Ticks (Acari: Ixodidae, Argasidae) associated with wild birds in Argentina.

The aim of this study was to report tick infestations on wild birds from four Phytogeographic Provinces of Argentina. A total of 1085 birds was captured (124 species, 97 genera, 29 families and 13 orders), and ticks were collected from 265 birds (48 species, 40 genera and five orders). A total of 1469 ticks (1102 larvae, 363 nymphs and 4 females) belonging to 15 tick species (Amblyomma calcaratum, Amblyomma dubitatum, Amblyomma nodosum, Amblyomma ovale, Amblyomma parvum, Amblyomma sculptum, Amblyomma tigrinum, Amblyomma triste, Haemaphysalis juxtakochi, Haemaphysalis leporispalustris, Ixodes auritulus sensu lato, Ixodes pararicinus, Ixodes silvanus, Ixodes sp. cf. I. affinis and Ornithodoros sp. cf. O. mimon). Eighty-one new associations between bird species and stages of tick species are detected. The families Thamnophilidae, Turdidae, Thraupidae, Passerellidae, Furnariidae and Troglodytidae were the most prevalent. According to the Phytogeographic Provinces involved in this study, the prevalence of infection for each of them in birds was: (1) Chaco: 28.2% (11 tick species); (2) Yungas: 22.0% (8 tick species); (3) Espinal: 11.1% (2 tick species); and (4) Pampa: 3.9% (1 tick species). This study provided information on the diversity of tick species that parasitize wild birds, the variability of the specific tick-bird associations between the different Phytogeographic Provinces and the relevance of some families of birds as hosts of different tick species.

Borrelia genospecies in Ixodes sp. cf. Ixodes affinis (Acari: Ixodidae) from Argentina.

The aim of this work was to evaluate the presence of Borrelia infection in Ixodes sp. cf. Ixodes affinis ticks from Argentina. Specimens of Ixodes sp. cf. I. affinis were collected on vegetation and birds in five locations belonging the most humid part of the Chaco Biogeographic Province. Specimens were tested for Borrelia infection by nested-PCR targeting the flaB gene and the rrfA-rrlB intergenic spacer region (IGS), sequenced and phylogenetically analyzed. A total of 48 Ixodes sp. cf. I. affinis (12 questing adults from vegetation and 20 nymphs and 16 larvae on nine bird species: Arremon flavirostris, Basileuterus culicivorus, Campylorhamphus trochilirostris, Myiothlypis leucoblephara, Tachyphonus rufus, Thlypopsis sordida, Turdus amaurochalinus, Turdus rufiventris and Troglodytes aedon) were collected. Twelve adults, 14 nymphs and 11 larvae (3 individually and 8 in 3 pools) were analyzed. Partial sequences were detected in 6 adults, 11 nymphs and 4 larvae (2 individual and 2 pools). Phylogenetically, the Borrelia found in Ixodes sp. cf. I. affinis belongs to the B. burgdorferi sensu lato (s. l.) complex. The partial sequences obtained from the borrelian gene flaB and IGS were associated to two groups formed by sequences previously detected in Ixodes fuscipes, Ixodes longiscutatus and Ixodes pararicinus from the Southern Cone of America in northern Argentina, southern Brazil and Uruguay. The results of this work suggest that the haplotypes of B. burgdorferi s. l. complex detected in the three species of the I. ricinus complex distributed in the Southern Cone of America are related and widely distributed.

Molecular detection of rickettsial bacteria in ticks of the genus Ixodes from the Southern Cone of America.

To obtain information about rickettsial bacteria in ticks of the genus Ixodes from Argentina and Uruguay, specimens of I. fuscipes (previously named as I. aragaoi), Ixodes pararicinus, Ixodes sp. cf. I. affinis, and Ixodes sp. were tested targeting the rickettsial gltA and ompA genes. Rickettsial bacteria was detected in all of these species. Rickettsia found in Ixodes sp. is closely related to Ca. Rickettsia mendelii, which was previously detected in I. ricinus of the Czech Republic and later in I. brunneus from the USA. Phylogenetic analyses of the Rickettsia strains found in I. fuscipes, I. pararicinus, and Ixodes sp. cf. I. affinis showed that these strains form a clade together with R. buchneri detected in I. scapularis from the USA, which is closely related to R. monacensis from Europe. Rickettsia buchneri, R. cooleyi and the Rickettsia detected in I. fuscipes, I. pararicinus, and Ixodes sp. cf. I. affinis clustered together in a clade well supported, which suggest that they are different strains of R. buchneri. The phylogenetic analysis shows that Ixodes ticks that are closely related in evolutionary terms (i.e. Ixodes species from the I. ricinus complex, I. brunneus-Ixodes sp.) share closely related rickettsial strains. The results of this study show that rickettsial bacteria are present in Ixodes ticks from Argentina and describe the first detection of Ca. R. mendelii in South America.

