The tick Ixodes uriae (Acari: Ixodidae): Hosts, geographical distribution, and vector roles

New tick records with notes on rickettsial infection from the wildlife of the state of Espírito Santo, southeastern Brazil

This work aimed to report ticks infesting the wildlife among 15 municipalities of the state of Espírito Santo between 2016 and 2021, within the Atlantic Forest biome of southeastern Brazil. A total of 576 tick specimens (187 males, 56 females, 149 nymphs, and 184 larvae) was collected from 41 species of wild vertebrates (two reptiles, nine mammals, and 30 birds). Ticks were identified by morphological or molecular methods into 18 species, being 12, four, one and one of the genera Amblyomma, Ixodes, Rhipicephalus and Ornithodoros, respectively. Amblyomma rotundatum was the only species collected from reptiles. Ticks collected from mammals were identified as Amblyomma brasiliense, Amblyomma calcaratum, Amblyomma dubitatum, Amblyomma longirostre, Amblyomma nodosum, Amblyomma pacae, Amblyomma sculptum, Amblyomma varium and Rhipicephalus microplus. Amblyomma sculptum was the species found on the widest variety of hosts, collected from four mammal orders and five bird orders. Passeriformes birds were infested by Amblyomma fuscum, A. longirostre (also found on non- passerine birds), A. nodosum, Amblyomma parkeri, Amblyomma romarioi, A. varium and Ixodes loricatus. An adult female of Ixodes rio was collected from a Piciformes bird. Seabirds of the order Procellariiformes were infested by Ixodes percavatus sensu lato and Ixodes uriae. The argasid Ornithodoros capensis was collected from an offshore metallic platform that was used by Suliformes seabirds. Rickettsial agents of the spotted fever group, Rickettsia amblyommatis and Rickettsia sp. strain Pampulha, were detected in the ticks A. longirostre [from the Paraguayan hairy dwarf porcupine (Coendou spinosus)] and A. dubitatum [from the capybara (Hydrochoerus hydrochaeris)], respectively. The following nine tick species are reported for the first time in Espírito Santo state: A. calcaratum, A. fuscum, A. pacae, A. parkeri, A. romarioi, I. loricatus, I. rio, I. uriae, and O. capensis. Although it is also the first report of I. uriae in Brazil, we do not consider it established in the country. Multiple new tick-host associations are reported in the present study.

Molecular-phylogenetic analyses of Ixodes species from South Africa suggest an African origin of bird-associated exophilic ticks (subgenus Trichotoixodes)

BACKGROUND

Among hard ticks (Acari: Ixodidae), the genus Ixodes comprises the highest number of species, which in turn are most numerous in the Afrotropical zoogeographic region. In South Africa extensive morphological studies have been performed on Ixodes species but only few reports included molecular analyses.

METHODS

In this study, 58 Ixodes spp. ticks, collected from ten mammalian and eight avian host species in South Africa, were molecularly and phylogenetically analyzed. In addition, a newly collected sample of the Palearctic Ixodes trianguliceps was included in the analyses.

RESULTS

Among the ticks from South Africa, 11 species were identified morphologically. The majority of ticks from mammals represented the Ixodes pilosus group with two species (n = 20), followed by ticks resembling Ixodes rubicundus (n = 18) and Ixodes alluaudi (n = 3). In addition, single specimens of Ixodes rhabdomysae, Ixodes ugandanus, Ixodes nairobiensis and Ixodes simplex were also found. Considering bird-infesting ticks, Ixodes theilerae (n = 7), Ixodes uriae (n = 4) and ticks most similar to Ixodes daveyi (provisionally named I. cf. daveyi, n = 2) were identified. Molecular analyses confirmed two species in the I. pilosus group and a new species (I. cf. rubicundus) closely related to I. rubicundus sensu stricto. Phylogenetic trees based on concatenated mitochondrial or mitochondrial and nuclear gene sequences indicated that the subgenus Afrixodes forms a monophyletic clade with bird-associated exophilic ticks (subgenus Trichotoixodes). Ixodes trianguliceps clustered separately whereas I. alluaudi with their morphologically assigned subgenus, Exopalpiger.

CONCLUSIONS

Phylogenetic analyses shed new lights on the relationships of Ixodes subgenera when including multiple sequences from subgenus Afrixodes and African as well as Palearctic species of subgenera Trichotoixodes and Exopalpiger. Subgenera Afrixodes and bird-associated Trichotoixodes share common ancestry, suggesting that the latter might have also originated in Africa. Regarding the subgenus Exopalpiger, I. alluaudi is properly assigned as it clusters among different Australian Ixodes, whereas I. trianguliceps should be excluded.

