Quantitative analysis of the probability of introducing equine encephalosis virus (EEV) into The Netherlands.

This study focuses on analyzing the chances of introducing the Equine encephalosis virus (EEV) into The Netherlands, a disease commonly observed in Africa and Israel. It investigates the potential sources of the virus, its transmission methods, and the efficiency of preventive measures.

Overview of the Study

In the study, a previously constructed stochastic risk model for assessing the risk of introducing African horse sickness virus (AHSV) was adapted for EEV since the two diseases share common vectors and show similar transmission patterns. The researchers divided the potential source areas of the virus into high, low, and very low-risk regions, based on the history of EEV and the presence of vectors competent in carrying the disease.

Possible Routes of Virus Introduction

The study considered two possible channels for EEV to enter The Netherlands:

• The importation of infected equines, or horses.
• The importation of infected vectors, such as midges, with a focus on those accompanying their vertebrate hosts.

Calculation of Risk of Virus Introduction

The probability of introducing the virus, termed PEEV, was derived through combining the probabilities of the virus being released via the two potential pathways, and the likelihood of the virus getting established following its introduction.

Findings of the Study

Based on calculations:

• The median annual probability of virus introduction by an infected equine was estimated at 0.012, and 4.0 x 10(-5) by an infected vector.
• Horses from high-risk regions contributed most significantly (74%) to the probability of virus introduction, followed by those from low-risk regions (18%) and very low-risk regions (8%).
• Horses participating in international equestrian events were identified to contribute most to the virus introduction from the high-risk regions, and also significantly from low and very low-risk regions.

Comparison with African Horse Sickness Virus (AHSV)

The study concluded that the probability of introducing EEV into The Netherlands is much higher than that of introducing AHSV. Among the two potential pathways for virus introduction, infected equines were identified as the most likely source.

Effect of Control Measures

The study found that control measures taken before the exportation of equines, such as mandatory disease testing and quarantine, significantly reduced the chances of introducing the virus.

Implications of the Study

The researchers suggest that the probable risk of EEV outbreaks should be considered when altering import regulations, due to the potentially high probability of introducing the virus under existing controls.