Recovering ancient parasites from Andean herbivores: test of the Mini-FLOTAC technique in archaeological samples

The optimization of techniques for recovering parasitic remains is key in paleoparasitology. The Mini-FLOTAC technique (MF) is based on passive flotation and is used for diagnosis of parasites and was never tested on ancient samples. Our objective was to assess the effectiveness of MF in paleoparasitology, aiming at improving the techniques for the recovery of parasitic remains in order to upgrade the interpretative potential of the paleoparasitological evidence. Three techniques were tested: MF, spontaneous sedimentation (SS), and centrifugation-sucrose flotation (CF) testing camelid and goat coprolites. Statistical tests were performed with the R software. Our result displayed that, in the case of SAC samples, MF recovered less number of parasitic species than SS, but obtained a greater number of positive samples for protozoa. For goat samples, MF recovered a higher number of positive samples and parasitic species than SS, added that it was the technique that recovered a greater number of parasite structures. Therefore, results vary according to the zoological origin of the samples and the parasitic species recorded. We suggest starting using MF on ancient samples as a complementary method to those traditionally used in paleoparasitology. It is important to highlight that MF was a simple and faster way. The incorporation of reliable quantitative techniques opens the door to a new way of analyzing archaeological remains, deepening the study of the parasite-host relationships and its evolution through time with an epidemiological approach. Although further studies are needed, our results suggest the complementarity of these techniques in future paleoparasitological studies.

Gastrointestinal parasite assemblages from the wild rodent capybara (Hydrochoerus hydrochaeris) inhabiting a natural protected area from Argentina

Knowledge about parasitic diseases of wildlife will help us to understand the dynamics of parasites and their effects on host populations. The capybara (Hydrochoerus hydrochaeris) is the largest living rodent in the world, and its distribution is associated with the presence of tropical and subtropical wetlands in South America. The Los Padres Lake Integral Reserve (LPLIR) is an important conservation zone in the pampean region of Argentina. One of the emblematic species found within the reserve is the capybara. The objective of this study was to determine the gastrointestinal parasites present in wild capybaras of the LPLIR and to compare different coprological methodologies. Free-ranging capybara fresh feces from 57 individuals were randomly collected from the area of LPLIR in the summer of 2022. Three different techniques were applied: spontaneous sedimentation technique (SS), INTA modified McMaster technique (MM), and Mini-FLOTAC (MF) technique. Fifty-six samples from all samples analysed (56/57, 98%) were found to be positive for gastrointestinal parasites. Two species of Strongylida, Protozoophaga obesa, Echinocoleus hydrochaeris, one unidentified nematode, one unidentified spirurid, and at least two morphotypes of Eimeria spp. oocysts were recorded. There were found significant differences in the proportion of positive samples and in richness by technique, but no significant differences were found in parasite counting. In conclusion, the choice of methodology depends on the specific objectives of the study. This is the first parasitological study of capybaras from the LPLIR and represents an exploration of parasite communities present in these wild rodents at their southernmost distribution.

Gastrointestinal parasites of domestic sheep from Patagonia throughout historical times: A paleoparasitological approach

Sheep husbandry in Patagonia, Argentina, started at the beginning of the 20th century from European settlers. Sanitary management is minimal, which has serious implications for the sheep health. Sheep can be infested by diverse parasites, with well over 150 species of internal and external parasites reported worldwide. Gastrointestinal parasitism is one of the most common and important infections in sheep concerning the health status, and is the cause of significant morbidity and mortality, which generates considerable production losses. The present work is the first paleoparasitological study of sheep coprolites from Patagonia throughout historical times. Fifty-seven coprolites from the 'Cueva Peligro' archaeological site (Patagonia, Argentina) were analyzed using the Lutz spontaneous sedimentation technique and the modified Faust flotation technique. Ancient DNA (aDNA) study was carried out in order to identify the zoological origin of coprolites. The results obtained from Cytb analysis confirmed the identity of the host as Ovis aries (domestic sheep). A total of 39 coprolites examined were positive for parasites by at least one of the studied methods. Thirty eight samples were positive by spontaneous sedimentation and 10 samples were positive by the modified Faust technique. The parasitic fauna found was Trichuris sp. (Trichinellida: Trichuridae), Nematodirus sp., Nematodirus spathiger (Strongylida, Trichostrongyloidea), two unidentified Strongylida-type egg morphotypes, Fasciola hepatica (Trematoda: Digenea) and coccidia oocysts of Eimeria spp. (Apicomplexa: Eimeriidae). The modified Faust technique provided satisfactory results in terms of sensitivity for the detection of Eimeria spp. The use of this methodology as a routine procedure enables the processing of ancient samples, in order to increase recoveries. These results show the importance of integrating different diagnostic approaches in order to optimize parasitic findings. The recorded parasite diversity appears to have not changed over the last 120 years. The study displayed the presence of different parasitic species which suggests potential exposure to parasitic diseases through the historical times, both for sheep and for other domestic and wild mammals from Patagonia. Also, suggests the presence of fasciolosis, a zoonotic disease that implies a potential risk for Patagonian populations in the past.

