Helminth infracommunity in a maned wolf,Chrysocyon brachyurus,from the humid Chaco,Argentina

Parasitism is an important factor in conservation worldwide, especially for endangered species, as it can affect host populations by reducing growth rates, fecundity and affecting nutritional status. The maned wolf Chrysocyon brachyurus, a near-threatened species, is distributed across different habitats from the south Amazonian forest in Brazil to northern Argentina, Paraguay and eastern Bolivia. Most studies on gastrointestinal parasites in wild maned wolves are based on coprological findings, and there is little information about adult parasites and parasite species richness. Therefore, this study aims to expand the knowledge about the helminth infracommunity of a maned wolf, describe adult parasites, and explore parasitic coinfections. We performed a necropsy of an adult individual found road killed in Chaco province, Argentina. We collected adult worms from subcutaneous tissues, from the right ventricle, kidneys, and intestine. The parasites were morphologically identified as Dirofilaria immitis, Dioctophyma renale and Spirometra sp. respectively. To our knowledge, this is the first record for adults of Dirofilaria immitis in maned wolves. Filarioids were located within the heart as well as in subcutaneous tissues with mature females containing uterine microfilariae; this study also adds C. brachyurus as a new host for Spirometra sp. in Argentina. Considering that the three helminths found herein are zoonotic and that the maned wolf is an endangered canid, it is essential provide baseline information to determine the risk factors involved in the transmission and extend the studies to sympatric wild and domestic canids in the area.     

Parasites of Cynoscion guatucupa along South American Atlantic coasts: evidence for stock discrimination

Two stocks of striped weakfish Cynoscion guatucupa in the south‐west Atlantic Ocean, were identified using parasites as biological tags. A total of 297 fish caught in Brazil, Uruguay and Argentina, contained 29 species of metazoan parasites. Univariate analysis on parasite populations, as well as multivariate discriminant analysis, calculated for juvenile and adult fish separately, allowed the identification of the two stocks, one from Argentina and Uruguay and the other from Brazil, to be made. Southern samples were characterized by higher prevalences and abundance of larval endohelminths, whereas in the northern stock, gastrointestinal and ectoparasitic species were common. Discriminant analyses on parasite infracommunities of Brazilian fish showed notable differences between juvenile and adult hosts; no such trend was observed in fish from Argentina and Uruguay, despite differences between juveniles and adults at the population level. Different oceanographic conditions and their influence on the distribution of parasites as well as of other hosts involved in their life cycles could be key factors for the differences observed among stocks of C. guatucupa .     

Helminth community structure of Scinax nasicus (Anura: Hylidae) from a South American subtropical area

The main goal of this study was to evaluate the relative influence of season, year of study, host body size, and host sex on abundance of helminth species parasitic in the frog Scinax nasicus. A total of 273 frogs was collected between December 2004 and November 2006 over all seasons in Corrientes City, Province of Corrientes, Argentina. Helminth community included 21 taxa, and was dominated particularly by larval trematodes. Infected frogs harboured a maximum of 7 species. Host sex and season played no significant effect in determining infracommunity parasite species abundance. Similarly, species richness was similar for both host sexes, and across time (year and season). However, occurrence of the parasites Opisthogonimus sp. 2 and Travtrema aff. stenocotyle greatly varied over time. Host body size was the main factor for determining infrapopulation structure of Centrorhynchus sp. Species richness was significantly and positively correlated with host body size. Strong associations were observed mainly between metacercariae of some species. The transmission strategies of parasites suggest that this hylid acquires infections by ingestion of infective larvae and through direct contact with larval parasites from aquatic and terrestrial habitats.     

