JAG consensus statements for training and certification in flexible sigmoidoscopy

Introduction

Joint Advisory Group (JAG) certification in endoscopy is awarded when trainees attain minimum competency standards for independent practice. A national evidence-based review was undertaken to update standards for training and certification in flexible sigmoidoscopy (FS).

Methods

A modified Delphi process was conducted between 2019 and 2020 with multisociety representation from experts and trainees. Following literature review and Grading of Recommendations, Assessment, Development and Evaluations appraisal, recommendation statements on FS training and certification were formulated and subjected to anonymous voting to obtain consensus. Accepted statements were peer-reviewed by national stakeholders for incorporation into the JAG FS certification pathway.

Results

In total, 41 recommendation statements were generated under the domains of: definition of competence (13), acquisition of competence (17), assessment of competence (7) and postcertification support (4). The consensus process led to revised criteria for colonoscopy certification, comprising: (A) achieving key performance indicators defined within British Society of Gastroenterology standards (ie, rectal retroversion >90%, polyp retrieval rate >90%, patient comfort <10% with moderate-severe discomfort); (B) minimum procedure count ≥175; (C) performing 15+ procedures over the preceding 3 months; (D) attendance of the JAG Basic Skills in Lower gastrointestinal Endoscopy course; (E) satisfying requirements for formative direct observation of procedural skill (DOPS) and direct observation of polypectomy skill (SMSA level 1); (F) evidence of reflective practice as documented on the JAG Endoscopy Training System reflection tool and (G) successful performance in summative DOPS.

Conclusion

The UK standards for training and certification in FS have been updated to support training, uphold standards in FS and polypectomy, and provide support to the newly independent practitioner.

JAG consensus statements for training and certification in colonoscopy

Introduction

In the UK, endoscopy certification is awarded when trainees attain minimum competency standards for independent practice. A national evidence-based review was undertaken to update and develop standards and recommendations for colonoscopy training and certification.

Methods

Under the oversight of the Joint Advisory Group (JAG), a modified Delphi process was conducted between 2019 and 2020 with multisociety expert representation. Following literature review and Grading of Recommendations, Assessment, Development and Evaluations appraisal, recommendation statements on colonoscopy training and certification were formulated and subjected to anonymous voting to obtain consensus. Accepted statements were peer reviewed by JAG and relevant stakeholders for incorporation into the updated colonoscopy certification pathway.

Results

In total, 45 recommendation statements were generated under the domains of: definition of competence (13), acquisition of competence (20), assessment of competence (8) and postcertification support (4). The consensus process led to revised criteria for colonoscopy certification, comprising: (1) achieving key performance indicators defined within British Society of Gastroenterology standards (ie, unassisted caecal intubation rate >90%, rectal retroversion >90%, polyp detection rate >15%+, polyp retrieval rate >90%, patient comfort <10% with moderate–severe discomfort); (2) minimum procedure count 280+; (3) performing 15+ procedures over the preceding 3 months; (4) attendance of the JAG Basic Skills in Colonoscopy course; (5) terminal ileal intubation rates of 60%+ in inflammatory bowel disease; (6) satisfying requirements for formative direct observation of procedure skills (DOPS) and direct observation of polypectomy skills (Size, Morphology, Site, Access (SMSA) level 2); (7) evidence of reflective practice as documented on the JAG Endoscopy Training System reflection tool; (8) successful performance in summative DOPS.

Conclusion

The UK standards for training and certification in colonoscopy have been updated, culminating in a single-stage certification process with emphasis on polypectomy competency (SMSA Level 2+). These standards are intended to support training, improve standards of colonoscopy and polypectomy, and provide support to the newly independent practitioner.

