…”

“…Lifeblood has developed a deterministic model ( Lifeblood WNV‐risk model ) to assess the WNV‐transmission risk associated with returning donors from overseas, which has been applied to the European Union and neighboring countries 14 …”

“…Lifeblood has developed a deterministic model (Lifeblood WNV-risk model) to assess the WNV-transmission risk associated with returning donors from overseas, which has been applied to the European Union and neighboring countries. 14 The aim of this study was to use a modified Lifeblood WNV-risk model to (a) estimate the monthly WNV TT risk during 2018 in Australia associated with donors returning from the US and (b) consider the implications of these risk estimates for mitigation strategies, including the discontinuation of the current restriction of only using donations from these donors for fractionated plasma products.…”