Suppression of giardiasis during the intestinal phase of trichinosis in the mouse.
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The interaction of the intestinal phases of Giardia muris and Trichinella spiralis was investigated in Swiss albino mice. Intraoesophageal inoculation of G. muris cysts seven days before, or seven days after, similar inoculation of T. spiralis larvae resulted in significant reduction in the numbers of Giardia trophozoites in small bowel and Giardia cysts in stools. This effect was not observed when G. muris cysts were administered after resolution of the intestinal phase of trichinosis. Giardiasis had no effect on trichinosis as assessed by numbers of adult worms in small bowel and larvae in skeletal muscles. Studies of small bowel morphology showed that the intestinal phase of trichinosis was associated with increased numbers of inflammatory cells in the lamina propria, a significant increase in Paneth cells in crypts, and a marked reduction in the villus:crypt ratio of jejunum. These observations suggest that the intestinal phase of trichinosis induced environmental changes in small bowel, perhaps related to inflammation, which resulted in suppression of proliferation of Giardia trophozoites. (+info)
The role of urocanic acid in UVB-induced suppression of immunity to Trichinella spiralis infection in the rat.
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The naturally occurring trans-isomer of urocanic acid (trans-UCA), found in the stratum corneum, absorbs ultraviolet light (UV) and isomerizes to the cis-form. Cis-UCA has been shown to impair some cellular immune responses, and has been proposed as an initiator of the suppression that follows UV irradiation. UVB exposure leads to an increase in cis-UCA in the skin of rats from about 10% to 40% of the total UCA. Previously it has been demonstrated that UVB lowers immune responses to Trichinella spiralis after oral infection of rats with the parasitic worm. In the present study we investigated the role of cis-UCA in the control of this parasitic infection. Rats were infected orally with T. spiralis and injected with different doses of cis- or trans-UCA subcutaneously. Mitogenic responses and the mixed lymphocyte reaction were not affected by either isomer. In contrast, the number of T. spiralis larvae in muscle tissue of infected rats was increased significantly in the cis-UCA-treated animals compared with the trans-UCA-treated animals. In addition, delayed-type hypersensitivity (DTH) to T. antigen in infected rats was significantly impaired by cis-UCA but not by trans-UCA. If rats were injected with a monoclonal antibody with specificity for cis-UCA 2 hr prior to UVB exposure, the UVB-induced suppression in DTH to T. spiralis and the increase in larvae counts were significantly inhibited compared with rats that were similarly injected with a control antibody. Thus cis-UCA can inhibit the specific resistance to parasitic infections and acts as an important mediator of UVB-induced suppression of immunity to T. spiralis in the rat. (+info)
A sausage-associated outbreak of trichinosis in Illinois.
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Twenty-three of 50 members of an extended Dutch-German family and their close friends who ate raw homemade summer sausage became ill with trichinosis; 12 patients were hospitalized for an average of 10 days each. The sausage had been made in three different batches according to an old family recipe. One of the batches made from USDA-inspected pork was found to contain Trichinella spiralis larvae by two Illinois State laboratories. The other two batches were negative. Seventeen of the 23 patients submitted information on medical expenses incurred and wages lost because of the outbreak. These costs totaled almost $20,000. There is need for a nationwide program for controlling trichinosis in swine. (+info)
Nematode-induced jejunal inflammation in the ferret causes long-term changes in excitatory neuromuscular responses.
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Enteric infections in animals and humans have proven the link between mucosal inflammation and gastrointestinal motor dysfunction. The goal of the present investigation was to study the long-term effects of mucosal inflammation on the neuromuscular functions of the small intestine in a ferret model of primary Trichinella spiralis infection. Myeloperoxidase activity and isometric contractions of isolated jejunal muscles were studied on days 8, 30, and 60 postinfection (PI). The peak increase in myeloperoxidase activity seen on day 8 PI returned to normal levels by day 60 PI. Contractions of the longitudinal and circular muscles evoked by electrical field stimulation of enteric nerves on day 8 PI showed no difference when compared with uninfected controls. However, during this enteric phase of the infection, neurally mediated responses were characterized by a disturbance in the balance between cholinergic and nonadrenergic, noncholinergic (NANC) excitation with both a reduction of cholinergic and a reciprocal enhancement of NANC neurotransmission. On days 30 and 60 PI the amplitude of neurally mediated responses and the balance between cholinergic and NANC excitation were restored in the circular but not in the longitudinal muscle. In addition, there were changes in the effector function involving smooth muscle hyperresponsiveness to high K+ or carbachol on days 8, 30, and 60 PI. However, a significant reduction in EC50 for carbachol was found only on day 60 PI. The results demonstrate that T. spiralis infection results in alterations of muscle contractility and enteric neurotransmission that persist after the resolution of mucosal inflammation. (+info)
From November 1998 through January 1999, 52 cases of trichinellosis were identified by the public health surveillance systems in 11 cities and districts of the state of Northrhine-Westfalia (NRW), Germany. In comparison, zero to 10 cases were reported annually in Germany during 1987-1997. This report summarizes the investigation of these cases, which indicated the existence of two simultaneous outbreaks-one caused by contaminated ground meat and the other by a commercially prepared raw smoked sausage. (+info)
IL-5 contributes to worm expulsion and muscle hypercontractility in a primary T. spiralis infection.