<Emphasis Type="Italic">Ixodes </Emphasis>(<Emphasis Type="Italic">Ixodes</Emphasis>) <Emphasis Type="Italic">pararicinus</Emphasis> Keirans &; Clifford, 1985 (Acari: Ixodidae): description of the immature stages,distribution, hosts and medical/veterinary importance

The immature stages of the Neotropical tick Ixodes (Ixodes) pararicinus Keirans & Clifford, 1985 are described from specimens in a laboratory colony initiated from engorged females collected on cattle and larvae fed on mice and chickens. The larva and nymph of I. pararicinus are described using SEM micrographs as well as drawings for some features of the larva. Additionally, immature stages of I. pararicinus collected on wild mice and birds in Uruguay and Argentina were compared with specimens from the laboratory colony. A taxonomic key to the nymphs of the species of the ricinus complex established in the Western Hemisphere is presented. The distribution of I. pararicinus comprises Argentina, Colombia and Uruguay, but it is also probably established in Bolivia, Brazil, Chile and Peru. Most adult ticks of this species have been found on introduced domestic artiodactyles, although Neotropical deer species must have been the ancestral host. Larvae and nymphs of I. pararicinus have also been found on sigmodontine rodents and passeriform birds. Although I. pararicinus is a member of the ricinus complex, which contains the main vectors of Borrelia burgdorferi (sensu lato), there are few studies concerning its potential for pathogen transmission.     

Genetic Variability of the Neogregarine Apicystis bombi,an Etiological Agent of an Emergent Bumblebee Disease

The worldwide spread of diseases is considered a major threat to biodiversity and a possible driver of the decline of pollinator populations, particularly when novel species or strains of parasites emerge. Previous studies have suggested that populations of introduced European honeybee (Apis mellifera) and bumblebee species (Bombus terrestris and Bombus ruderatus) in Argentina share the neogregarine parasite Apicystis bombi with the native bumblebee (Bombus dahlbomii). In this study we investigated whether A. bombi is acting as an emergent parasite in the non-native populations. Specifically, we asked whether A. bombi, recently identified in Argentina, was introduced by European, non-native bees. Using ITS1 and ITS2 to assess the parasite’s intraspecific genetic variation in bees from Argentina and Europe, we found a largely unstructured parasite population, with only 15% of the genetic variation being explained by geographic location. The most abundant haplotype in Argentina (found in all 9 specimens of non-native species) was identical to the most abundant haplotype in Europe (found in 6 out of 8 specimens). Similarly, there was no evidence of structuring by host species, with this factor explaining only 17% of the genetic variation. Interestingly, parasites in native Bombus ephippiatus from Mexico were genetically distant from the Argentine and European samples, suggesting that sufficient variability does exist in the ITS region to identify continent-level genetic structure in the parasite. Thus, the data suggest that A. bombi from Argentina and Europe share a common, relatively recent origin. Although our data did not provide information on the direction of transfer, the absence of genetic structure across space and host species suggests that A. bombi may be acting as an emergent infectious disease across bee taxa and continents.     

Cryo transmission X-ray imaging of the malaria parasite,P. falciparum

Cryo transmission X-ray microscopy in the “water window” of photon energies has recently been introduced as a method that exploits the natural contrast of biological samples. We have used cryo tomographic X-ray imaging of the intra-erythrocytic malaria parasite, Plasmodium falciparum, to undertake a survey of the cellular features of this important human pathogen. We examined whole hydrated cells at different stages of growth and defined some of the structures with different X-ray density, including the parasite nucleus, cytoplasm, digestive vacuole and the hemoglobin degradation product, hemozoin. As the parasite develops from an early cup-shaped morphology to a more rounded shape, puncta of hemozoin are formed; these coalesce in the mature trophozoite into a central compartment. In some trophozoite stage parasites we observed invaginations of the parasite surface and, using a selective permeabilization process, showed that these remain connected to the RBC cytoplasm. Some of these invaginations have large openings consistent with phagocytic structures and we observed independent endocytic vesicles in the parasite cytoplasm which appear to play a role in hemoglobin uptake. In schizont stage parasites staggered mitosis was observed and X-ray-dense lipid-rich structures were evident at their apical ends of the developing daughter cells. Treatment of parasites with the antimalarial drug artemisinin appears to affect parasite development and their ability to produce the hemoglobin breakdown product, hemozoin.     

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.     

