Helminthic Infections and Vaccine Efficacy in Cattle: Implications for Disease Control and Sustainable Livestock Production.

Vaccination remains a cornerstone of livestock disease control, yet its effectiveness under field conditions is often compromised by concurrent infections, particularly parasitic helminths. This review explores how infections shape vaccine-induced immunity in cattle, emphasizing the immunoregulatory mechanisms by which helminths interfere with protective responses. Chronic infections with Fasciola hepatica and Ostertagia ostertagi induce Th2-biased and regulatory immune environments that suppress antigen presentation, cytokine production, and memory formation and maintenance, leading to reduced vaccine efficacy. Evidence from experimental and field studies is scarce and constitutes a gap in our knowledge on how vaccines work in the field. Available data indicate that infection timing, intensity, and chronicity critically determine the extent of vaccine interference. The review highlights diagnostic approaches that can support targeted deworming before vaccination and proposes integrated management strategies combining parasite control, immunization, and nutritional optimization. Such approaches can mitigate helminth-driven immune suppression, enhance herd protection, and reduce dependence on anthelmintics. However, the impact of helminth infections on vaccine efficacy in cattle should be further assessed in the field. Understanding parasite-vaccine interactions is essential to refine vaccination programs, guide the development of next-generation vaccines, and promote sustainable livestock health in parasite-endemic areas.