Impact and process evaluation of a primary-school Food Education and Sustainability Training (FEAST) program in 10-12-year-old children in Australia: pragmatic cluster non-randomized controlled trial

BACKGROUND

Environmentally sustainable food initiatives accompanying nutrition education, such as the Food Education and Sustainability Training (FEAST) program, have gained traction in school settings. The aim of this trial was to conduct an impact and process evaluation of FEAST, to evaluate its effect on children's fruit and vegetable (F&V) intakes, and secondary outcomes: F&V variety consumed, nutrition knowledge, food preparation/cooking skills, self-efficacy and behaviours, food waste knowledge and behaviours, and food production knowledge.

METHODS

FEAST was a 10-week curriculum-aligned program, designed to educate children about healthy eating, food waste, and sustainability, while teaching cooking skills. It was implemented by classroom teachers, face-to-face and online, during COVID-19 school closures, in Australia in 2021. A custom designed survey was used to collect baseline and post-intervention data from students. Generalised linear mixed models (GLMM) estimated group differences in pre-post changes for primary and secondary outcomes. Surveys were also administered to students and teachers to evaluate intervention implementation.

RESULTS

Twenty schools participated and self-selected to be either intervention schools (n = 10) or wait-list control (WLC) schools (n = 10). A total of 977, 5th and 6th grade children participated in the trial with a mean age of 11.1 years (SD ± 0.7). The FEAST intervention, compared to WLC, did not result in significant increases in primary outcomes nor secondary outcomes. The process evaluation revealed FEAST was well-received by students and teachers, but COVID-19 school closures hindered implementation fidelity with a less intense program delivered under the constraints of pandemic lockdowns.

CONCLUSIONS

This is the first cluster non-randomized controlled trial designed to independently evaluate FEAST in the primary-school setting. No evidence was found for improved F&V intakes in children, nor secondary outcomes. However, the positive process evaluation results suggest that further trials of the program are warranted. If implemented as originally designed (pre-pandemic), with increased duration and complemented by supporting school policies, such programs have the potential to improve children's daily F&V intakes, cooking skills and food waste behaviours. This would support the Australian curriculum and contribute to: health promotion within schools and sustainable schools initiatives, the national agenda to reduce food waste and sustainable development goals. AUSTRALIAN AND NEW ZEALAND CLINICAL TRIALS REGISTRY: [ACTRN12620001347954]- Registered prospectively on 14/12/2020.

The path to evidence-based guidelines for food insecurity during pregnancy

Background

Food insecurity has negative health implications during and after pregnancy, however, identifying and then assisting women who are food insecure is complex. Successful screening programs are often embedded in practice guidelines that include referral and treatment guidance. Screening for food insecurity is vital to address food insecurity, however, it is not present in Australia, nor are there any guidelines for healthcare settings. This presentation will describe the steps taken to gather evidence to inform the development of practice guidelines.

Methods

The creation of practice guidelines for screening and responding to the needs of food insecure pregnant women was informed by 1) qualitative interviews with food insecure pregnant women, and 2) qualitative interviews with clinicians about their experiences of assisting hungry and food insecure pregnant women, 3) quantitative research with a cross-section of pregnant women about their experiences managing their food supply, 4) a systematic review describing the existing interventions addressing food insecurity during pregnancy, and 5) a modified Delphi to gather the opinions of experts on the best ways to address food insecurity in pregnancy.

Results

This work highlight the potential effectiveness of a food insecurity screening tool in the antenatal setting, the readiness of clinicians to respond to this need, the breadth and depth of current interventions to address food insecurity, and the opinions of experts on how this issue needs to be addressed. The combined impact of these 5 studies is the identification of a number of responces to food insecurity and hunger during pregnancy.

Conclusions

Given the lack of screening, standard care, and treatment of food insecurity in a clinical setting in Australia, it is essentail that guidelines are created that standardise patient care and control costs through efficient use of health care resources.

Key messages

• Food insecurity during pregnancy has significant implications for both mother and baby.

• Creating supportive evidence-based mechanisms to address food insecurity will lead to positive outcomes.

Evaluating OzHarvest's primary-school Food Education and Sustainability Training (FEAST) program in 10-12-year-old children in Australia: protocol for a pragmatic cluster non-randomized controlled trial

Background

The promotion of healthy eating is a public health priority. Poor dietary behaviours, including low fruit and vegetable (F&V) consumption are of particular concern among children. Novel nutrition promotion strategies are needed to improve F&V consumption. Sustainability education could be used to support nutrition education within the school context. The purpose of this paper is to report the protocol for impact and process evaluation of the school-based Food Education and Sustainability Training (FEAST) program, designed to educate children about sustainability, food waste and nutrition, using hands-on cooking activities.

Methods

A pragmatic, parallel, cluster non-randomized controlled trial with pre- and post-measures, will be implemented among 20 primary schools (10 intervention vs 10 wait-list-control) within NSW, Australia, involving children in Grades 5–6. FEAST is a curriculum-aligned program, delivered as a 1.5-h lesson/week, for a 10-week unit of inquiry, incorporating theory and cooking. FEAST was developed using theoretical frameworks which included Social Cognitive Theory and the Precede-Proceed Planning model. Primary outcomes include children’s self-reported F&V intakes (serves/day). Food literacy constructs such as: nutrition knowledge, food preparation and cooking skills, self-efficacy and behaviours, food waste knowledge and behaviours and food production knowledge, will be assessed as secondary outcomes. Process evaluation will assess program reach, adoption, implementation, maintenance, satisfaction and perceived benefits by teachers and students. An online survey (including quantitative and qualitative questions) was developed for administration at baseline (impact evaluation) and immediately post-intervention (impact and process evaluation). Intervention effects on quantitative study outcomes will be estimated with ​generalised linear mixed models, including random effects and will follow the intention-to-treat principles. Open-ended questions embedded within the surveys will be analysed qualitatively using content and thematic analyses.

Discussion

Results from this trial will provide valuable information on the value of adding environmental sustainability strategies to nutrition education in schools. Results will inform the design of future research and programs focused on primary-school children’s nutrition, sustainability-related behaviours and experiential school-based interventions.

Trial registration

Trial registered 14th December 2020 with the Australian and New Zealand Clinical Trials Registry (ACTRN12620001347954).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10302-0.

