New paleoparasitological investigations from the pre-inca to hispanic contact period in northern Chile

Eimeria leuckarti in equid coprolites from the Sassanid Era (2nd-6th century CE) excavated in Chehrabad Salt Mine archaeological site, Iran

OBJECTIVE

This study reports coccidian oocysts in an equid coprolite dated to the Sassanid Empire (2nd-6th century CE) recovered in Chehrabad Salt Mine archaeological site, Iran.

METHODS

Between 2015 and 2017, an archaeoparasitological investigation led to the discovery of an equid coprolite in the Chehrabad Salt Mine archeological site, (Douzlakh), western Iran. Samples were rehydrated using trisodium phosphate solution and were examined by light microscopy.

RESULTS

Seven oocysts of Eimeria leuckarti (Flesch, 1883) were identified; they were in various stages of sporulation.

CONCLUSION

This is the first report of ancient coccidian oocysts from equids. The importance of this observation is discussed, and current knowledge of eimeriid oocysts at archaeological sites is reviewed.

SIGNIFICANCE

The observations of E. leuckarti increases current knowledge of parasite biodiversity in ancient Iran when it rested along the Silk Road, a network of trade routes connecting the East and West that was central to economic, cultural, political, and religious interactions between these regions, and to livestock movement that could contribute to the transmission of the parasites from/to other regions.

LIMITATIONS

The contextual information about animal species present in and around the Salt Mine during its working periods, including Achaemenid dynasty (6th to 4th century BCE) and Sassanid era (2nd to 6th century CE), is very limited and does not allow secure conclusions regarding the host origin of the coprolites.

SUGGESTIONS FOR FURTHER RESEARCH

Application of molecular biology tools to identify the correct host origin of the coprolites and to detect more parasite species is advocated.

The Technological Advance and Application of Coprolite Analysis

Coprolites (mummified or fossilized feces), belonging to the group of ichnofossils, are fossilized remains of feces produced by animals. Various types of data from coprolites provide detailed evidence of the producer’s condition, like diet, intestinal microbiome, virus infection and parasites diseases. In addition, the palaeoenvironment information relevant to producers’ ecological niche can be drawn from taphonomy details the coprolites mirrored. At present, the phylogenetic clues of the producer’s population can be determined by advanced molecular biotechnologies. With the integration of multiple methods and techniques, coprolite has been widely accepted as an ideal material to study the diet, evolution, and palaeoenvironment of producers. In this paper, we reviewed the history of coprolite research, enumerated and interpreted the data recovered from coprolites, and explained their research value to palaeocoprology and evolutionary biology. Finally, we summarized the current directions of coprolite research and looked into its future prospects.

Machine learning approach to support taxonomic species discrimination based on helminth collections data

Background

There are more than 300 species of capillariids that parasitize various vertebrate groups worldwide. Species identification is hindered because of the few taxonomically informative structures available, making the task laborious and genus definition controversial. Thus, its taxonomy is one of the most complex among Nematoda. Eggs are the parasitic structures most viewed in coprological analysis in both modern and ancient samples; consequently, their presence is indicative of positive diagnosis for infection. The structure of the egg could play a role in genera or species discrimination. Institutional biological collections are taxonomic repositories of specimens described and strictly identified by systematics specialists.

Methods

The present work aims to characterize eggs of capillariid species deposited in institutional helminth collections and to process the morphological, morphometric and ecological data using machine learning (ML) as a new approach for taxonomic identification. Specimens of 28 species and 8 genera deposited at Coleção Helmintológica do Instituto Oswaldo Cruz (CHIOC, IOC/FIOCRUZ/Brazil) and Collection de Nématodes Zooparasites du Muséum National d’Histoire Naturelle de Paris (MNHN/France) were examined under light microscopy. In the morphological and morphometric analyses (MM), the total length and width of eggs as well as plugs and shell thickness were considered. In addition, eggshell ornamentations and ecological parameters of the geographical location (GL) and host (H) were included.

Results

The performance of the logistic model tree (LMT) algorithm showed the highest values in all metrics compared with the other algorithms. Algorithm J48 produced the most reliable decision tree for species identification alongside REPTree. The Majority Voting algorithm showed high metric values, but the combined classifiers did not attenuate the errors revealed in each algorithm alone. The statistical evaluation of the dataset indicated a significant difference between trees, with GL + H + MM and MM only with the best scores.

Conclusions

The present research proposed a novel procedure for taxonomic species identification, integrating data from centenary biological collections and the logic of artificial intelligence techniques. This study will support future research on taxonomic identification and diagnosis of both modern and archaeological capillariids.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04721-6.

A review of coccidiosis in South American camelids

Camelids (llamas, alpacas, vicuñas, guanacos) are important for the economy of South America and Eimeria infections are important as cause of mortality in camelids. Of the five most prevalent species of Eimeria in South American camelids, Eimeria macusaniensis, Eimeria lamae, Eimeria alpacae, Eimeria punoensis, and Eimeria ivitaensis, E. macusaniensis is considered the most pathogenic. There is considerable confusion concerning the endogenous developmental stages of Eimeria spp. in camelids. Many papers on camelid coccidiosis were published in local Peruvian journals, not easily accessible to wider audience. The objective of the present paper is to summarize information on history, validity of Eimeria species, life cycle, pathogenicity, prevalence, epidemiology, diagnosis, and control of coccidiosis in camelids.

Gametogony of Eimeria macusaniensis Guerrero, Hernandez, Bazalar and Alva, 1971 in llama (Lama glama)

Camelids (llama, alpaca, vicunãs, guanacos) are important for the economy of South America and Eimeria infections are an important cause of mortality in camelids. Of the six species of Eimeria in camelids, Eimeria macusaniensis, considered the most pathogenic, is distinctive; its oocysts are the largest among all Eimeria species in animals, its prepatent period is more than 1 month, and its oocysts have been found in mummies from prehistoric times. Although, E. macusaniensis gametogonic stages are found associated with enteritis in naturally infected camelids, the schizogonic stages are unknown and clinical disease has been reported in some camelids with no oocysts in feces. Described herein are morphological details of gametogonic development and oocyst formation of E. macusaniensis in a naturally infected llama (Lama lama), solely infected with this parasite. Microgamonts, macrogamonts and oocysts were located in large (up to 300 µm diameter) parasitophorous vacuoles of enterocytes in the ileum. Schizonts were not found. Review of previous reports suggests that multinucleated microgamonts have been mistaken for schizonts. Gametogonic development described in the present study can serve as a guide for differential diagnosis of Eimeria species in the histological sections of intestines.