Contribution of ultrasound examination in diagnosing platynosomiasis and correlation with macro and microscopic findings in callitrichids kept under human care

BACKGROUND

Platynosomiasis in non-human primates kept under human care causes chronic disease of the bile ducts and liver, which initially presents with nonspecific signs and can culminate in the death of the animal. Diagnosing this disease is a challenge, and an ultrasound examination can be an excellent tool when it is suspected.

METHODS

This study describes the ultrasound findings from 57 marmosets with suspected infection by Platynosomum sp., the correlated hepatobiliary changes, and the anatomopathological findings that confirmed the occurrence of platynosomiasis.

RESULTS

In six marmosets (one C. aurita, two C. jacchus, and three Callithrix sp.), Platynosomum infection was confirmed macroscopically (presence of adult trematodes in the gallbladder) and microscopically (adults, larvae, and eggs in histological examinations and eggs in bile and feces). These findings were compatible with the hepatobiliary changes and with images suggestive of parasitic structures in ante-mortem assessments.

CONCLUSION

Ultrasound examination demonstrated its usefulness within the clinical routine for investigating this parasitosis.

Helminths of Wied's marmoset (Callithrix kuhlii (Coimbra-Filho, 1985) (Primates: Callitrichidae)) from the Atlantic Forest, Southern Bahia State, Brazil

Callithrix kuhlii is present in forest mosaics, edge habitats, and abandoned fields in the Atlantic Forest. In Bahia and Minas Gerais. This study aimed to identify helminths from C. kuhlii and relate them to the clinical data, weights, and indices of the liver and gonads. Necropsies were performed on 13 adult marmosets that were run over on the BA-001 highway. A principal component analysis (PCA) was conducted to describe the relationships between the variables investigated. Fifty-one helminths were collected from 30.77% (4/13) of the marmosets analyzed. Helminths were classified based on their morphological and morphometric characteristics. Primasubulura jacchi (Marcel, 1857), Platynosomum illiciens (Dougherty, 1946), and Prosthenorchis confusus (Dougherty, 1946) were the species identified, with prevalence rates of 7.69%, 7.69%, and 15.38%, respectively. In addition, this is a new host record of P. confusus. The two main axes of the PCA explained a high variability (PCA=67.7%), indicating reduced weight and indices of the organs of parasitized animals. This study expands the knowledge on parasites of C. kuhlii and its vulnerability to parasites, contributing to constructing an epidemiological profile of environmental health.

Parasites and Viruses in Callithrix in Brazil

PURPOSE

As a result of environmental imbalances of anthropogenic origin, the potential for transmission of parasites and viruses between different primates, including humans, might increase. Thus, parasitic studies have great relevance to primatology, which motivated us to conduct a literature review to synthesize the information available in American primates of the Callithrix genus.

METHODS

We carried out the bibliographic search on the main groups of parasites (protozoa, helminths, arthropods, ectoparasites) and viruses found in Callithrix in Brazil in search platforms and consider all manuscript that appeared in search engines, published between the years 1910 and December 2022. In each selected article, the following information was recorded: the host species; parasite taxa; scientific classification of the parasite; host habitat (free-living, captive); diagnostic technique; state; and bibliographic reference. Data were tabulated and arranged in a parasite-host table.

RESULTS

Some endemic genera, such as Callithrix, are widely distributed geographically across Brazil and have characteristics of adaptation to different habitats due to their flexibility in diet and behavior. These factors can make them subject to a greater diversity of parasites and viruses in the country. Here, we identified 68 parasitic taxa, belonging to the clades protozoa (n = 22), helminths (n = 34), ectoparasites (n = 7), and viruses (n = 5). Out of this total, 19 have zoonotic potential. Of the six existing marmoset species, Callithrix jacchus was the most frequent in studies, and Callithrix flaviceps did not have reports. All regions of the country had occurrences, mainly the Southeast, where 54% of the cases were reported. In 46% of the reported parasites and viruses, it was not possible to identify the corresponding species.

CONCLUSION

We conclude that in part of the works the identification methods are not being specific, which makes it difficult to identify the species that affects Callithrix spp. Furthermore, the studies present geographic disparities, being concentrated in the southeast of the country, making it impossible to have a more uniform analysis of the findings. Thus, it is observed that information about parasites and viruses is incipient in the genus Callithrix in Brazil.

Prevalence of Platynosomum spp infection and its association with biliary lithiasis and secondary bacterial infections in free-ranging marmosets (Callithrix spp) of the Brazilian Atlantic Forest

Platynosomosis is a parasitic disease caused by a trematode of the genus Platynosomum, a bile duct and gallbladder fluke that has been described in captive neotropical primates (New World primates; NWPs) and causes high morbidity and variable mortality. Although it is a major concern for ex-situ conservation of these animals, there are only a few studies of platynosomosis in free-ranging NWPs. Therefore, the aim of this study was to characterize platynosomosis in a free-ranging population of marmosets (Callithrix spp) from the Brazilian Atlantic Forest, focusing on the epidemiological and pathological aspects of the disease. A total of 1,001 marmosets were evaluated and on the basis of clinicoepidemiological data, histopathology, histochemistry and immunohistochemistry, we concluded that Platynosomum spp infection has a prevalence of 8.9% (confidence interval: 7.3-10.8%) in free-ranging marmosets, with a higher frequency in the Metropolitan Region of Rio de Janeiro. Infection was associated with fibrosing and proliferative cholangiohepatitis associated with biliary lithiasis (3.0% of cases) and secondary bacterial infections (14.6% of cases).

