Blood parasite infections in a wild population of ravens (Corvus corax) in Bulgaria

Abstract

BackgroundBlood parasites have been studied intensely in many families of avian hosts, but corvids, a particularly cosmopolitan family, remain underexplored. Haemosporidian parasites of the common raven (Corvus corax) have not been studied, although it is the largest, most adaptable, and widespread corvid. Genetic sequence data from parasites of ravens can enhance the understanding of speciation patterns and specificity of haemosporidian parasites in corvids, and shed light how these hosts cope with parasite pressure.MethodsA baited cage trap was used to catch 86 ravens and a nested PCR protocol was used to amplify a 479 bp fragment of the haemosporidian cytochrome b gene from the samples. The obtained sequences were compared with the MalAvi database of all published haemosporidian lineages and a phylogenetic tree including all detected raven parasites was constructed. An examination of blood smears was performed for assessment of infection intensity.ResultsTwenty blood parasite lineages were recovered from ravens caught in a wild population in Bulgaria. The prevalence of generalist Plasmodium lineages was 49%, and the prevalence of Leucocytozoon lineages was 31%. Out of 13 detected Leucocytozoon lineages six were known from different corvids, while seven others seem to be specific to ravens. A phylogenetic reconstruction suggests that Leucocytozoon lineages of ravens and other corvids are not monophyletic, with some groups appearing closely related to parasites of other host families.ConclusionsSeveral different, morphologically cryptic groups of Leucocytozoon parasites appear to infect corvids. Ravens harbour both generalist corvid Leucocytozoon as well as apparently species-specific lineages. The extraordinary breeding ecology and scavenging lifestyle possibly allow ravens to evade vectors and have relatively low blood parasite prevalence compared to other corvids.

Blood Parasites in Sympatric Vultures: Role of Nesting Habits and Effects on Body Condition

“…Our current results do not confirm if the adaptations connected with carrion-feeding lifestyle and gut microbiome suppress transmission, or otherwise affect the blood parasite fauna. In conjunction with the patterns found in previous studies on raptor and non-raptor scavengers, it appears probable that habitat features play an important role in the transmission of blood parasites [26,62]. An additional role in the specific features of the host immunity needs to be further explored.…”

The prevalence of Leucocytozoon spp. in nestlings of three wild raptor species including implications on haematological and blood chemistry values

“…Studies on the prevalence of Leucocytozoon and other haemosporidian parasites in raptors are numerous and mostly suggest high prevalence, in some cases up to 100% ( Jeffries et al, 2015 ; Valkiunas, 2005 ). Recent studies have shown Leucocytozoon infections to be highly prevalent also in passerine species with similar or shorter altricial periods than the studied raptors ( Schmid et al, 2017 ; Schumm et al, 2019 ; Shurulinkov et al, 2018 ). In this study, Leucocytozoon infections were detected in nestlings of all three studied raptor species, as expected from related results ( Bensch et al, 2009 ).…”

Avian haemosporidians in the cattle egret (Bubulcus ibis) from central-western and southern Africa: High diversity and prevalence

“…Studies on haemosporidians involving a single host bird species have reported a lower number of lineages in comparison to those found in the cattle egret. A study on the house wren ( Troglodytes aedon ) from the Andes and bordering lowlands revealed 23 distinct lineages [52], while twenty new lineages of haemosporidians were described in a raven ( Corvus corax ) population [15]. The order Ciconiiformes, which includes the cattle egret, had previously been described as having only 33 avian malaria lineages [34].…”

“…There are relatively few examples of single-species studies focusing on spatial patterns in the occurrence of haemosporidians [9, 12–15]. This approach enables comparing the effects of environmental factors on the prevalence and diversity of haemosporidians.…”