A novel variant of Babesia sp. (Piroplasmida) as a hemoparasite in procellariiform seabirds

Procellariiformes includes pelagic seabirds that only use land for breeding; and also, these sites mostly occur in insular habitats. These peculiar habits make the investigation of hemoparasites a challenging issue. Thus, the data on the blood parasites of Procellariiformes are still scarce. In the order Piroplasmida, 16 species of Babesia have been described in terrestrial birds and seabirds. However, there is no register for Babesia spp. in procellariiform seabirds. Hence, the objective of this survey was to investigate the occurrence of Babesia spp. in these seabirds. A total of 220 tissue samples from 18 different seabird species were analyzed; the samples comprised blood and fragments of liver and spleen. The samples were obtained from live rescued animals and carcasses found along the southern coast of Brazil. Polymerase chain reaction (PCR) was conducted, followed by phylogenetic analysis. Only one blood sample yielded a positive result, from an adult female Thalassarche chlororhynchos (Atlantic yellow-nosed albatross). The sequence obtained showed the highest identity with sequences of Babesia spp. of birds from the South Pacific, and the isolate was named Babesia sp. strain Albatross. In the phylogenetic analysis, the sequence was grouped within the Babesia sensu stricto group, and further still into a subgroup including Babesia spp. of the Kiwiensis clade (parasites from birds). The phylogenetic analysis also showed that Babesia sp. strain Albatross clustered apart from the Peircei group, a clade that includes Babesia spp. from seabirds. As far as it is known, this is the first report of Babesia sp. in procellariiform seabirds. Babesia sp. strain Albatross may constitute a novel variant of tick-borne piroplasmids associated with the Procellariiformes order.

The Eurasian shrew and vole tick Ixodes trianguliceps: geographical distribution, climate preference, and pathogens detected

The Eurasian shrew and vole tick Ixodes trianguliceps Birula lives in the nests and burrows of its small mammalian hosts and is-along with larvae and nymphs of Ixodes ricinus or Ixodes persulcatus-one of the most commonly collected tick species from these hosts in its Eurasian range. Ixodes trianguliceps is a proven vector of Babesia microti. In this study, up-to-date maps depicting the geographical distribution and the climate preference of I. trianguliceps are presented. A dataset was compiled, resulting in 1161 georeferenced locations in Eurasia. This data set covers the entire range of I. trianguliceps for the first time. The distribution area between 8[Formula: see text] W-105[Formula: see text] E and 40-69[Formula: see text] N extends from Northern Spain to Western Siberia. To investigate the climate adaptation of I. trianguliceps, the georeferenced locations were superimposed on a high-resolution map of the Köppen-Geiger climate classification. The Köppen profile for I. trianguliceps, i.e., a frequency distribution of the tick occurrence under different climates, shows two peaks related to the following climates: warm temperate with precipitation all year round (Cfb), and boreal with warm or cold summers and precipitation all year round (Dfb, Dfc). Almost 97% of all known I. trianguliceps locations are related to these climates. Thus, I. trianguliceps prefers climates with warm or cold summers without dry periods. Cold winters do not limit the distribution of this nidicolous tick species, which has been recorded in the European Alps and the Caucasus Mountains up to altitudes of 2400 m. Conversely, I. trianguliceps does not occur in the Mediterranean area with its hot and dry summers.

Climate change in the Arctic: Testing the poleward expansion of ticks and tick-borne diseases

