Capillariids in the New World.

Capillariid findings in the New World are not much numerous than in the Old World (Fig 2). In North America, only two studies have identified capillariid eggs. Reinhard and coauthors (1986) were the first to find capillariid in archaeological material, i.e. samples of crocodile coprolites dated about 6000 years before present (BP), collected in the United States, in the Florida state. It was possible to observe the presence of two species of capillariid in which despite the good preservation of the eggs, the larval material had been degraded [6]. McConnell and Zavada (2013) found capillariids in sediments associated with skeleton of an extinct tapir (Tapirus polkensis), which lived in the Miocene-Pliocene period (4.5–7 million years BP). The authors revealed very poorly preserved structures that have similar characteristics and measures to capillariid eggs [7]. This structure may represent an evidence of a longstanding host-parasite interaction of capillariid with this group of mammals.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Fig 2. Worldwide paleodistribution of capillariids.

The symbols represent the locals where the parasites were found in the archeological material. Relative data see map numbers in Tables 1 and 2. The host of capillariids is indicated whenever is known.

https://doi.org/10.1371/journal.pone.0216150.g002

In South America, the research on archaeological material, mostly coprolites, have revealed numerous findings of capillariid eggs. It is noteworthy the findings in Patagonia region, Argentina. There are a number of studies with the identification of different morphotypes of capillariid eggs in a range of hosts, such as canids, rodents, camelids, felids, birds and even humans.

The first publication, by Fugassa and Guichón, (2005), showing capillariid parasites in archaeological material from Patagonia, was in human coprolites [8]. In the same region, sediments taken from skeletons and graves dating from 3720–3978 BP were also analyzed. In this material, capillariid eggs were identified, but the authors suggested the presence of more than one species, since a variety of measures and ornaments on the eggshells was found [9]. Two studies examined parasites in sediment associated with sacral region. The first study was conducted on skeletons recovered in three archaeological sites (Nombre de Jesús, Las Mandíbulas, Caleta Falsa) from the Patagonia region, and stored in museum collections in Argentina. Although the cleanse of the skeletal remains, as part of museological curation process, the recovery of helminth eggs was possible with the identification of two capillariid morphotypes, one of them attributed to Calodium hepaticum [10]. In the second study, an egg of capillariid was found in a rodent coprolite found in sediment associated with a body dating from the Hispanic post-contact period (212 ± 35 years BP) [11].

Some coprolites of uncertain zoological origin, with characteristics of both human and canid feces, were also analyzed in the Patagonia region. Coprolites dated of 3480 and 2740 years BP, showed eggs of Calodium sp. (n = 98), and another unidentified capillariid species (n = 4) [12]. In coprolites with older dating (9730 ± 100 to 8920 ± 200 years BP), corresponding to the transition from the Pleistocene to Holocene, the presence of Calodium sp. eggs suggested the consumption by hunter-gatherer of infected rodents, possibly by C. hepaticum [13]. The taxonomic identification was performed based on eggshell ornaments, which have particular striations that permit the genus discrimination. A canid coprolite (6540 ± 110 years BP), probably from Pseudalopex culpaeus, revealed numerous eggs (n = 171) with different measures, that were identified as capillariid [14].

Feline coprolites were also analyzed in Patagonia [15]. A number of Calodium sp. eggs (n = 563) were found and identified as C. hepaticum based on the morphometric data and the similarity of eggshell ornaments. Taking into consideration the life cycle of the parasite, the finding could represent an environment contaminated by C. hepaticum, which could have affected humans who shared the same location. In the same study, another capillariid, similar to Eucoleus sp. was also found, but in lower frequency (n = 4) [15]. A carnivore coprolite from Epullán Chica site, in Argentina, revealed one egg of Eucoleus sp., probably a Eucoleus aerophilus [16].

Although the morphological characteristics of C. hepaticum egg are very singular (small average size and typical ornamentation), the possibility of other species with similar egg morphology cannot be ruled out. The analysis of a coprolite of camelid from Patagonian region, dating 8300 ± 130 to 7920 ± 115 BP [17], revealed eggs similar to C. hepaticum. However, the infection is not supported by the parasite life cycle and their herbivore host diet. Therefore, it was suggested that other species with eggs similar to C. hepaticum circulated in that environment. Coprolites of camelid collected from the Andean region, dated to 9640 ± 190 to 3920 ± 80, revealed three capillariid morphotypes. One morphotype was compatible with Calodium sp., which usually infects the gastrointestinal tract of a variety of host, and has been found in coprolites of humans, canids, felids and rodents. Other morphotype was comparable to Eucoleus sp. and the third morphotype had not matching with any capillariid described in camelids until that time [18]. An study done in this region showed once more the same morphotype compatible with Calodium sp. and one other morphotype never seen before in camelid coprolites, increasing the number of species found in this host [19].

