Ecology of fleas and their hosts in the trifinio of north-east Argentina: first detection of Rickettsia asembonensis in Ctenocephalides felis felis in Argentina.

Fleas are important in public health due to their role as parasites and vectors of pathogens, including Rickettsia. The aim of this study was to evaluate the diversity, abundance and prevalence of fleas and the presence of Rickettsia in the trifinio of north-east Argentina. Fleas from household and synanthropic animals were obtained from urban and periurban areas. They were taxonomically identified and samples of 227 fleas in 86 pools were analysed by polymerase chain reaction targeting the gltA and ompB genes of Rickettsia spp. The study revealed that Ctenocephalides felis felis was dominant on dogs, cats and opossums, with higher prevalence in the periurban area. The Shannon-Wiener and Morisita-Horn indices expressed differences in the diversity and similarity values of the absolute abundances of the species between the areas compared. DNA amplifications revealed 30.8% C. f. felis pools positive for Rickettsia spp. Phylogenetic analysis showed that the haplotype obtained was identical to Rickettsia asembonensis from Peru and Brazil. This is the first detection in Argentina of R. asembonensis that infects C. f. felis, and we emphasize the importance of conducting research from a 'One Health' perspective on the role of opossums and rodents in the integration of the transmission cycles of rickettsial bacteria.

A new species of Laelaps Koch, 1836 (Mesostigmata: Laelapidae) parasitic of the sigmodontine rodent Oligoryzomys flavescens Waterhouse, 1837 (Rodentia: Cricetidae): Molecular and morphological characterization.

Laelaps schatzi sp. nov. (Mesostigmata: Laelapidae) is described on the bases of mites collected from the sigmodontine Oligoryzomys flavescens Waterhouse, 1837 (Rodentia: Cricetidae) in Pereyra, Buenos Aires, Argentina, based on morphological, morphometric and molecular data. Two DNA fragments, mtDNA cytochrome oxidase subunit I (COI) and nuclear 18.S-ITS1-5.8S-ITS2 partial gene sequence were deposited in the public Genbank datebase. The DNA extraction was conducted nondestructively using Chelex®100 modified for this study, to prevent vouchers for further microscopically examination. Laelaps schatzi sp. nov. is similar in general appearance to Laelaps paulistanensis Fonseca, 1936 and Laelaps fonsecai Gettinger, 1992, but the new species is unique in presenting a reticulated surface pattern on the genital shield from level of Zv1 up to posterior margin, and in the presence of one or two additional impair seta/e between J4 setae of dorsal shield. Also, the phylogenetic analyses separate the new species from all other species available in the GenBank of Laelaps.

Molecular detection of Bartonella in fleas (Hexapoda, Siphonaptera) collected from wild rodents (Cricetidae, Sigmodontinae) from Argentina.

Bartonella are facultative intracellular Gram-negative bacteria, transmitted mainly by hematophagous arthropods, and the rodents act as a natural reservoir. Different species of Bartonella associated with rodents have been implicated as causing human disease. Studies from Argentina are scarce and no Bartonella from fleas have been reported previously. The present study investigated the presence of Bartonella spp. in fleas associated with sigmodontine rodents in four localities of the Santa Cruz Province, Argentina. In total, 51 fleas (four species) were analysed of which 41.2% were found to be positive for the gltA gene fragment via a nested polymerase chain reaction. All positive fleas were of the species Neotyphloceras crackensis from three different localities. Eight of the 21 amplified samples were sequenced, and the presence of three different genotypes was detected with an identity of 95.5-98.8% amongst themselves. Bartonella genotypes from American rodents and rodent fleas were recovered in a monophyletic group. Similarly, most of the Peruvian and all Argentinean variants constitute a natural group sister of the American remainder. The importance of the Bartonella spp. with respect to public health is unknown, although future studies could provide evidence of the possible involvement of N. crackensis in the Bartonella transmission cycles.

Origin, evolution, phylogeny and taxonomy of Pulex irritans.

