Fasciolosis in India: An overview

Advancement in Diagnosis, Treatment, and Vaccines against Fasciola hepatica: A Comprehensive Review

In this review article, we aim to provide an overview of fasciolosis in ruminants. Diagnosis through new coprological methods (such as Flukefinder®, FLOTAC®, and Mini-FLOTAC®) remains the most suitable approach for farms. Regarding treatment, there is a scarcity of available drugs, and resistance to them has prompted new approaches (including drug combinations, enhanced metabolism, or the use of natural compounds) to address this issue. Additionally, several researchers have developed vaccines to control the disease, but their efficacy varies, and none are currently sufficient for commercial use. Further studies are needed to better understand all aspects discussed in this manuscript, with the goal of improving diagnosis, treatment, and disease control. It is important to note that this manuscript does not delve into in-depth knowledge of the discussed aspects; rather, it provides an overview of the different methodologies related to these three aspects of parasitic disease.

Advances in diagnostic approaches to Fasciola infection in animals and humans: An overviews

Fasciolosis, caused by Fasciola hepatica and F. gigantica, is an impediment to the livestock industry’s expansion and has a massively negative socio-economic impact due to its widespread prevalence in livestock. It is a waterborne zoonosis affecting human populations in the countries where rural economies are associated with livestock rearing. Conventional diagnosis of Fasciola infection is done by detecting parasite eggs in the faeces of infected animals or by immunological methods. Accurate and quick immunodiagnosis of Fasciola infection in animals and humans is based on the detection of antibodies and specific antigens expressed in the prepatent stage of the parasite. Both molecular and serodiagnostic tests developed thus far have enhanced the reliability of Fasciola diagnosis in both man and animals but are not widely available in resource-poor nations. A pen-side diagnostic test based on a lateral flow assay or a DNA test like loop-mediated isothermal amplification (LAMP) would be simple, fast, and cost-effective, enabling clinicians to treat animals in a targeted manner and avoid the development of drug resistance to the limited flukicides. This review focuses on the recent advances made in the diagnosis of this parasite infection in animals and humans.

Seroprevalence and risk factors of bovine fasciolosis in the municipalities of Colombia

Background and Aim

Bovine fasciolosis is a reemerging neglected disease with a worldwide distribution caused by the trematode Fasciola spp., which parasitize various hosts. Bovine fasciolosis is responsible for large economic losses in the bovine livestock sector. This study aimed to estimate the seroprevalence and risk factors of bovine fasciolosis in the municipalities of Colombia.

Materials and Methods

This was a descriptive cross-sectional study with simple random sampling conducted on 1140 cattle from the municipalities of Chiquinquirá, San Miguel de Sema, and Ubaté for a duration of 3 months. Serum samples were processed using the commercial Fasciola hepatica Antibody Test Kit IDEXX® Fasciolosis Verification (IDEXX, United States), which identified immunoglobulin G antibodies for gf2 antigen purified from Fasciola extracts. The f2 antigen is extremely immunogenic and highly specific for F. hepatica. An epidemiological survey was performed to record variables related to the sampled animals and herd management practices. Data were processed using the statistical program Epi Info® (Centers for Disease Control and Prevention; Atlanta, Georgia). The prevalence ratio was estimated to evaluate the association between fasciolosis and the hypothesized causal factors and the significance of this association using Pearson's Chi-square test. Finally, a logistic regression model was developed.

Results

The overall seroprevalence was 72.3%. The seroprevalence was 83.9% (323/385) in Chiquinquirá, 68.17% (257/377) in Ubaté, and 64.55% (244/378) in San Miguel de Sema. The seroprevalence was higher in male animals in Chiquinquirá and in female animals in San Miguel de Sema and Ubaté. Similarly, sex showed a statistically significant association with disease prevalence in Ubaté. The highest prevalence was found in cattle aged >2 years. The Holstein breed showed maximum seroprevalence in Chiquinquirá (p ≤ 0.05) and San Miguel de Sema, whereas crossbreed showed higher seroprevalence in Ubaté. Similarly, in Chiquinquirá, the association between the seroprevalence of fasciolosis and the presence of other species was statistically significant (95% confidence interval [CI]: 0.9601-3.4944; p = 0.0448). In Ubaté, the disease presentation was also associated with pasture rental (95% CI: 0.4047-1.0023; p = 0.003) and attendance to livestock expositions (95% CI: 0.2313-1.0636; p = 0.044). However, in San Miguel de Sema, water from the stream showed a statistically significant association with disease presentation (95% CI: 0.5209-1.0985; p = 0.00649785). Female sex and diarrhea occurrence were considered risk factors for fasciolosis.