Plasma oxylipin levels associated with preterm birth in preterm labor✰

INTRODUCTION

Preterm labor is a common clinical problem in obstetrics. Since the majority of women with preterm labor eventually deliver at full term, biomarkers are needed to more accurately predict who will deliver preterm. Oxylipins, given their importance in inflammation regulation, are highly interesting in this respect since labor is an inflammatory process.

METHODS

Eighty women with preterm labor before 34 weeks of gestation were enrolled in a prospective observational multi-center cohort study. Oxylipin levels of 67 analytes in plasma samples were analyzed by liquid chromatography coupled to tandem mass spectrometry.

RESULTS

Twenty-one (26%) of the women delivered before 34 weeks of gestation, and of those women, fourteen delivered within 48 h of admission. Logistic multivariate regression showed that lower levels of 9,10-DiHODE were associated with delivery before 34 weeks of gestation (aOR 0.12 (0.024-0.62)) and within 48 h ((aOR 0.13 (0.019-0.93)). Furthermore, higher levels of 11,12-DiHETrE were associated with delivery before 34 weeks of gestation ((aOR 6.19 (1.17-32.7)) and higher levels of 8-HETE were associated with delivery within 48 h ((aOR 5.01 (1.13-22.14)).

CONCLUSIONS

The oxylipin 9,10-DiHODE may be protective in preterm labor, both for delivery after 34 weeks of gestation and for delivery later than 48 h of admission, whereas 11,12-DiHETrE and 8-HETE display the opposite effect. Larger studies are needed to validate these mediators as biomarkers for prediction of preterm birth following preterm labor.

Myenteric networks of interstitial cells of Cajal are reduced in horses with inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is a well-recognised but poorly understood disease complex in the horse. Clinical signs may vary but often include weight loss, diarrhoea and colic. The effect this disease process may have on the gastrointestinal pacemaker cells (the interstitial cells of Cajal), enteric neurons and glial cells has not been previously evaluated in the horse.

OBJECTIVES

To compare the density of the interstitial cells of Cajal (ICC), enteric neurons and glial cells in horses with IBD to those of normal horses using immunohistochemical markers.

STUDY DESIGN

Retrospective, quantitative immunohistochemical study.

METHODS

Ileal samples were collected during post-mortem examinations from 14 horses with a clinical and histopathological diagnosis of IBD and from eight normal controls. All horses were Standardbreds 1-15 years of age. Six of the IBD cases had eosinophilic gastroenteritis (EG) while the remaining eight had granulomatous enteritis (GE). Tissue sections were labelled with anti-CD117 (c-Kit), anti-TMEM16 (TMEM16), anti-protein gene product (PGP9.5) and anti-glial fibrillary acidic protein (GFAP) using standard immunohistochemical labelling techniques. Image analysis was performed to quantify the presence of ICC (CD117, TMEM16) as well as neuronal (PGP9.5) and enteroglial (GFAP) networks.

RESULTS

Interstitial cells of Cajal networks were significantly reduced in the myenteric plexus (MP) region in IBD horses compared with the controls for both markers (P<0.05). There was no significant difference in the density of the neuronal or glial cell markers between the two groups (P>0.05).

MAIN LIMITATIONS

The number of horses included in the study.

CONCLUSIONS

Disruption to ICC networks may contribute to the clinical signs of colic in some horses with IBD. Further studies are needed to establish the pathophysiological mechanisms involved and the functional effects of the reduced ICC networks.

New aspects of longitudinal instabilities in electron storage rings

Novel features of the longitudinal instability of a single electron bunch circulating in a low-emittance electron storage ring are discussed. Measurements and numerical simulations, performed both in time and frequency domain, show a non-monotonic increase of the electron beam energy spread as a function of single bunch current, characterized by the presence of local minima and maxima, where a local minimum of the energy spread is interpreted as a higher-order microwave instability threshold. It is also shown that thresholds related to the same zero-intensity bunch length depend linearly on the accelerating radio frequency voltage. The observed intensity-dependent features of the energy spread, confirmed by measurements with two independent diagnostics methods, i.e. horizontal beam profile measurements by a synchrotron light monitor and photon energy spectrum measurements of undulator radiation, are given a theoretical interpretation by applying a novel eigenvalue analysis based on the linearized Vlasov equation.

Adult weight management across the community: population-level impact of the LOSE IT to WIN IT challenge

Objective

Excess body weight negatively impacts health, but there are few evaluations of low-intensity weight management challenge programs in defined populations. This study examined weight change in adults who participated in the LOSE IT to WIN IT (LIWI) health challenge in a US community. The community-level impact on body mass index was also explored.

Methods

Body weight was analysed over 1 year in the cohort of LIWI enrolees, stratified by participants who were healthy weight or overweight/obese at baseline. Secondarily, a multiple cross-sectional analysis compared the 2.5-year trends in body mass index between community adults who did vs. did not participate in LIWI.

Results

LOSE IT to WIN IT participants who were overweight/obese lost a mean (95% confidence interval) 1.6 (1.2, 2.0) kg (~2%) over 1 year (p < 0.001), whereas healthy weight participants lost 0.7 (0.3, 1.1) kg. Across the community, LIWI participants and non-participants both gained 0.4 kg m-2 over the 2.5-year study period (p = 0.884).

Conclusions

LOSE IT to WIN IT was modestly effective among enrolees, resulting in a small weight loss of 2% over 1 year among those who were overweight/obese. However, LIWI did not impact weight gain in the community. To slow such community-level weight gain trends, weight management challenges must reach larger fractions of the populations that they target.

Percutaneousc Gastrostomy

Fluoroscopic percutaneous gastrostomy for the purpose of nutrition was performed in 28 patients with the aid of a specially designed gastrostomy set. No major complications were reported. Exchange to Foley catheter was performed after 7 days and could be used without complications for the patients' remaining life span. In order to evaluate the formation of a gastrocutaneous tract, an experimental study with the same instruments as in clinical practice was performed in 13 rabbits. Within one week a gastrocutaneous tract was formed, which was possible to dilate for insertion of a balloon catheter of larger size. The described procedure is a simple and time-saving method for a percutaneous gastrostomy in debilitated patients with dysphagia.

Early detection of neutralizing antibodies to interferon-beta in multiple sclerosis patients: binding antibodies predict neutralizing antibody development

BACKGROUND

Neutralizing antibodies (NAb) affect efficacy of interferon-beta (IFN-b) treatment in multiple sclerosis (MS) patients. NAbs evolve in up to 44% of treated patients, usually between 6-18 months on therapy.

OBJECTIVES

To investigate whether early binding antibody (BAb) titers or different IFN-b biomarkers predict NAb evolution.

