Multiple warren use by subadult wild rabbits, Oryctolagus cuniculus, and its implications for disease transmission

2017 ◽  
Vol 44 (7) ◽  
pp. 582 ◽  
Author(s):  
Scott Jennings ◽  
Gregory Mutze

Context Contact rates are a key determinant of disease transmission. Territorial behaviour has generally been considered to limit contact between European rabbits occupying different warrens, particularly during the breeding season. Aims We investigated warren use by subadult rabbits during a period of low population density to determine their potential role in transmission of rabbit haemorrhagic disease and myxomatosis. Methods Subadult rabbits were radio-collared in late summer and relocated twice-weekly for 25 weeks, during which time they grew to adult size and breeding commenced. Key results Rabbits of both sexes used an average of four warrens each on a regular basis, even after older rabbits had commenced breeding. Warrens used by individual rabbits formed a continuously overlapping, irregular array. Subadult rabbits did not belong to separate social groups that utilised separate groups of warrens. Conclusions Subadult or young adult rabbits did not display the same territorial warren fidelity that had been previously described for rabbits. They have potential to carry pathogens between warrens at a landscape scale. Implications Movement of subadult rabbits between warrens is therefore likely to play a critical role in disease transmission, particularly when population density is low. This may help to explain the prevalent seasonality of RHD epizootics in spring when first-born litters of each breeding season typically reach that size.

2002 ◽  
Vol 83 (10) ◽  
pp. 2461-2467 ◽  
Author(s):  
S. R. Moss ◽  
S. L. Turner ◽  
R. C. Trout ◽  
P. J. White ◽  
P. J. Hudson ◽  
...  

Millions of domestic and wild European rabbits (Oryctolagus cuniculus) have died in Europe, Asia, Australia and New Zealand during the past 17 years following infection by Rabbit haemorrhagic disease virus (RHDV). This highly contagious and deadly disease was first identified in China in 1984. Epidemics of RHDV then radiated across Europe until the virus apparently appeared in Britain in 1992. However, this concept of radiation of a new and virulent virus from China is not entirely consistent with serological and molecular evidence. This study shows, using RT–PCR and nucleotide sequencing of RNA obtained from the serum of healthy rabbits stored at 4 °C for nearly 50 years, that, contrary to previous opinions, RHDV circulated as an apparently avirulent virus throughout Britain more than 50 years ago and more than 30 years before the disease itself was identified. Based on molecular phylogenetic analysis of British and European RHDV sequences, it is concluded that RHDV has almost certainly circulated harmlessly in Britain and Europe for centuries rather than decades. Moreover, analysis of partial capsid sequences did not reveal significant differences between RHDV isolates that came from either healthy rabbits or animals that had died with typical haemorrhagic disease. The high stability of RHDV RNA is also demonstrated by showing that it can be amplified and sequenced from rabbit bone marrow samples collected at least 7 weeks after the animal has died.


2004 ◽  
Vol 31 (4) ◽  
pp. 415 ◽  
Author(s):  
B. D. Cooke ◽  
J.-L. Chapuis ◽  
V. Magnet ◽  
A. Lucas ◽  
J. Kovaliski

Rabbits have caused enormous damage to the vegetation on seven islands in the sub-Antarctic Kerguelen archipelago, including the main island, Grande Terre. Rabbit sera collected during 2001–02 were tested for antibodies against myxoma virus and rabbit haemorrhagic disease virus with a view to considering the wider use of these viruses to control rabbits. The results confirmed work done 15–20 years earlier that suggested that myxoma virus has not spread across all parts of Grande Terre and occurs at low prevalence among rabbits. By contrast, on Ile du Cimetière, where European rabbit fleas were introduced in 1987–88, the prevalence of myxoma antibodies is high and the rabbit population is relatively low, supporting the idea that the fleas are effective vectors of myxoma virus. Consequently, there should be benefits in releasing fleas on Grand Terre to enhance disease transmission. Reactivity of some rabbit sera in RHD-specific ELISAs suggested that a virus similar to RHDV may be present at low prevalence on Grande Terre but most rabbits are likely to be susceptible and this virus could be considered for use as a future biological control agent.