Climate change is most strongly felt in the polar regions of the world, with significant impacts on the species that live there. The arrival of parasites and pathogens from more temperate areas may become a significant problem for these populations, but current observations of parasite presence often lack a historical reference of prior absence. Observations in the high Arctic of the seabird tick Ixodes uriae suggested that this species expanded poleward in the last two decades in relation to climate change. As this tick can have a direct impact on the breeding success of its seabird hosts and vectors several pathogens, including Lyme disease spirochaetes, understanding its invasion dynamics is essential for predicting its impact on polar seabird populations. Here, we use population genetic data and host serology to test the hypothesis that I. uriae recently expanded into Svalbard. Both black-legged kittiwakes (Rissa tridactyla) and thick-billed murres (Uria lomvia) were sampled for ticks and blood in Kongsfjorden, Spitsbergen. Ticks were genotyped using microsatellite markers and population genetic analyses were performed using data from 14 reference populations from across the tick's northern distribution. In contrast to predictions, the Spitsbergen population showed high genetic diversity and significant differentiation from reference populations, suggesting long-term isolation. Host serology also demonstrated a high exposure rate to Lyme disease spirochaetes (Bbsl). Targeted PCR and sequencing confirmed the presence of Borrelia garinii in a Spitsbergen tick, demonstrating the presence of Lyme disease bacteria in the high Arctic for the first time. Taken together, results contradict the notion that I. uriae has recently expanded into the high Arctic. Rather, this tick has likely been present for some time, maintaining relatively high population sizes and an endemic transmission cycle of Bbsl. Close future observations of population infestation/infection rates will now be necessary to relate epidemiological changes to ongoing climate modifications.

Cold hardening improves larval tick questing under low temperatures at the expense of longevity

Questing in ticks is essential for locating a host, and this behavioral response can occur at regionally specific low temperatures for most tick species. Little is known about the dynamics between tick questing behavior and temperature in ticks, specifically how this may impact other aspects of tick biology. Here, we examine whether cold hardening increases questing in three larval tick species (Ixodes uriae, Dermacentor variabilis, and Amblyomma americanum) at low temperatures and whether cold hardening impacts longevity. Rapid cold hardening and prolonged cold acclimation benefitted ticks by decreasing the temperature of chill coma onset, and increased survival, activity, and questing in ticks at low temperatures. Oxygen consumption increased at low temperatures following acclimation in larvae, suggesting this process has a distinct metabolic expense. This increased metabolism associated with hardening led to a substantial reduction in larval longevity as nutrient reserves are limited and cannot be replenished until a host is located. These studies suggest that tick larvae, and likely other developmental stages, require a delicate balance between the need for questing at low temperatures and survival until the first blood meal.

Atlas of ticks (Acari: Argasidae, Ixodidae) in Germany

An updated and increased compilation of georeferenced tick locations in Germany is presented here. This data collection extends the dataset published some years ago by another 1448 new tick locations, 900 locations of which were digitized from literature and 548 locations are published here for the first time. This means that a total of 3492 georeferenced tick locations is now available for Germany. The tick fauna of Germany includes two species of Argasidae in the genera Argas and Carios and 19 species of Ixodidae in the genera Dermacentor, Haemaphysalis, and Ixodes, altogether 21 tick species. In addition, three species of Ixodidae in the genera Hyalomma (each spring imported by migratory birds) and Rhipicephalus (occasionally imported by dogs returning from abroad with their owners) are included in the tick atlas. Of these, the georeferenced locations of 23 tick species are depicted in maps. The occurrence of the one remaining tick species, the recently described Ixodes inopinatus, is given at the level of the federal states. The most common and widespread tick species is Ixodes ricinus, with records in all 16 federal states. With the exception of Hamburg, Dermacentor reticulatus was also found in all federal states. The occurrence of the ixodid ticks Ixodes canisuga, Ixodes frontalis, Ixodes hexagonus and I. inopinatus were documented in at least 11 federal states each. The two mentioned argasid tick species were also documented in numerous federal states, the pigeon tick Argas reflexus in 11 and the bat tick Carios vespertilionis in seven federal states. The atlas of ticks in Germany and the underlying digital dataset in the supplement can be used to improve global tick maps or to study the effects of climate change and habitat alteration on the distribution of tick species.

Arthropod parasites of Antarctic and Subantarctic birds and pinnipeds: A review of host-parasite associations

Due to its cold and dry climate and scarcity of ice-free land, Antarctica has one of the most extreme environments on our planet. To survive in the Antarctic region, parasitic arthropods must either remain closely associated with their hosts throughout the entire life cycle or develop physiological adaptations to survive in the terrestrial habitat while their hosts are away foraging at sea or overwintering at lower latitudes. Forty-eight species of birds and seven species of pinnipeds breed in the Antarctic region, with 158 species/subspecies of parasitic arthropods recorded thus far, comprising: sucking lice (Echinophthiriidae), chewing lice (Menoponidae, Philopteridae), fleas (Ceratophyllidae, Pygiopsyllidae, Rhopalopsyllidae), pentastomes (Reighardiidae), hard ticks (Ixodidae), nest-associated haematophagous mites (Laelapidae), nasal mites (Halarachnidae, Rhinonyssidae) and feather mites (Alloptidae, Avenzoariidae, Xolalgidae, Freyanidae). In this review, we provide an updated compilation of the available information on the host-parasite associations of arthropods infesting birds and pinnipeds in the Antarctic region, and discuss some over-arching ecological patterns and gaps of knowledge.