The Ixodes ricinus complex (Acari: Ixodidae) in the Southern Cone of America: Ixodes pararicinus, Ixodes aragaoi, and Ixodes sp. cf. I. affinis.

The goal of this study was to clarify the taxonomic status of the Ixodes ricinus complex in the Southern Cone of America, by using morphological characters and molecular markers (mitochondrial 16SrDNA and cox1 genes). The morphological analysis indicates that three different taxa of the I. ricinus complex occur in this region: Ixodes pararicinus, Ixodes aragaoi, and Ixodes sp. cf. I. affinis. The most prominent diagnostic character among them is the size of scutal punctations in both male and female ticks. In the males of Ixodes sp. cf. I. affinis, the punctations on the central field and along the median marginal groove of the scutum are clearly larger than in the males of I. aragaoi and I. pararicinus, while the punctations of I. aragaoi are larger but less numerous than in I. pararicinus. The punctations in Ixodes sp. cf. I. affinis females are larger and deeper than in females of I. aragaoi and I. pararicinus, and those of I. aragaoi are slightly larger than in I. pararicinus. The length of the lateral posterior denticles of the male hypostome is comparatively longer in I. aragaoi than in the other two species, and longer in Ixodes sp. cf. I. affinis than in I. pararicinus. In the 16S analysis, I. pararicinus and I. aragaoi are monophyletic (99% and 98% bootstrap support, respectively), while Ixodes cf. I. affinis does not represent a single lineage. In the cox1 analysis, both I. pararicinus and I. aragaoi are well-defined taxa, but the bootstrap support for Ixodes sp. cf. I. affinis is low (67%). In general, there are considerable 16SrRNA differences among lineages of Ixodes sp. cf. I. affinis from different geographical areas. These results may be indicative of the existence of different species. The populations morphologically compatible with I. affinis from Argentina, Colombia, Panama, Belize, and USA should be provisionally named as Ixodes sp. cf. I. affinis until an integrative taxonomic work with further evidence redefines whether or not this taxon actually represents a species complex.

Rhipicephalus sanguineus (Latreille, 1806): Neotype designation, morphological re-description of all parasitic stages and molecular characterization.

The aims of this work were to re-describe all parasitic stages of Rhipicephalus sanguineus sensu stricto, to select and deposit a neotype, and to characterize some of its diagnostic molecular traits. A male of R. sanguineus s.s. collected in Montpellier, France, was designated as neotype. The diagnostic characters unique to the male of R. sanguineus s.s. are: spiracular plate elongated and subtriangular in shape with a dorsal prolongation narrow and usually visible dorsally, with the dorsal prolongation narrower than the width of the adjacent festoon; punctations of the scutum moderate in number and unequal in size; marginal groove conspicuous, deep and punctate; posteromedian groove distinct and elongated, and posterolateral grooves often sub-circular, shorter than posteromedian groove; adanal plates long, wide, and subtriangular in shape, with a clear concavity in its inner margin and posterior margin broadly rounded or truncated; accessory adanal plates with the posterior end pointed, narrower than the width of adjacent festoon. The female of R. sanguineus s.s. can be diagnosed by a combination of broadly U-shaped genital aperture, spiracular plate with a narrow dorsal prolongation visible dorsally, basis capituli hexagonal with broad lateral angles, and scutum barely longer than broad with posterior margin sinuous and punctations moderate in number and unequal in size, larger and more numerous along cervical fields. The nymph has a basis capituli sub-triangular dorsally with lateral angles slightly curved and presence of ventral processes, scutum approximately as long as broad with lateral margins nearly straights, posterior margin broadly rounded, and cervical grooves short and sigmoid in shape extending posteriorly to the level of the eyes. The larva is characterized by basis capituli broader than long with lateral angles short and slightly curved and with posterior margin slightly convex, cervical grooves short, shallow and subparallel, and scutum almost twice broader than long. The phylogenetic analysis of DNA sequences support R. sanguineus s.s. as a well-defined taxon when compared with other species of the R. sanguineus group: R. turanicus s.s., R. camicasi, R. guilhoni, R. sulcatus, R. pusillus, R. rossicus and R. leporis. Molecularly R. sanguineus s.s. also encompasses the so-called "temperate lineage" from the New World (Argentina, southern Brazil, Chile, Uruguay, and USA). The evidence currently available supports the presence of R. sanguineus s.s. in Europe (France, Italy, Spain, Switzerland and Portugal) and America (Argentina, Brazil, Chile, Uruguay and U.S.A.), but further studies are needed to determine the exact geographic range of this taxon.

