Haemonchus contortus Susceptibility and Resistance to Anthelmintics in Naturally Infected Egyptian Sheep

Investigation on parasite infection and anthelmintic resistance of gastrointestinal nematodes in sheep in Hinggan league (City), China

BACKGROUND

Different areas of sheep infected with different types of parasites, all will cause serious harm to the local sheep, and the widespread use and repeated use of anthelmintics have produced different degrees of anthelmintic resistance (AR) in various regions. We re-investigated the infection of common parasites and AR of Gastrointestinal Nematodes (GINs) in sheep in Horqin Right Wing Front Banner, and first investigated the common parasite types and AR of GINs in sheep at other four areas in Hinggan league (city), China.

RESULTS

A total of 1770 fecal samples were collected from 1 prefecture-level city and 4 counties in Hinggan league, in which the infection rate of Coccidia ranged from 83.3% to 96.06%, that of Ascaris ovis ranged from 10.17% to 15.19%, that of Moniezia benedeni ranged from 0.6% to 1%, that of Moniezia expansa ranged from 0.33% to 8.15%. The infection rate of GINs was 100%, and Haemonchus contortus was still the dominant species. The AR results showed that only the closantel in Horqin Right Wing Middle Banner was low resiatant, and the other three regions had been resistant. Levamisole also occurred AR in the other four regions, the widely used ivermectin and albendazole had produced serious AR in five areas. The research shows that GINs are becoming more and more resistant to various anthelmintics, which has made the problem worse.

CONCLUSIONS

Understanding the dynamic changes of parasite infections and the development trend of AR in sheep in the region in this paper, the development trend seems to be more serious than imagined. Therefore only by deeply understanding the parasitic infections of sheep in this land can more reasonable medication guidance be carried out. It is expected to provide new ideas formore innovative, scientific and sustainable methods of preventing and controlling parasites.

Anthelmintic resistance in soil-transmitted helminths: One-Health considerations

The One-Health approach recognizes the intricate connection between human, animal, and environmental health, and that cooperative effort from various professionals provides comprehensive awareness and potential solutions for issues relating to the health of people, animals, and the environment. This approach has increasingly gained appeal as the standard strategy for tackling emerging infectious diseases, most of which are zoonoses. Treatment with anthelmintics (AHs) without a doubt minimizes the severe consequences of soil-transmitted helminths (STHs); however, evidence of anthelmintic resistance (AR) development to different helminths of practically every animal species and the distinct groups of AHs is overwhelming globally. In this regard, the correlation between the application of anthelmintic drugs in both human and animal populations and the consequent development of anthelmintic resistance in STHs within the context of a One-Health framework is explored. This review provides an overview of the major human and animal STHs, treatment of the STHs, AR development and drug-related factors contributing towards AR, One-Health and STHs, and an outline of some One-Health strategies that may be used in combating AR.

Understanding anthelmintic resistance in livestock using "omics" approaches

Widespread and improper use of various anthelmintics, genetic, and epidemiological factors has resulted in anthelmintic-resistant (AR) helminth populations in livestock. This is currently quite common globally in different livestock animals including sheep, goats, and cattle to gastrointestinal nematode (GIN) infections. Therefore, the mechanisms underlying AR in parasitic worm species have been the subject of ample research to tackle this challenge. Current and emerging technologies in the disciplines of genomics, transcriptomics, metabolomics, and proteomics in livestock species have advanced the understanding of the intricate molecular AR mechanisms in many major parasites. The technologies have improved the identification of possible biomarkers of resistant parasites, the ability to find actual causative genes, regulatory networks, and pathways of parasites governing the AR development including the dynamics of helminth infection and host-parasite infections. In this review, various "omics"-driven technologies including genome scan, candidate gene, quantitative trait loci, transcriptomic, proteomic, and metabolomic approaches have been described to understand AR of parasites of veterinary importance. Also, challenges and future prospects of these "omics" approaches are also discussed.