Establishing a baseline for tick surveillance in Alaska: Tick collection records from 1909-2019

The expanding geographic ranges of tick species that are known pathogen vectors can have implications for human, domestic animal, and wildlife health. Although Alaska is home to several hard tick species, it has historically been outside of the range of the most common medically important ticks in the contiguous United States and western Canada. To assess the status of tick species establishment in the state and to provide a baseline for tracking future change in the distribution of ticks, we reviewed and compiled historical tick records and summarized recent tick occurrence records collected through the development of the Alaska Submit-A-Tick Program and through tick drag sampling at sentinel sites in southcentral Alaska. Between 1909-2019, there were 1190 tick records representing 4588 individual ticks across 15 species in Alaska. The majority of ticks were species historically found in Alaska: Haemaphysalis leporispalustris, Ixodes angustus, Ixodes auritulus, Ixodes howelli, Ixodes signatus, and Ixodes uriae. Over half of all tick records in the state were collected in the last 10 yr. During this time, the number of tick records and the number of tick species recorded in Alaska each year has increased substantially. Between 2010-2019, there were 611 tick records representing 1921 individual ticks. The most common hosts for reported ticks were domestic animals (n = 343, 56 %) followed by small wild mammals (n = 147, 24 %), humans (n = 49, 8%), and wild birds (n = 31, 5%). Less than 5% of records (n = 25) were of unattached ticks found in the environment. Since 2007, non-native tick species have been documented in the state every year, including Amblyomma americanum, Dermacentor andersoni, Dermacentor occidentalis, Dermacentor variabilis, Ixodes pacificus, Ixodes ricinus, Ixodes scapularis, Ixodes texanus, and Rhipicephalus sanguineus sensu lato (s.l.). Almost half of the records (n = 68, 48 %) of non-native tick species from 2010 to 2019 represented ticks found on a host (usually a dog or a human) that had traveled outside of Alaska in the two weeks prior to collection. However, A. americanum, D. variabilis, I. pacificus, I. texanus, and R. sanguineus s.l. have been found on humans and domestic animals in Alaska without reported recent travel. In particular, there is evidence to suggest that there is local establishment of R. sanguineus s.l. in Alaska. A tick species historically found in the state, I. angustus was frequently found on human and dogs, suggesting a potential role as a bridge vector of pathogens. Given the inconsistency of tick monitoring in Alaska over the past century, it is difficult to draw many conclusions from temporal trends in the data. Continued monitoring through the Alaska Submit-A-Tick Program will allow a more accurate assessment of the changing risk of ticks and tick-borne diseases in the state and provide information for setting clinical and public health guidelines for tick-borne disease prevention.

Diversity and Distribution of Mites (Acari: Ixodida, Mesostigmata, Trombidiformes, Sarcoptiformes) in the Svalbard Archipelago

Svalbard is a singular region to study biodiversity. Located at a high latitude and geographically isolated, the archipelago possesses widely varying environmental conditions and unique flora and fauna communities. It is also here where particularly rapid environmental changes are occurring, having amongst the fastest increases in mean air temperature in the Arctic. One of the most common and species-rich invertebrate groups in Svalbard is the mites (Acari). We here describe the characteristics of the Svalbard acarofauna, and, as a baseline, an updated inventory of 178 species (one Ixodida, 36 Mesostigmata, 43 Trombidiformes, and 98 Sarcoptiformes) along with their occurrences. In contrast to the Trombidiformes and Sarcoptiformes, which are dominated in Svalbard by species with wide geographical distributions, the Mesostigmata include many Arctic species (39%); it would thus be an interesting future study to determine if mesostigmatid communities are more affected by global warming then other mite groups. A large number of new species (42 spp.) have been described from Svalbard, including 15 that have so far been found exclusively there. It is yet uncertain if any of these latter species are endemic: six are recent findings, the others are old records and, in most cases, impossible to verify. That the Arctic is still insufficiently sampled also limits conclusions concerning endemicity.