Paleoparasitological analysis of rodent coprolites in holocenic samples from Patagonia, Argentina

The aim of the present study was to examine the parasite fauna present in rodent coprolites collected from Cerro Casa de Piedra (CCP7), located in Perito Moreno National Park (P.N.PM., 47 degrees 57'S and 72 degrees 05'W), Santa Cruz Province, Argentina. Eight coprolites obtained from the layer XIII of CCP7, with an antiquity considered as 7,920 +/- 130 yr B.P, were examined for parasites. Each coprolite was whole processed, rehydrated, homogenized, spontaneously sedimented, and examined using light microscopy. Eggs of parasites were measured and photographed. All the samples were parasitized by nematodes, with 267 eggs of Trichuris sp., 24 eggs of an aspidoderid, and 3 capillariid eggs. The rodent host was tentatively identified as a species of Ctenomys, the hypogeic rodents endemic to South America. The finding of Paraspidodera in Patagonian samples represents new evidence that strengthens the co-phylogenies between nematodes of this genus and Ctenomys and reinforces the value of parasites as tags in paleoparasitology.     

Eimeria meleagrimitis, E. adenoeides, and E. dispersa: Severity of infection and changes in the intestinal mucosa of the Turkey

Glucose and methionine were malabsorbed in some intestinal regions of turkeys infected with Eimeria meleagrimitis, E. adenoeides, or E. dispersa. The decrease in absorption was not always related to the numbers of parasites in the cells or the extent of damage to the mucosa. With E. adenoeides, malabsorption was found in the jejunum even though parasites were not present. Conversely, with E. dispersa, no malabsorption was observed in the duodenum even though light microscopy showed numerous parasites. In many intestinal regions, damage to the mucosal surface visible with scanning electron microscopy (SEM) was slight or absent, although malabsorption was marked. No changes were noted with SEM in the structure and orientation of the brush border in these regions. Villar height was significantly reduced in the regions of heaviest infection when intestinal damage was visible. Conversely, the crypts of Lieberkühn were often two or three times as deep in infected poults as in uninfected poults. In general, no differences were found in the thickness of the circular and longitudinal muscle layers between the infected and uninfected poults. The dry weight of the intestinal tissue was less from infected poults than from uninoculated controls and was related to both region of the intestine and severity of the infection.     

A new host of Trypanosoma cruzi from Jujuy, Argentina: Octodontomys gliroides (Gervais & D'Orbigny, 1844) (Rodentia, Octodontidae).

To identify wild hosts of Trypanosoma cruzi, surveys were conducted in the subandean valleys of Jujuy Province, Argentina, between June 1986 and March 1987. Seventy two mammals from 13 different species were examined by xenodiagnosis. Fifty two of them were mostly rodents trapped at the localities of Maimará, León and Tilcara, and the remainder had been kept in captivity at the Estación Biológica Experimental, in Jujuy. Trypanosoma cruzi infection was detected only in 2 Octodontomys gliroides (2 pos./8 exam. 25%) from all 72 examined mammals. Isolates were called Octodontomys Argentina 1 and 2 (OA1 and OA2). Both infected animals were caught at the archaelogical ruin of Pucará, at Tilcara. Repeated searches for triatomines in the ruin itself and in neighbour houses rendered negative results. Groups of mice inoculated with either OA1 or OA2 isolates became infected between 7 (OA1) to 12 days (OA2) postinoculation PI. Parasitemia peaks were observed between day 12th-14th PI. Scarce amastigote nests were found in myocardium and skeletal muscle. Mortality was observed only for mice inoculated with OA1. Isoenzyme patterns of OA1 and OA2 were identical to one found in dogs and slightly different from that of human parasites in Argentina. Bones from Octodontomys sp., were recently found in a cave, dated 10200-8600 BC, in Pumamarca, near Tilcara, Jujuy. There are evidences that O. gliroides cohabited with man in ancient times and was associated to the domestic cycle of T. cruzi transmission, playing a role like that of domestic caves in Bolivia.     

