Capillaria hepatica in China

Human parasitic infections of the class Adenophorea: global epidemiology, pathogenesis, prevention and control

BACKGROUND

Human parasitic infections caused by Adenophorean nematodes encompass a range of diseases, including dioctophymiasis, trichuriasis, capillariasis, trichinellosis, and myositis. These infection can result in adverse impacts on human health and cause societal and economic concerns in tropical and subtropical regions.

METHODS

This review conducted searches in PubMed, Embase and Google Scholar for relevant studies that published in established databases up to April 26, 2024. Studies that focused on the common morphology, life cycle, disease distribution, clinical manifestations, and prevention and control strategies for Adenophorean parasitic diseases in humans were included.

RESULTS

Adenophorean nematodes exhibit shared morphological characteristics with a four-layered cuticle; uninucleate epidermal cells; pseudocoelom with six or more coelomocytes; generally three caudal glands; five esophageal glands; two testes in males with median-ventral supplementary glands in a single row; tail in males rarely possessing caudal alae; amphids always postlabial; presence of cephalic sensory organs; absence of phasmids; and a secretory-excretory system consisting of a single ventral gland cell, usually with a non-cuticularized terminal duct. Humans play two important roles in the life cycle of the nematode class, Adenophorea: 1) as a definitive host infected by ingesting undercooked paratenic hosts, embryonated eggs, infective larvae in fish tissue and meat contaminated with encysted or non-encysted larvae, and 2) as an accidental host infected by ingesting parasitic eggs in undercooked meat. Many organs are targeted by the Adenophorean nematode in humans such as the intestines, lungs, liver, kidneys, lymphatic circulation and blood vessels, resulting in gastrointestinal problems, excessive immunological responses, cell disruption, and even death. Most of these infections have significant incidence rates in the developing countries of Africa, Asia and Latin America; however, some parasitic diseases have restricted dissemination in outbreaks. To prevent these diseases, interventions together with education, sanitation, hygiene and animal control measures have been introduced in order to reduce and control parasite populations.

CONCLUSIONS

The common morphology, life cycle, global epidemiology and pathology of human Adenophorean nematode-borne parasitic diseases were highlighted, as well as their prevention and control. The findings of this review will contribute to improvement of monitoring and predicting human-parasitic infections, understanding the relationship between animals, humans and parasites, and preventing and controlling parasitic diseases.

Gastrointestinal parasites of wild carnivores from conservation institutions in the Cerrado of Goiás, Brazil

Increased interaction between wild and urban environments owing to human population growth, increased anthropization of biomes, and habitat loss for wild animals increases the spread of infectious and parasitic agents. The present study reports on the occurrence of gastrointestinal parasites in carnivorous mammals at two conservation institutions in the state of Goiás, Brazil. Fecal samples from 39 adult carnivores were collected after spontaneous defecation and analyzed by flotation and sedimentation. The structure and management data of each institution were recorded. Parasitism prevalence, binomial confidence intervals (CI) at 95%, variables associated with the presence of contact animals, size of the enclosure and type of food were recorded. The overall prevalence of gastrointestinal parasites in the samples analyzed was 71.8% (CI 55.1-83.0; 28/39). Ancylostomatidae, Toxocara spp., Toxascaris leonina, Strongyloides spp., Calodium hepaticum, and Trematoda eggs, and Cystoisospora spp. oocysts were detected. Environmental conditions were not correlated with parasitism prevalence; however, the parasites found could be managed, considering their biology, such as controlling synanthropic and domestic animals in captivity, feeding with healthy feed.

Spatial parasitology and the unmapped human helminthiases

Helminthiases are a class of neglected tropical diseases that affect at least 1 billion people worldwide, with a disproportionate impact on resource-poor areas with limited disease surveillance. Geospatial methods can offer valuable insights into the burden of these infections, particularly given that many are subject to strong ecological influences on the environmental, vector-borne or zoonotic stages of their life cycle. In this study, we screened 6829 abstracts and analysed 485 studies that use maps to document, infer or predict transmission patterns for over 200 species of parasitic worms. We found that quantitative mapping methods are increasingly used in medical parasitology, drawing on One Health surveillance data from the community scale to model geographic distributions and burdens up to the regional or global scale. However, we found that the vast majority of the human helminthiases may be entirely unmapped, with research effort focused disproportionately on a half-dozen infections that are targeted by mass drug administration programmes. Entire regions were also surprisingly under-represented in the literature, particularly southern Asia and the Neotropics. We conclude by proposing a shortlist of possible priorities for future research, including several neglected helminthiases with a burden that may be underestimated.