Circumpolar diversification of the Ixodes uriae tick virome

Ticks (order: Ixodida) are a highly diverse and ecologically important group of ectoparasitic blood-feeding organisms. One such species, the seabird tick (Ixodes uriae), is widely distributed around the circumpolar regions of the northern and southern hemispheres. It has been suggested that Ix. uriae spread from the southern to the northern circumpolar region millions of years ago and has remained isolated in these regions ever since. Such a profound biographic subdivision provides a unique opportunity to determine whether viruses associated with ticks exhibit the same evolutionary patterns as their hosts. To test this, we collected Ix. uriae specimens near a Gentoo penguin (Pygoscelis papua) colony at Neko harbour, Antarctica, and from migratory birds—the Razorbill (Alca torda) and the Common murre (Uria aalge)—on Bonden island, northern Sweden. Through meta-transcriptomic next-generation sequencing we identified 16 RNA viruses, seven of which were novel. Notably, we detected the same species, Ronne virus, and two closely related species, Bonden virus and Piguzov virus, in both hemispheres indicating that there have been at least two cross-circumpolar dispersal events. Similarly, we identified viruses discovered previously in other locations several decades ago, including Gadgets Gully virus, Taggert virus and Okhotskiy virus. By identifying the same or closely related viruses in geographically disjunct sampling locations we provide evidence for virus dispersal within and between the circumpolar regions. In marked contrast, our phylogenetic analysis revealed no movement of the Ix. uriae tick hosts between the same locations. Combined, these data suggest that migratory birds are responsible for the movement of viruses at both local and global scales.

As host populations diverge, so may those microorganisms, including viruses, that are dependent on those hosts. To examine this key issue in host-microbe evolution we compared the co-phylogenies of the seabird tick, Ixodes uriae, and their RNA viruses sampled from the far northern and southern hemispheres. Despite the huge geographic distance between them, phylogeographic analysis reveals that the same and closely related viruses were found both within and between the northern and southern circumpolar regions, most likely reflecting transfer by virus-infected migratory birds. In contrast, genomic data suggested that the Ix. uriae populations were phylogenetically distinct between the northern and southern hemispheres. This work emphasises the importance of migratory birds and ticks as vectors and sources of virus dispersal and introduction at both the local and global scales.

Sustained RNA virome diversity in Antarctic penguins and their ticks

Despite its isolation and extreme climate, Antarctica is home to diverse fauna and associated microorganisms. It has been proposed that the most iconic Antarctic animal, the penguin, experiences low pathogen pressure, accounting for their disease susceptibility in foreign environments. There is, however, a limited understanding of virome diversity in Antarctic species, the extent of in situ virus evolution, or how it relates to that in other geographic regions. To assess whether penguins have limited microbial diversity we determined the RNA viromes of three species of penguins and their ticks sampled on the Antarctic peninsula. Using total RNA sequencing we identified 107 viral species, comprising likely penguin associated viruses (n = 13), penguin diet and microbiome associated viruses (n = 82), and tick viruses (n = 8), two of which may have the potential to infect penguins. Notably, the level of virome diversity revealed in penguins is comparable to that seen in Australian waterbirds, including many of the same viral families. These data run counter to the idea that penguins are subject to lower pathogen pressure. The repeated detection of specific viruses in Antarctic penguins also suggests that rather than being simply spill-over hosts, these animals may act as key virus reservoirs.

Determinants of external and blood parasite load in African penguins (Spheniscus demersus) admitted for rehabilitation

We investigate the factors associated with the occurrence and abundance of external and blood parasites in African penguins (Spheniscus demersus), an endangered seabird that breeds exclusively on the coasts of Namibia and South Africa. External parasites were collected using the dust-ruffling method from 171 African Penguins admitted at a rehabilitation facility in the Western Cape, South Africa. Additionally, blood smears were obtained upon admission and weekly during rehabilitation and examined for blood parasites. Fleas Parapsyllus longicornis humboldti, ticks Ornithodoros capensis and lice Austrogoniodes demersus were recovered from 93, 63 and 40%, respectively, of the penguins upon admission to the centre. Rescue location and age group were identified as significant determinants of flea abundance, whereas month of admission was a significant determinant of tick abundance. Blood parasites were also common on admission, with Babesia being the most frequent (46% prevalence) whereas Borrelia was recorded sporadically (1.2%) and Plasmodium was recorded once. The prevalence and abundance of ticks on admission was positively associated with Babesia infection on admission. Our findings demonstrate the variability and contributing factor of parasite infections in an endangered species of penguin, and highlight the need for additional research on the parasite-host dynamics involving these potential disease vectors.