METHODS

We included patients with MS or clinically isolated syndrome (CIS) receiving de novo IFN-b treatment in this prospective European multicenter study. Blood samples were collected at baseline, before and after the first IFN-b administration, and again after 3, 12 and 24 months on that therapy; for determination of NAbs, BAbs, gene expression of MxA and protein concentrations of MMP-9, TIMP-1, sTRAIL, CXCL-10 and CCL-2.

RESULTS

We found that 22 of 164 (13.4%) patients developed NAbs during a median time of 23.8 months on IFN-b treatment. Of these patients, 78.9% were BAb-positive after 3 months. BAb titers ≥ 1:2400 predicted NAb evolution with a sensitivity of 74.7% and a specificity of 98.5%. Cross-sectionally, MxA levels were significantly diminished in the BAb/NAb-positive samples; similarly, CXCL-10 and sTRAIL concentrations in BAb/NAb-positive and BAb-positive/NAb-negative samples, respectively, were also diminished compared to BAb/NAb-negative samples.

CONCLUSIONS

BAb titers reliably predict NAbs. CXCL-10 is a promising sensitive biomarker for IFN-b response and its abrogation by anti-IFN-b antibodies.

Expression of tlr4, md2 and cd14 in equine blood leukocytes during endotoxin infusion and in intestinal tissues from healthy horses

The expression of tlr4, md2 and cd14 was studied in equine blood leukocytes and in intestinal samples using real time PCR. The stability of three commonly used reference genes, glyceraldehyde-3P-dehydrogenase (GAPDH), hypoxantine ribosyltransferase (HPRT) and succinate dehydrogenase complex subunit A (SDHA), was evaluated using qbase(PLUS). The equine peripheral blood mononuclear cells (eqPBMC) examined were either stimulated in vitro with Phorbol 12-myristate 13-acetate (PMA) and ionomycin or with the CpG oligodeoxynuclotide 2216 (CpG-ODN 2216) or obtained from horses before, during and after infusion of endotoxin. Intestinal tissue from healthy horses was sampled at ileum, right dorsal colon and rectum. Ranking of the three reference genes used for normalisation identified the combination HPRT/SDHA as most suitable both when determined ex vivo in leukocytes obtained from experimentally induced endotoxaemia and in eqPBMC activated in vitro while HPRT/GAPDH were most appropriate for the intestinal samples. The relative amounts of mRNA for TLR4 and MD-2 increased threefold during in vitro activation of the cells with CpG-ODN 2216 but was decreased in cultures stimulated with PMA/ionomycin. A transient elevation in the transcription of tlr4 and md2 was also evident for equine blood leukocytes following endotoxaemia. The levels of mRNA for CD14 on the other hand remained unaffected both during the induction of endotoxaemia and in the in vitro stimulated PBMCs. A low steady expression of TLR4, MD-2 and CD14 mRNA was demonstrated for the intestinal samples with no variation between the intestinal segments analysed. Thus, the foundation for real time PCR based levels of analysis of mRNA for all three components in the equine LPS receptor complex in different intestinal segments was set, making it possible to carry out future expression studies on clinical material.

Emittance-exchange-based high harmonic generation scheme for a short-wavelength free electron laser

Generation of short-wavelength radiation by a free-electron laser using up-frequency conversion of an electron bunch density modulation is currently an area of active research. We propose a new scheme for producing the longitudinal electron bunch density modulation similar to the recently proposed echo-enabled harmonic generation but based on an emittance exchange beam line and a multislit mask. Beam line analysis and start-to-end simulation are presented.

Th17 central memory T cells are reduced by FTY720 in patients with multiple sclerosis

OBJECTIVE

FTY720 is a sphingosine 1-phosphate (S1P) receptor modulator that showed efficacy in phase II and III clinical trials in patients with multiple sclerosis (MS). FTY720 inhibits lymphocyte egress from secondary lymphoid organs into the peripheral circulation, thereby reducing the number of circulating naïve and central memory T cells, but not effector memory T cells in blood. Little is known to which of these memory T-cell subsets interleukin 17 (IL-17)-producing T cells (Th17 cells) belong, which are considered to be key mediators of inflammation in MS, and how they are affected by treatment with FTY720. In this study, we determined the phenotype and frequency of Th17 cells in blood of untreated, FTY720-treated, and interferon-beta (IFNbeta)-treated patients with MS and healthy donors.

METHODS

In a prospective observational study, circulating T cells were phenotypically characterized and Th17 cells enumerated in T-cell subsets ex vivo. Production of IL-17 upon activation and expression of the Th17-specific transcription factor RORC2 was assessed in vitro.

RESULTS

Th17 cells were found primarily within central memory T cells in all study populations. FTY720 treatment reduced blood central memory T cells, including RORC2+ and IL-17-producing T cells, by >90%. FTY720 did not per se affect IL-17 production when added to activated T cells in vitro.

CONCLUSION

Phenotypic Th17 cells are defined by a central memory T-cell phenotype. FTY720 reduces these Th17 cells in blood. This is presumably because central memory T cells are retained by FTY720 in secondary lymphoid organs.

Persistent immune responses in late infection and after treatment in experimental Schistosoma bovis infections in goats

This study explored host immune responses and their possible relationship to the anti-fecundity phenomenon in Schistosoma bovis-infected goats. The design comprised a primary infection with or without treatment at week (wk) 13, and with or without challenge at wk 36. Necropsy was performed at 36 or 52wk. Serum levels of anti-egg IgG, and anti-worm IgG and IgM, were measured by ELISA. In chronic infection, anti-worm antibodies stayed high, reflecting persisting worm burdens, whereas anti-egg IgG remained high despite minimized egg excretion. After treatment, anti-worm IgM and anti-egg IgG were minimized, but anti-worm IgG remained above the values of the uninfected controls. Histopathology showed lowered numbers of perioval granulomas in chronic infection and resolution of liver fibrosis with time, but intestinal lymphoplasmacytic perivasculitis and hepatic eosinophilic infiltrates were maintained at wk 52. Significant splenic plasmacytosis persisted after treatment. The results indicated that persistent immune responses, in chronically infected and in treated goats, may explain sustained worm fecundity depression at challenge infection.