Canine hepatic calodiosis with cirrhosis

The nematode parasite Calodium hepaticum (Capillaria hepatica) has a global distribution and is commonly reported in rodents (definitive host), dogs, cats and wild animals. Humans especially children are more susceptible to the parasitic infection. This paper documents an incidental finding of hepatic calodiosis with cirrhosis in a stray dog and discusses the zoonotic implications. A non descript dog was brought for necropsy examination to the Department of Veterinary Pathology, Madras Veterinary College, Tamil Nadu, India. Liver appeared dark brown, mottled with multifocal random variably sized, grey white flat firm areas. Histopathologically, liver tissue revealed multiple random encysted large collection of eggs surrounded by mild inflammation with a few lymphocytes, macrophages and fine fibrosis. The eggs had characteristic barrel shape, bipolar ends, bilayered wall, cross striations between the walls, and yolk. Periodic acid Schiff stain demonstrated the glycolic wall of ova. Marked portal to portal fibrosis was demonstrated by Masson's trichrome (for collagen) and by Warthin-Starry (for reticulin) stains. The stage of parasitic infection was diagnosed as intermediate to chronic due to fibrosis. A need to study the prevalence of the disease in rodents, human and animals is emphasized. Improper burial of carcasses of rodents and dogs may contribute to spread of infection. Pets and stray animals may transmit infection to human and pose health risk.

An annotated checklist of the eukaryotic parasites of humans, exclusive of fungi and algae

The classification of "parasites" in the medical field is a challenging notion, a group which historically has included all eukaryotes exclusive of fungi that invade and derive resources from the human host. Since antiquity, humans have been identifying and documenting parasitic infections, and this collective catalog of parasitic agents has expanded considerably with technology. As our understanding of species boundaries and the use of molecular tools has evolved, so has our concept of the taxonomy of human parasites. Consequently, new species have been recognized while others have been relegated to synonyms. On the other hand, the decline of expertise in classical parasitology and limited curricula have led to a loss of awareness of many rarely encountered species. Here, we provide a comprehensive checklist of all reported eukaryotic organisms (excluding fungi and allied taxa) parasitizing humans resulting in 274 genus-group taxa and 848 species-group taxa. For each species, or genus where indicated, a concise summary of geographic distribution, natural hosts, route of transmission and site within human host, and vectored pathogens are presented. Ubiquitous, human-adapted species as well as very rare, incidental zoonotic organisms are discussed in this annotated checklist. We also provide a list of 79 excluded genera and species that have been previously reported as human parasites but are not believed to be true human parasites or represent misidentifications or taxonomic changes.

Capillaria hepatica (syn. Calodium hepaticum) as a Cause of Asymptomatic Liver Mass

Capillaria hepatica (syn. Calodium hepaticum) is a parasitic nematode of rodents, rarely infecting humans. An asymptomatic Israeli adult male with extensive travel history was diagnosed with a liver mass on routine post-thymectomy follow-up. Imaging and computer tomography (CT) guided biopsy were inconclusive. Surgical excision revealed an eosinophilic granuloma with fragments of a nematode suspected to be C. hepatica. Molecular methods verified the diagnosis, and the patient was treated empirically. This is the first case of hepatic capillariasis described in Israel, and the first to be diagnosed using molecular methods.