Novel Ehrlichia sp. detected in Magellanic penguins (Sphenicus magellanicus) and in the seabird tick Ixodes uriae from Magdalena Island, southern Chile

Ehrlichia spp. are obligatory intracellular microorganisms that infect hematopoietic, endothelial or blood cells of mammals. Ticks are the only vectors of these agents in nature. To date, the role of birds and their associated ticks as reservoirs of ehrlichiae remains almost unexplored. In this study, we performed a molecular screening for bacteria of Anaplasmataceae family in samples of spleen (n = 72) and lung (n = 17), recovered from 72 carcasses of Magellanic penguins (Spheniscus magellanicus) in Brazil and Chile. One apparently unengorged tick (Ixodes uriae) was also collected while wandering upon one of the carcasses and submitted to molecular analyses as well. Through conventional and nested PCR protocols three genes (16S rRNA, dsb and groEL) of a new Ehrlichia sp. were partially characterized upon organs of three penguins and in the tick coming from Magdalena Island (Chile). First matches after BLASTn comparisons showed that our sequences share 99.4% (16S rRNA), 94.6% (groEL) and 79.3% (dsb) of identity with "Candidatus Ehrlichia ornithorhynchi", Ehrlichia sp. NS101 and Ehrlichia canis CCZ, respectively. Matrixes of genetic distance including other representatives of the Ehrlichia genus point a 99.4%, 94.0%, and 80.0% of identity with 16S rRNA, groEL and dsb genes from Ehrlichia sp. It25, Ehrlichia sp. NS101, and Ehrlichia chaffeensis San Louis, respectively. A Bayesian phylogenetic analysis of Anaplasmataceae 16S rRNA gene places the detected Ehrlichia sp. into a group with Ehrlichia sp. BAT and Ehrlichia sp. Natal. Although depicting different topologies, Bayesian unrooted phylogenetic trees constructed for groEL and dsb genes position this Ehrlichia sp. into well-supported branches, which reinforces the finding of a new taxon. For the moment, any pathogenic effect of this new Ehrlichia sp. on penguins is still unknown. However, this fact becomes important to assess from a conservation point of view since populations of Magellanic penguins are currently threatened and in an ongoing decrease.

Hard tick (Acari: Ixodidae) survey of Oleoducto trail, Soberania National Park, Panama

Hard tick diversity was determined along the Oleoducto trail (OT), Soberania National Park, from February 2013 to September 2014. Ticks were surveyed at four sites of 500 m² each and with increasing forest cover gradient and decreasing disturbance. Tick collections were made by dragging and flagging vegetation, and traps and mist nets were used to capture mammals and birds. Animals confiscated from poachers were also examined. To obtain information about potential hosts along the trail, 20 camera traps were used. 1536 ticks were collected, representing 20 species; of these, 1089 were questing ticks (10 species) collected on flags. We examined 143 birds (30 species) and 59 mammals (10 species), of which 40 birds and 36 mammals had ticks. Site 1 presented the lowest number of species and also the lowest number of potential hosts. Artiodactyls were the most frequent mammals photographed in camera traps, and ticks that parasitize these animals were among the most abundant in sites 2-4. Of these, Haemaphysalis juxtakochi was the most abundant species. Differences among sites were consistent with the gradient of forest cover, disturbance along OT and distribution of potential hosts.

Parasites of seabirds: A survey of effects and ecological implications

Parasites are ubiquitous in the environment, and can cause negative effects in their host species. Importantly, seabirds can be long-lived and cross multiple continents within a single annual cycle, thus their exposure to parasites may be greater than other taxa. With changing climatic conditions expected to influence parasite distribution and abundance, understanding current level of infection, transmission pathways and population-level impacts are integral aspects for predicting ecosystem changes, and how climate change will affect seabird species. In particular, a range of micro- and macro-parasites can affect seabird species, including ticks, mites, helminths, viruses and bacteria in gulls, terns, skimmers, skuas, auks and selected phalaropes (Charadriiformes), tropicbirds (Phaethontiformes), penguins (Sphenisciformes), tubenoses (Procellariiformes), cormorants, frigatebirds, boobies, gannets (Suliformes), and pelicans (Pelecaniformes) and marine seaducks and loons (Anseriformes and Gaviiformes). We found that the seabird orders of Charadriiformes and Procellariiformes were most represented in the parasite-seabird literature. While negative effects were reported in seabirds associated with all the parasite groups, most effects have been studied in adults with less information known about how parasites may affect chicks and fledglings. We found studies most often reported on negative effects in seabird hosts during the breeding season, although this is also the time when most seabird research occurs. Many studies report that external factors such as condition of the host, pollution, and environmental conditions can influence the effects of parasites, thus cumulative effects likely play a large role in how parasites influence seabirds at both the individual and population level. With an increased understanding of parasite-host dynamics it is clear that major environmental changes, often those associated with human activities, can directly or indirectly affect the distribution, abundance, or virulence of parasites and pathogens.