Immunomodulation of the hepatic egg granuloma in Schistosoma japonicum-infected pigs

Immunomodulation of perioval granulomas is a well-known phenomenon in schistosome-infected mice, but only little is known about granuloma modulation in other animal models of human schistosomiasis. In the present study, we explored immunomodulation of egg granulomas in the liver in a pig model of schistosomiasis japonica. Granuloma size was measured and T cells, B cells and IgG(+) plasma cells in granulomas were quantified in pigs at 9, 12 and 21 weeks post infection (wpi) with Schistosoma japonicum. Granulomas were largest at 9 wpi, had decreased significantly in size at 12 wpi and remained small at 21 wpi (9 vs. 12 and 21 wpi: P < 0.05). The size of granulomas containing mature and immature eggs, respectively, did not differ significantly. The density of T (CD3epsilon(+)) cells and IgG(+) plasma cells in granulomas was the same, irrespective of granuloma size and time points. B (CD79alpha(+)) cells were rare in granulomas. The results indicate that in pigs, S. japonicum egg granulomas in the liver are immunomodulated at an early stage of infection, and that not only mature but also immature eggs induce a marked granulomatous reaction in this species.

Consecutive pathological and immunological alterations during experimentally induced swine dysentery - a study performed by repeated endoscopy and biopsy samplings through an intestinal cannula

The development of intestinal lesions after inoculation with Brachyspira hyodysenteriae was followed by repeated endoscopy and biopsy sampling through a caecal cannula. Seven eight-week-old pigs were cannulated and inoculated, two were cannulated but not inoculated, and two pigs were inoculated but not cannulated. Endoscopy, biopsy, and blood sampling to determine SAA (serum amyloid A), haptoglobin, cortisol, and WBC counts were performed at scheduled time-points. At the third day of disease, endoscopy showed a hyperaemic, perturbed mucosa and excessive amount of mucus. Histologically, crypt hyperplasia, depletion of goblet cell mucus, and erosions were noted. Simultaneously, elevated acute phase proteins and circulating monocytes, and decreased number of intraepithelial CD3⁺ cells were observed. After five days the pigs recovered. Intestinal lesions were demarcated and interspersed among apparently normal mucosa and blood parameters returned to initial values. Endoscopy through an intestinal cannula made it possible to follow the development of intestinal alterations in vivo and describe the sequential events during the course of swine dysentery. The number of animals used in a study could thus be minimised and the precision of the experiment increased.

Treatment efficacy and regulatory host responses in chronic experimental Schistosoma bovis infections in goats

The aim of this study was to elucidate the regulatory responses and the long-term effect of praziquantel treatment in chronically Schistosoma bovis-infected West African Dwarf goats. Forty-two goats were used and the design comprised a primary infection followed by treatment at week 13, challenge infection at week 36 and termination at week 52. Dependent variables included clinico-pathological data, worm numbers, faecal and tissue egg counts, and gross pathology of the liver. The results showed that primary infections remained suppressed for up to 52 weeks and, although challenge infections imposed on 36-week-old primary infections established fully, the impairment of their egg production capacity provided protection against clinico-pathological consequences measured by body weight and haemoglobin levels. The study also confirmed a high efficacy (97.7%) of praziquantel for treatment of S. bovis infection in goats and showed that anthelminthic removal of primary infections does not interfere with the ability of the goat to elicit a marked resistance to a subsequent challenge infection. Although treated goats had more fibrous scarring of livers than untreated goats, no negative effects of liver lesions were reflected in weight gains of treated goats. This study provides strong evidence for the beneficial effects of anthelminthic treatment of young domestic stock as an element of treatment and preventive programmes.

Experimental contagious caprine pleuropneumonia: a long term study on the course of infection and pathology in a flock of goats infected with Mycoplasma capricolum subsp. capripneumoniae

Contagious caprine pleuropneumonia (CCPP) is a major threat to goat farming in parts of Africa and Asia. It classically causes acute high morbidity and mortality early in infection, but little is known of its long term epizootiology and course. In this study, 10 goats were inoculated with Mycoplasma capricolum subsp. capripneumoniae (M. capripneumoniae) and then mixed with 15 goats for contact transmission. The disease course was monitored in each goat for 56-105 days, whereafter the goats were killed and necropsied. Varying features signifying infection occurred in altogether 17 goats (7 inoculated, 10 in-contact). Clinical signs were severe in 8 goats but no fatalities occurred. Only 6 goats had serum antibody titres against M. capripneumoniae in ELISA. Fourteen goats (5 inoculated, 9 in-contact) had chronic pleuropulmonary lesions compatible with CCPP at necropsy and 7 of those showed M. capripneumoniae antigen in the lung by immunohistochemistry. Neither cultivation nor PCR tests were positive for the agent in any goat. The results indicate that the clinical course of CCPP in a flock may be comparatively mild, M. capripneumoniae-associated lung lesions may be present at a late stage of infection, and chronic infection may occur without a significant serological response.

IFNbeta lowers MMP-9/TIMP-1 ratio, which predicts new enhancing lesions in patients with SPMS

OBJECTIVE

To 1)determine serum levels of matrix metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and TIMP-2 in patients with secondary progressive (SP) MS; 2)determine the relationship between these serum levels and MRI activity; and 3) evaluate the effect of interferon (IFN) therapy on these measures.

BACKGROUND

High serum levels of MMP-9 and low levels of TIMP-1 predict the appearance of new gadolinium-enhancing (Gd+) lesions in relapsing-remitting (RR) MS.

METHODS

Monthly Gd+ brain MRI and measures of serum MMP-2, MMP-9, TIMP-1, and TIMP-2 at 3-month intervals were performed for up to 3 years in 33 patients with SPMS participating in a phase III study of IFNbeta-1b.

RESULTS

Patients who developed new Gd+ lesions had higher levels of MMP-9 than patients who did not develop Gd+ lesions (median 351 vs 226 ng/mL, p = 0.049). The ratio of MMP-9/TIMP-1 predicted new Gd+ lesion on the concurrent scan (OR = 2.23, 95% CI 0.99 to 4.99, p = 0.052) and on the following scan (OR = 2.16, 95% CI 1.01 to 4.63, p = 0.048), whereas levels of MMP-2/TIMP-2 did not. Median levels of TIMP-1 were higher and MMP-9 trended lower for IFNbeta compared to placebo recipients (TIMP-1: 1,450 vs 1,185 ng/mL, p = 0.024; MMP-9: 225 vs 339 ng/mL, p = 0.081). IFNbeta did not influence levels of MMP-2 and TIMP-2.

CONCLUSION

The ratio of MMP-9/TIMP-1 may predict MRI activity in SPMS. The effect of IFNbeta-1b in MS, as measured by reduction in new Gd+ lesions, may be partly explained by altering MMP-9/TIMP-1 ratio.