Parasites in micromammal fecal pellets throughout the Late Holocene ("Cueva Peligro" paleontological site, Patagonia, Argentina)

Parasite remains in micromammal fecal pellets collected from the paleontological site "Cueva Peligro" (CP 43°40'18"S, 66°24'52"W), Chubut Province, Argentina, were examined. The samples were obtained from two grids, dated between 1220 ± 70¹⁴C yr B.P. to modern dates. Fecal pellets were whole processed, rehydrated, homogenized, and examined via light microscopy. Eggs of parasites found were measured and photographed. Fecal pellets belong to one or more insectivore to omnivore unidentified micromammal species, possibly sigmodontine rodents. A high number of helminthes species was recorded (11 species), eight nematodes, two anoplocephalid cestodes and one acanthocephalan species. The sigmodontine-parasite relationship varied throughout the studied period and between studied grids. This is the first time that Gongylonema sp. and Syphacia sp. are reported from ancient times from Patagonia. The obtained results contribute to the knowledge of parasite assemblages associated to native South American sigmodontine rodents and the zoonoses present in the area throughout the lasts 1200 years.

First paleoparasitological study of micromammal coprolites from the holocene of the Somuncurá Plateau Protected Natural Area (Patagonia Argentina)

The Somuncurá Plateau is a Protected Natural Area located in the middle of the northern extra-Andean arid Patagonia. Inhabited by at least 20 small mammal species, is the place with the uppermost species richness in Patagonia. The aim of this study was to examine the parasite remains from micromammal coprolites collected in association with a bone sequence recovered at the east of the Somuncurá Plateau (site "Alero Las Lechuzas"). Coprolites came from the four temporal units previously defined: unit I (4790 ± 100 yrs. ¹⁴C B.P.), unit II, unit III (7840 ± 120 yrs. ¹⁴C B.P.) and unit IV. Each coprolite was processed, rehydrated, homogenized, processed by spontaneous sedimentation and examined using a light microscope. Coprolites and eggs were described, measured and photographed. Samples were positive for two nematode species: Helminthoxys caudatus Freitas, Lent & Almeida, 1937 (Oxyurida, Oxyuridae) and Trichuris spp. (Trichinellida: Trichuridae). This is the first paleoparasitological study developed for the Somuncurá Plateau Protected Area. Moreover, this is the first time that the genus Helminthoxys is reported from ancient times worldwide. Coprolites were attributed to the mountain cavy Microcavia australis (Rodentia, Caviidae).The presence of H. caudatus for the Middle Holocene of northern Patagonia contributes to the study of the history of the histricomorphs and pinworms relationships.

New record of anoplocephalid eggs (Cestoda: Anoplocephalidae) collected from rodent coprolites from archaeological and paleontological sites of Patagonia, Argentina

Results of paleoparasitological examination of rodent coprolites collected from archaeological and paleontological sites from Patagonia, Argentina, are present. Each coprolite was processed, rehydrated, homogenized, spontaneously sedimented and examined using light microscope. Coprolites and eggs were described, measured and photographed, and were compared with current faeces of Lagidium viscacia. Eggs with morphological features, attributed to an anoplocephalid cestode were found in samples collected from Cueva Huenul 1 (36°56'45″S, 69°47'32″W, Neuquén Province, Holocene) and Los Altares Profile (43º53'35″S, 68º23'21″W, Chubut Province, Late Holocene). These are the first findings of this anoplocephalid from faecal material from patagonic rodents.

The burrowing crab Neohelice granulata as potential bioindicator of heavy metals in estuarine systems of the Atlantic coast of Argentina

This paper presents the concentrations of total copper, lead, cadmium, and zinc in hepatopancreas of the burrowing crab Neohelice granulata from the Samborombón Bay (La Plata River estuary) and the Mar Chiquita coastal lagoon, Argentina. The highest accumulation of lead was observed in Mar Chiquita samples, whereas copper, zinc, and cadmium concentrations were higher in those from Samborombón Bay. Marked temporal and geographic availability differences were observed, while sexual differences only were observed for zinc. Finally, the validity of using this species as bioindicator of heavy-metal pollution within the assessed estuarine ecosystems is discussed.

