The two sides of border disease in Pyrenean chamois (Rupicapra pyrenaica): silent persistence and population collapse

Abstract

In 2001, border disease virus (BDV) was identified as the cause of a previously unreported disease in Pyrenean chamois (Rupicapra pyrenaica) in Spain. Since then, the disease has caused a dramatic decrease, and in some cases collapse, of chamois populations and has expanded to nearly the entire distribution area in the Pyrenees. Chamois BDV was characterized as BDV-4 genotype and experimental studies confirmed that it was the primary agent of the disease. The infection has become endemic in the Central and Eastern Pyrenees. However, while most Pyrenean chamois populations have been severely affected by the disease, others have not, despite the circulation of BDV in apparently healthy individuals, suggesting the existence of different viral strategies for persisting in the host population. Changes in the interplay of pathogen, host and environmental factors may lead to the formation of different disease patterns. A key factor influencing disease emergence may be pathogen invasiveness through viral mutation. Host factors, such as behavior, immunity at the population level and genetic variability, may also have driven different epidemiological scenarios. Climatic and other ecological factors may have favored secondary infections, such as pneumonia, that under particular circumstances have been major contributing factors in the high mortality observed in some areas.

Spatial and Temporal Phylogeny of Border Disease Virus in Pyrenean Chamois (Rupicapra p. pyrenaica)

“…These outbreaks have decimated several Pyrenean chamois populations, with mortalities ranging from 40% to 85% [16]. After the severe BDV-4 outbreaks, different epidemiological scenarios have appeared in the Pyrenees, having a prolonged negative impact on host population dynamics in some areas [17].…”

The European hare ( Lepus europaeus ) as a potential wild reservoir for ruminant pestiviruses

“…The etiological agent of these infections was classified into the BDV4 genogroup (Arnal et al, 2004). Fifteen years after the first outbreak, pestivirus are still circulating among Pyrenean chamois and this situation suggests an endemic and asymptomatic virus circulation in some areas (Marco et al, 2015). Although Pyrenean chamois' sympatric ruminant species have been suspected to be involved in the maintenance of the virus in the Pyrenees, low antibody seroprevalences, absence of PI individuals and no clinical infections have been reported (Fernández-Sirera et al, 2012b).…”

Experimental infection with high‐ and low‐virulence strains of border disease virus (BDV) in Pyrenean chamois (Rupicapra p. pyrenaica) sheds light on the epidemiological diversity of the disease

“…After 17 years since the first outbreak of border disease (BD) in Pyrenean chamois and at least since 28 years of pestivirus presence in Pyrenean chamois populations, several studies have investigated the factors that rule the diversity of the epidemiological scenarios (Fernández‐Sirera et al, ; Marco et al, ; Martin et al, ; Pioz et al, ). This study unravel that pathogen virulence is most probably the main factor driving disease presentation and impact on chamois populations.…”

“…Field studies carried out in France, Andorra, and Spain have shown different epidemiological scenarios in chamois populations (Pioz et al, ; Marco et al, ; Martin et al, ). Pestivirus infections in chamois populations from the Pyrenees mainly cause mortality outbreaks with different impacts at the population level.…”

“…Strikingly, pestivirus circulation has been detected in an area of the eastern Pyrenees (Freser‐Setcases National Hunting Reserve) since 1996 without a significant impact on the chamois population (Marco et al, ). To date, no mass mortality, and only one clinical case has been found in this area where more than a half of the chamois population have neutralizing antibodies against pestivirus (Marco et al, ). Different hypotheses may explain the persistence of the pestivirus in this population, related to BDV strain variability, genetic diversity of chamois, and/or environmental factors.…”