In coprolites of rodents, dating from 7920 ± 130 years BP, the presence of capillariids identified as Eucoleus sp. (n = 3), and other helminth eggs were described. Although the genus identified represent parasites that usually infect the respiratory tract, the presence in coprolites could be a result of swallowing of expelled secretion with eggs [20]. Another analysis in rodent coprolites showed a high number (n = 239) and variety of capillariid morphotypes (n = 4). The eggs were identified as suggestive of genera Calodium, Eucoleus, Echinocoleus and an unidentified capillariid species [21].

Besides coprolites, ancient pellets were analyzed, which are structures resulting of the regurgitation process of prey birds. Some studies have performed microscopic analysis on this material and showed capillariid eggs with radially ornamented eggshell, and morphometry compatible with C. hepaticum. Because rodent bones, often preys of raptors, were recovered in the pellets, Fugassa and collaborators (2007) attributed the infection to rodents [22]. In Beltrame and coauthors (2011), despite the identification of C. hepaticum eggs in raptor pellets, it was pondered the presence of others capillariid species attributed to the genera Aonchotheca and Eucoleus, which include some species that parasitize bird esophagi [23]. The archaeological site has several caves and rock shelters with evidence of human occupation, suggesting a probable exposure of humans to zoonotic parasites of rodents and, perhaps, of birds [23].

In Brazil, only two findings of capillariids are known in coprolites. Sianto and coauthors [24] recovered Calodium sp. eggs (N = 2) in feline coprolite (2840 ± 100 years BP), collected in Serra da Capivara, Northeast Brazil. Morphologically identified as Calodium cf. hepaticum, the finding could represent a case of false parasitism by consuming the parasite’s final host, and consequently, the eggs appeared in feces without acquiring the infection [24]. Confalonieri [25] identified Echinocoleus hydrochoery (syn. Capillaria hydrochoery) in coprolites of capybara (Hydrochoerus hydrochoeris) from Lapa da Angélica archaeological site, Goiás state, central west region. Currently, the parasite affects capybaras in the region. However, the coprolite eggs are slightly larger (Table 1) than those found nowadays [25].

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 1. Capillariids on New World.

https://doi.org/10.1371/journal.pone.0216150.t001

The identification of eggs in all studies is defined as capillariids, although it could include all genera, or be restricted to Capillaria genus. The species identification is infrequent, due to morphological variety of capillariid eggs, an important lack of knowledge on egg structures, and/or by the action of taphonomic agents that would have altered the structure of eggs and therefore, made the taxonomic identification more difficult. It was possible to suggest the capillariid species in few cases (Table 1).

Capillariids in the Old World.

As in the New World, capillariid findings in the Old World are quite frequent. However, unlike the New World, the findings are more common in sediments, latrine, or burial, mainly in Western Europe where most of the analyses were conducted (Table 2).

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 2. Capillariids on Old World.

https://doi.org/10.1371/journal.pone.0216150.t002

In France, Bouchet [26] accomplished the first recovery of capillariid egg in the Old World. Sediments of latrines and pits from a medieval site in Beauvais (13^th to 17^th century) revealed capillariid eggs [26]. Later, during the investigations on the lakeside archaeological site of Chalain (Jura, France), human coprolites dated to the Neolithic period (5216–4996 years BP) tested positive for two different morphotypes of capillariids. The first presenting reticulated outer eggshell, and the second presenting punctuated outer eggshell [27]. The same two morphotypes were recovered during the analysis of several Neolithic sites from Germany and Switzerland in Lakes Federsee and Bodensee [28].

In the scenario of World War I, Le Bailly et al. (2014) analyzed samples from German soldiers [29]. The samples were collected in the abdominal cavity of three bodies, recovered in a military gallery collapsed in March 1918. Two individuals showed capillariid eggs, which were identified using morphometric analysis as Eucoleus gastricus, a parasite of rodents. The authors explained the finding by the historical data recording the presence and the circulation of rats inside the galleries, as well as, the close contact and interaction between soldiers and these rodents.

An unusual capillariid finding was made in a body dating from the Roman period in France [30]. X-ray and cross section analysis identified two hydatid cysts, probably developed by the larval stage of Echinococcus sp. tapeworm. Analysis of the residue allowed to visualize Calodium hepaticum eggs, showing a coinfection by these two parasites [30].

In Belgium, in the Raversijde archaeological site (16^th century) mainly inhabited by fishermen, few eggs of capillariids were observed in organic materials [31]. Based on the findings of eggs of Trichuris trichiura and Ascaris lumbricoides, it was possible to suggest the human origin of the material. In the Place d’Armes site in Namur, which had seven stratigraphic layers representing different historical ages, organic materials were collected from latrines, pits and cesspits. Capillariid eggs were found in layers dated to the Roman period (2^nd-3^rd centuries), the Carolinean period (9^th-11^th centuries), and a medieval period from12^th to 13^th centuries [32]. In addition, during the analysis performed in the historical center of Nivelles, dated to the medieval period, human samples from pelvic region were analyzed. One individual revealed a high abundance of capillariid eggs (332 eggs per gram), but the species could not be identified [33].