Review of 2022 WHO guidelines on the control and elimination of schistosomiasis

Schistosomiasis is a helminthiasis infecting approximately 250 million people worldwide. In 2001, the World Health Assembly (WHA) 54.19 resolution defined a new global strategy for control of schistosomiasis through preventive chemotherapy programmes. This resolution culminated in the 2006 WHO guidelines that recommended empirical treatment by mass drug administration with praziquantel, predominately to school-aged children in endemic settings at regular intervals. Since then, school-based and community-based preventive chemotherapy programmes have been scaled-up, reducing schistosomiasis-associated morbidity. Over the past 15 years, new scientific evidence-combined with a more ambitious goal of eliminating schistosomiasis and an increase in the global donated supply of praziquantel-has highlighted the need to update public health guidance worldwide. In February, 2022, WHO published new guidelines with six recommendations to update the global public health strategy against schistosomiasis, including expansion of preventive chemotherapy eligibility from the predominant group of school-aged children to all age groups (2 years and older), lowering the prevalence threshold for annual preventive chemotherapy, and increasing the frequency of treatment. This Review, written by the 2018-2022 Schistosomiasis Guidelines Development Group and its international partners, presents a summary of the new WHO guideline recommendations for schistosomiasis along with their historical context, supporting evidence, implications for public health implementation, and future research needs.

681 Increasing Representation in Surgical Careers – the First Cut Mentorship Programme for Medical Students

Background

Surgical specialties in the medical literature are described as having low workforce diversity. Classically underrepresented groups among surgeons include women, trainees from Black, Asian and Minority Ethnic (BAME) backgrounds and those possessing visible or hidden disabilities. As advocates for underserved communities, increasing the representation of these groups is vital to ensure that their values and perspectives influence the progression and practice of surgery. A mentorship programme was created to address this need and help break down the reported barriers which often deter medical students from pursuing surgical careers.

Method

A 6-month mentorship programme for students from underrepresented groups in surgery was designed and co-developed by four medical students and three university faculty members: a consultant HPB surgeon, a professor of medical education and an educational enhancement manager.

Results

30 medical students received one-to-one mentorship from consultant surgeons. All participants (mentors and mentees) were from underrepresented groups in surgery. Students were provided with exposure to the life of a surgeon, personal development, and careers advice by their mentors. Opportunities for professional development in academic, educational and management roles were also offered to go beyond the scope of the standard clinical responsibilities of surgeons. This descriptive case study offers an approach to implementing this within a large medical school.

Conclusions

The First Cut project is currently in its pilot phase. Feedback will be collected and analysed at the end of the programme for evaluation and improvement. These results will demonstrate the value of mentorship programmes to students from underrepresented groups.

Impact of a national basic skills in colonoscopy course on trainee performance: An interrupted time series analysis

BACKGROUND

The Joint Advisory Group on Gastrointestinal Endoscopy basic skills in colonoscopy (BSC) course was introduced in 2009 to improve colonoscopy training within the United Kingdom, but its impact on trainee performance is unknown.

AIM

To assess whether attendance of the BSC could improve colonoscopy performance.

METHODS

Trainees awarded colonoscopy certification between 2011-2016 were stratified into 3 groups according to pre-course procedure count (< 70, 70-140 and > 140). Study outcomes, comprising the unassisted caecal intubation rate (CIR) and the performance indicator of colonic intubation (PICI), were studied over the 50 procedures pre and post- course. Interrupted time series analyses were performed to detect step-change changes attributable to the course.

RESULTS

A total of 369 trainees with pre-course procedure counts of < 70 (n = 118), 70-140 (n = 121) and > 140 (n = 130) were included. Over the 50 pre-course procedures, significant linear improvements in CIR were found, with average increases of 4.2, 3.6 and 1.7 percentage points (pp) per 10 procedures performed in the < 70, 70-140 and > 140 groups respectively (all P < 0.001). The < 70 procedures group saw a significant step-change improvement in CIR, increasing from 46% in the last pre-course procedure, to 51% in the first procedure post-course (P = 0.005). The CIR step-change was not significant in the 70-140 (68% to 71%; P = 0.239) or > 140 (86% to 87%; P = 0.354) groups. For PICI, significant step-change improvements were seen in all three groups, with average increases of 5.6 pp (P < 0.001), 5.4 pp (P = 0.003) and 3.9 pp (P = 0.014) respectively.