Histopathological features and prevalence of Capillaria hepatica infection in Rattus spp. in Philippine Mount Makiling forest reserve and its adjacent areas

Rats are recognized as reservoir hosts of several pathogens that pose a threat to human health. Although rats are reported to be hosts of a large number of pathogens, a survey of Capillaria hepatica carried by rats in various settings such as residential, agroforestry, and agricultural areas in the Philippines has not been conducted. A total of 90 rats composed of Rattus norvegicus, Rattus tanezumi, and Rattus exulans were collected through trapping in selected residential, agroforestry, and agricultural areas in Los Baños Laguna, Philippines. The overall prevalence of C. hepatica among rats was 21.11%. Among the rat species collected, R. norvegicus showed the highest prevalence (55.56%), followed by R. exulans (14.29%), then R. tanezumi (5.36%) (differences significant at p < 0.05). Moreover, residential areas had the highest prevalence of C. hepatica infection (50%), followed by agroforestry and agricultural areas at 6.7% each (significant at p < 0.05). However, the difference in C. hepatica infection between male (11.43%; 4/35) and female (27.27%; 15/55) rats was not significant (p > 0.05). Most of the infected rats were moderately infected (68.42%), while few were lightly and severely infected (15.78% each). Lastly, the presence of C. hepatica in liver is suggestive of presence of lymphocytes, amyloid, granuloma, and the occurrence of necrosis, hypertrophy, fibrosis, and cholestasis in the liver of the host. Capillariasis could be occurring in Philippine human populations, hence there is need for screening the population with appropriate means and to create awareness of this emerging disease.

Clinical and laboratory characterizations of hepatic capillariasis

Hepatic capillariasis is a rare and neglected parasitic disease caused by infection with Capillaria hepatica in human liver. The disease is not well described and the information for the disease's clinical manifestation, laboratory findings and disease management strategy is not well reported. The limited information for this neglected infection often results in the delay of diagnosis or misdiagnosed to other diseases, therefore the real prevalence or severity of the infection may be underestimated. More case report with systemic analysis and features summary of this disease is needed to better understand the serious zoonotic disease. This study included systemic analysis of 16 patients infected with hepatic capillariasis in China between 2011-2017, including clinical manifestations, laboratory/radiative image findings and treatment results. Clinical manifestation included sustained fever (56.25%), respiratory disorder (37.5%), abdominal pain (37.5%), diarrhea (25%), leukocytosis (93.75%) and eosinophilia (100%). No egg was detected in feces of all patients. Over 60% patients showed elevated level of hepatic enzymes and proteins related to liver fibrosis in sera. Ultrasound and MRI examinations displayed scattered parasitic granuloma leisure in affected liver. Liver biopsy revealed parasite eggs, necrotized parasitic granulomas and septal fibrosis. Treatment with albendazole combined with corticoids for several treatment courses cured all patients with capillariasis. The difficulty of diagnosis, apparent damage of liver functions and potential fibrosis make the disease's prevalence and severity underestimated.

A Systematic Overview of Zoonotic Helminth Infections in North America

Zoonotic helminths are frequent human parasites that generally complete their natural life cycle in the absence of humans. This review encompasses 30 common or clinically relevant zoonotic helminth infections that are endemic to North America. For each organism or disease, the following information is briefly reviewed: taxonomy, biology, and life cycle, epidemiology, route of transmission for the human host, clinical manifestations, pathologic features, treatment, and laboratory diagnosis. Illustrations are provided for select parasites.

The molecular identification of Calodium hepaticum in the wild brown rat (Rattus norvegicus) in Poland

Calodium hepaticum is a parasitic nematode found primarily in rodents but known to infect numerous other mammal species, and causing in humans the hepatic calodiasis. Herein, we present the first finding of C. hepaticum in Rattus norvegicus in Poland. In this study, we have used the combined pepsin-HCl digestion and molecular techniques to detect C. hepaticum infection in the liver. The results confirm the usefulness of molecular approaches for investigating the biology and epidemiology of C. hepaticum. Additionally in this study, the parts of the small subunit rRNA (18S rRNA) gene of Aonchotheca annulosa from bank vole, Aonchotheca erinacei and Eucoleus sp. from hedgehog were amplified, yielding the first 18S rRNA gene sequences of these Capillariinae nematodes.