In Spain, a Neolithic site La Draga, dated of 7270–6930 BP, showed the presence of two capillariid morphotypes with different ornamentations. Considering the characteristics of the eggs, especially the ornamentation, the authors suggested that the reticulated-type egg was from a Bovidae infection and the punctuated-type was probably related with fish-eating habits or the presence of rodents [34].

In Germany, Dittmar and Teegen (2003) found capillariid eggs in sediment associated with pelvic region of human and cattle, dated of 4500 years BP. The authors considered the finding as a probably contamination by feces of rodents [35].

In Italy, an study analyzed pits from both Roman and Medieval period. These pits, particularly in the medieval period, were used as garbage, and contained organic materials, wood, charcoal, pottery and various artifacts. Capillariid eggs (n = 1913) were found in two samples. Because of the nature of the samples it was not possible to associated the parasite to a host [36,37].

Finally in the Czech Republic, it was also possible to recover capillariid eggs from a well and a pit belong to 18^thand 19^th centuries, but here again no species discrimination could be made [38].

In Asia, some findings of capillariid were recorded in different hosts and contexts. In coprolites of rodents (Alticola sp.) from the eastern Mongolia, dating from at least 1440 years BP [39]; in coprolites of goats (Capra cylindricornis) from the North Ossetia republic, Russian Federation, dating from 700 years BP; and in canid coprolites from sites on northern Moscow, recovered from layers dating from the Neolithic and Mesolithic periods. Regarding the findings in goats, the authors discussed that the defeat of tribes in the region by Mongolian troops, followed the establishment of settlements with breeding of herds of these animals nearby, and consequently, the increased frequency of these parasites [40]. In Iran two morphotypes of capillariids were found in sheep coprolites, and assumed as Aonchotheca bovis due the host [41]. In Korea, capillariid eggs with morphometry comparable to Paracapillaria philippinensis, were identified in a human burial from the Joseon Dynasty (17^th century). However, the authors affirmed that further investigations should be conducted to defined the diagnosis because of the low number of cases of intestinal capillariasis is known in the country [42].

In Oceania, New Zealand, some studies with coprolites of extinct birds known as Moa was performed [43,44]. Coprolites dated of <3000 and 6368 ± 31 years BP of four moa species from different regions were analyzed. Capillariid eggs were found in two moa species from different regions, but the parasite species could not be identified [43].

Despite the lack of findings in Africa, that could be explained by less paleoparasitological material studied in the region, capillariids are distributed worldwide (Fig 2). Both, animal and human capillariids were found in the New and the Old World since several millenniums, which show a presence and a circulation of zoonotic capillariids, as C. hepaticum, in ecosystems that were inhabited by humans and animals. Besides, humans as other carnivores can act as paratenic hosts, carrying and dispersing the parasite in the environment.

Morphological differentiation and taxonomic identification strategies.

In attempt to identify capillariid eggs and understand the dynamics of the paleodistribution of different capillariid morphotypes, some works have performed biostatistical analysis.

First, Fugassa and collaborators (2008) based on data of findings in Patagonian archaeological material, conducted a statistical analysis to evaluate morphometric and morphological differences, considering the size of eggs, ornament patterns in eggshell and size of polar plugs. The results showed a significant discrimination between four egg morphotypes using the linear variables, length and width, with greater importance for width parameter. Thus, to the authors correlated egg morphotypes with some well-known species, such as C. hepaticum, Aonchotheca putorii and E. aerophilus [45].

The biometric analysis conducted by Taglioretti and coauthors (2014), evaluated length and width variables and investigated if eggs that had similar morphotype in different scenarios belong to the same species. In the analysis, the eggs were selected randomly from different archaeological samples and Permutation Multivariate Analysis of Variance (PERMANOVA) approach was applied. The result showed that hosts, diet, archaeological sites, or dating, had no significant effect in morphometry of capillariid eggs. Thus, the authors concluded that capillariid eggs with the same morphotype in different scenarios were, in fact, from the same species [46].

In samples from German soldiers of World War I, Le Bailly and collaborators (2014) applied a statistical approach for capillariid identification. The study used Gower Algorithm followed by a Multivariate Regression Tree on a data set on various capillariid eggs including measurements and ornamentation patterns. The statistical test suggested species definition of the egg as E. gastricus, and proving a complementary tool to conventional diagnostic techniques for taxonomic identification [29].

These studies showed that with a mathematical approach it might be possible to achieve the differentiation and identification of capillariid eggs found in archaeological material. This approach can supplement paleoparasitological data obtained by microscopy, molecular and immunological techniques.