Abstract:
Heterogeneity in the transmission rates of pathogens across hosts or environments may produce disease hotspots, which
are defined as specific sites, times or species associations in which the infection rate is consistently elevated. Hotspots for
avian influenza virus (AIV) in wild birds are largely unstudied and poorly understood. A striking feature is the existence of a
unique but consistent AIV hotspot in shorebirds (Charadriiformes) associated with a single species at a specific location and
time (ruddy turnstone Arenaria interpres at Delaware Bay, USA, in May). This unique case, though a valuable reference, limits
our capacity to explore and understand the general properties of AIV hotspots in shorebirds. Unfortunately, relatively few
shorebirds have been sampled outside Delaware Bay and they belong to only a few shorebird families; there also has been a
lack of consistent oropharyngeal sampling as a complement to cloacal sampling. In this study we looked for AIV hotspots
associated with other shorebird species and/or with some of the larger congregation sites of shorebirds in the old world. We
assembled and analysed a regionally extensive dataset of AIV prevalence from 69 shorebird species sampled in 25 countries
across Africa and Western Eurasia. Despite this diverse and extensive coverage we did not detect any new shorebird AIV
hotspots. Neither large shorebird congregation sites nor the ruddy turnstone were consistently associated with AIV
hotspots. We did, however, find a low but widespread circulation of AIV in shorebirds that contrast with the absence of AIV
previously reported in shorebirds in Europe. A very high AIV antibody prevalence coupled to a low infection rate was found
in both first-year and adult birds of two migratory sandpiper species, suggesting the potential existence of an AIV hotspot
along their migratory flyway that is yet to be discovered.