2009 ◽  
Vol 31 (1) ◽  
pp. 65 ◽  
Author(s):  
David E. Peacock ◽  
Ron G. Sinclair

A population of European rabbits (Oryctolagus cuniculus) has been monitored since November 1996 through mark–recapture as part of a longitudinal epidemiological study into two Australian rabbit biocontrol agents, rabbit haemorrhagic disease (RHD) and myxomatosis. A female rabbit, first captured as a subadult in late November 1999, was recaptured 18 times before its final capture at the end of February 2007. The longevity of this rabbit, being from its calculated birth date to the date it was last captured, was 7.6 years. A review of the literature indicates this to be the longest lifespan recorded for a European rabbit in the wild.


2018 ◽  
Vol 182 (20) ◽  
pp. 574-574 ◽  
Author(s):  
Greg Mutze ◽  
Nicki De Preu ◽  
Trish Mooney ◽  
Dylan Koerner ◽  
Darren McKenzie ◽  
...  

Lagovirus europaeus GI.2, also commonly known as rabbit haemorrhagic disease virus 2, was first detected at two long-term monitoring sites for European rabbits, Oryctolagus cuniculus, in South Australia, in mid-2016. Numbers of rabbits in the following 12–18 months were reduced to approximately 20 per cent of average numbers in the preceding 10 years. The impact recorded at the two South Australian sites, if widespread in Australia and persistent for several years, is likely to be of enormous economic and environmental benefit.


2002 ◽  
Vol 29 (6) ◽  
pp. 627 ◽  
Author(s):  
Ben Reddiex ◽  
Graham J. Hickling ◽  
Grant L. Norbury ◽  
Chris M. Frampton

The impact of predation and rabbit haemorrhagic disease (RHD) on population dynamics of rabbits, and the survival of juvenile rabbits, was investigated between July 1999 and March 2000 in North Canterbury, New Zealand. Rabbit abundance and pre- and post-emergent rabbit mortality were monitored on four sites, two of which were subject to predator control. RHD spread naturally through all sites from late November to early December. Rabbit densities declined on all sites, but after the RHD epidemic, declines were significantly greater where populations of predators had not been controlled. Survival of rabbit nestlings was lower where predators were not controlled. All post-emergent radio-collared rabbits died at sites where predators were not controlled, whereas 18% of those collared at sites where predators were controlled survived to maturity. In contrast to the results from previous studies, rabbits born at the start of the breeding season had very high rates of post-emergent mortality, as they appeared to be susceptible to the RHD virus later in the breeding season. The age at which juvenile rabbits become susceptible to RHD, the timing of RHD epidemics, and the abundance of predators are likely to be important in determining survival of juvenile rabbits. This study demonstrates that predation can reduce rabbit populations to low levels, but only in combination with other factors, in this case RHD.


PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249271
Author(s):  
Karla Therese L. Sy ◽  
Laura F. White ◽  
Brooke E. Nichols

The basic reproductive number (R0) is a function of contact rates among individuals, transmission probability, and duration of infectiousness. We sought to determine the association between population density and R0 of SARS-CoV-2 across U.S. counties. We conducted a cross-sectional analysis using linear mixed models with random intercept and fixed slopes to assess the association of population density and R0, and controlled for state-level effects using random intercepts. We also assessed whether the association was differential across county-level main mode of transportation percentage as a proxy for transportation accessibility, and adjusted for median household income. The median R0 among the United States counties was 1.66 (IQR: 1.35–2.11). A population density threshold of 22 people/km2 was needed to sustain an outbreak. Counties with greater population density have greater rates of transmission of SARS-CoV-2, likely due to increased contact rates in areas with greater density. An increase in one unit of log population density increased R0 by 0.16 (95% CI: 0.13 to 0.19). This association remained when adjusted for main mode of transportation and household income. The effect of population density on R0 was not modified by transportation mode. Our findings suggest that dense areas increase contact rates necessary for disease transmission. SARS-CoV-2 R0 estimates need to consider this geographic variability for proper planning and resource allocation, particularly as epidemics newly emerge and old outbreaks resurge.