Intestinal cannulation: model for study of the midgut of the pig

PURPOSE

To develop a pig model that would enable repeated biopsy specimen collection and endoscopic monitoring of the gut. This would increase precision of the experiment and reduce the number of experimental animals required.

METHODS

Six 10-week-old Yorkshire pigs underwent surgery, and a cannula was inserted in the cecum. Two pigs served as non-operated controls. The health status of the animals was monitored by clinical, hematologic, and biochemical examinations and by studies of gut motility and microbial flora. The experimental period lasted for eight weeks and approximately 45 biopsy specimens were obtained from each animal.

RESULTS

Repeated endoscopy was performed and biopsy specimens were taken. Adverse effects on the animal's health were not apparent, and differences were not evident in transit time of digesta or in diversity of the gut microbial flora. After surgery there was a transient increase in the concentrations of haptoglobin, serum amyloid A, and plasma cortisol, and in body temperature and white blood cell count.

CONCLUSIONS

It is possible to use an intestinal cannula in the cecum both for endoscopy and biopsy specimen collection. The procedures did not influence health status of the pigs, nor alter gut function. The method will be useful in experimental infection studies as well as in other physiologic investigations.

Pathology and course of natural Schistosoma japonicum infection in pigs: results of a field study in Hubei province, China

In order to obtain information on the natural course of porcine infection with Schistosoma japonicum, pigs were exposed to the cercariae of this parasite in a highly endemic region of China. Five, 5-month-old pigs previously infected with S. japonicum (group A) and 10, schistosome-naïve piglets (group B) were allowed on a pasture infested with Oncomelania snails for one transmission period (approximately 5.5 months). All the piglets rapidly acquired infection, and both groups remained infected throughout the study period. Group B showed fever, diarrhoea and anorexia in the early egg-excretion phase, and marked growth reduction. In both groups, post-mortem examination revealed live schistosomes and lesions associated with dead worms in the intestinal and mesenteric vasculature, and egg-related pathology in the large intestine and liver. Major findings were exudative lesions connected with egg excretion in the intestine, and granulomatous obstruction of portal veins in the liver. Signs of granuloma modulation were found in the liver, but not in the intestine. In conclusion, the study showed that field exposure of pigs to S. japonicum for one transmission period resulted in clinical disease and growth retardation in the youngest pigs, and significant pathology in both groups. Self cure, prominent in experimental porcine infections produced with single, high-dose inocula, was not induced in either group.

Tissue responses in experimental schistosomiasis japonica in the pig: a histopathologic study of different stages of single low- or high-dose infections

The tissue responses of pigs exposed to either 100 or 2,000 Schistosoma japonicum cercariae were examined at 4, 11, 17, and 24 weeks postinfection (PI) to explore the pig as an animal model for pathologic aspects of human schistosomiasis japonica. Egg granulomas were present in the liver, intestine, and occasionally in the lungs from 11 weeks PI. There were also many free eggs and early exudative reactions to eggs in the intestine. At 11 weeks PI, pigs in the higher dose group showed marked periportal and septal fibrosis with minimal parenchymal destruction. Thereafter, lesions regressed spontaneously as the pigs underwent a self-cure. The lower dose group showed only mild lesions throughout the study. The degree of hepatic fibrosis was correlated with the density of eggs and granulomas in liver tissue. The results indicate that the pig would be particularly useful for studies of the development and resolution of schistosomal hepatic fibrosis, and also for investigations of the mechanisms behind the self-cure phenomenon.

An approach to management of critical indoor air problems in school buildings

This study was conducted in a school center that had been the focus of intense public concern over 2 years because of suspected mold and health problems. Because several attempts to find solutions to the problem within the community were not satisfactory, outside specialists were needed for support in solving the problem. The study group consisted of experts in civil engineering, indoor mycology, and epidemiology. The studies were conducted in close cooperation with the city administration. Structures at risk were opened, moisture and temperature were measured, and the causes of damage were analyzed. Microbial samples were taken from the air, surfaces, and materials. Health questionnaires were sent to the schoolchildren and personnel. Information on the measurements and their results was released regularly to school employees, students and their parents, and to the media. Repairs were designed on the basis of this information. Moisture damage was caused mainly by difficult moisture conditions at the building site, poor ventilation, and water leaks. Fungal genera (concentrations <200 colony-forming units (cfu)/m(3), <3000 cfu/cm(2)) typical to buildings with mold problems (e.g., Aspergillus versicolor, Eurotium) were collected from the indoor air and surfaces of the school buildings. Where moisture-prone structures were identified and visible signs of damage or elevated moisture content were recorded, the numbers of microbes also were high; thus microbial results from material samples supported the conclusions made in the structural studies. Several irritative and recurrent symptoms were common among the upper secondary and high school students. The prevalence of asthma was high (13%) among the upper secondary school students. During the last 4 years, the incidence of asthma was 3-fold that of the previous 4-year period.

Congenital transmission of Schistosoma japonicum in pigs

Congenital transmission of Schistosoma japonicum in pigs was investigated by experimentally infecting sows at four weeks gestation (n = 3), 10 weeks gestation (n = 3), or a few weeks prior to insemination (n = 2). None of the piglets born to sows infected prior to insemination or in early pregnancy were found to be infected. However, all of the piglets (n = 26) born to sows infected at 10 weeks gestation were found to harbor schistosomes with S. japonicum eggs recovered from both their feces and livers. The findings show that congenital S. japonicum infection of pigs can occur if sows are infected during mid-to-late pregnancy and may have important implications not only for pigs but also for other mammalian hosts of schistosomes, including humans.

An immunohistological study of phenotypic characteristics of cells of the inflammatory response in the intestine of Schistosoma bovis-infected goats

The cellular inflammatory response in the small intestine of 21 goats infected with Schistosoma bovis was phenotypically characterized by immunohistochemistry between 6 and 32 weeks post-exposure, with particular reference to perioval granulomatous reactions. Macrophages of granulomas consistently expressed MHC class II molecules, whereas multi-nucleated giant cells in general did not. Most granulomas contained moderate infiltrates of CD2+ (CD4+ or CD8+) and gamma/delta (T19+) T cells, whereas B lymphocytes were sparse. Intact extravascular mucosal eggs, lacking appreciable cellular reactivity on plain histopathology, displayed surrounding collars of MHC class II+ macrophages. Gamma/delta T cells and MHC class II+ macrophages were the predominant cell types in perivascular inflammatory cell clusters in the submucosa. The phenotypic cellular composition of granulomas did not change appreciably with duration of infection. The results indicate the importance of MHC class II-restricted immune events in the caprine S. bovis egg granulomas and also suggest a role of gamma/delta T cells in their pathogenesis. It is hypothesized that the early appearance of perioval macrophage collars may serve to protect eggs from ovicidal host defence mechanisms, facilitating excretion and continuation of the life-cycle.

