Spatiotemporal distribution of rabies in Arctic foxes in Greenland

Abstract

The temporal occurrence, spatial distribution, spread, and prevalence of rabies in Arctic foxes, Vulpes lagopus, in Greenland were studied using historical observations from 1969 to 2011 and survey data collected in the winters 1992 and 1993. Regionally, the prevalence of rabies ranged between 0 and 7.1 %. Wavelet analysis was used to identify periodicities in the abundance of rabies cases based on the historical observations. No general length of the cyclic interval of rabies occurrences in Greenland could be demonstrated. The frequency of outbreaks was found to be variable but can be grouped as short (less than 5 years), medium (5-10 years), and long (more than 10 years). Moreover, rabies outbreaks in neighboring regions were found to be more closely correlated compared to regions further apart. In West Greenland, the temporal outbreaks of rabies were found to occur along a north-south trajectory.

Spatio-temporal Analysis of the Genetic Diversity of Arctic Rabies Viruses and Their Reservoir Hosts in Greenland

“…Interestingly, the most ancestral RABV still circulating (subclade arctic 3.II) has the widest geographic spread across the entire western part of Greenland. Such spread has also been demonstrated epidemiologically [ 13 ]. The dynamic observed here is further demonstrated by the observation that older subclades previously found in Greenland ( Fig 2 ), [ 15 – 18 ] seem to have disappeared.…”

“…These results may be useful for future control strategies of arctic fox rabies. In contrast to previous statements [ 13 ], given the unique geographical location of Greenland, the expected reduction of connectivity by pack-ice due to climate change [ 54 , 55 ] and the geographic separation of individual host and virus genetic subclades despite long distance movement [ 36 ], the idea of arctic rabies control using oral rabies vaccination (ORV) in selected coastal areas appears feasible [ 56 , 57 ]. While preliminary field trials in Newfoundland (Canada) [ 58 ] and even northern Greenland [ 59 ] demonstrated in principle that ORV could be undertaken in remote northern regions, a targeted vaccination strategy would have to be developed before an elimination program could be implemented.…”

“…For a long time, there has been limited knowledge on the epidemiology of arctic rabies in Greenland [ 9 – 12 ]. It was only recently that the temporal occurrence, spatial distribution, and spread of arctic rabies in Greenland was investigated based on historical observations [ 13 ], however, this study did not provide any context to the RABV circulating on the island. While previous molecular epidemiological studies on RABV from Greenland using partial N gene sequences revealed that they belong to the arctic-3 lineage [ 16 , 17 ], unfortunately, the number of samples and the sequence length examined prevented further in-depth phylogenetic analyses.…”

“…samples are only submitted from areas where close fox-human encounters are possible and there is a lack of samples from central and eastern parts of Greenland ( Fig 1 ). For instance, in sparsely populated east Greenland only 12 cases have been observed since the late 1960s until 2014 [ 13 ], suggesting either low level of infection or underreporting [ 17 , 34 ]. Whilst in previous studies only selected RABV were considered [ 16 – 18 ], here nearly all viruses from rabies cases detected between 2005 and 2014 were included, together with selected samples from an earlier study [ 16 ] that were available for re-analysis using NGS.…”

“…The disease is considered endemic among the arctic fox population of Greenland [ 11 , 12 ]. A recent epidemiological study of arctic fox rabies in Greenland between 1969 and 2011 revealed that the disease flared up every 5–10 years on average, whereby most rabid foxes were reported from southern Greenland [ 13 ].…”