The human flea Pulex irritans Linnaeus, 1758 (Siphonaptera: Pulicidae) is one of the most studied species together with the cat flea Ctenocephalides felis Bouché, 1835, because they have a cosmopolitan distribution and are closely related to humans. The present study aimed to carry out a comparative morphometric and molecular study of two different populations of P. irritans (Spain and Argentina). Accordingly, internal transcribed spacer (ITS)1 and ITS2 of rDNA and the partial cytochrome c oxidase subunit 1 (cox1) and cytochrome b (cytb) mtDNA genes of these taxa were sequenced. Furthermore, the taxonomy, origin, evolution and phylogeny of P. irritans was assessed. The morphometric data obtained did not show significant differences between P. irritans specimens from Spain and Argentina, even when these two populations were collected from different hosts; however, there was a considerable degree of molecular divergence between both populations based on nuclear and mitochondrial markers. Thus, it is proposed that P. irritans, in contrast with other generalist fleas, maintains a certain degree of morphological similarity, at least between Western Palearctic and Neotropical areas. Furthermore, two well defined geographical genetic lineages within the P. irritans species are indicated, suggesting the existence of two cryptic species that could be discriminated by a polymerase chain reaction-linked restriction fragment length polymorphism.

Diversity, distribution and parasitism rates of fleas (Insecta: Siphonaptera) on sigmodontine rodents (Cricetidae) from Argentinian Patagonia.

Fleas have great medical relevance as vectors of the causative agents of several diseases in animals and humans and rodents are the principal reservoirs for these pathogens. Argentinian Patagonia has the highest diversity of rodent fleas in South America. However, parasitism rates of rodents by fleas, the factors that influence them and the ecological aspects that modulate geographical distributions of flea-host association remain unknown for this region. This is the first study to record the diversity, prevalence, abundance, geographical distributions and host ranges of fleas in Argentinian Patagonia. It also compares parasitism rates among Patagonian ecoregions and host species. We captured 438 rodents belonging to 13 species, which harboured 624 fleas from 11 species and subspecies (P = 46%; mean abundance = 1.44). The high parasitism rates obtained were consistent with previous records for other arid regions, suggesting that Patagonia favours the survival and development of Siphonaptera. Host geographic range and abundance were related to the parasitological indexes: host species with high-density populations had the highest mean flea abundance and prevalence, whereas widely distributed hosts had the highest richness and diversity of flea species. Our results contribute to the knowledge of the flea-host-environment complex. Our analysis of flea distributions and parasitism rate in Central Patagonia may be useful in epidemiological studies of flea-borne diseases and provide a basis for implementing surveillance systems for better risk assessment of emerging zoonoses in the region.

The tropical fowl mite, Ornithonyssus bursa (Acari: Macronyssidae): environmental and host factors associated with its occurrence in Argentine passerine communities.

The tropical fowl mite, Ornithonyssus bursa, is a common avian parasite found on diverse bird species worldwide. In the Neotropical region, O. bursa is present in wild birds, but it may also infect poultry and bite humans. Little is known about the ecology and epidemiology of this parasite. We conducted a thorough longitudinal study in passerine assemblages from central Argentina, gathering data from six reproductive seasons, with the aim of identifying factors that have a role in driving the occurrence and distribution of O. bursa in its natural hosts. We focused on the brood and microhabitat levels, accounting for potential confounders of higher levels. The results hereby presented contribute to our knowledge on the eco-epidemiology of O. bursa in natural hosts of the Neotropical region. Among the many variables assessed, nest material and host species appeared to be the most important correlates of O. bursa prevalence. Nonetheless, supplementary analyses showed that host species is a stronger predictor than nest material. Moreover, mite burden (parasite intensity) was found to depend on host species, but not on nest material. The association with species depended on nestling age, suggesting that resistance builds up as the nestling develop, but at a different pace depending on the bird species. Brood size was inversely correlated with intensity of parasitism, suggesting a dilution of the parasite burden on each nestling.

Fleas of the genus Neotyphloceras associated with rodents from Bolivia: new host and distributional records, description of a new species and remarks on the morphology of Neotyphloceras rosenbergi.

The flea genus Neotyphloceras Rothschild (Siphonaptera: Ctenophthalmidae) includes five species and two subspecies distributed from Venezuela to southern Chile and Argentina. Only Neotyphloceras crassispina hemisus Jordan has been registered in Bolivia. The present study examines species of Neotyphloceras collected in Bolivian localities in the Departments of La Paz, Cochabamba and Tarija, and describes the morphology of the modified abdominal segments in males and females of Neotyphloceras rosenbergi Rothschild on the basis of type material and specimens collected from Tarija. A new species, Neotyphloceras boliviensis n. sp., is described and new host associations are reported for N. rosenbergi, Neotyphloceras crassispina crassispina and N. crassispina hemisus. Neotyphloceras c. crassispina and N. rosenbergi are reported for the first time in Bolivia. The distribution of N. rosenbergi is extended 1600 km to the south. Given the potential medical and veterinary significance of fleas as disease vectors, and considering that in the Departments of La Paz and Tarija several human cases of plague have been reported, and species of flea have been identified as main vectors of these diseases, the new records of fleas in Bolivia reported herein may be useful for epidemiological studies on flea-borne diseases.

