Botanical Products in the Treatment and Control of Schistosomiasis: Recent Studies and Distribution of Active Plant Resources According to Affected Regions

Global distribution of zoonotic digenetic trematodes: a scoping review

BACKGROUND

Digenetic trematodes, including blood flukes, intestinal flukes, liver flukes, lung flukes, and pancreatic flukes, are highly diverse and distributed widely. They affect at least 200 million people worldwide, so better understanding of their global distribution and prevalence are crucial for controlling and preventing human trematodiosis. Hence, this scoping review aims to conduct a comprehensive investigation on the spatio-temporal distribution and epidemiology of some important zoonotic digenetic trematodes.

METHODS

We conducted a scoping review by searching PubMed, Web of Science, Google Scholar, China National Knowledge Infrastructure, and Wanfang databases for articles, reviews, and case reports of zoonotic digenetic trematodes, without any restrictions on the year of publication. We followed the inclusion and exclusion criteria to identify relevant studies. And relevant information of the identified studies were collected and summarized.

RESULTS

We identified a total of 470 articles that met the inclusion criteria and were included in the review finally. Our analysis revealed the prevalence and global distribution of species in Schistosoma, Echinostoma, Isthmiophora, Echinochasmus, Paragonimus, Opisthorchiidae, Fasciolidae, Heterophyidae, and Eurytrema. Although some flukes are distributed worldwide, developing countries in Asia and Africa are still the most prevalent areas. Furthermore, there were some overlaps between the distribution of zoonotic digenetic trematodes from the same genus, and the prevalence of some zoonotic digenetic trematodes was not entirely consistent with their global distribution. The temporal disparities in zoonotic digenetic trematodes may attribute to the environmental changes. The gaps in our knowledge of the epidemiology and control of zoonotic digenetic trematodes indicate the need for large cohort studies in most countries.

CONCLUSIONS

This review provides important insights into the prevalence and global distribution of some zoonotic digenetic trematodes, firstly reveals spatio-temporal disparities in these digenetic trematodes. Countries with higher prevalence rate could be potential sources of transmitting diseases to other areas and are threat for possible outbreaks in the future. Therefore, continued global efforts to control and prevent human trematodiosis, and more international collaborations are necessary in the future.

Vernonia britteniana Root Phytochemical Studies, In Vitro Cercaricidal Activity on the Larval Stage of Schistosoma mansoni and Antioxidant Activities

Vernonia britteniana Hiern. (Asteraceae) is a medicinal plant used in traditional Angolan medicine against schistosomiasis. Our study aimed to investigate the phytochemical composition and the cercaricidal and antioxidant activities in vitro of a traditional herbal preparation (Water-Vbr) and a 70% hydroethanolic extract (EtOH70%-Vbr) prepared with this medicinal plant. The activity of the extracts against Schistosoma mansoni cercariae was assessed at different extract concentrations (500, 438, and 125 µg/mL) and at different time intervals, and the phytochemical profiles were obtained by LC-UV-ESI/MS-MS. In addition, the major chemical classes of the identified metabolites were quantified by colorimetry, and the antioxidant potential was assessed using the DPPH and FRAP methods. After 30 min, 100% cercarial mortality was observed at a concentration of 500 μg/mL after exposure, and after 120 min, an LC₅₀ of 438 μg/mL was observed for both extracts. Phenolic acid derivatives (chlorogenic acid, caffeic acid; 3,4-di-O-caffeoylquinic acid; 3,5-di-O-caffeoylquinic acid; and 4,5-di-O-caffeoylquinic acid) and triterpenoids (stigmastane-type steroidal saponins; vernoamyoside D and vernonioside D1; vernoamyoside B; and vernoniamyoside A and C) were identified as the main secondary metabolites. The Water-Vbr extract showed the highest antioxidant activity-DPPH: IC₅₀ = 1.769 ± 0.049 µg/mL; FRAP: mean = 320.80 ± 5.1325 µgAAE/g.