Trichostrongyle infections in domestic ruminants from Egypt: A systematic review and meta-analysis

Trichostrongylid nematodes can cause serious loss in the livestock economy; nevertheless, infections with these ubiquitous nematodes in animals from developing countries are largely neglected. The present paper provides a systematic review and meta-analysis to evaluate the status of trichostrongyle infections in domestic ruminants from Egypt. Out of 626 collected publications, 118 were defined suitable for inclusion in this review and represented trichostrongyle infections in 5 ruminant species (sheep, goats, cattle, buffaloes and camels) from Egypt. Published surveys have mostly focused on sheep, which had the highest (44.8%) pooled prevalence of trichostrongyle infections based on 95% confidence interval (35.9-53.6%) with no significant variations among sheep in different Egyptian regions. Goats had lower infection prevalence (31.2%, 21.5-40.8%) in comparison to sheep, and no significant regional differences were also found. The management and marketing practices likely account for the wide distribution of infection among small ruminants across Egypt. Variable trichostrongyle infection rates were estimated for camels (38.8%, 28.9-48.7%), cattle (27.4%, 14.4-40.3%) and buffaloes (12.2%, 8.0-16.4%). The prevalence of infection was significantly high during winter (52.1%, 32.2-72.1%), which provide favorable conditions for development and survival of larvae on pastures. The most common trichostrongyle identified in infected animals was Haemonchus contortus. The parasite was detected in 38.8% (29.9-47.6%) of infected sheep, 35.3% (24.8-45.7%) of infected goats and in 40.6% (18.6-62.5%) of infected camels. Clinical infections have been reported in a limited number of studies. Analysis of fecal egg counts (FECs) revealed that more than half (52.7%, 30.4-75.0%) of the tested sheep had low counts (<500 eggs per gram EPG), whereas only a few sheep (6.1%, 3.5-8.7%) had high counts >2000 EPG, implying that subclinical infections are common; however, the clinical infections cannot be completely ruled out. Anthelmintic resistance does not appear to be serious in trichostrongyle populations infecting ruminants from Egypt; nonetheless there have been a few cases of albendazole resistance in trichostrongyles infecting sheep. This paper contributes to a better understanding of the epidemiology and economic implications of trichostrongyle infections in ruminants from Egypt, which is crucial for establishing effective control strategies against these ubiquitous nematodes.

Monoclonal Antibodies for Protozoan Infections: A Future Reality or a Utopic Idea?

Following the SARS-CoV-2 pandemic, several clinical trials have been approved for the investigation of the possible use of mAbs, supporting the potential of this technology as a therapeutic approach for infectious diseases. The first monoclonal antibody (mAb), Muromonab CD3, was introduced for the prevention of kidney transplant rejection more than 30 years ago; since then more than 100 mAbs have been approved for therapeutic purposes. Nonetheless, only four mAbs are currently employed for infectious diseases: Palivizumab, for the prevention of respiratory syncytial virus (RSV) infections, Raxibacumab and Obiltoxaximab, for the prophylaxis and treatment against anthrax toxin and Bezlotoxumab, for the prevention of Clostridium difficile recurrence. Protozoan infections are often neglected diseases for which effective and safe chemotherapies are generally missing. In this context, drug resistance and drug toxicity are two crucial problems. The recent advances in bioinformatics, parasite genomics, and biochemistry methodologies are contributing to better understand parasite biology, which is essential to guide the development of new therapies. In this review, we present the efforts that are being made in the evaluation of mAbs for the prevention or treatment of leishmaniasis, Chagas disease, malaria, and toxoplasmosis. Particular emphasis will be placed on the potential strengths and weaknesses of biological treatments in the control of these protozoan diseases that are still affecting hundreds of thousands of people worldwide.

The trypsin inhibitor-like domain is required for a serine protease inhibitor of Haemonchus contortus to inhibit host coagulation

Haemonchus contortus, a blood-feeding nematode, inhibits blood coagulation at the site of infection to facilitate blood-sucking and digesting for successful parasitism. However, the mechanism underlying anti-coagulation at the host-parasite interface is largely unknown. In the current study, Hc-spi-i8, which has two greatly different transcripts named Hc-spi-i8a and Hc-spi-i8b, respectively, was described. Hc-SPI-I8A was a serine protease inhibitor containing a trypsin inhibitor-like cysteine rich (TIL) domain, while Hc-SPI-I8B was not. Hc-SPI-I8A/B were primarily expressed in the hypodermis, intestines and gonads in the parasitic stages of H. contortus. Hc-SPI-I8A interacted with Ovis aries TSP1-containing protein (OaTSP1CP), which was determined by yeast two-hybrid, co-immunoprecipitation (Co-IP), pull down and co-localization experiments. The blood clotting time contributed by the TIL domain was prolonged by Hc-SPI-I8A. Hc-SPI-I8A is most likely interfering in the extrinsic coagulation cascade by interacting with OaTSP1CP through its TIL domain and intrinsic coagulation cascade by an unknown mechanism. These findings depict a crucial point in the host-parasite interaction during H. contortus colonization, which should contribute to drug discovery and vaccine development in fighting against this important parasite worldwide.