First paleoparasitological results from late Holocene in Patagonian coprolites

These are the first paleoparasitological results from the Late Holocene in Patagonian coprolites. Coprolites collected from layers dated at 3,480 and 2,740 yr before present (B.P.), from the archaeological site Cerro Casa de Piedra, were examined. The site is a hill located in a forest steppe ecotone in Perito Moreno National Park. The coprolites could belong to humans or to other carnivores such as canids. After rehydration and spontaneous sedimentation of the samples, the parasite contents were examined. Results obtained showed the common presence of eggs of a Calodium sp., eggs of other capillariids and trichostrongylids, oocysts of Eimeria macusaniensis (Apicomplexa), and eggs of taeniids (Cestoda). Although the generic identification of some parasites could not be provided, the presence of tapeworm eggs represents the first record for the Late Holocene in Patagonia and shows that parasitism by cestodes existed in the region in pre-Columbian times. Results indicate that in the Late Patagonic Holocene, zoonotic helminths may have been commonly present in the inhabitants of Patagonia. The parasites found in the coprolites allow us to deduce what these people were eating and, thus, indicate what other pathogens, such as viruses, bacteria, and parasitic protozoans, may have infected them via the same sources.

Zoonotic parasites associated with felines from the Patagonian Holocene

Feline coprolites were examined for parasites with the aim of studying ancient infections that occurred in the Patagonian region during the Holocene period. Eggs compatible to Trichuris sp., Calodium sp., Eucoleus sp., Nematodirus sp., Oesophagostomum sp. (Nematoda), Monoecocestus sp. (Cestoda) and Eimeria macusaniensis (Coccidia) were recovered from faecal samples. The results obtained from the analysis provide evidence of consumption by felids of the viscera of both rodents and camelids. This knowledge allows for improved explanations as to the distribution of parasitism and its significance to the health of humans and animals inhabiting the area under study during the Middle Holocene.

Influences of sex, habitat, and seasonality on heavy-metal concentrations in the burrowing crab (Neohelice granulata) from a coastal lagoon in Argentina

Cadmium, chromium, copper, and manganese concentrations were determined in hepatopancreas of both sexes as well as in eggs at different embryonic development stages of the burrowing crab Neohelice granulata (Brachyura, Varunidae) from Mar Chiquita Coastal Lagoon, a biosphere reserve from Argentina, during a period of 1 year, to assess the bioaccumulation of metals associated with sex and seasonality. Furthermore, metal levels in associated superficial sediment samples were also determined. Two different "cangrejales," one in a mudflat and another one in a salt marsh, were studied. The results showed high concentrations of copper within the hepatopancreas, which was considered a strong reflection of high exposure of N. granulata to this metal. Metal accumulation in hepatopancreas from both study sites and sexes did not present significant differences, as did seasonality. In this sense, both spring and summer metal levels in hepatopancreas were the greatest. Eggs did not present differences in metal accumulation, with the exception of manganese, between sites or between crabs at different embryonic stages. For this metal, eggs from female crabs inhabiting mudflats showed higher levels than those from inhabiting salt marshes. Moreover, eggs in the late embryonic stage also showed the highest manganese concentrations. Metal levels in sediments, however, were similar in both sites. These are the first results of metal level in biota and sediments in this particular environment. Such results could be used as a baseline for the monitoring of metal levels in future studies in Mar Chiquita Coastal Lagoon.

Effects of zinc on molting and body weight of the estuarine crab Neohelice granulata (Brachyura: Varunidae)

The semiterrestrial burrowing crab Neohelice granulata is one of the main inhabitants of the supratidal and intertidal zones of brackish salt marshes, estuaries and coastal lagoons from South America's Atlantic littoral. A large population of this species spreads out Mar Chiquita coastal lagoon (in Argentina) and its corresponding wetlands, and is considered as a key species within this system. Since high values of dissolved heavy metals (including Zn) have been recently reported within Mar Chiquita coastal lagoon, with levels unusually higher than those from other coastal systems within Argentina, it has been explored that the existence of a risk of environmental conditions endanger these populations. So, juveniles of this estuarine crab were experimentally exposed to increasing concentrations of dissolved Zn (i.e., 0, 0.5 and 1 mg Zn(2+)L(-1)) during six months, the time involved between two successive molts; in addition, both the size and weight reached after each molt were also studied in this assay. It can be concluded that zinc can be toxic to crabs only at high concentrations. Considering that levels up to 1 mg ZnL(-1) were recently reported in Mar Chiquita coastal lagoon waters, the potential occurrence of mean chronic effects on the crab population within the coastal lagoon is discussed.