Contamination by helminths in public places of the province of Chubut, Argentina

Canine-borne helminthiases constitute a worldwide problem. Some of these parasites can originate serious pathologies in humans. Given the potential existence of these zoonoses in Argentina, horizontal surveys on contamination degree evaluated as faeces per hectare and on parasite prevalence in faeces were carried out in six localities of the Province of Chubut. The behaviour of people visiting public places was also analyzed qualitatively. All of the survey sites were contaminated with faeces and with some parasitic forms. Contamination degrees ranged from 32 to 147 faeces/ha. Toxocara sp. (17.4%), Strongyloides sp. (5.1%), and Ancylostoma. sp (5.6%) were the main genera among other parasites detected. As a whole, the analysis revealed that contamination degree, prevalence and human behaviour in relation to the exposure to the parasite would be the main factors to be taken into account in formulating control measures. Transmission risk patterns in Chubut were not homogeneous; therefore, studies and control strategies should be devised and implemented at the local scale.     

Impact of a caged-trout farm on parasites of Galaxias maculatus in Lake Moreno, southern Argentina

The present study was conducted to determine the impact of a caged-trout farm on the helminth parasites of the wild fish puyen chico (Galaxias maculatus) in Lake Moreno, southern Argentina. Samples of water, fish (G. maculatus), and snails (Heleobia hatcheri) were taken at 4 sampling stations in January 2001. Wild fish were parasitized by 8 helminth species, all of which are endemic in the region; therefore, the farm did not introduce any helminth parasite to G. maculatus. Fish captured near the farm were not infected by the digenean Steganoderma szidati, whereas the abundance of the digenean Acanthostomoides apophalliformis in these fish was significantly lower than that in fish captured away from the farm. This lower abundance may be explained by the absence in this area of the snail H. hatcheri, the parasite's first intermediate host, because of the effect of sediments and ammonium produced by the farm. To our knowledge, this is the first study in the Americas linking fish-farm pollution to helminth parasites in wild fish.     

A comparative study of the host-parasite relationship of Pomphorhynchus patagonicus (Acanthocephala) in two species of fish from Lake Rosario (Chubut, Argentina).

Some aspects of the host-parasite relationships of Pomphorhynchus patagonicus (Acanthocephala) in 2 fish species from Lake Rosario (Chubut, Argentina) were studied. The fish species Patagonina hatcheri (Atherinidae) is autochthonous, and Oncorhynchus mykiss (Salmonidae) is introduced. The host species appears to influence attachment, size, sexual maturity, and distribution of parasites along the digestive tract. In P. hatcheri, an effective major host, parasites are attached firmly to the wall of the gut, well developed, attain a greater size, and a large proportion of females is gravid with ripe eggs. In O. mykiss, an unsuccessful host, there were many unattached parasites that were small and not well developed; gravid females were rare and never had ripe eggs.     

Larval trypanorhynchs (Platyhelminthes: Eucestoda: Trypanorhyncha) from black-scabbard fish, Aphanopus carbo and oceanic horse mackerel, Trachurus picturatus in Madeira (Portugal)

Four different types of trypanorhynch postlarvae were found attached to the stomach mucosa, external stomach wall or free in the body cavity of two marine fishes from Madeira, namely blackscabbard fish, Aphanopus carbo and oceanic horse mackerel, Trachurus picturatus. Morphological features shown by SEM indicated that the postlarvae belonged to the species Tentacularia coryphaenae, Sphyriocephalus tergestinus, Nybelinia lingualis and possibly N. yamaguitii. Prevalence [mean intensity (range)] of T. coryphaenae, S. tergestinus and Nybelinia spp. in A. carbo (n = 135) was 12.6% [1.65 +/- 1.27(1-6)], 5.9% [1.57 +/- 0.79 (1-3)] and 2.2% [1.33 +/- 0.58 (1-2)] respectively. The prevalence of T. coryphaenae and S. tergestinus showed some seasonality, with a rise in prevalence of T. coryphaenae corresponding to a decrease in prevalence of S. tergestinus. However these differences were not significant. In T. picturatus (n = 304) only N. lingualis was found at a prevalence of 9.6%. Both S. tergestinus and N. lingualis were recovered only from the stomach mucosa or external stomach wall, while T. coryphaenae was observed either attached to the stomach mucosa or free in the visceral cavity of the fish. The paper presents the first scanning electron micrographs (SEM) of Sphyriocephalus tergestinus and a new geographical record of N. lingualis in T. picturatus.     

