City Guy raised the subject of a cow's immune response to parasites. That subject is complicated. I hope Lucky joins this thread.
Invertebrate parasites cross many Phyla from Protozoa to Chordata. The best example of a Chordate parasite is the lamprey which attaches itself to a fish and sucks the body fluids.
The question is: Does a producer rely on his cattle producing a natural immunity to parasites or does he employ a parasiticide? In the case of protozoan parasites, cattle develop effective immunity but even in the case of coccidia, it often becomes necessary to administer a coccidiastat or coccidiacide.
In the case of nematodes which is one of the largest groups of helminth parasites of cows, immunity is not always effective. No informed progressive producer would rely on a cows innate immunity to protect the cow from tape worms, round worms or lung worms.
Here is a summary from an article that is part of a series of reviews covering Mucosal Immunity appearing in Volume 260 of Immunological Reviews. It provides some background on how complex the issue of parasite immunity is. Keep in mind as you read this that it acknowledges innate and adaptive immunity occur but the series also acknowledges that those mechanisms do not fully protect a host from all species and circumstances:
Immune responses to gastrointestinal nematodes have been studied extensively for over 80 years and intensively investigated over the last 30–40 years. The use of laboratory models has led to the discovery of new mechanisms of protective immunity and made major contributions to our fundamental understanding of both innate and adaptive responses. In addition to host protection, it is clear that immunoregulatory processes are common in infected individuals and resistance often operates alongside modulation of immunity. This review aims to discuss the recent discoveries in both host protection and immunoregulation against gastrointestinal nematodes, placing the data in context of the specific life cycles imposed by the different parasites studied and the future challenges of considering the mucosal/immune axis to encompass host, parasite, and microbiome in its widest sense.
Introduction
Infection by gastrointestinal (GI) nematodes is the norm, and almost any animal with a GI tract will have at least one species of GI nematode that infects it for at least part, but more likely, most of its lifetime. This also includes man in areas of the world without access to modern intervention strategies and accounts for over 1 billion infected individuals worldwide. These parasitic species conform to the standard general nematode morphology and undergo the characteristic four molts during growth and development. The parasitic species considered here are dioecious and life spans vary from weeks to years. Investigation of these infections is not only of direct relevance to human and animal health, but also because they present a constant and major challenge to the immune system especially via the intestinal tract. They have done so throughout the course of evolution and are likely to have been a major driving force in the evolution and development of immune responses in the GI tract (and at other mucosal surfaces). Thus, analysis of immune responses to such parasites has application not only to the development of diagnostics and approaches to immunological based control measures such as vaccination, but also to our fundamental understanding of immunological mechanisms per se.
Ultimately, to fully understand the immune response to these parasites, it is important to appreciate their epidemiology and life cycle strategies to provide a basis for interpretation of immunological analysis of studies undertaken in endemic regions where infection is acquired naturally. This will place laboratory studies in context and allow recognition of the limitations of each approach. Notwithstanding this, it is clear that study of immunity to GI nematodes has greatly enriched our overall understanding of host protective responses and generated new concepts of immune regulation.
Invertebrate parasites cross many Phyla from Protozoa to Chordata. The best example of a Chordate parasite is the lamprey which attaches itself to a fish and sucks the body fluids.
The question is: Does a producer rely on his cattle producing a natural immunity to parasites or does he employ a parasiticide? In the case of protozoan parasites, cattle develop effective immunity but even in the case of coccidia, it often becomes necessary to administer a coccidiastat or coccidiacide.
In the case of nematodes which is one of the largest groups of helminth parasites of cows, immunity is not always effective. No informed progressive producer would rely on a cows innate immunity to protect the cow from tape worms, round worms or lung worms.
Here is a summary from an article that is part of a series of reviews covering Mucosal Immunity appearing in Volume 260 of Immunological Reviews. It provides some background on how complex the issue of parasite immunity is. Keep in mind as you read this that it acknowledges innate and adaptive immunity occur but the series also acknowledges that those mechanisms do not fully protect a host from all species and circumstances:
Immune responses to gastrointestinal nematodes have been studied extensively for over 80 years and intensively investigated over the last 30–40 years. The use of laboratory models has led to the discovery of new mechanisms of protective immunity and made major contributions to our fundamental understanding of both innate and adaptive responses. In addition to host protection, it is clear that immunoregulatory processes are common in infected individuals and resistance often operates alongside modulation of immunity. This review aims to discuss the recent discoveries in both host protection and immunoregulation against gastrointestinal nematodes, placing the data in context of the specific life cycles imposed by the different parasites studied and the future challenges of considering the mucosal/immune axis to encompass host, parasite, and microbiome in its widest sense.
Introduction
Infection by gastrointestinal (GI) nematodes is the norm, and almost any animal with a GI tract will have at least one species of GI nematode that infects it for at least part, but more likely, most of its lifetime. This also includes man in areas of the world without access to modern intervention strategies and accounts for over 1 billion infected individuals worldwide. These parasitic species conform to the standard general nematode morphology and undergo the characteristic four molts during growth and development. The parasitic species considered here are dioecious and life spans vary from weeks to years. Investigation of these infections is not only of direct relevance to human and animal health, but also because they present a constant and major challenge to the immune system especially via the intestinal tract. They have done so throughout the course of evolution and are likely to have been a major driving force in the evolution and development of immune responses in the GI tract (and at other mucosal surfaces). Thus, analysis of immune responses to such parasites has application not only to the development of diagnostics and approaches to immunological based control measures such as vaccination, but also to our fundamental understanding of immunological mechanisms per se.
Ultimately, to fully understand the immune response to these parasites, it is important to appreciate their epidemiology and life cycle strategies to provide a basis for interpretation of immunological analysis of studies undertaken in endemic regions where infection is acquired naturally. This will place laboratory studies in context and allow recognition of the limitations of each approach. Notwithstanding this, it is clear that study of immunity to GI nematodes has greatly enriched our overall understanding of host protective responses and generated new concepts of immune regulation.
