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Gastrointestinal nematode (GIN) infections of ruminant livestock have traditionally been controlled through regular, “suppressive”, treatment with anthelmintic drugs, but this has resulted in the evolution of anthelmintic resistance and reduced efficacy. There is now a critical need to reduce anthelmintic use to maintain anthelmintic efficacy by creating refugia where susceptible GIN reside. Targeted selective treatment (TST) strategies only treat animals that need it, ensuring animals affected by GIN maintain their performance, while animals unaffected by GIN are not treated unnecessarily. TST is generally agreed to reduce anthelmintic use without drastically reducing animal performance or increasing GIN faecal egg count (FEC), but there is considerable variation in results reported by studies comparing TST with other strategies. To explore the effectiveness of TST and identify factors affecting previous results, we applied meta-analysis to data collected from 20 studies comparing TST to other strategies. Overall, TST was associated with a statistically significant, but small, reduction in animal performance, no effect on worm FEC, and 50% lower anthelmintic use. Experimental design affected study outcome: basing treatment decisions on body condition scores resulted in less favourable outcomes compared to other methods. Meanwhile, TST was associated with negligible reductions in performance compared to “suppressive” treatment, and although FEC was increased slightly in the TST group, anthelmintic use was reduced by around two-thirds. Differences between TST and “strategic” treatments were smaller, but TST still reduced anthelmintic use by 25%. Overall, the results support the use of TST to reduce anthelmintic use while maintaining efficacy and animal performance.
The poultry red mite, Dermanyssus gallinae, is a haematophagous ectoparasite causing significant economic losses in the commercial egg-laying sector. Blood meal digestion by D. gallinae is required for nutrient acquisition, with acidic lysosomal proteinases such as cathepsin L and cathepsin D playing a critical role in haemoglobin digestion. This study investigated the role of a cathepsin D-like aspartyl proteinase, Dg-CatD-1, in the haemoglobin digestion cascade. Haemoglobin processing was investigated by RNA interference (RNAi)-mediated silencing of Dg-CatD-1 and assessing the impact on haemoglobin digestion. RNAi-mediated knockdown of Dg-CatD-1 was achieved by feeding a target-specific double-stranded RNA (dsRNA) to D. gallinae in a blood meal. The minimum length and concentration of Dg-CatD-1 dsRNA for effective knockdown was determined. In addition, the effect of Dg-CatD-1 knockdown on mite digestive physiology, haemoglobin digestion, and egg-laying by adult female mites was assessed. Feeding Dg-CatD-1 dsRNAs via a blood meal to adult female D. gallinae mites resulted in a substantial knockdown of target gene expression. The minimum length and concentration of dsRNA required for effective Dg-CatD-1 knockdown were 25 base pairs (bp, at 200 ng/μl) (61
Waddlia chondrophila is a strict intracellular bacterium belonging to the Chlamydiales order, which also encompasses important human and animal pathogens, including Chlamydia trachomatis and Chlamydia psittaci. Like all other members of the order, W. chondrophila displays a biphasic developmental cycle, alternating between infectious extracellular and replicative intracellular forms.First isolated from a bovine aborted foetus, W. chondrophila was later demonstrated to be associated, in women, with adverse pregnancy outcomes, such as miscarriage. Furthermore, recent studies have demonstrated a high prevalence of anti-W. chondrophila antibodies in asymptomatic women who consulted doctors regarding infertility problems, and in the male patients of infertile couples. Additionally, a role for this bacterium in respiratory tract infections has been suggested, as it has also been recovered from respiratory samples.Although the cause of miscarriage is not identified in ∼50% of cases, nowadays, no systematic diagnostic testing for the presence of W. chondrophila is routinely performed. Implementing large-scale testing in women with reproductive health issues would undoubtedly increase our knowledge of W. chondrophila prevalence and its implications for disease outcomes.
Secretions are central to the ability of the salmon louse Lepeophtheirus salmonis to parasitize salmonid hosts by promoting immunomodulation and feeding. Previous characterizations of secretory and excretory products (SEPs) have relied on pooled individuals, preventing assessment of inter-individual variation and responses to host-derived cues. A novel SEP collection method was developed to obtain samples from individual adult female L. salmonis, enabling evaluation of secretory profiles following exposure to conditioned seawater from a susceptible host, Atlantic salmon (Salmo salar), or a resistant host, coho salmon (Oncorhynchus kisutch). SEP concentrations ranged from 328 to 1597 µg mL⁻¹ , with no effects of host species or conditioning treatment on protein yield. Across 16 individuals, a mean of 101.4 proteins were detected per replicate, including 61.2 secretory proteins, indicating substantial inter-individual variation. Conditioning did not alter protein richness, yet conditioned treatments showed clear qualitative differences in composition. S. salar-conditioned lice uniquely secreted 40 proteins, including proteases, protease inhibitors, C-type lectins, gamma crystallins, and labial gland factors, whereas controls yielded a single unique protein. O. kisutch conditioning was further associated with additional proteases, protease inhibitors, epidermal growth factor-like proteins, and other putative virulence factors. Detection of chitin deacetylase-7 and an LY6/uPAR domain protein across multiple conditions highlights previously uncharacterised candidates relevant to louse-host interactions. In total, these findings establish individual-level SEP collection as a robust and sensitive approach for resolving secretomic diversity in L. salmonis and detecting host-associated modulation of parasite secretory activity obscured by pooled analyses.