Acute infection with Platynosomum illiciens (Trematoda: Dicrocoeliidae) as a clinically relevant and potentially fatal disease in Falco sparverius (Aves: Falconidae) in Brazil

Platynosomum illiciens is a dicrocoeliid trematode from the biliary tract of warm-blooded vertebrates (felines, primates, marsupials, and birds) reported in different parts of the world. Although the veterinary relevance of platynosomosis in mammals, especially in domestic felines, has been increasingly evidenced in the scientific literature, studies involving avian disease caused by P. illiciens are comparatively scarce. In the present study, a female specimen of the American kestrel, Falco sparverius L., found dead, in November 2019, in Brazil, was necropsied. Parietal biliary effusion in the celomatic cavity was observed, suggesting biliary transudation and gallbladder stasis, which possibily preceded the distension and rupture of gallbladder noted during necropsy. In the microscopic analysis of the bile content, small trematodes were found and characterized as immature stages of Platynosomum after the morphological study. Partial sequences of the cox-1 gene enabled the identification of P. illiciens, with 100% similarity with previously sequenced sympatric isolates from mammals. The finding of immature specimens in a ruptured gallbladder strongly suggests a role for the parasite in biliary flow dysfunction, indicating acute platynosomosis as a clinically relevant and potentially fatal condition that has not yet been discussed.

Parasites of Free-Ranging and Captive American Primates: A Systematic Review

The diversity, spread, and evolution of parasites in non-human primates (NHPs) is a relevant issue for human public health as well as for NHPs conservation. Although previous reviews have recorded information on parasites in NHPs (Platyrrhines) in the Americas, the increasing number of recent studies has made these inventories far from complete. Here, we summarize information about parasites recently reported in Platyrrhines, attempting to build on earlier reviews and identify information gaps. A systematic literature search was conducted in PubMed, ISI Web of Science, and Latin American and Caribbean Health Sciences Literature (LILACS), and following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Ninety-three studies were included after the screening process. Records for 20 genera of NHPs, including 90 species were found. Most of the studies were conducted on captive individuals (54.1%), and morphological approaches were the most used for parasite identification. The most commonly collected biological samples were blood and stool, and Protozoa was the most frequent parasite group found. There is still scarce (if any) information on the parasites associated to several Platyrrhine species, especially for free-ranging populations. The use of molecular identification methods can provide important contributions to the field of NHPs parasitology in the near future. Finally, the identification of parasites in NHPs populations will continue to provide relevant information in the context of pervasive habitat loss and fragmentation that should influence both human public health and wildlife conservation strategies.

Platynosomum illiciens (Trematoda: Dicrocoeliidae) in a hybrid marmoset (Callithrix sp.) in the Municipality of Seropédica, RJ, Brazil - Case report

Platynosomum illiciens is a liver trematode encountered infecting mainly felids although it has also been reported in birds and in additional mammalian species, including non-human primates. The current study reports a natural P. illiciens infection primate of the genus Callithrix. The diagnosis was made using a combination of copro-parasitological techniques, morphological evaluation of adult specimens recovered from the liver during necropsy, and molecular analyses. Eggs were brown in color, oval, operculated, and contained a miracidium. Adult specimens recovered during necropsy were measured and showed dimensions compatible with P. illiciens. Molecular characterization of the trematode involved amplification by polymerase chain reaction (PCR), in combination with nucleotide sequencing, of an approximately 900 base pairs fragment corresponding to 18S-ITS1-5.8S ribosomal DNA. Sequenced amplicons showed 100% nucleotide identity with sequences deposited in the GenBank database as derived from specimens of P. illiciens recovered from cats in Malaysia and Brazil. It was concluded that the morphological and molecular analyses presented herein, confirmed the identification of the trematode recovered as P. illiciens.

Anatomopathological lesions of infection caused by Platynosomum illiciens (Braun, 1901) in Neotropical primates kept in captivity

This study described the hepatobiliary anatomopathological lesions associated with trematode Platynosomum illiciens parasitism in Neotropical primates kept in captivity. In the evaluated organs, we observed portal fibrosis, biliary epithelial hyperplasia, and inflammatory reaction with a predominance of lymphocytes and plasmocytes, and in some cases infiltration of eosinophils and neutrophils.

Treatment of primate platynosomosis: A word of caution about the use of praziquantel in marmosets

BACKGROUND

The successive reports of Platynosomum illiciens in Neotropical captive primates have increased interest in platynosomosis; however, its treatment is little known.