CONCLUSION

Attendance of the BSC was associated with a significant step-change improvement in PICI, regardless of prior procedural experience. However, CIR data suggest that the optimal timing of course attendance appears to be at earlier stages of training (< 70 procedures).

The feasibility and effectiveness of Catch It, an innovative CBT smartphone app

BACKGROUND

The widespread use of smartphones makes effective therapies such as cognitive-behavioural therapy (CBT) potentially accessible to large numbers of people.

AIMS

This paper reports the usage data of the first trial of Catch It, a new CBT smartphone app.

METHOD

Uptake and usage rates, fidelity of user responses to CBT principles, and impact on reported negative and positive moods were assessed.

RESULTS

A relatively modest proportion of people chose to download the app. Once used, the app tended to be used more than once, and 84% of the user-generated content was consistent with the basic concepts of CBT. There were statistically significant reductions in negative mood intensity and increases in positive mood intensity.

CONCLUSIONS

Smartphone apps have potential beneficial effects in mental health through the application of basic CBT principles. More research with randomised controlled trial designs should be conducted.

DECLARATION OF INTEREST

None.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

Inner workings of thrombolites: spatial gradients of metabolic activity as revealed by metatranscriptome profiling

Microbialites are sedimentary deposits formed by the metabolic interactions of microbes and their environment. These lithifying microbial communities represent one of the oldest ecosystems on Earth, yet the molecular mechanisms underlying the function of these communities are poorly understood. In this study, we used comparative metagenomic and metatranscriptomic analyses to characterize the spatial organization of the thrombolites of Highborne Cay, The Bahamas, an actively forming microbialite system. At midday, there were differences in gene expression throughout the spatial profile of the thrombolitic mat with a high abundance of transcripts encoding genes required for photosynthesis, nitrogen fixation and exopolymeric substance production in the upper three mm of the mat. Transcripts associated with denitrification and sulfate reduction were in low abundance throughout the depth profile, suggesting these metabolisms were less active during midday. Comparative metagenomics of the Bahamian thrombolites with other known microbialite ecosystems from across the globe revealed that, despite many shared core pathways, the thrombolites represented genetically distinct communities. This study represents the first time the metatranscriptome of living microbialite has been characterized and offers a new molecular perspective on those microbial metabolisms, and their underlying genetic pathways, that influence the mechanisms of carbonate precipitation in lithifying microbial mat ecosystems.

Schistosome immunology: more questions than answers

The past 30 years have seen research on the immunology of schistosomiasis move to encompass studies of responses in naturally exposed human populations, in addition to the studies in animal model systems. While animal systems still retain an important place in research on the immunology of schistosomiasis, recent debate has centred on aspects of human immunological responses that may or may not be associated with resistance or susceptibility to infection. In this article, Paul Hagan, Patricia Ndhlovu and David Dunne take stock of the present state of knowledge and offer their views on prospects for the future.

Gentamicin-attenuated Leishmania infantum: cellular immunity production and protection of dogs against experimental canine leishmaniasis

An attenuated line of Leishmania infantum (L. infantum H-line) has been established by culturing promastigotes in vitro under gentamicin pressure. Here, we show that L. infantum H-line induced significantly higher levels of IFN-γ and lower levels of IL-10 compared with those in dogs infected with L. infantum wild type (WT). Anti-Leishmania-specific total IgG, IgG1, and IgG2 antibodies were present in the serum of all infected dogs, with levels of IgG2 subclass highest in the sera of dogs inoculated with L. infantum H-line. Relatively high levels of IgG1 were found in the sera of dogs infected with L. infantum WT. Six of seven dogs immunized intradermally (i.d.) with the attenuated line later showed a positive skin test to leishmanin, whereas the dogs infected with L. infantum WT did not. No clinical abnormalities were observed, and no parasites found in the visceral organs of the dogs inoculated intravenously (i.v.) with L. infantum H-line over 24 months post-inoculation. Dogs which had been immunized with L. infantum H-line i.d. 12 months previously were protected against challenge with L. infantum WT. These data suggest that the L. infantum H-line was safe and induced a protection which is correlated with cellular immunity in dogs.