Capillaria hepatica (Calodium hepaticum) infection in a horse: a case report

Background

Capillaria hepatica is a zoonotic parasite in humans and animals and has a worldwide distribution. However, infections in mammals apart from rodents, which are natural hosts of the parasite, have rarely been reported. This report describes the first known case of C. hepatica infection in a horse in Japan.

Case presentation

A 3-year-old filly without clinical signs was presented at a slaughterhouse in Japan. Gross examination revealed white to tan nodules 0.5 to 1.5 cm in diameter in the parenchyma of the liver. Histologically, the nodules had mature fibrous capsules and consisted of multifocal to coalescing granulomatous inflammations with numerous nematode eggs. The eggs were barrel shaped with an opercular plug on each end and double-layered shells; these findings are consistent with the features of C. hepatica eggs.

Conclusions

To our knowledge, this is the first case of C. hepatica infection in a horse in Japan. The pathological findings confirmed the presence of this pathogen in this part of the world, and they highlight the importance of this nematode in the differential diagnosis of hepatic granulomatous lesions in horses.

Prevalence of Calodium hepaticum (SYN. Capillaria hepatica) in Rattus norvegicus in the urban area of Rio de Janeiro, Brazil

The nematode Calodium hepaticum (syn. Capillaria hepatica) is a zoonotic helminth found mainly infecting rats. It was studied the prevalence of C. hepaticum infection in Rattus norvegicus in an urban area of Rio de Janeiro (Brazil), with low urban planning and sanitation. The presence of C. hepaticum was identified through visible yellowish-white lesions in liver tissue and histological analyses. The total prevalence of infection was 45%, with no significant differences between sex and age. The presence of infected rodents near the peridomestic area poses substantial risk to human health.

High occurrence of Calodium hepaticum (syn. Capillaria hepatica) spurious infection in a village in the Atlantic Forest of southern Brazil

Calodium hepaticum (syn. Capillaria hepatica) is a nematode of the Capillariidae family that infects rodents and other mammals. In Brazil, human spurious infections of C. hepaticum have been detected in indigenous or rural communities from the Amazon Basin, but not in the southern states of the country. Here, we report the highest occurrence (13.5% of 37 residents) of C. hepaticum human spurious infection detected in Brazil and the first record in a southern region, Guaraqueçaba. The finding is explained by the area being located in the Atlantic Forest of the state of Paraná, surrounded by preserved forests and because the inhabitants consume the meat of wild mammals.

Probable hepatic capillariosis and hydatidosis in an adolescent from the late Roman period buried in Amiens (France)

Two calcified objects recovered from a 3rd to 4th-century grave of an adolescent in Amiens (Northern France) were identified as probable hydatid cysts. By using thin-section petrographic techniques, probable Calodium hepaticum (syn. Capillaria hepatica) eggs were identified in the wall of the cysts. Human hepatic capillariosis has not been reported from archaeological material so far, but could be expected given the poor level of environmental hygiene prevalent in this period. Identification of tissue-dwelling parasites such as C. hepaticum in archaeological remains is particularly dependent on preservation conditions and taphonomic changes and should be interpreted with caution due to morphological similarities with Trichuris sp. eggs.

Biometric identification of capillariid eggs from archaeological sites in Patagonia

Numerous eggs of capillariid nematodes have been found in coprolites from a wide range of hosts and in raptor pellets in archaeological samples from Patagonia. The structure and sculpture of the eggshell of these nematodes and their biometry are commonly used for identification. The aim of this study was to determine whether eggs of the genus Calodium with similar morphology, found in different archaeological samples from Patagonia, belong to the same species. For this purpose, capillariid eggs (N= 843) with thick walls and radial striations were studied by permutational multivariate analysis of variance (PERMANOVA). Eggs exhibiting similar shape and structure also showed similar biometry, regardless of the zoological origin of coprolites (P= 0.84), host diet (P= 0.19), character of the archaeological sites (P= 0.67) and chronology (P= 0.66). Thus, they were attributed to the same species. We suggest that an unidentified zoonotic species of the genus Calodium occurred in the digestive tract of a wide range of hosts in Patagonia during the Holocene and that both human and animal populations were exposed to this parasite during the Holocene in the study area.

