Genetic characterization, distribution and prevalence of avian pox and avian malaria in the Berthelot’s pipit (Anthus berthelotii) in Macaronesia

Abstract

Exotic pathogens have been implicated in the decline and extinction of various native-island-bird species. Despite the fact that there is increasing concern about the introduction of diseases in island ecosystems, little is known about parasites in the islands of Macaronesia. We focus on Berthelot's pipit (Anthus berthelotii), an endemic and widespread Macaronesian bird species, using a combination of field studies and molecular techniques to determine: (1) the range and prevalence of avian pox and malaria in Berthelot's pipits throughout the species' distribution, (2) the genetic characterization of both parasites in order to ascertain the level of host specificity. We sampled 447 pipits across the 12 islands inhabited by this species. Overall, 8% of all individuals showed evidence of pox lesions and 16% were infected with avian malaria, respectively. We observed marked differences in the prevalence of parasites among islands both within and between archipelagos. Avian pox prevalence varied between 0-54% within and between archipelagos and avian malaria prevalence varied between 0-64% within and between archipelagos. The diversity of pathogens detected was low: only two genetic lineages of avian malaria and one lineage of avian pox were found to infect the pipit throughout its range. Interestingly, both avian malaria parasites found were Plasmodium spp. that had not been previously reported in the Macaronesian avifauna (but that had been observed in the lesser kestrel Falco naumannii), while the avian pox was a host specific lineage that had previously been reported on two of the Canary Islands.

Biogeographical patterns and co-occurrence of pathogenic infection across island populations of Berthelot’s pipit (Anthus berthelotii)

“…For avian malaria, no Haemoproteus was detected, but two Plasmodium strains were identified. These same strains were detected in Berthelot's pipits by Illera et al (2008). In the present study, the most common Plasmodium strain, TF413, was found in all but two of the individuals infected with Plasmodium.…”

“…No evidence for trypanosome infection was found in any of our samples, despite the successful amplification of trypanosome DNA from positive controls. For avian pox, successful amplification was achieved in seven samples from 2006 (six from Porto Santo and one from Lanzarote), all of which gave identical sequences, apparently unique to Berthelot's pipit (Illera et al 2008). We were unable to achieve amplifications from any 2009 samples (discussed later).…”

“…For avian pox, primers developed by Lee and Lee (1997) were used, which amplify a 578 bp fragment of the 4b gene. For both malaria and pox PCR reactions, the reagents and conditions described in Illera et al (2008) were used. For trypanosomes, primers developed by Maslov et al (1996) were used as well as the nested PCR reaction described in Sehgal et al (2001), which amplifies a 326 bp fragment of the small subunit ribosomal RNA gene.…”

Worldwide Phylogenetic Relationship of Avian Poxviruses

“…The lifestyle of wild birds allows avian poxviruses to reach new hosts through bird migration, species introductions, and habitat change. Avian pox has been identified as an important risk factor in the conservation of small and endangered populations, particularly in island bird species (4). The impact of the introduction of avian pox has been disastrous for the avifauna of various archipelagos (11).…”

Avipoxvirus in great tits (Parus major)

“…In passerine birds (Passeriformes) from the family Paridae, the avipoxvirus infection has been described in tufted titmouse (Baeolophus bicolor) in the USA (Goodpasture and Anderson 1962), African blue tit (Cyanistes teneriffae) in the Canary Islands (Illera et al 2008), and great tit (Parus major) in Europe (Holt and Krogsrud 1973;Literak et al 2004;Gruber et al 2007;Palade et al 2008). The fact that great tits are among species susceptible to avipoxvirus infection was proven by experimental infections already in 1901 (Polowinkin 1901).…”