Echinococcus granulosus hydatid cyst location is modified by Fasciola hepatica infection in cattle

Assessment of oxidative stress and tissue damage in Echinococcus granulosus naturally infected bovine liver

Echinococcus granulosus is a zoonotic parasite infects many livestock species, especially cattle, sheep, goat and buffalo, causing cystic echinococcosis. The aim of this study was to demonstrate the presence of the parasite and parasitic tissue damage histopathologically and to determine the role of oxidative stress in the tissue damage through the immunohistochemical detection of the oxidative damage-marker malondialdehyde (MDA) and the antioxidant response-marker superoxide dismutase (SOD). The material of the study consisted of 20 liver samples with Echinococcus cysts and 10 E.granulosus- negative healthy liver samples obtained from different cattle at various times from slaughterhouses in Kırıkkale province, Turkey. Histopathologically, Echinococcus cysts of various sizes were observed along with the surrounding fibrous connective tissue. Giant cells, mononuclear cells, and eosinophilic leukocytes were found between the fibrous connective tissue and the cyst. In the parenchymal tissue distant from the cyst, inflammatory changes were observed, including vacuolation and necrosis in hepatocytes, congestion and dilation sinusoidal capillaries. Immunohistochemically, MDA immunopositivity was observed in both hepatocytes surrounding the cyst and areas distant from the cyst, while SOD immunopositivity was mainly detected in fibrous connective tissue and hepatocytes surrounding the Echinococcus cysts. A significant increase in MDA immunoreactivity was observed in E.granulosus s.l.-infected livers. Although no statistically significant change was observed in SOD immunopositivity in the liver tissues with cystic echinococcosis, regional variations were noted. Germinal layer (GL) of Echinococcus cyst showed immunopositive staining for MDA, while laminated layer (LL) exhibited immunonegative staining. To the authors' best understanding, this study represents a pioneering effort in showcasing and evaluating the immunoreactivities of MDA and SOD within the liver tissue afflicted with Echinococcus cysts. Simultaneously, the examination extends to encompass tissue damage and the infiltration of inflammatory cells. This study highlights the role of oxidative stress in the pathogenesis of Cystic Echinococcosis (CE) and the need for further investigation of antioxidant defense mechanisms and their regional variations.

Molecular characterization and haplotypes of hydatid cyst isolates collected from humans and ruminants in Setif Province (northeast of Algeria) based on mitochondrial cytochrome C oxidase subunit 1 (mt-CO1) gene sequences

Cystic echinococcosis (CE) is a disease that can be transmitted from animals to humans, caused by the metacestode of Echinococcus granulosus. The disease has significant health and economic impacts worldwide, particularly in endemic areas. The study aimed to evaluate the prevalence of hydatid cysts in ruminants (cattle and sheep) (n = 2060) from the Setif Province of Algeria using microscopy. The results showed that hydatid cysts were detected in 9.6% (198/2060) of ruminants, with a higher prevalence in cattle (16.8%; 56/333) compared to sheep (8.2%; 142/1727). Molecular techniques were used to analyze a subset of animals consisting of 30 sheep and 4 cattle. Specifically, a fragment of the mitochondrial cytochrome c oxidase subunit 1 (mt-CO1) gene was sequenced and compared to sequences from seven humans from the same region. The results indicated that all isolates were identified as E. granulosus sensu stricto. Haplotype analysis identified 19 E. granulosus s.s. haplotypes arranged like a star, with the dominant haplotype (Hap04) at the center. Hap04 has been assigned a total of 17 positives, including positives from sheep, cattle, and two humans. This study is noteworthy for being the first to use a molecular approach to human and ruminant echinococcosis in Setif, a significant breeding region in Algeria.

First report of Echinococcus ortleppi and E. canadensis (genotype G6) from southern Punjab, Pakistan and a global overview on genetic structure and host adaptation of E. ortleppi