Ixodes chilensis Kohls, 1956 (Acari: Ixodida: Ixodidae): re-description of the female, description of the nymph, and phylogenetic position inferred from mitochondrial DNA sequences of the 16S rRNA gene.

This paper provides a re-description of the female and a description of the nymph of Ixodes chilensis Kohls, 1956. Additionally, the phylogenetic position of the species of Ixodes Latreille, 1796 belonging to the subgenus Pholeoixodes Schulze, 1942 was analysed and discussed based on a phylogenetic pattern obtained with mitochondrial DNA sequences of the 16S rRNA gene. The diagnostic characters unique for the female of I. chilensis are a combination of coxae I-IV of legs with one external minute triangular spur each (barely perceptible) and lacking internal spur, tarsus I with a subapical dorsal hump, basis capituli subrectangular with sinuous posterior margin, hypostome rounded apically, cornua and auriculae absent, scapulae pointed, palps short, porose areas rounded separated by an interporose area wider than the diameter of one area, scutum with posterior margin straight and surface in the anterolateral field rugose, with punctations larger in the posterior field. The nymph of I. chilensis is characterised by the presence of scutum with posterior margin nearly straight, lateral carinae absent, basis capituli subrectangular in shape with posterior margin nearly straight, small auriculae as lateral ridges, palps short, hypostome rounded apically, and coxae I-IV of legs with just one external small triangular spur each (barely perceptible) and lacking internal spurs. Analysis of 16S sequences showed that I. chilensis form a well-supported clade with the following species with a wide geographical distribution but mostly established in the Palaearctic region and none from the Neotropics: I. simplex Neumann, 1906; I. arboricola Schulze & Schlottke, 1929; I. lividus Koch, 1844; I. canisuga Johnston, 1849; I. vespertilionis Koch, 1844; I. ariadnae Hornok, 2014; I. collaris Hornok, 2016; and I. kangdingensis Gou, Sun, Xu & Durden, 2017. The phylogenetic analysis also has demonstrated that the subgenus Pholeoixodes Schulze, 1942 is not monophyletic. The species considered as belonging to this subgenus were grouped in two different clades which did not have a well-supported common node defining monophyly.

Seasonal dynamics, geographical range size, hosts, genetic diversity and phylogeography of Amblyomma sculptum in Argentina.

The aim of this work was to generate knowledge on ecological aspects of Amblyomma sculptum in Argentina, such as seasonal dynamics, geographical range size, hosts, genetic diversity and phylogeography. Adult and immature A. sculptum ticks were collected in different localities of Argentina to know the geographical range size and hosts. The genetic diversity of this tick was studied through analyses of 16S rDNA sequences. To describe the seasonal dynamics, free-living ticks were monthly collected from October 2013 to October 2015. A. sculptum shows a marked ecological preference for Chaco Húmedo eco-region and "Albardones" forest of the great rivers in the wetlands in the Chaco Biogeographical Province, and for Selvas Pedemontanas and Selva Montana in the Yungas Biogeographical Province. This species has low host specificity, and it has large wild and domestic mammals as principal hosts to both immature and adult stages. Amblyomma sculptum is characterized by a one-year life cycle. Larvae peak in early winter, nymphs peaked during mid-spring, and adults during late summer and mid-summer. The genetic divergence was low and the total genetic variability was attributable to differences among populations. This fact could be associated to stochastics process linked to micro-habitat variations that could produce a partial restriction to gene flow among populations. The geographic regions do not contribute much to explain the A. sculptum population genetic structure, with an ancestral haplotype present in most populations, which gives rise to the rest of the haplotypes denoting a rapid population expansion.

