Submitted to: Book Chapter
Publication Type: Review Article
Publication Acceptance Date: 10/19/1998
Publication Date: N/A
Interpretive Summary: Control of parasitic worm infections in man and livestock is often overlooked unless there is an open expression of disease and death. The consequences of this approach are that subclinical infections are often disregarded and not treated properly. The present report discusses the ramifications of infections with parasitic worms on the ability of opportunistic bacteria to invade and exacerbate the general health of man and animals. The results show that a particular interaction between the whip worm, Trichuris suis, and a major diarrhea producing bacteria, Campylobacter jejuni, frequently results in a severe disease outcome. It becomes clear that care must be taken to adequately control the general health of a population by monitoring the types of infections that are present and by taking measures to eliminate or minimize the potential for harmful interactions. This information is of interest to public health officials as well as scientists studying infectious diseases and veterinarians that recommend parasite control procedures.
Technical Abstract: Gastrointestinal nematode parasites can evoke dramatic and stereotypical changes in the intestinal milieu of the infected mammalian host. These changes may be inconsequential or result in protective immunity, pathology or an alteration in the immune response to opportunistic organisms that inhabit the intestine. There are also structural and physiological changes in the intestine that include increases in the quantity and composition of mucous secretions, a net accumulation of fluids into the lumen, smooth muscle contractility and alterations in lumenal content transit time, as well as changes in epithelial cell function and proliferation. The interplay of cytokines can work in both directions so that intracellular parasites, bacteria and viruses that elicit a strong Th1 response can down regulate a type 2 response primarily through the growth limiting activity of IFN-gamma on Th2 cells. Infections that strongly shift an immune response in one direction or another can predictably result in restricted immune flexibility that can be exploited by opportunistic infections. The current report describes changes in intestinal immunity induced by gastrointestinal nematode parasites and a specific situation where natural infection of pigs with Trichuris suis enhances susceptibility of colonic epithelial cells and gut-associated lymphoid tissue in the distal colon to invasion by Campylobacter jejuni.