Cystic echinococcosis (CE), caused by Echinococcus granulosus sensu lato, is a neglected tropical disease known mainly for its zoonotic nature. CE is endemic to Pakistan, however, the disease is not given due consideration and millions of people remain at health risk. This study was undertaken to assess the species and genotypes of E. granulosus sensu lato in sheep, buffaloes and cattle, brought to slaughterhouses of two major cities (Multan and Bahawalpur) of south Punjab, Pakistan. A total of 26 hydatid cyst specimens were characterized through complete cox1 mitochondrial gene (1609 bp) sequencing. Species and genotypes of E. granulosus sensu lato discovered in the southern Punjab consisted of E. granulosus sensu stricto (n =21), E. ortleppi (n=4) and E. canadensis G6 genotype (n=1). Of E. granulosus s.s. isolates, the genotype G3 was predominantly involved in causing infections to the livestock of this region. Since all of these species are zoonotic, wide and effective surveillance studies are required to ascertain the risks to human population in Pakistan. Additionally, a global overview on cox1 phylogenetic structure of E. ortleppi was carried out. Despite the widespread occurrence, the species is mostly limited to the southern hemisphere. The highest burden has been reported in the South America (62.15%) and Africa (28.44%) and by far the most common host is cattle, accounting for >90% of cases.

Pathological Findings in Cattle Slaughtered in Northeastern Algeria and Associated Risk Factors

Meat is a food of animal origin, which can be contaminated by infectious, parasitic and other non-infectious agents responsible for diseases, which threaten the health of consumers. This still poses a public health problem in Algeria and in many countries. In order to assess the epidemiological situation of certain diseases in the Taher region in Jijel and to determine the influence of certain variation factors and to estimate the risk on public health, a study was extended over a period of 14 months on a total of 1756 cattle slaughtered at the Taher slaughterhouse. The results showed that 609 cattle (34.68%) showed lesions. The highest rate of pathological findings was observed on the liver (37.27%) followed by the lungs (30.21%). The lowest rate was recorded on the digestive system (0.33%) followed by the kidneys (1.14%). In addition, the liver and lungs were more contaminated with hydatid cyst compared to other organs (20.69%, 19.05%, respectively). Our data showed that the diseases affected more females (55.82%) than males (44.17%) (p < 0.001). Furthermore, cattle aged between 3 and 5 years were the most affected (43.51%) and local breed cattle showed more lesions (71.59%). These results testify to the real risk represented by the consumption of organs affected by diseases, and the need to recognize the agents of contamination and the mode of transmission and to implement an extension and control program in this region depending on the epidemiological aspect of the lesions.

Response patterns in adventitial layer of Echinococcus granulosus sensu stricto cysts from naturally infected cattle and sheep

Cystic echinococcosis is a zoonotic disease caused by the metacestode of Echinococcus granulosus sensu lato. The disease is characterized by the development of cystic structures inside viscera of the intermediate host, mainly liver and lungs. These cysts are formed by three layers: germinal, laminated, and adventitial layer, the latter being the local host immune response. Metacestodes that develop protoscoleces, the infective stage to the definitive host, are termed fertile, whereas cysts that do not produce protoscoleces are termed non-fertile. Sheep usually harbor fertile cysts while cattle usually harbor non-fertile cysts. Adventitial layers with fibrotic resolution are associated to fertile cysts, whereas a granulomatous reaction is associated with non-fertile cysts. The aim of this study was to analyze cellular distribution in the adventitial layer of fertile and non-fertile E. granulosus sensu stricto cysts found in liver and lungs of cattle and sheep. A total of 418 cysts were analyzed, 203 from cattle (8 fertile and 195 non-fertile) and 215 from sheep (64 fertile and 151 non-fertile). Fertile cysts from cattle showed mixed patterns of response, with fibrotic resolution and presence of granulomatous response in direct contact with the laminated layer, while sheep fertile cysts always displayed fibrotic resolution next to the laminated layer. Cattle non-fertile cysts display a granulomatous reaction in direct contact with the laminated layer, whereas sheep non-fertile cysts display a granulomatous reaction, but in direct contact with the fibrotic resolution. This shows that cattle and sheep cystic echinococcosis cysts have distinct local immune response patterns, which are associated to metacestode fertility.

Parasitic causes of meat and organs in cattle at four slaughterhouses in Sistan-Baluchestan Province, Southeastern Iran between 2008 and 2016