Conclusion

A high seroprevalence of antibodies to Fasciola spp. was detected in cattle in the study municipalities, indicating a high parasite distribution in these areas. Female sex and diarrhea were established as risk factors associated with fasciolosis in Ubaté and San Miguel de Sema, respectively. Further, research is necessary to establish prevention and control programs against parasitosis.

Human and Animal Fascioliasis: Origins and Worldwide Evolving Scenario

Fascioliasis is a plant- and waterborne zoonotic parasitic disease caused by two trematode species: (i) Fasciola hepatica in Europe, Asia, Africa, the Americas, and Oceania and (ii) F. gigantica, which is restricted to Africa and Asia. Fasciolid liver flukes infect mainly herbivores as ruminants, equids, and camelids but also omnivore mammals as humans and swine and are transmitted by freshwater Lymnaeidae snail vectors. Two phases may be distinguished in fasciolid evolution. The long predomestication period includes the F. gigantica origin in east-southern Africa around the mid-Miocene, the F. hepatica origin in the Near-Middle East of Asia around the latest Miocene to Early Pliocene, and their subsequent local spread. The short postdomestication period includes the worldwide spread by human-guided movements of animals in the last 12,000 years and the more recent transoceanic anthropogenic introductions of F. hepatica into the Americas and Oceania and of F. gigantica into several large islands of the Pacific with ships transporting livestock in the last 500 years. The routes and chronology of the spreading waves followed by both fasciolids into the five continents are redefined on the basis of recently generated knowledge of human-guided movements of domesticated hosts. No local, zonal, or regional situation showing disagreement with historical records was found, although in a few world zones the available knowledge is still insufficient. The anthropogenically accelerated evolution of fasciolids allows us to call them "peridomestic endoparasites." The multidisciplinary implications for crucial aspects of the disease should therefore lead the present baseline update to be taken into account in future research studies.

Superoxide dismutase inhibits cytotoxic killing of Fasciola gigantica newly excysted juveniles expressed by sheep invitro

Fasciola gigantica faces a series of threats from various free radicals produced by the host immune system during its invasion through the abdominal cavity and establishment in the bile duct of ruminants, limiting the fluke viability. The role of the superoxide radical produced by Muzaffarnagari sheep immune effector cells against F. gigantica newly excysted juveniles (NEJs) is highlighted in this study, as is the critical role of superoxide dismutase enzyme (SOD) in dismutation of superoxide radicals derived from host immune effector cells in vitro. Three concentrations of the ovine immune effector cells viz. 2.5, 5, and 10 × 10⁶ cells were tested for their ability to induced cytotoxic killing of the parasite. All the three cell concentrations caused significant (p < 0.01) cytotoxic killing of NEJs in comparison to the control groups. Also, reduction of the immune effector cell concentration directly correlates with the NEJs killing. Attachment of immune effector cells to the parasite tegument in the presence of anti-F. gigantica antibodies was found to be critical in inducing NEJs killing via antibody-dependent cell-mediated cytotoxicity (ADCC). However, the addition of SOD greatly inhibits cytotoxic killing of NEJs, demonstrating the importance of SOD enzyme in fluke survival and parasite evasion of the host immunity. Thus, F. gigantica SOD warrants a promising candidate for immunoprophylactic studies in ruminants against the tropical liver fluke.

A young female with fever, abdominal pain and eosinophilia

Fascioliasis has been reported from many countries across the globe. Acute phase of liver fluke is characterised by fever, abdominal pain and peripheral blood eosinophilia while the chronic phase is marked by chronic inflammation involving biliary tract. It is commonly diagnosed by a radiologist due to characteristic branching abscesses seen on CT scan, highly suggestive of liver fluke. Diagnosis is made by demonstration of eggs on direct microscopic examination of duodenal aspirate or bile. Screening of family members is recommended once diagnosis is has been made. Triclabendazole is the drug of choice for treatment.

Prospects for liver fluke vaccines

Fasciola spp., Opisthorchis spp. and Clonorchis sinensis are common liver flukes that can cause a variety of diseases, mainly cholangiocarcinoma induced by clonorchiasis and liver damage and associated pathology induced by fascioliasis. Because these trematodes are parasites of humans and domestic animals, they have greatly affected the economy of agricultural industries and public health worldwide. Due to the emergence of drug resistance and the living habits of flukes, among other reasons, a possibility of reinfection remains even when antiparasitic drugs are used. Therefore, developing a safe, efficient and cost-effective vaccine against trematodes is an important goal. Here, we briefly describe the progress in the development of vaccines against liver flukes. Related innovations may provide effective protection against these helminths and the diseases that they cause.