Abstract
Bat-borne viruses have been linked to a number of zoonotic diseases; in 2014 there have been human cases of Nipah virus (NiV) in Bangladesh and Ebola virus in West and Central Africa. Here we describe a model designed to provide initial quantitative predictions of the risk of entry of such viruses to European Union (EU) Member States (MSs) through four routes: human travel, legal trade (e.g. fruit and animal products), live animal movements and illegal importation of bushmeat. The model utilises available datasets to assess the movement via these routes between individual countries of the world and EU MSs. These data are combined with virus specific data to assess the relative risk of entry between EU MSs. As a case study, the model was parameterised for NiV. Scenario analyses showed that the selection of exporting countries with NiV and potentially contaminated trade products were essential to the accuracy of all model outputs. Uncertainty analyses of other model parameters identified that the model expected number of years to an introduction event within the EU was highly susceptible to the prevalence of NiV in bats. The relative rankings of the MSs and routes, however, were more robust. The UK, the Netherlands and Germany were consistently the most likely points of entry and the ranking of most MSs varied by no more than three places (maximum variation five places). Legal trade was consistently the most likely route of entry, only falling below human travel when the estimate of the prevalence of NiV in bats was particularly low. Any model-based calculation is dependent on the data available to feed into the model and there are distinct gaps in our knowledge, particularly in regard to various pathogen/virus as well as host/bat characteristics. However, the strengths of this model lie in the provision of relative comparisons of risk among routes and MSs. The potential for expansion of the model to include other routes and viruses and the possibility of rapid parameterisation demonstrates its potential for use in an outbreak situation.
Highlights
In the current era there are many factors which connect disparate parts of the world, from tourism to immigration and legal trade of goods to illegal trade of wild animals
In this paper we have described the development of a risk assessment framework for the introduction of bat-borne viruses to the European Union (EU) through a number of routes previously identified to be a risk, namely; human travel, legal trade, live animal movements and illegal importation of bushmeat
The model utilises large, freely available, global datasets on human travel, legal trade and live animal movements to assess the volume of traffic between individual countries of the world and EU Member States (MSs)
Summary
In the current era there are many factors which connect disparate parts of the world, from tourism to immigration and legal trade of goods to illegal trade of wild animals. We have seen geographical spread of cases of viruses such as Avian Influenza, Middle East Respiratory Syndrome coronavirus (MERS-CoV) and Ebola virus (EBOV) at unprecedented distances from the initial source of the outbreak This raises the concern that other viruses that are currently restricted to more localised geographic areas, such as Nipah Virus (NiV), may spread to many other countries. Spread within the EU will depend on a number of other factors, such as whether the virus can get established, but if unprepared, the consequences of virus entry could potentially be severe leading to an epidemic, or even pandemic Such consequences have been witnessed in West Africa where over 20,000 suspected cases and 7,800 deaths have been reported due to the 2014 EBOV outbreak [2], which has been suggested originated from only one human index case involving spill-over from a wildlife reservoir [3]
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