Some Tissue Reactions to the Nematode Parasites of Animals

Abstract

Publisher Summary This chapter reviews some recent work conducted on the reactions of the mammalian animal to its nematode parasites. The associations between the parasite and host are of various kinds. In some, presumably those where the two organisms have been in association for long periods of time, there is little reaction, but in others, the reactions are acute and are associated with disease. Foreign body and irritant responses are common, while eosinophils are of such regular occurrence that their presence in the tissues of a domestic animal leads to a suspicion of parasitism. Hyperplastic reactions occur and metaplasia is reported, but true neoplasia seems rare. Susceptible animals do not react like immune ones in which the responses are enhanced and lymphocytic and plasma cell proliferation may occur. Many nematode parasites inhabit the lung; some are merely temporary but others reside there as adults. Although some nematodes may not reach adulthood in an unusual host they do nevertheless gain entrance to the tissues, where the reaction to them may be so pronounced that disease results. This is especially true in visceral larva migrans. The chapter illustrates the changing environment in which a nematode may have to live.