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Enteric nematode infections lead to increased interleukin (IL)-5 expression, eosinophilic inflammation, and intestinal smooth muscle hypercontractility. Although eosinophils release inflammatory mediators that cause smooth muscle contraction, the role of IL-5 and eosinophils in enteric smooth muscle hypercontractility is unclear. IL-5-deficient mice and their wild-type controls were infected with the nematode Trichinella spiralis. Intestinal parasites and eosinophils were counted, and jejunal longitudinal muscle contractility was assessed. During infection, IL-5 gene expression increased significantly in wild-type mice and was accompanied by significant intestinal eosinophilia in wild-type but not IL-5-deficient mice. Although both strains developed increased muscle contractility during infection, contraction was significantly less in the IL-5-deficient mice at days 16 and 21 postinfection. In addition, parasite expulsion was transiently delayed at day 16 in IL-5-deficient mice. Thus, in the nematode-infected mouse, IL-5 appears essential for intestinal eosinophilia and contributes to, but is not essential for, the development of muscle hypercontractility. IL-5 also appears to play a minor role in expelling a primary T. spiralis infection from the gut. (+info)
Second generation effects of maternal ethanol consumption on immunity to Trichinella spiralis in female rats.
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The deleterious effects of maternal ethanol consumption on neonatal immune development and early immune responses has been well documented. However, the effects of such neonatal exposure to maternally consumed ethanol on the neonates' immune responses in their adult life, especially in combination with additional ethanol exposure, has received little attention. For these experiments, female rats were fed on either 6% ethanol or pair-fed isocaloric control Lieber-DeCarli liquid diets for 30 days prior to, and during, pregnancy and lactation. One day after weaning their pups, the mothers were infected with 1000 Trichinella spiralis larvae, and maintained on diets for an additional 20 days. At this time, they were challenged with 2000 T. spiralis larvae, killed 3 days later, and their immune status determined. These animals served as the first generation alcohol animals. Their female offspring served as the experimental second generation animals. These animals received maternal ethanol during pregnancy and lactation and control diet during their juvenile period (from weaning to 90 days of age). They were then subjected to a schedule of ethanol or pairfeeding, identical to the first generation dams. Two groups of second generation animals were established: Group 1 was exposed to ethanol during their dam's pregnancy and lactation periods only, with no subsequent ethanol treatment; Group 2 received ethanol during their dam's pregnancy and lactation periods and then again throughout their adult experimental period. Our previous studies showed only minimal changes following a secondary challenge in T. spiralis-immunized rats; however, neonates born to alcohol-consuming mothers did show some depressed secondary immune responses when challenged soon after weaning. We chose to use a secondary immune challenge to assess further immune alterations in second generation adult animals. No differences between any of the ethanol and pair-fed groups were observed in intestinal worm burdens, which is similar to data previously reported for adult alcohol-consuming animals. However, second generation group 2 animals demonstrated significantly reduced proliferation responses to T. spiralis antigen and Concanavalin A (Con A) stimulation relative to the ethanol first generation and to the second generation Group 1 animals. This group also demonstrated significantly lower absorbencies in the ELISA assay for specific IgM and IgG anti-T. spiralis antibodies than the pair-fed, ethanol first and second generation Group 1 animals. The proportion of total T cells and cytotoxic T cells was significantly lower and the proportion of natural killer cells was elevated in both second generation ethanol Groups 1 and 2 relative to the ethanol first generation and pair-fed groups. In addition, Group 2 second generation animals showed significantly lower proportions of total leukocytes and T cells than Group 1 second generation animals. Although secondary immune responses to T. spiralis infection were not altered in rats exposed to ethanol only as adults, exposure to maternal ethanol does affect some specific immune responses in second generation adult life and maternal exposure may exert cumulative immune effects in concert with later consumption of ethanol by offspring born to alcoholic mothers. (+info)
Dominance of immunoglobulin G2c in the antiphosphorylcholine response of rats infected with Trichinella spiralis.
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The antibody response to the L1 stage of Trichinella spiralis has been described as biphasic. Worms resident in the intestine during the first week of infection stimulate an antibody response against a subset of larval proteins. L1 larvae in the muscle at the end stage of infection stimulate a second antibody response against tyvelose-bearing glycoproteins. Antityvelose antibodies protect rats against challenge infection with larvae. The aim of this study was to characterize the rat B-cell response against larval antigens during the intestinal phase of T. spiralis infection and to test the antiparasitic effects of such antibodies. Strain PVG rats were infected orally with 500 larvae. Antibodies specific for phosphorylcholine-bearing proteins of L1 larvae first appeared in serum 9 days postinfection. Absorption experiments showed that the majority of antilarval antibodies produced in rats 16 days after infection with T. spiralis were specific for phosphorylcholine-bearing proteins. A fraction of these antibodies bound to free phosphorylcholine. Immunoglobulin G2c (IgG2c) producing cells in the mesenteric lymph node dominated this early antibody response. IgG2c is associated with T-independent immune responses in the rat; however, a comparison of athymic rats with euthymic controls suggested that only a small fraction of the phosphorylcholine-related antibody response against T. spiralis was T independent. Phosphorylcholine is a common epitope in antigens of bacteria and nematode parasites and has been shown to be a target of protective immunity in certain bacteria. A monoclonal IgG2c antibody was prepared from infected rats and shown to be specific for phosphorylcholine. Monoclonal phosphorylcholine-specific IgG2c failed to protect rats against intestinal infection with T. spiralis. Therefore, our findings do not support a role for phosphorylcholine-bearing antigens in immune defense against T. spiralis; however, the potency of the immune response induced suggests an immunomodulatory role for the lymphocytes involved. (+info)