Eph signaling is required for segmentation and differentiation of the somites

Somitogenesis involves the segmentation of the paraxial mesoderm into units along the anteroposterior axis. Here we show a role for Eph and ephrin signaling in the patterning of presomitic mesoderm and formation of the somites. Ephrin-A-L1 and ephrin-B2 are expressed in an iterative manner in the developing somites and presomitic mesoderm, as is the Eph receptor EphA4. We have examined the role of these proteins by injection of RNA, encoding dominant negative forms of Eph receptors and ephrins. Interruption of Eph signaling leads to abnormal somite boundary formation and reduced or disturbed myoD expression in the myotome. Disruption of Eph family signaling delays the normal down-regulation of her1 and Delta D expression in the anterior presomitic mesoderm and disrupts myogenic differentiation. We suggest that Eph signaling has a key role in the translation of the patterning of presomitic mesoderm into somites.

Dietary zinc oxide in weaned pigs--effects on performance, tissue concentrations, morphology, neutrophil functions and faecal microflora

The uptake and distribution of zinc in tissues and the effects of 2500 ppm dietary zinc oxide on health, faecal microflora, and the functions of circulating neutrophils were evaluated in weaned pigs. One group was fed a zinc supplement diet and another group was used as a control. All pigs remained healthy throughout the study, but the supplemented animals showed better performance than the controls. The serum zinc values rose rapidly. At autopsy, carried out at the age of 63 days, the zinc concentrations in liver tissue were 4.5 times higher, and in renal tissue two times higher in the supplemented group than in controls (P<0.001). Microscopic examination showed increased lipid accumulation in hepatocytes from supplemented pigs. No effect on the number of excreted Escherichia coli and enterococci per gram faeces or on the functions of circulating neutrophils was observed. Dietary supplementation with 2500 ppm ZnO for up to two weeks after weaning appears to be potentially beneficial in the prevention of postweaning diarrhoea in pigs.

Late lesions of experimental contagious caprine pleuropneumonia caused by Mycoplasma capricolum ssp. capripneumoniae

A clinical, bacteriological, serological and patho-anatomical study was carried out on 12 goats surviving the acute stage of contagious caprine pleuropneumonia (CCPP), experimentally produced with Mycoplasma capricolum ssp. capripneumoniae (M. capripneumoniae), with the major aims of investigating the chronic stage of the disease and elucidating the possibility of a carrier state beyond the acute fulminant phase. The goats were killed 9, 16, 82 or 126 days after the onset of acute clinical signs. On day 9, clinical signs included low grade fever and persistent coughing. Thereafter, only intermittent coughing was recorded. Serum titres of complement-fixing antibodies to M. capripneumoniae were high at the period of fever but dropped thereafter. Post-mortem examination showed acute fibrinous pleuropneumonia on days 9 and 16, and chronic pleuropneumonia on days 82 and 126, including sequester formations in goats killed on day 126. Mycoplasma capripneumoniae was isolated on days 9 and 16 but not on later occasions. The study showed that goats recovered from acute CCPP may have lesions for a long time thereafter but provide no evidence of a carrier state among long-term survivors.

Schistosoma japonicum in the pig: the host-parasite relationship as influenced by the intensity and duration of experimental infection

Parasitologic, clinicopathologic, and pathologic aspects of Schistosoma japonicum infections of varying durations and intensities were studied in growing pigs injected intramuscularly with a dose of either 0, 100, 500, or 2,000 cercariae and killed at 4, 11, 17, or 24 weeks postinfection (PI). The number of viable worm pairs decreased significantly in the high dose group after 11 weeks PI but not in the lower dose groups; however, a stable population of immature worms persisted throughout the study in all dose groups. Liver egg counts also tended to decrease in the high dose group after 11 weeks but not in the other groups. Fecal egg excretion began at six weeks PI, was highest at eight weeks PI with a pronounced peak occurring only in the high dose group, and then decreased to low levels by 14 weeks PI in all groups. Egg counts from the feces as well as the liver correlated strongly with worm pair numbers during the acute phase of infection. The only clinicopathologic abnormality observed was an increase in circulating eosinophils corresponding to cercarial dose in all infected pigs by week six with peak counts occurring between six and eight weeks PI. The pigs exhibited no clinical signs of disease aside from diarrhea at the onset of patency. However, lesions were present throughout the large intestine of all infected pigs from 11 weeks PI, gradually decreasing with time. Severe liver fibrosis occurred in the 500 and 2,000 dose groups mainly at 11 weeks PI and then decreased in severity. In the liver, but not in the intestine, the severity of lesions at all time points was proportional to the cercarial dose given. The results indicate that after several weeks of patency, pigs with high intensities of S. japonicum infection are able to effectively eliminate the majority of adult worms while maintaining a stable population of immature schistosomes.

Radiography of spontaneous periodontitis in dogs

The pattern and distribution of periodontitis were investigated in 162 randomly selected dogs available for necropsy in veterinary practice. There were 82 males and 80 females of 50 different breeds (150 dogs were pure-bred and 12 were mongrels, aged between 7 months and 14 yr. Presence of periodontitis was determined by assessment of alveolar bone loss on radiographs of the skulls and jaws. Periodontitis occurred frequently with increasing age, although the prevalence varied markedly among and within different breeds. Of the breeds most represented in the sample, periodontitis was most frequently seen in poodles and dachshunds but was rarely recognized in German shepherd dogs. Regardless of age, the vast majority of the dogs displayed either one or both of two different radiographic patterns of alveolar bone loss. One pattern was characterized by slight, horizontal alveolar bone loss involving interradicular and interdental areas. The other pattern was one of predominantly crater-like, or narrow, vertical bone defects which, when advanced, often extended around a single root or tooth to surround the root apices. The two types of patterns did not seem to be breed-dependent. The posterior maxillary and mandibular premolars and molars were the most frequently affected teeth. Alveolar bone loss was most severe in the maxilla, while corresponding bone loss in the mandible was more often related to increasing age.