This 8‐year (from 2008 to 2016) retrospective study calculated the percentage of carcass and organ (lung and liver) condemnations and estimated the direct financial costs at four slaughterhouses in Sistan‐Baluchestan Province, Southeastern Iran. Each carcass and organ (lung and liver) was thoroughly examined through inspection, palpation and incision following the standard protocol. Identification of the parasites was performed macroscopically. The total direct economic loss due to meat's condemnation was estimated by adding weights of each organ or carcass part and multiplying individual organ totals by their 2016 market unit price. A total of 857,039 cattle were slaughtered during this period, 64,497 livers (7.5%), 31,401 lungs (3.6%) and the carcasses of 1,171 cattle (0.1%) were condemned due to lesions caused by parasites. The main parasitic lesions in the condemned livers were attributed to Echinococcus granulosus (4.2%), Fasciola spp. (3.1%) and Dicrocoelium dendriticum (0.1%). All the condemned lungs were due to E. granulosus (3.6%). Taenia saginata cysticerci were detected in 0.1% of inspected animals. Liver condemnation due to cystic echinococcosis was the highest in fall (4.7%, p < 0.001); while lung condemnation was the highest during spring (3.98%, p < 0.001). Liver condemnation due to Fasciola spp. was the lowest in winter (2.99%, p < 0.001). Carcass condemnation as a result of cysticercosis was the highest in summer (p < 0.001). Considering the 2016 market prices, condemnations due to the studied parasites caused direct costs estimated U.S. $ 3,191,879. To the best of our knowledge, this is the first report estimating the monetary losses due to parasitic infections in the slaughterhouses of this province. Due to the high financial impact of the studied parasites, a control programme should be implemented to decrease this impact.

Fasciola hepatica co-infection enhances Th1 immune response in the adventitial layer of non-fertile Echinococcus granulosus cysts

Cystic echinococcosis is a widespread zoonosis caused by the larval stage of the tapeworm Echinococcus granulosus. In intermediary hosts, two types of echinococcal cysts can be found: fertile, which produce protoscoleces, the infective form of the parasite to dogs; and infertile, that do not present protoscoleces and therefore are not able to continue with the parasite life cycle. The adventitial layer, the local immune response against the cyst, plays an important role in cyst fertility. Grazing cattle can often feature Fasciola hepatica co-infection, a parasite known to modulate the host systemic immune response. In this work the cellular Th1/Th2 immune profiles were evaluated in the adventitial layer of fertile and non-fertile cysts with and without co-infection with Fasciola hepatica. Measuring with immunohistochemistry and qPCR in adventitial layer, we report that non-fertile cysts present higher levels of Th1 cytokines (IFN-γ (P < 0.0001) and TNF-α (P < 0.05)), and fertile cysts have higher levels of Th2 cytokines (IL-4 (P < 0.001)). Co-infection with Fasciola hepatica is associated with a decrease in the expression of IL-4 (P < 0.05) and an increase in the expression of IFN-γ (P < 0.0001) in the adventitial layer of fertile cysts. Non-fertile cysts were associated with higher levels of Th1 cytokines in the adventitial layer, with IFN-γ expression enhanced by F. hepatica co-infection (P < 0.0001), confirming that polyparasitism should be considered in the treatment and control of naturally infected cattle.

Cattle co-infection of Echinococcus granulosus and Fasciola hepatica results in a different systemic cytokine profile than single parasite infection

E. granulosus is a cestode that causes Cystic Echinococcosis (CE), a zoonotic disease with worldwide presence. The immune response generated by the host against the metacestode induces a permissive Th2 response, as opposed to pro-inflammatory Th1 response. In this view, mixed Th2 and regulatory responses allow parasite survival. Overall, larval Echinococcus infections induce strong regulatory responses. Fasciola hepatica, another common helminth parasite, represents a major infection in cattle. Co-infection with different parasite species in the same host, polyparasitism, is a common occurrence involving E. granulosus and F. hepatica in cattle. ‘While it is known that infection with F. hepatica also triggers a polarized Th2/Treg immune response, little is reported regarding effects on the systemic immune response of this example of polyparasitism. F. hepatica also triggers immune responses polarized to the Th2/ Treg spectrum. Serum samples from 107 animals were analyzed, and were divided according to their infection status and Echinococcal cysts fertility. Cytokines were measured utilizing a Milliplex Magnetic Bead Panel to detect IFN-γ, IL-1, IL-2, IL-4, IL-6, IL-10, IL-12 and IL-18. Cattle infected only with F. hepatica had the highest concentration of every cytokine analyzed, with both 4.24 and 3.34-fold increases in IL-10 and IL-4, respectively, compared to control animals, followed by E. granulosus and F. hepatica co-infected animals with two-fold increase in IL-10 and IL-4, compared to control animals, suggesting that E. granulosus co-infection dampens the cattle Th2/Treg immune response against F. hepatica. When considering Echinococcal cyst fertility and systemic cytokine concentrations, fertile cysts had higher IFN-γ, IL-6 and IL-18 concentrations, while infertile cysts had higher IL-10 concentrations. These results show that E. granulosus co-infection lowers Th1 and Th2 cytokine serological concentration when compared to F. hepatica infection alone. E. granulosus infections show no difference in IFN-γ, IL-1, IL-2, IL-6 and IL-18 levels compared with control animals, highlighting the immune evasion mechanisms of this cestode.

