The transmission potential of Rift Valley fever virus among livestock in the Netherlands: a modelling study

Abstract

AbstractsRift Valley fever virus (RVFV) is a zoonotic vector-borne infection and causes a potentially severe disease. Many mammals are susceptible to infection including important livestock species. Although currently confined to Africa and the near-East, this disease causes concern in countries in temperate climates where both hosts and potential vectors are present, such as the Netherlands. Currently, an assessment of the probability of an outbreak occurring in this country is missing. To evaluate the transmission potential of RVFV, a mathematical model was developed and used to determine the initial growth and the Floquet ratio, which are indicators of the probability of an outbreak and of persistence in a periodic changing environment caused by seasonality. We show that several areas of the Netherlands have a high transmission potential and risk of persistence of the infection. Counter-intuitively, these are the sparsely populated livestock areas, due to the high vector-host ratios in these areas. Culex pipiens s.l. is found to be the main driver of the spread and persistence, because it is by far the most abundant mosquito. Our investigation underscores the importance to determine the vector competence of this mosquito species for RVFV and its host preference.

Modelling the potential spatial distribution of mosquito species using three different techniques

“…Beyond describing species distributions, these models have become an important and widely used decision making tool for a variety of biogeographical applications, such as mapping risk of vector-borne disease spread, and determining locations that are potentially susceptible to invasion [19]. Species distribution modelling using flexible machine learning approaches has been successfully applied to quantify and to map the global distribution of hosts [20], disease vectors [21], pathogens [22], and infection and outbreak risk [23]. …”

Zoonotic risks from small ruminants

“…Humans can become infected with the virus following contact with infected animals or animal products, although less likely as a result of a mosquito bite. Rift valley fever in humans is generally mild or inapparent, but occasionally severe and potentially fatal complications of the disease can occur (Swanepoel and Coetzer, 2004;Chevalier et al, 2010;Fischer et al, 2013). Beside the losses, major economic disturbances is induced by trade restrictions, as, even after the outbreaks, livestock trades may be restricted for several years (Rodolakis, 2014).…”

Rift Valley fever virus: strategies for maintenance, survival and vertical transmission in mosquitoes

“…Potential routes of entry of RVFV into Europe and the USA have been identified [22][23][24] and the risk of establishment into North Africa [25], Italy [26], the Netherlands [27] and Spain [28] reviewed. The conclusions collectively identify a need to determine competence in local vectors to accurately evaluate risks, and guide control and surveillance activities [23,24].…”