Schistosomiasis: Discovery of New Molecules for Disease Treatment and Vaccine Development

The parasite blood flukes belonging to the genus Schistosoma cause schistosomiasis. Among the Schistosoma species that infect humans, three stand out: Schistosoma japonicum (S. japonicum), which occurs in Asia, mainly in China and the Philippines; Schistosoma haematobium (S. haematobium), which occurs in Africa; and Schistosoma mansoni (S. mansoni), which occurs in Africa and South America and the center of Venezuela (Brazil). Research has shown that these species comprise strains that are resistant to Praziquantel (PZQ), the only drug of choice to fight the disease. Moreover, patients can be reinfected even after being treated with PZQ , and this drug does not act against young forms of the parasite. Therefore, several research groups have focused their studies on new molecules for disease treatment and vaccine development. This chapter will focus on (i) parasite resistance to PZQ , (ii) molecules that are currently being developed and tested as possible drugs against schistosomiasis, and (iii) candidates for vaccine development with a primary focus on clinical trials.

First In Silico Screening of Insect Molecules for Identification of Novel Anti-Parasitic Compounds

Schistosomiasis is a neglected tropical disease caused by blood flukes of the genus Schistosoma. In silico screenings of compounds for the identification of novel anti-parasitic drug candidates have received considerable attention in recent years, including the screening of natural compounds. For the first time, we investigated molecules from insects, a rather neglected source in drug discovery, in an in silico screening approach to find novel antischistosomal compounds. Based on the Dictionary of Natural Products (DNP), we created a library of 1327 insect compounds suitable for molecular docking. A structure-based virtual screening against the crystal structure of a known druggable target in Schistosoma mansoni, the thioredoxin glutathione reductase (SmTGR), was performed. The top ten compounds predominantly originated from beetles and were predicted to interact particularly with amino acids in the doorstop pocket of SmTGR. For one compound from a jewel beetle, buprestin H, we tested and confirmed antischistosomal activity against adult and juvenile parasites in vitro. At concentrations with anti-parasitic activity, we could also exclude any unspecific cytotoxic activity against human HepG2 cells. This study highlights the potential of insect molecules for the identification of novel antischistosomal compounds. Our library of insect-derived molecules could serve not only as basis for future in silico screenings against additional target proteins of schistosomes, but also of other parasites.

Efficacy of a Dietary Polyherbal Formula on the Performance and Gut Health in Broiler Chicks after Experimental Infection with Eimeria spp

One-hundred and fifty, one-day-old Ross-308 female chicks were randomly allocated to five equal treatments: NCONTR negative control—not challenged; PCONTR positive control—challenged; PHERB1 and PHERB2 diets were supplemented with phytogenic formula (1 and 2 g/kg feed, respectively)—challenged; PSALIN diet was supplemented with salinomycin (60 mg/kg feed)—challenged. Challenge was made by oral inoculation with 3.5 × 10⁴E. acervulina, 7.0 × 10³E. maxima and 5.0 × 10³E. tenella oocysts, at 14 days of age. One week post inoculation, bloody diarrhea, oocysts numbers, and intestinal lesions were evaluated, along with intestinal microbiota, viscosity, and pH of digesta, and histopathology. PHERB2 had a comparable (p ≤ 0.001) growth performance and feed conversion ratio to PSALIN. PHERB1 and PHERB2 had similar (p ≤ 0.001) oocyst counts to PSALIN and lower than PCONTROL. PHERB2 and PSALIN had lower (p ≤ 0.001) jejunal, ileal, and cecal lesion scores compared to PCONTR. PHERB1 and PHERB2 had higher (p ≤ 0.001) jejunal and cecal lactobacilli and lower (p ≤ 0.001) coliform counts compared to other treatments. PCONTR had lower (p ≤ 0.001) jejunum villus height, height to crypt ratio, and villus goblet cells. Breast and thigh meat resistance to oxidation was improved (p ≤ 0.001) in PHERB1 and PHERB2 compared to the PCONTR. The polyherbal formula exerted a substantial improvement on growth performance and intestinal health of the Eimeria-challenged birds.