Ticks infesting cattle and humans in the Yungas Biogeographic Province of Argentina, with notes on the presence of tick-borne bacteria.

This study was performed to determine the tick species that infest cattle and humans throughout an altitudinal gradient in the Yungas Biogeographic Province of Argentina. The presence of tick-borne bacteria of the genera Rickettsia, Ehrlichia and Borrelia in the collected ticks was also evaluated. Samples of ticks parasitizing cattle and humans were carried out in different seasons. Questing ticks (adults and nymphs) were collected from vegetation and analyzed to detect the presence of Rickettsia, Ehrlichia and Borrelia by a battery of different PCRs. Five species of hard ticks were found parasitizing cattle: Amblyomma sculptum, Amblyomma tonelliae, Amblyomma hadanii, Haemaphysalis juxtakochi and Ixodes pararicinus. Amblyomma sculptum (immature and adults), A. tonelliae (immature and adults), A. hadanii (larvae) and one nymph of I. pararicinus were found attached to humans. Rickettsia amblyommatis was detected in one nymph of A. hadanii. DNA of a Borrelia genospecies belonging to the B. burgdorferi s.l. complex (phylogenetically related to haplotypes previously reported in Ixodes aragaoi from Uruguay and I. pararicinus from Argentina) was detected in adults of I. pararicinus. Amblyomma sculptum and I. pararicinus appear to be the tick species more frequent on cattle in the YBP from Argentina, and A. sculptum and A. tonelliae, were the main ticks found attached to humans. The medical importance of the bacteria of the genus Rickettsia and Borrelia detected in this work remains unknown.

Presence of Borrelia in different populations of Ixodes pararicinus from northwestern Argentina.

This work was performed to evaluate the presence of Borrelia in different populations of Ixodes pararicinus from northwestern Argentina (Jujuy, Salta and Tucumán provinces). Questing adults and nymphs of I. pararicinus were collected from vegetation, and I. pararicinus nymphs were also collected on birds. Eighty-two ticks were tested for Borrelia presence by PCR targeting the gene flagellin and the rrfA-rrlB intergenic spacer region. Pools of ticks positive to Borrelia were formed by two nymphs collected on Turdus rufiventris in Tucumán, one nymph collected on Syndactyla rufosuperciliata in Jujuy, one nymph collected on Turdus nigriceps in Tucumán, three nymphs collected on T. nigriceps in Tucumán, and two females collected from vegetation in Salta. Two haplotypes of Borrelia sp. belonging to the Borrelia burgdorferi sensu lato complex were found. One of them is closely related to the haplotypes of Borrelia genospecies previously reported in I. aragaoi from Uruguay (haplotypes D and E) and in I. pararicinus from Jujuy Province in Argentina. The second haplotype (detected in the sample of Salta) is closely related to the haplotypes A, B and C associated with I. aragaoi from Uruguay. All these results suggest that the presence of B. burgdorferi s.l. genospecies in I. pararicinus ticks is widespread along the entire distribution of this tick species in northwestern Argentina. However, the Borrelia presence in I. pararicinus cannot be directly assumed as a phenomenon of medical relevance, because Ixodes ticks are not relevant as human parasites in South America, and none of the two Borrelia genospecies detected in this work is related to any of the Borrelia genospecies currently known to be pathogenic to humans.

Spotted fever group rickettsiae in Amblyomma ticks likely to infest humans in rural areas from northwestern Argentina.

This work was performed to detect Rickettsia species of the spotted fever group in Amblyomma ticks likely to infest humans in rural areas from northwestern Argentina. Free-living ticks were collected and determined as Amblyomma tigrinum, Amblyomma neumanni and Amblyomma tonelliae. Rickettsia infection was determined by polymerase chain reactions which amplify fragments of the rickettsial genes gltA and ompA. A high frequency (35/44, 79.5%) of Candidatus "Rickettsia andeanae" was observed in A. tigrinum ticks, and Candidatus "Rickettsia amblyommii" was found in three out of 14 nymphs of A. neumanni. All 14 Amblyomma tonelliae ticks were negative for rikettsiae. The infection with spotted fever group rickettsiae in ticks aggressive for humans reveals the potential risk of exposure to tick-borne pathogens of people inhabiting rural areas of northwestern Argentina.