Description of the Males of Androlaelaps misionalis and Androlaelaps ulysespardinasi (Acari: Parasitiformes: Laelapidae) Parasitic of Sigmondontine Rodents From Northeastern Argentina.

Laelapinae mites are common ectoparasites of small mammals, mainly sigmodontine rodents, but males are not frequent in natural populations. In this study, the morphology of the unknown males of Androlaelaps misionalis Lareschi, 2010 and Androlaelaps ulysespardinasi Lareschi, 2011 are described. The males of these species differ from the male of Androlaelaps rotundus (da Fonseca, 1936), a close species, because of the size and shape of their dorsal shield and the length of paranal and sternal st1 and st2 setae. The males of A. misionalis and A. ulysespardinasi differ in their size, in the distance of j6 setae in the dorsal shield, length of hypostomal seta hyp3, number of accessory setae in holoventral shield, length of postanal and sternal st3 setae, number of opisthogastric setae in unarmed integument lateral to level of coxae IV, and shape of tip of movable digit in the chelicera.

Revision of fleas of the genus Plocopsylla belonging to the 'angusticeps-lewisi' complex in the Andean biogeographic region, with the description of a new species.

In Argentina, the Andean biogeographic region accommodates the most diverse population of fleas in the country. The Craneopsyllinae (Siphonaptera: Stephanocircidae) represent one of the most commonly found subfamilies in this region and show some endemism and high diversity. Plocopsylla is the most diverse genus of Craneopsyllinae; it includes 10 species mainly distributed in the Patagonian subregion, which parasitize sigmodontine rodents (Rodentia: Cricetidae). We describe and illustrate the morphology of the aedeagus in species of Plocopsylla that belong to the 'angusticeps-lewisi' complex. This character is of diagnostic value in differentiating among species. A new species of this complex, Plocopsylla (Plocopsylla) linardii sp. n., is described and identified by the shape and chaetotaxy of the distal arm of sternite IX, as well as by the shape of the median dorsal lobe of the aedeagus. New host associations for this complex and range extensions for most of its species are reported. Plocopsylla (P.) silewi is recorded for the first time in Argentina. The southern limits of the distributions of Plocopsylla (P.) lewisi and Plocopsylla (P.) wilesi are extended to Santa Cruz Province. The angusticeps-lewisi complex is found for the first time in San Juan Province. The information may be useful in epidemiological studies of flea-borne diseases.

A new species of Tunga perforating the osteoderms of its armadillo host in Argentina and redescription of the male of Tunga terasma.

A new species of Tunga (Siphonaptera: Tungidae) collected from armadillos in Argentina is described. The new species is characterized by large and pigmented eyes, the presence of two bristles on antennal segment II, two bristles at the base of the maxilla, and a discoid neosome compressed anteroposteriorly. The gravid female is located in the carapace of the host, perforating the osteoderms. The new species resembles Tunga penetrans and Tunga terasma in general appearance. However, it differs by the greater anteroposterior compression of the neosome, a more angular head, and a manubrium with a pointed proximal end and convex ventral margin (the proximal end of the manubrium is rounded or slightly pointed in T. terasma, and the ventral margin is straight in both T. penetrans and T. terasma). In addition, specimens of T. penetrans have more bristles in antennal segments II and III, and lack bristles in the posterior tibia. This is the first report of a species of Tunga perforating the osteoderms of its host and thereby showing a high degree of specialization. Tunga terasma is recorded for the first time in Argentina; the male is described again and the characteristics of the species amended. This information may be useful in epidemiological studies of diseases caused by species of Tunga.

Fleas associated with non-flying small mammal communities from northern and central Chile: with new host and locality records.

Fleas associated with small mammals from seven localities from northern and central Chile were assessed. We captured 352 small mammals belonging to 12 species from which we obtained 675 fleas belonging to 15 different species. The most frequently captured flea species were Neotyphloceras crassispina crassispina (n = 198) and N. chilensis (n = 175). High values of flea species richness and diversity were found in Fray Jorge National Park (NP), a north-central Chilean site, whereas the highest values of mean abundance (MA) and prevalence were found in three diverse sites that include Los Molles River, a high altitude site located in north-central Chile, Fray Jorge NP and Dichato, in south-central Chile. On the other hand, high values of flea richness and diversity were found on two rodent species, Abrothrix olivacea and A. longipilis, whereas the highest values of MA and prevalence were found on Oligoryzomys longicaudatus, A. longipilis and Phyllotis xanthopygus. A total of three new host recordings, nine new localities and nine new host species and locality recordings are reported. Also, this study represents the first known record of Tetrapsyllus (Tetrapsyllus) comis in Chile and the first ecological analysis of Neotyphloceras chilensis.