Experimental Schistosoma bovis infection in goats: the inflammatory response in the small intestine and liver in various phases of infection and reinfection

In a histopathological study of goats experimentally infected with Schistosoma bovis, the characteristics of the inflammatory response in the small intestine and liver related to tissue egg counts and fecal egg excretion were compared between goats at different time periods of primary infection and of primary infection followed by challenge. At early patency, coinciding with increasing egg excretion, the intestinal lamina propria showed numerous intact schistosome eggs devoid of any inflammatory reaction, whereas egg-associated inflammatory foci in the intestine were significantly few. Later in primary infection and after challenge, intestinal changes were marked by a granulomatous anti-egg response, with only a minor component of eggs lacking inflammatory change, and were consistent with a reduction of egg transfer into the gut wall. Hepatocellular necrosis with eosinophil infiltration was pronounced only during the early patent stage. The results indicate that the early cascade of fecal egg excretion in caprine schistosomosis bovis is aided by a low degree of tissue reactivity to eggs in the intestine. They also lend support to previous findings indicating that an anti-fecundity effect is operative after exposure to challenge in this parasitic infection in goats.

The impact of primary Schistosoma bovis infection on a subsequent challenge infection in goats

Experimental primary and challenge Schistosoma bovis infections were studied in West African Dwarf goats, using clinicopathological and parasitological parameters. The experiment included 44 goats divided into 4 groups of which group A received primary infection, group B received primary and challenge infection, group C received a challenge control infection, and group D included noninfected controls. Primary infection (wk 0) and challenge infection (wk 16) both comprised exposure to 1,000 cercariae per goat, and necropsies took place 16, 22 and 32 wk following primary infection. Clinicopathological effects were moderate in all infected groups. Egg excretion became gradually reduced following peak levels during early primary infection, and egg excretion increased only marginally following challenge infection in the primary- and challenge-infection group. Similarly, challenge infection of primary-infected goats did not result in an increase in tissue egg counts. Worm recovery and tissue egg counts in primary-infected goats remained comparable throughout the experiment, and although evidence was obtained for a delay in maturation, challenge worm establishment was comparable with challenge-control worm establishment. An anti-fecundity effect is thus an essential component of the regulatory response to both primary and challenge S. bovis infection in the goats. However, it was also shown that the intrauterine egg count is an unreliable parameter for fecundity assessments.

Two Eph receptor tyrosine kinase ligands control axon growth and may be involved in the creation of the retinotectal map in the zebrafish

The isolation and characterisation of two zebrafish Eph receptor ligand cDNAs which we have called zfEphL3 and zfEphL4 is described. These genes are expressed in the presumptive midbrain of developing embryos from 6 somites. By 24 hours L3 is expressed throughout the midbrain including the region of the presumptive tectum whereas L4 is strongly expressed in the midbrain caudal to the presumptive tectum. At later stages of development L3 is expressed in a graded fashion throughout the tectum and L4 is maintained at its posterior margin. Growth cone collapse and pathway selection assays demonstrate that both these proteins have a collapse activity for retinal ganglion cells. When faced with a choice of substrate on which to grow, temporal axons from chick retinal ganglion cells selectively avoided membranes from Cos cells transfected with L3, whereas nasal axons did not. Both temporal and nasal axons avoided membranes from Cos cells transfected with L4. The expression patterns together with the functional data suggest that although both ligands may be able to guide retinal ganglion cells axons in vitro, they have different roles in the guidance of retinotectal projections in vivo. The expression of L3 is consistent with a role in the guidance of retinal ganglion cells to their targets on the tectum whereas that of L4 suggests a role in delineating the posterior boundary of the optic tectum.

Neurological disease and encephalitis in cats experimentally infected with Borna disease virus

Barrier-bred cats were inoculated intracerebrally with either the rabbit-adapted Borna disease virus (BDV) strain V or a newly isolated feline BDV, obtained from a cat with natural staggering disease (SD). Three out of eight inoculated cats developed neurological signs and non-suppurative encephalitis; all three recovered from the acute stage of disease. Sero-conversion and the development of neutralizing antibodies occurred in all of the virus-inoculated cats. In addition, cats inoculated with feline BDV showed an early peripheral T cell response not present in cats inoculated with BDV strain V, suggesting that the feline virus exerted a more vigorous effect on the immune system. Using immunohistochemistry and a reverse transcriptase-polymerase chain reaction assay, BDV-specific antigen and nucleic acid could be demonstrated in brain samples from each cat with encephalitis, showing that incomplete viral clearance was probably responsible for the maintenance of inflammation. The successful induction of neurological signs and encephalitis in one cat infected with feline BDV, together with the detection of BDV-specific antigen and nucleic acid in the brain, provides strong evidence for the notion that BDV is the etiological agent behind feline SD.

Rectal biopsy diagnosis in horses with clinical signs of intestinal disorders: a retrospective study of 116 cases

The histology from rectal biopsy specimens taken 1980-1990 on 131 occasions from 116 horses, age 1-18 years, with clinical signs of intestinal disease was evaluated and classified retrospectively. In 40 horses, autopsy results were studied for comparison. Biopsy specimens (21 horses) and post mortem rectal tissue (9 horses) from 30 healthy horses, age 4-22 years, were used as controls. In 105 clinical cases, a biopsy was performed on only one occasion, while repeat biopsy was performed in 11 cases. Specimens showed pathological changes in 60 horses. The findings were classified into acute, chronic or chronic active simple proctitis, granulomatous enteritis, eosinophilic granulomatosis/gastroenteritis, eosinophilic proctitis, erosive/ulcerative proctitis, pseudomembranous proctitis, proctitis with vasculitis and malignant lymphoma. Mild scattered neutrophil infiltration in the lamina propria was found in controls, but neutrophils in crypt or surface epithelia were abnormal findings. Depletion or hyperplasia of goblet cells sometimes accompanied inflammation. Simple proctitis occurred in association with malignant lymphoma and various inflammatory disorders of the gastrointestinal tract apparent at autopsy. Eosinophilic granulomatosis/gastroenteritis and granulomatous enteritis were diagnosed from biopsy specimens in 6 of 12 and 4 of 9 cases, respectively, of these diseases confirmed at autopsy. Reduction of acid mucins in goblet cells was a prominent feature of eosinophilic granulomatosis. Rectal biopsy was found to be a useful adjunct for evaluation of intestinal disease in the horse.