Can a Terrestrial Ectoparasite Disperse with Its Marine Host?

One of the most extreme examples of parasite adaptation comes from terrestrial ectoparasites exploiting marine hosts. Despite the ubiquity of such ectoparasitism and its ecological and evolutionary importance, investigations of the responses of ectoparasites to conditions encountered on their hosts are rare. In the case of penguins and their ticks, current understanding suggests that ticks freely parasitize their hosts on land but are incapable of surviving extended oceanic journeys. We examined this conjecture by assessing the physiological capacity of little penguin ticks to endure at-sea foraging and dispersal events of their hosts. Survival in penguins ticks was not significantly compromised by exposure to depths commonly associated with host dives (40 and 60 m), repeated seawater exposure relevant to the most common (30 s) and longest (120 s) recorded host dives, or extended (48 h) exposure to seawater. Mean (±SD) closed-phase durations in adult and nymphal ticks exhibiting discontinuous gas exchange ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>339</mml:mn><mml:mo>±</mml:mo><mml:mn>237</mml:mn></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>240</mml:mn><mml:mo>±</mml:mo><mml:mn>295</mml:mn></mml:mrow></mml:math> s, respectively) exceeded that of the maximum recorded host dive duration (120 s). Normoxic-anoxic-normoxic respirometry also confirmed spiracle closure. Mean metabolic rates ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.354</mml:mn><mml:mo>±</mml:mo><mml:mn>0.220</mml:mn></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>4.853</mml:mn><mml:mo>±</mml:mo><mml:mn>4.930</mml:mn></mml:mrow></mml:math> μL/h at 25°C for unfed and fed adult females, respectively) were significantly influenced by temperature; optimal and LT₅₀ temperatures for adult ticks and fed nymphal ticks were typically higher than swimming penguin body temperatures. These findings suggest that marine host dispersal is unlikely to present an insurmountable barrier to long-distance tick dispersal. Such dispersal has important implications for evolutionary theory, conservation, and epidemiology.

A novel candidate species of Anaplasma that infects avian erythrocytes

Background

Anaplasma spp. are Gram-negative obligate intracellular bacteria transmitted by ticks. Even though numerous studies have detected DNA from Anaplasma spp. in the blood of birds, thus far mammals were the only vertebrates demonstrated to serve as competent hosts to these organisms. We report a novel candidate species of Anasplasma that was associated with cytoplasmic inclusions in the erythrocytes of an African penguin (Spheniscus demersus) in South Africa.

Methods

Cytoplasmic inclusions were morphologically characterized from freshly-produced blood smears, and phylogenetic analysis of 16S rRNA and groEL genes were used to evaluate the evolutionary relationships of the organism to other Anaplasmataceae.

Results

Dark-purple round or oval inclusions consistent with Anaplasmataceae morulae were observed in the cytoplasm of erythrocytes. Phylogenetic trees produced using different methods agreed that the organism detected in this study belongs to the genus Anaplasma, and suggested that it is most closely related to the cluster comprising A. centrale, A. capra, A. marginale and A. ovis. We propose provisionally naming the strain detected in this study as “Candidatus Anaplasma sphenisci”.

Conclusions

This is the first species of Anaplasma shown to produce cytoplasmic inclusions in avian cells, opening the possibility that cytoplasmic inclusions in avian erythrocytes that had previously been attributed to Aegyptianella sp. might in fact correspond to Anaplasma. Further studies on the molecular biology of avian-infecting Anaplasmataceae will be valuable to provide insight into the evolution and epidemiology of these organisms.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3089-9) contains supplementary material, which is available to authorized users.