Fasciola hepatica coinfection modifies the morphological and immunological features of Echinococcus granulosus cysts in cattle

Polyparasitism occurs when animals harbour multiple parasites concomitantly. It is a common occurrence but is generally understudied in wild and domestic animals. Fasciola hepatica and Echinococcus granulosus, which are helminths of ungulates, frequently coinfect cattle. The effects of this particular type of polyparasitism are not well documented. The metacestode of Echinococcus granulosus is surrounded by the adventitial layer, which constitutes the host immune response to the parasite. This layer in cattle is produced by a granulomatous reaction and is involved in echinococcal cyst (EC) fertility. Due to the systemic immune-modulating abilities of Fasciola hepatica, coinfection possibly generates a favourable environment for EC growth. A total of 203 Echinococcus granulosus sensu stricto cysts were found in 82 cattle, of which 42 ECs were found in 31 animals coinfected with Fasciola hepatica. The overall infection intensity was 3 cysts per animal. Coinfection with Fasciola hepatica decreased the mean infection intensity to 1.4 cysts per animal. Regarding EC size, coinfection resulted in smaller ECs (15.91 vs 22.09 mm), especially for infertile lung cysts. The adventitial layer of ECs in coinfected animals lacked lymphoid follicles and palisading macrophages, which are generally hallmarks of the granulomatous immune response. The ECs in coinfected animals had organized laminated layers, whereas those in animals without coinfection did not. Although coinfection was not statistically associated with EC fertility, we did not find fertile cysts in the livers of coinfected animals. We concluded that coinfection with Fasciola hepatica and Echinococcus granulosus has a detrimental effect on ECs, particularly infertile cysts.

Multiple haplotypes of Echinococcus granulosus sensu stricto in single naturally infected intermediate hosts

Cystic echinococcosis is a disease that affects both humans and animals, caused by cryptic species complex belonging to the platyhelminth Echinococcus granulosus sensu lato (s.l.). This disease is distributed worldwide, with E. granulosus sensu stricto (s.s.) being the most widespread of the species. High genetic variability has been demonstrated within E. granulosus s.s. studying single cyst per infected animal identifying a number of different haplotypes. However, few studies have addressed the genetic diversity of this parasite within a single intermediate host with multiple Echinococcus cysts. To date, it remains unknown if specific haplotypes of E. granulosus s.s. produce differences in biological features of the cyst. Here, we use the full length of the mitochondrial gene cox1 to determine E. granulosus s.s. haplotypes in samples from both cattle and sheep which harboured more than one cyst in different areas in Chile, where this parasite is endemic. We found 16 different haplotypes in 66 echinococcal cysts from 10 animals, and both cattle and sheep can harbour up to five different haplotypes of E. granulosus s.s. in the same animal. Regarding cyst fertility, five animals had both fertile and infertile Echinococcus cysts in both single and multiple haplotype infections. There was no association between haplotype and cyst fertility, size, or adventitial layer characteristics. Sampling and sequencing every Echinococcus cyst found in the intermediate host reveals a high molecular variability. We speculate that multiple haplotype infections could also suggest that intermediate hosts come from hyperendemic areas.

An eight-year retrospective study of hydatid disease (Echinococcus granulosus sensu stricto) in beef cattle slaughtered at an Australian abattoir