Experimental Schistosoma bovis infection in goats: pathological consequences of praziquantel treatment

Schistosoma bovis-infected goats were treated with praziquantel (60 mg/kg) and killed for examination 1, 7 or 28 days later. Infected non-treated goats and parasite-free, treated or non-treated goats were included for comparison. The gross pathological changes seen in the infected non-treated groups were mild to moderate. The liver appeared discoloured and moderately enlarged. The intestinal lesions were most prominent in the small intestines, which showed catarrhal inflammation with numerous tiny corpuscles beneath the luminal surface. The mesenteric lymph nodes were slightly to moderately enlarged. In contrast, on macroscopical examination, the infected treated groups invariably showed pronounced liver changes and marked enlargement of the lymph nodes, whereas the lesions in the intestines were comparatively slight. Histological lesions related to dead worms were seen in the livers of all treated animals. These lesions included pronounced inflammatory cellular infiltrates, thrombophlebitis, necrosis and periportal fibrosis, still severe 4 weeks after treatment. In the intestines, the deposition of new eggs with little cellular reaction had almost completely ceased 1 week after treatment. Four weeks after treatment, only a very few egg-associated lesions were noted in the intestines. The presence of severe lesions attributable to dead worms in the liver indicates the need for caution when treating animals with high worm loads or concomitant liver disease.

Staggering disease in cats: isolation and characterization of the feline Borna disease virus

A Borna disease virus (BDV)-like agent was isolated from the central nervous system (CNS) of cats with a spontaneous non-suppurative encephalomyelitis ('staggering disease'). In contrast to the rabbit-adapted BDV strain V, which can be propagated in several primary and permanent cell cultures, the cat virus grew only in embryonic mink brain cells. Infection of adult Wistar rats with feline brain tissue material did not result in clinical disease during a period of 5 months, nor in growth of infectious virus in the brain. However, using the brain suspension of a newborn rat inoculated with feline brain tissue material, it was possible to induce typical Borna disease (BD) in four adult rats. This indicates a possible adaptation of the cat virus during passages in rats. By the use of an RT-PCR technique, BDV-specific RNA could be detected in a majority of brain samples from diseased cats. BDV-specific antigen was demonstrated in feline CNS samples both by immunohistochemistry and ELISA. However, the amount of BDV RNA and BDV antigen was less in the cats as compared to horses with BD, providing further support for the notion that a distinct feline BDV strain exists.

Use of magnetic resonance imaging in central nervous system tumors

MRI provides additional information about tumor location, extent, and margins. MRI was used in 158 patients with CNS tumors for treatment planning from 1985-89 and they were studied in a prospective manner. The most common site was cerebrum (73 pts), then extradural spinal axis (21 pts) posterior fossa (17 pts), brain stem (14 pts) and pituitary (13 pts), etc. The most common histological primary tumor was glioblastoma multiform (25 pts), then low grade astrocytoma (22 pts), anaplastic astrocytoma (14 pts), pituitary tumor (13 pts), medulloblastoma (9 pts), ependymoma (7 pts), and germ cell tumors (6 pts). Twenty-nine patients had metastasis to the brain. A majority of the patients with CNS tumors had the studies using Gadolinium-DTPA. Of the patients with CNS tumors, 120 (76%) had better information based on the MRI, which improved the treatment planning (using the three dimensional images) and field arrangement. In 89 patients (56%) the MRI was very decisive in the treatment volume and field arrangement. In 31 patients (20%) the MRI was beneficial and confirmed the treatment plan. MRI provides important additional information for radiation therapy planning.

Immunoreactivity of the central nervous system in cats with a Borna disease-like meningoencephalomyelitis (staggering disease)

The inflammatory cell composition and the expression of major histocompatibility complex (MHC) antigens in the central nervous system (CNS) of 13 cats with a spontaneous, Borna disease-like meningoencephalomyelitis (staggering disease) was investigated by immunohistochemistry with a panel of monoclonal and polyclonal antibodies. T lymphocytes were the predominating inflammatory cells within the adventitial space. CD4+ T cells were more abundant than CD8+ T cells. Scattered IgG-, IgA- and IgM-containing cells were found in the adventitial space and surrounding neuropil, often adjacent to neurons. There was a markedly increased MHC class II expression in cells morphologically resembling microglia. In several cats, Borna disease virus specific antigen was detected, but only in a few cells, mainly of macrophage character. Our findings indicate a long-standing inflammatory reaction in the CNS of cats with staggering disease, possibly triggered and sustained by a persistent viral infection.

Acquired resistance against Schistosoma bovis after single or repeated low-level primary infections in goats

Experimental Schistosoma bovis infections were studied in groups of six goats for 32 weeks. Two types of primary infections, a single exposure to 400 cercariae per goat or repeated (trickle) exposure to 200 cercariae per goat weekly for 10 weeks, were followed by a challenge infection with 2000 cercariae per goat in week 16 of the experiment. Periods of high faecal egg excretion were associated with reduced weight gain, anaemia, hypoalbuminaemia and blood eosinophilia; these changes gradually diminished with decreasing faecal egg excretion but never disappeared completely. The pathogenic effects of the trickle exposure exceeded those of the single primary exposure. After the challenge, the goats excreted few or no additional eggs and no additional clinicopathological changes were observed in the group previously exposed to a trickle infection. However, the primary single infection did not provide full protection against the effects of the challenge infection.

Tissue response of goats to single or repeated low-level doses and to a massive challenge dose of Schistosoma bovis

The inflammatory tissue response to Schistosoma bovis in the small intestine and liver of goats was studied by light microscopy 32 weeks after they had been exposed to 10 weekly ('trickle') doses of 200 cercariae or to a single dose of 400 cercariae, and 32 weeks after the same dosing schedules followed by a challenge exposure to 2000 cercariae in week 16 of the experiment, and 16 weeks after a single exposure to 2000 cercariae in week 16 (challenge control). The tissue egg counts in the small intestine were highest in the challenge control group and comparable in the other groups, and corresponded well with the numbers of inflammatory foci per histological section of gut wall. The tissue egg counts in the liver were also highest in the challenge control group, but diffuse hepatic portal fibrosis was more pronounced in the groups with a primary exposure followed by a challenge. The intestinal pathology was compatible with a smaller component of vigorous and acute inflammatory reactions to the eggs in the older than in the more recent infections. The magnitude and morphological characteristics of the inflammatory tissue response did not differ markedly between the goats exposed to the trickle infections and the single doses, and they were not substantially affected by the challenge infection.