Calodium hepaticum: household clustering transmission and the finding of a source of human spurious infection in a community of the Amazon region

Background: Calodium hepaticum (syn. Capillaria hepatica) is a worldwide helminth parasite of which several aspects of transmission still remain unclear. In the Amazon region, the mechanism of transmission based on the ingestion of eggs present in the liver of wild mammals has been suggested as the cause of the spurious infections described. We performed an epidemiological investigation to determine the incidence, risk of spurious infection and the dynamics of transmission of C. hepaticum in a community of the Brazilian Amazon. Methodology/Principal Findings: Stool samples of 135 individuals, two dog feces and liver tissue from a peccary (captured and eaten by the residents) were analyzed by conventional microscopy. Dog feces were collected from the gardens of households presenting human cases of spurious C. hepaticum infections. Community practices and feeding habits related to the transmission of the parasite were investigated. The individual incidence of spurious infection was 6.7% (95% CI: 2.08–11.24). Cases of spurious infection were observed in 7.5% of the families and the household incidence was from 50% to 83.3%. The risk of spurious infection was 10-fold greater in persons consuming the liver of wild mammals (p = 0.02). The liver tissue of a peccary and one feces sample of a dog presented eggs of C. hepaticum. The consumption of the infected liver was the cause of the spurious infections reported in one household. Conclusions/Significance: This is the first identification of a source of spurious infection by C. hepaticum in humans and we describe a high rate of incidence in household clusters related to game liver alimentary habits. The finding of a dog feces contaminating peridomiciliary ground suggests the risk of new infections. We conclude that the mechanism of transmission based on the ingestion of liver is important for the dynamics of transmission of C. hepaticum in the studied area.

The zoonotic parasite Calodium hepaticum is the causative agent of rarely reported liver disease (hepatic calodiasis) and spurious infections in humans. In spurious infections eggs of this parasite are excreted in the stools without causing disease. It has been suggested that the cause of this type of infection in Amazonian areas is the ingestion of liver of wild mammals infected with the eggs of the parasite. Nonetheless, studies are needed to confirm this mechanism of transmission and investigate its epidemiological importance. In the present study we report the high individual (6.7%) and household incidence (50%–83.3%) of spurious infection in a rural community of the Brazilian Amazon. We found a high risk of spurious infection among subjects who usually ate the liver of wild mammals and detected a source of spurious infection in humans (peccary liver) as well as, for the first time, ground contamination with infected dog feces in a household presenting human cases. We confirm the existence of this mechanism of transmission of C. hepaticum and suggest that it is important for transmission not only in this area but probably also in other areas of the Amazon with similar sociocultural characteristics.

Pathological alterations in natural cases of Capillaria hepatica infection alone and in concurrence with Cysticercus fasciolaris in Bandicota bengalensis

The present study reports the natural occurrence and pathomorphological alterations of Capillaria hepatica infection alone and in concurrence with Cysticercus fasciolaris infection in the liver of Bandicota bengalensis. Out of the eighteen mature male B. bengalensis autopsied, livers of eight rats (44.4 %) were found infected with parasites comprising two (11.1 %) rats infected with C. hepatica alone, four (22.2 %) infected with C. fasciolaris alone and two (11.1 %) infected with C. hepatica in concurrence with C. fasciolaris. Gross lesions comprising of pale cystic areas or streaks on the surface of liver in rats revealed the presence of eggs of C. hepatica scattered in the parenchyma of the liver. Histologically, granulomatous reaction around the eggs, adult worms and dead components of parasites were observed.

Capillaria hepatica in man--an overview of hepatic capillariosis and spurious infections

Capillaria hepatica (syn. for Calodium hepaticum) is a zoonotic nematode parasitizing in the livers of rodents as main hosts and in numerous other mammals including humans. It is the causative agent of the rare conditions of hepatic capillariosis and spurious C. hepatica infections in humans. In this review, 163 reported cases of infestations with this parasite (72 reports of hepatic capillariosis, 13 serologically confirmed infestations and 78 observations of spurious infections) are summarized with an overview on the distribution, symptoms, pathology, diagnosis, serology and therapy of this rare human pathogen.