Molecular characterization of Babesia peircei and Babesia ugwidiensis provides insight into the evolution and host specificity of avian piroplasmids

There are 16 recognized species of avian-infecting Babesia spp. (Piroplasmida: Babesiidae). While the classification of piroplasmids has been historically based on morphological differences, geographic isolation and presumed host and/or vector specificities, recent studies employing gene sequence analysis have provided insight into their phylogenetic relationships and host distribution and specificity. In this study, we analyzed the sequences of the 18S rRNA gene and ITS-1 and ITS-2 regions of two Babesia species from South African seabirds: Babesia peircei from African penguins (Spheniscus demersus) and Babesia ugwidiensis from Bank and Cape cormorants (Phalacrocorax neglectus and P. capensis, respectively). Our results show that avian Babesia spp. are not monophyletic, with at least three distinct phylogenetic groups. B. peircei and B. ugwidiensis are closely related, and fall within the same phylogenetic group as B. ardeae (from herons Ardea cinerea), B. poelea (from boobies Sula spp.) and B. uriae (from murres Uria aalge). The validity of B. peircei and B. ugwidiensis as separate species is corroborated by both morphological and genetic evidence. On the other hand, our results indicate that B. poelea might be a synonym of B. peircei, which in turn would be a host generalist that infects seabirds from multiple orders. Further studies combining morphological and molecular methods are warranted to clarify the taxonomy, phylogeny and host distribution of avian piroplasmids.

•

Babesia peircei (Bp) infects penguins and B. ugwidiensis (Bu) infects cormorants.

•

Gene sequences of Bp and Bu were analyzed from birds sampled in South Africa.

•

Phylogenetic analysis reveals at least three paraphyletic groups of avian Babesia.

•

Bp and Bu form a phylogenetic group along with other Babesia from aquatic birds.

•

Avian Babesia might not be host-specific at the order level as previously thought.

Blood parasites of penguins: a critical review

Blood parasites are considered some of the most significant pathogens for the conservation of penguins, due to the considerable morbidity and mortality they have been shown to produce in captive and wild populations of these birds. Parasites known to occur in the blood of penguins include haemosporidian protozoans (Plasmodium, Leucocytozoon, Haemoproteus), piroplamid protozoans (Babesia), kinetoplastid protozoans (Trypanosoma), spirochete bacteria (Borrelia) and nematode microfilariae. This review provides a critical and comprehensive assessment of the current knowledge on these parasites, providing an overview of their biology, host and geographic distribution, epidemiology, pathology and implications for public health and conservation.

Do blood parasites infect Magellanic penguins (Spheniscus magellanicus) in the wild? Prospective investigation and climatogeographic considerations

Magellanic penguins (Spheniscus magellanicus) are native to Argentina, Chile and the Falkland Islands. Magellanic penguins are highly susceptible to blood parasites such as the mosquito-borne Plasmodium spp., which have been documented causing high morbidity and mortality in zoos and rehabilitation centres. However, to date no blood parasites have been detected in wild Magellanic penguins, and it is not clear whether this is reflective of their true absence or is instead related to an insufficiency in sampling effort or a failure of the diagnostic methods. We examined blood smears of 284 Magellanic penguins from the Argentinean coast and tested their blood samples with nested polymerase chain reaction tests targeting Haemoproteus, Plasmodium, Leucocytozoon and Babesia. No blood parasites were detected. Analysing the sampling effort of previous studies and the climatogeography of the region, we found there is strong basis to conclude that haemosporidians do not infect wild Magellanic penguins on the Argentinean coast. However, at present it is not possible to determine whether such parasites occur on the Chilean coast and at the Falkland Islands. Furthermore, it is troubling that the northward distribution expansion of Magellanic penguins and the poleward distribution shift of vectors may lead to novel opportunities for the transmission of blood parasites.

Occurrence of blood parasites in seabirds admitted for rehabilitation in the Western Cape, South Africa, 2001-2013

Blood parasites are generally uncommon in seabirds, and knowledge on their epidemiology is further limited by the fact that they often inhabit remote locations that are logistically difficult or expensive to study. We present a long term data set of blood smear examinations of 1909 seabirds belonging to 27 species that were admitted to a rehabilitation centre in Cape Town (Western Cape, South Africa) between 2001 and 2013. Blood parasites were detected in 59% of species (16/27) and 29% of individuals examined (551/1909). The following blood parasites were recorded: Babesia ugwidiensis, Babesia peircei, Babesia sp., Plasmodium sp., Leucocytozoon ugwidi, Hepatozoon albatrossi, Haemoproteus skuae and Spirochaetales. Several of the records are novel host-parasite associations, demonstrating the potential of rehabilitation centres for parasite and disease surveillance, particularly for species infrequently sampled from which no host-specific parasites have been described.