Arthropod parasites of the red-bellied squirrel Callosciurus erythraeus introduced into Argentina.

The introduction of an exotic species usually modifies parasite-host dynamics by the import of new parasites or the exotic species' acquiral of local parasites. The loss of parasites may determine the outcome of an invasion if the introduced species is liberated from co-evolved parasites in its range of invasion. In addition, an introduced species may pose sanitary risks to humans and other mammals if it serves as a reservoir of pathogens or carries arthropod vectors. The red-bellied squirrel, Callosciurus erythraeus (Pallas) (Rodentia: Sciuridae), was introduced into Argentina in 1970, since when several foci of invasion have been closely associated with humans. Investigation of the parasitological fauna of C. erythraeus in Argentina will generate new information about novel parasite-host dynamics and may provide new insight into the reasons for the successful invasion of this species. The objective of this study was to describe the arthropod parasites of C. erythraeus in Argentina in comparison with previous studies of parasites of this species in its native habitat and in the ranges of its invasion. Occasional host-parasite associations with local arthropod parasites not previously described for C. erythraeus are reported; these include the mites Androlaelaps fahrenholzi (Ewing) (Mesostigmata: Laelapidae) and Ornithonyssus cf. bacoti (Mesostigmata: Macronyssidae), the flea Polygenis (Polygenis) rimatus Jordan (Siphonaptera: Rhopalopsyllidae) and the botfly Cuterebra Clark (Diptera: Oestridae: Cuterebrinae). Cheyletus sp. mites (Trombidiformes: Cheyletidae) were also found. The low prevalence and mean intensity of ectoparasite species may influence invasion dynamics.

Surface ultrastructure of the eggs of Malacopsylla grossiventris and Phthiropsylla agenoris (Siphonaptera: Malacopsyllidae).

The fleas of the Malacopsyllidae are known only by their adults. In this study, we describe the eggs of Malacopsylla grossiventris and Phthiropsylla agenoris and compare their surface ultrastructure using scanning electron microscopy. Eggs of both flea species are similar in their general appearance, i.e., the presence of disks and absence of lateral aeropyles, but they differ in size, texture of the surface, and number of micropyles and aeropyles. In addition, the eggs of M. grossiventris and P. agenoris are larger (719-800 µm) than most of the flea eggs known (<600 µm), and the length/width ratio is 2.0, while it varies between 1.6 and 1.8 in other species. As opposed to other large species, malacopsyllids have expandable (telescoping) abdomens that display growth. It is possible that a clutch of eggs has more than 2 eggs. Females of M. grossiventris were observed fixed with their mouthparts to the skin of their hosts. Indeed, some of these specimens were observed copulating on the venter of their hosts. These results contribute to the knowledge about the biology of malacopsyllids.

Determinants of ectoparasite assemblage structure on rodent hosts from South American marshlands: the effect of host species, locality and season.

The relative effects of host species identity, locality and season on ectoparasite assemblages (relative abundances and species richness) harboured by four cricetid rodent hosts (Akodon azarae, Oligoryzomys flavescens, Oxymycterus rufus and Scapteromys aquaticus) were assessed across six closely located sites in Buenos Aires province, Argentina. Relative abundances of ectoparasites (14 species including gamasid mites, an ixodid tick, a trombiculid mite, lice and fleas), as well as total ectoparasite abundance and species richness, were determined mainly by host species and to a lesser extent by locality (despite the small spatial scale of the study), whereas seasonal effect was weak, albeit significant. The abundances of some ectoparasites were determined solely by host, whereas those of other ectoparasites (sometimes belonging to the same higher taxon) were also affected by locality and/or season. In gamasids, there was a significant effect of locality for some species, but not for others. In fleas and lice, the effect of locality was similar in different species, suggesting that this effect is related to the characteristic life history strategy.

Finding of an ixodid tick inside a late Holocene owl pellet from northwestern Argentina.