A retrospective study was conducted on 1,178,329 cattle slaughtered at an eastern Australian abattoir between 2010 and 2018. The data were searched for records in which a diagnosis of hydatid disease was made by routine meat inspection and apparent prevalence was calculated. True prevalence of hydatid disease in any organ was then estimated using previously reported sensitivity and specificity for diagnosis of hepatic hydatid disease by routine meat inspection. Mixed effects logistic regression was conducted to assess putative associations between dentition (age), sex, and feed-type (grass- or grain-fed), and hydatid disease reported at slaughter, with origin (Property Identification Code [PIC] region) included as a random effect. Regression was also conducted on subsets stratified by dentition and feed-type to account for measurement bias resulting from differences in sensitivity and specificity between groups of cattle. Discrete-Poisson models (SaTScan, v.9.5) were used to detect spatio-temporal clustering of hydatid-positive cattle within PIC regions. The apparent prevalence of hydatid disease reported in any organ was 8.8% (n = 104,038; 95% confidence interval [CI] 8.8-8.9%). The liver, lungs, heart, spleen, and kidneys were reported infected with hydatid cysts. Of cattle reported infected with hydatid cysts, 75.6% had both the liver and lungs reported infected. True prevalence was estimated to be 33.0% (95% CI 24.4-44.4%). Significant interaction between dentition and feed-type was identified. Risk of reported hydatid disease was highest in both eight-tooth grass- and eight-tooth grain-fed cattle (OR 17.5, 95% CI 17.0-18.1, reference level [ref] zero-tooth; OR 4.8, 95% CI 4.4-5.2, ref zero-tooth, respectively). Sex was also significantly associated with reported cases of hydatid disease at slaughter, with the highest odds in females (two-tooth group, OR 1.2, 95% CI 1.1-1.2, ref male). Three spatio-temporal clusters of hydatid-positive regions were identified. The most likely cluster was located in north eastern New South Wales from June 2012 to September 2015 (log likelihood ratio 4774, P < 0.001). This study indicates a higher prevalence of hydatid disease than previously recognised and demonstrates that an effect of sex cannot be ruled out. The identification of clusters could indicate periods when hosts of Echinococcus were more abundant, or localised climatic events that facilitated transmission to cattle. Given the high prevalence, the financial impact of hydatid disease on the Australian beef industry and risk factors associated with variation in spatial distribution should be determined to target interventions.

Lymphocyte Populations in the Adventitial Layer of Hydatid Cysts in Cattle: Relationship With Cyst Fertility Status and Fasciola Hepatica Co-Infection

Cystic echinococcosis is a worldwide zoonosis caused by the cestode Echinococcus granulosus. Two types of hydatid cysts occur in intermediate hosts: fertile cysts that generate protoscoleces from the germinal layer of the cyst, and infertile cysts that do not produce protoscoleces and are unable to continue the life cycle of the parasite. The adventitial layer, a host-derived fibrous capsule surrounding the hydatid cyst, is suggested to play an important role in local immune regulation during infection and in fertility of the cysts. Fasciola hepatica, another important parasite of cattle, induces a characteristic Th2-like immune response that could modulate the immune response against E. granulosus. Natural co-infection of both parasites is common in cattle, but no reports describe the local immune response against E. granulosus with F. hepatica infection in the same host. This study analyzed the number and distribution of T and B cells in the adventitial layer of liver and lung cysts and the relationship with cyst fertility and F. hepatica co-infection. T lymphocytes were the predominant cell type in the adventitial layer of infertile hydatid cysts and were more numerous in infertile hydatid cysts. B lymphocyte numbers were not associated with hydatid cyst fertility. Mast cells were infrequent in the adventitial layer. The number of T and B cells was not associated with F. hepatica co-infection. The present study contributes to the understanding of local immune responses in bovine cystic echinococcosis.

New insights of the local immune response against both fertile and infertile hydatid cysts

BACKGROUND

Cystic echinococcosis is caused by the metacestode of the zoonotic flatworm Echinococcus granulosus. Within the viscera of the intermediate host, the metacestode grows as a unilocular cyst known as hydatid cyst. This cyst is comprised of two layers of parasite origin: germinal and laminated layers, and one of host origin: the adventitial layer, that encapsulates the parasite. This adventitial layer is composed of collagen fibers, epithelioid cells, eosinophils and lymphocytes. To establish itself inside the host, the germinal layer produces the laminated layer, and to continue its life cycle, generates protoscoleces. Some cysts are unable to produce protoscoleces, and are defined as infertile cysts. The molecular mechanisms involved in cyst fertility are not clear, however, the host immune response could play a crucial role.

METHODOLOGY/PRINCIPAL FINDINGS

We collected hydatid cysts from both liver and lungs of slaughtered cattle, and histological sections of fertile, infertile and small hydatid cysts were stained with haematoxylin-eosin. A common feature observed in infertile cysts was the disorganization of the laminated layer by the infiltration of host immune cells. These infiltrating cells eventually destroy parts of laminated layer. Immunohistochemical analysis of both parasite and host antigens, identify these cells as cattle macrophages and are present inside the cysts associated to germinal layer.

CONCLUSIONS/SIGNIFICANCE

This is the first report that indicates to cell from immune system present in adventitial layer of infertile bovine hydatid cysts could disrupt the laminated layer, infiltrating and probably causing the infertility of cyst.