METHODS

Callithrix penicillata (n = 10) naturally and chronically infected with P. illiciens were treated with praziquantel (25 mg/kg BW, three s.c. doses at 24 hours intervals), and coproparasitological tests performed over 67 days. The proportions of primates with a reduction in fecal egg counts (FEC) or negative results progressively increased after treatment, and at the last fecal tests, marmosets were negative.

RESULTS AND CONCLUSIONS

Although all primates tolerated the initial days of study well, 40% (4/10) of them died between the 8th and 16th days after the onset of treatment. Clinical signs and necropsies indicated the occurrence of hepatic involvement, biliary obstruction, and cholangitis. Marmosets with a higher previous FEC were more likely to die after treatment. Use of praziquantel should be considered carefully on a case-by-case basis.

New dicrocoeliid digeneans from mammals in Ecuador including a highly genetically divergent new genus from an ancient marsupial lineage

The Dicrocoeliidae is a highly diverse and broadly distributed family of digeneans typically parasitic in the gall bladder and liver of their tetrapod hosts. So far, no study has reported dicrocoeliids, or any digeneans, from the ancient marsupial family Caenolestidae. Herein, we describe a new genus of dicrocoeliids (Otongatrema n. gen.) from Tate's shrew opossum Caenolestes fuliginosus and a new species of Metadelphis (Metadelphis cesartapiai n. sp.) from a phyllostomid bat Anoura peruana collected in Ecuador. Otongatrema can be readily distinguished from the morphologically closest dicrocoeliid genera Concinnum, Conspicuum and Canaania based on the position of the genital pore, distribution/position of the uterus and extent of vitellarium. Metadelphis cesartapiai can be easily differentiated from other Metadelphis spp. based on a combination of morphological characters including body shape and size, distribution of vitellarium, shape of the gonads as well as size of suckers and cirrus sac. In addition, we used newly generated partial sequences of the nuclear 28S rRNA gene and mitochondrial cox1 genes to examine phylogenetic affinities of the new taxa within the Dicrocoeliidae. Both the 28S and cox1 phylogenies confidently positioned Otongatrema as a sister/basal group to all other dicrocoeliids sequenced so far. The phylogenetic position of Otongatrema may be explained by a close co-evolutionary relationship with Caenolestidae, one of the most basal and most ancient groups of marsupials. In addition, our 28S phylogeny provides evidence that the complete or partial loss of intestinal structures has likely occurred independently at least 3 times in the evolutionary history of the Dicrocoeliidae.

Infection by Platynosomum illiciens (= P. fastosum) in domestic cats of Araguaína, Tocantins, northern Brazil

Abstract Platynosomiasis is a hepatopathy caused by Platynosomum illiciens(= P. fastosum) (Trematoda: Dicrocoelidae), which occurs mainly in domestic and wild cats in tropical and subtropical areas. The objective of this study was to verify the occurrence of P. illiciens infection in domestic cats in the city of Araguaína, Tocantins, Brazil, using necropsy and coproparasitological tests. Additionally, we aimed to evaluate the use of two different techniques to diagnose P. illiciens infection in domestic cats and verify whether this parasitism was associated with individual feline characteristics. For this, 54 cats of different ages were analyzed. The percentage of infection was 33.3% (CI = 21.1-47.5%), parasite load was 9-509, mean intensity was 151.7, and mean abundance was 50.5 trematodes per animal. The risk of infection was higher for females than for males (OR = 5.00; P = 0.017). The spontaneous sedimentation coproparasitological test demonstrated the greatest sensitivity and specificity in diagnosing P. illiciens. This study is the first to report the occurrence of P. illiciens in cats in the state of Tocantins, northern Brazil.

Molecular phylogeny provides new insights on the taxonomy and composition of Lyperosomum Looss, 1899 (Digenea, Dicrocoeliidae) and related genera

Lyperosomum Looss, 1899 is one of the largest genera of the Dicrocoeliidae and is one of the best examples of the systematic complexity and taxonomic instability within this family. We present the molecular analyses based on novel sequences of nuclear and mitochondrial genes obtained from 56 isolates of adult flukes and larval stages of dicrocoeliids belonging to Lyperosomum, Skrjabinus, Zonorchis as well as previously available sequence data. According to obtained results we propose to return Zonorchis clathratus and Z. petiolatus into Lyperosomum, and to recognize L. alagesi as a synonym of L. petiolatum. Our study shows that L. petiolatum commonly occurs in Europe in corvids as well as in several species of migratory songbirds, e.g. Sylvia atricapilla. At the same time, the Turdidae appear to host a distinct species of Lyperosomum. The phylogenetic analysis has clearly demonstrated the paraphylepic nature of Lyperosomum and indicated the need of its thorough revision preferably using specimens from type hosts and type territories of nominal species. In addition, inclusion of numerous not yet sequenced dicrocoeliid genera into future phylogenetic studies is necessary to clarify the interrelationships of taxa within the family and stabilize its system.