In the present study, we report the earliest record of Ixodes sigelos from the late Holocene in Argentina. The tick was recovered from an owl pellet collected within a small mammal sequence in Las Máscaras Cave, Catamarca, Argentina (27 degrees 01'12S'', 66 degrees 44'37''W) and dated at 990 + or - 35 cal yr. Based on bones also present in the pellet, the tick most-likely parasitized a rodent, identified as an Eligmodontia sp., which had been ingested by the owl.

Prediction of prevalence from mean abundance via a simple epidemiological model in mesostigmate mites from two geographical regions.

We analysed data on the abundance and distribution of 26 species of mesostigmate mites with different feeding habits collected from bodies of small mammalian hosts in 2 geographical regions (West Siberia and Argentina). We tested whether prevalence of a mite can be reliably predicted from a simple epidemiological model that takes into account mean abundance and its variance. We theorized that the difference between prevalence predicted from the model and observed prevalence would be smallest in obligatory haematophagous mites, intermediate in facultatively haematophagous mites and greatest in non-haematophagous mites. We also theorized that prevalence of mites from the region with sharp seasonality (Siberia) would be predicted accurately only if host number would be taken into account. We found that the success of a simple epidemiological model to predict prevalence in mites was similar to that reported earlier for other ectoparasitic arthropods. Surprisingly, the model predicted prevalence of obligatory exclusively haematophagous mites less successfully than that of mites with other feeding habits. No difference in the model performance between mites occurring in the 2 geographical regions were found independent of whether the model took the number of hosts into account.

The ticks (Acari: Ixodida: Argasidae, Ixodidae) of Paraguay.

The ticks reported in Paraguay, which are here reviewed, can be categorized as 'endemic or established' (Argas persicus or a sibling species, Ornithodoros hasei, O. rostratus, O. rudis, O. talaje/O. puertoricensis, Amblyomma aureolatum, Am. auricularium, Am. brasiliense, Am. cajennense, Am. calcaratum, Am. coelebs, Am. dissimile, Am. dubitatum, Am. incisum, Am. longirostre, Am. nodosum, Am. ovale, Am. pacae, Am. parvum, Am. pseudoconcolor, Am. rotundatum, Am. scutatum, Am. tigrinum, Am. triste, Dermacentor nitens, Haemaphysalis juxtakochi, H. leporispalustris, Ixodes loricatus, Rhipicephalus microplus, and Rh. sanguineus), 'probably endemic or established' (Ar. miniatus, Ar. monachus, Am. argentinae, Am. humerale, Am. naponense, Am. oblongoguttatum, Am. pseudoparvum, I. aragaoi/I. pararicinus, I. auritulus, I. luciae), or 'erroneously reported from Paraguay' (O. coriaceus, Am. americanum and Am. maculatum). Most Paraguayan tick collections have been made in the Chaco phyto-geographical domain, in the central part of the country. Argas persicus or a related species, Am. cajennense, D. nitens, Rh. microplus and Rh. sanguineus are important parasites of domestic animals. Ornithodoros rudis, Am. aureolatum, Am. brasiliense, Am. cajennense, Am. coelebs, Am. incisum, Am. ovale and Am. tigrinum have all been collected from humans. In terms of public health, the collections of Am. cajennense and Am. triste from humans may be particularly significant, as these species are potential vectors of Rickettsia rickettsii and Ri. parkeri, respectively.

Sigmodontinae rodents as hosts for larvae and nymphs of Ixodes loricatus Neumann, 1899 (Acari: Ixodidae).

Larvae and nymphs of Ixodes loricatus Neumann, 1899 ticks (confirmed by morphological characters and by comparison of 16S mitochondrial rDNA sequences) were collected from Sigmodontinae Wagner, rodents in central and northern Argentina and Uruguay. A total of 100 larvae and 38 nymphs of I. loricatus were collected on the genera Akodon Meyen (n = 36 individuals), Calomys Waterhouse (n = 2), Oligoryzomys Bang in = 12), Oxymycterus Waterhouse (n = 9), and Scapteromys Waterhouse (n = 13). 72 larvae and 18 nymphs were collected on Akodon. Adults of I. loricatus were found in central Argentina and Uruguay on Didelphimorphia of the genera Didelphis Linnaeus and Lutreolina Thomas. Ixodes loricatus has been considered a species with strict total specificity to Didelphimorphia. Our results show that this statement may not be justified. Sigmodontinae rodents are sympatric and share habitats with the phylogenetically distant Didelphimorphia; infestation with I. loricatus seems to be its consequence. We tentatively consider I. loricatus moderately specific to Didelphimorphia.