2004 ◽  
Vol 31 (6) ◽  
pp. 605 ◽  
Author(s):  
John S. Bruce ◽  
Laurie E. Twigg

Although several different cELISAs have been used to assess the exposure of European rabbits to rabbit haemorrhagic disease (RHD), the interpretation of the results of such assays is not always straight-forward. Here we report on such difficulties, and on the likely presence of a non-virulent rabbit haemorrhagic disease virus–like virus (nvRHDV-LV) in south-western Australia. Analysis of sera collected from European rabbits at Kojaneerup (near Albany) in Western Australia provided the first serological evidence of the likely presence of a nvRHDV-LV in wild rabbit populations outside the east coast of Australia and New Zealand, before the deliberate introduction of RHDV as biological control agent in both countries. Six out of 30 rabbits (20%) sampled 1–2 months before the known arrival of RHDV at Kojaneerup were seropositive to RHD on the basis of their IgG isoELISAs. However, none of these positive samples were positive for the RHDV antibody cELISA (1 : 10), indicating likely exposure to nvRHDV-LV. Subsequent serological analysis of 986 rabbits sampled between September 1996 and August 1999 at Kojaneerup indicated that nvRHDV-LV persisted in these rabbits following the natural arrival of RHDV in September 1996. At least 10–34% of rabbits appeared to have been exposed to nvRHDV-LV during the 3-year study. The presence of nvRHDV-LV seemed to offer only limited protection to rabbits from RHDV during the initial epizootic; however, persistence of nvRHDV-LV may have mitigated further RHDV activity after this epizootic. Fewer than 1% of rabbits (9 of 986) showed evidence of RHDV-challenge during the 30 months following the initial RHDV epizootic. Furthermore, except for the epizootic in September 1996, no clinical signs of the disease were apparent in the population until RHDV was deliberately reintroduced in April 1999. Mortality of rabbits exposed to RHDV at this time appeared to be correlated with their IgG isoELISA titre.


2018 ◽  
Vol 55 (6) ◽  
pp. 2954-2962 ◽  
Author(s):  
Louise K. Barnett ◽  
Thomas A. A. Prowse ◽  
David E. Peacock ◽  
Gregory J. Mutze ◽  
Ron G. Sinclair ◽  
...  

2002 ◽  
Vol 29 (6) ◽  
pp. 557 ◽  
Author(s):  
G. P. Edwards ◽  
W. Dobbie ◽  
D. McK. Berman

Before the establishment of rabbit haemorrhagic disease (RHD) in central Australia in May 1996, a program was instituted to monitor its impacts at six localities broadly distributed across the region. At these sites, population trends in rabbits and other wildlife were studied over a 2.5-year period. Rabbit populations declined by approximately 85% following establishment of RHD at the sites, and had not recovered 22 months later. More varanid lizards were detected on our survey plots 12–22 months after RHD than during the preceding period. Although numbers of dingoes and wedge-tailed eagles varied during the study, significant population reductions were not detected in either species in the wake of RHD. Significant population changes were not detected in red foxes, feral cats, red kangaroos, small mammals, or other raptor species.


2002 ◽  
Vol 29 (6) ◽  
pp. 567 ◽  
Author(s):  
G. P. Edwards ◽  
W. Dobbie ◽  
D. McK. Berman

The impacts of warren ripping on European rabbits and other wildlife were studied at four sites in central Australia over a 2.5-year period. At each site, treated (ripped) and untreated plots were established. On the treated plots, warrens were ripped over an area of 20–140 km2. Rabbit haemorrhagic disease (RHD) became established in central Australia during the study. There were fewer rabbits on ripped plots compared with untreated plots both before and after the establishment of RHD. There was also less sign of exotic predators (red foxes and feral cats) on ripped plots. The amount of dingo sign observed and the number of peregrine falcons, brown falcons, kites and goshawks combined and kestrels and hobby falcons combined changed with time but no treatment effect was detected. No consistent treatment effect was detected for red kangaroos, varanid lizards, small mammals or other raptor species.


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