New host,geographic records,and histopathologic studies of Angiostrongylus spp (Nematoda: Angiostrongylidae) in rodents from Argentina with updated summary of records from rodent hosts and host specificity assessment

To date, 21 species of the genus Angiostrongylus (Nematoda: Angiostrongylidae) have been reported around the world, 15 of which are parasites of rodents. In this study, new host, geographic records, and histopathologic studies of Angiostrongylus spp in sigmodontine rodents from Argentina, with an updated summary of records from rodent hosts and host specificity assessment, are provided. Records of Angiostrongylus costaricensis from Akodon montensis andAngiostrongylus morerai from six new hosts and geographical localities in Argentina are reported. The gross and histopathologic changes in the lungs of the host species due to angiostrongylosis are described. Published records of the genus Angiostrongylus from rodents and patterns of host specificity are presented. Individual Angiostrongylusspecies parasitise between one-19 different host species. The most frequent values of the specificity index (STD) were between 1-5.97. The elevated number of host species (n = 7) of A. morerai with a STD = 1.86 is a reflection of multiple systematic studies of parasites from sigmodontine rodents in the area of Cuenca del Plata, Argentina, showing that an increase in sampling effort can result in new findings. The combination of low host specificity and a wide geographic distribution of Angiostrongylus spp indicates a troubling epidemiological scenario although, as yet, no human cases have been reported.     

A new workerless social parasite in the ant genus Pseudomyrmex (Hymenoptera: Formicidae), with a discussion of the origin of social parasitism in ants

The New World ant genus Pseudomyrmex (subfamily Pseudomyrmecinae) contains about 180 species, of which only one workerless social parasite, P . leptosus , from Florida, has been previously recorded. A new species discovered recently in northern Argentina, P . inquilinus sp. nov., is more derived morphologically and behaviourally than P . leptosus and has convergently developed features characteristic of the workerless inquilines known in other ant subfamilies. These features include diminutive size, reduced mouthparts, a broadened petiole and postpetiole, well-developed subpetiolar and subpostpetiolar processes, and the habit of straddling the gaster of the host queen. A cladistic analysis confirms that the new species is not closely related to its host nor to P . leptosus ; it belongs in fact to a different species complex within the genus Pseudomyrmex . Two widespread Neotropical species, P.filiformis and P.subater , to which P.inquilinus appears to be related, show indications of being temporary social parasites on other, unrelated species of Pseudomyrmex . Thus, there is evidence from comparative natural history that the extreme social parasitism seen in the new species from Argentina was preceded by a period of temporary social parasitism, but 'Emery's Rule'– the claim that social parasites are close relatives of, and evolve from, their hosts – is not supported. Rather, parasitism in Pseudomyrmex seems to have arisen through interspecific colonization and exploitation of congeners. A review of the evidence suggests that Emery's Rule has received too uncritical an acceptance in the literature on social parasitism. Uncertainties about the generality of Emery's Rule and about the plausibility of achieving prezygotic isolation under sympatric conditions undermine the theory that social parasites evolve from within populations of their host species.     

Ultrastructure of Proechinophthirus zumpti (Anoplura,Echinophthiriidae) by scanning electron microscopy

The ultrastructure of Proechinophthirus zumpti Werneck, 1955, mainly the external chorionic features of the egg, is described through electronic microscopy techniques. This species was first cited in Argentina, infesting Arctocephalus australis (Zimmermann, 1873). The morphological adaptations of adults and nymphs are described in both species of Proechinophthirus parasitic on Otariidae: P. fluctus (Ferris, 1916) and P. zumpti.