Characterization, cloning and expression of NS3 protein gene of hepatitis C genotype 4a

Clone and express NS3 gene of the Egyptian strain ED43 of HCV genotype 4a in E. coli was studied. Gene and protein sequences of NS3 gene of the ED43 strain were first analyzed using PC/GENE program. DNA homology was 89% the homologies and that of the protein was 78.8% indicating that NS3 gene of the genotype 4a is different from those isolated from other strains. DNA of NS3 region of genotype 4a was amplified from HCV_ED43/PUC19 plasmid. The PCR product was cloned and expressed in E. coli M15 using pQE-30 vector. Fusion protein containing the peptides coded by HCV NS3 (NS3_4a) was expressed by Escherichia coli. The specific HCV antigenicity of the NS3_4a fusion protein was identified by western blotting.

Identification, cloning and expression of core protein gene of hepatitis C genotype 4a

Although Egypt has very high rates of HCV, not much is known about genotype 4a which is the most predominant genotype in Egypt. In the present study, core (C_ED43) gene of the Egyptian strain ED43 of HCV genotype 4a was first analyzed using PC/GENE program. Computer analysis of Core region of the isolate ED43 revealed that the Egyptian genotype 4a is different from those isolated from Europe and Central Africa and that it is closely related to genotype 1b. The DNA region coding for the Core was amplified from HCV_ED43/PUC19 plasmid. The PCR product was then cloned and expressed in E. coli M15 using pQE-30 vector. The expression and antigenicity of the core (Core_4a) protein in E. coli was confirmed by SDS-PAGE and western blotting, which will make it useful for developing assay systems for detecting anti-HCV antibodies and HCV antigen, respectively and which might help in the design of a vaccine against the Egyptian genotype 4a.

Towards control of schistosomiasis in sub-Saharan Africa

Approximately 80% of the 200 million people infected with schistosomiasis inhabit sub-Saharan Africa, and the annual mortality is estimated to be 280,000. Praziquantel is the drug of choice in the treatment of schistosomiasis and pregnant women may now be treated. It was agreed at the World Health Assembly in 2001 that at least 75% of school-aged children in high burden areas should be treated for schistosomiasis and soil-transmitted helminth infections by 2010 to reduce morbidity. A grant from the Bill and Melinda Gates Foundation to the Schistosomiasis Control Initiative, Imperial College of Science, Technology and Medicine, London has enabled control programmes to be initiated in Uganda, Tanzania, Zambia, Burkina Faso, Niger and Mali. Additional programmes have recently commenced in Zanzibar with a grant from the Health Foundation to The Natural History Museum, London and in Cameroon. Combination treatment for schistosomiasis, gastrointestinal helminths and filariasis reduces costs of control programmes. The EC Concerted Action Group on ‘Praziquantel: its central role in the chemotherapy of schistosome infection’ met in Yaoundé Cameroon in 2004 to discuss recent developments in laboratory and field studies. The use of standard operating procedures will enable data on drug action on schistosomes produced in different laboratories to be compared. With the ever increasing use of praziquantel there is a possibility of the development of resistance by schistosomes to the drug, hence the necessity to explore the activities of other compounds. Artemether, unlike praziquantel, is effective against immature schistosomes. The effectiveness of mirazid, an extract of myrrh, is controversial as data from different laboratories are equivocal. It is suggested that an independent body such as the World Health Organization should determine whether mirazid should be used in the treatment of schistosomiasis.

Role of the employment status and education of mothers in the prevalence of intestinal parasitic infections in Mexican rural schoolchildren

Background

Intestinal parasitic infections are a public health problem in developing countries such as Mexico. As a result, two governmental programmes have been implemented: a) "National Deworming Campaign" and b) "Opportunities" aimed at maternal care. However, both programmes are developed separately and their impact is still unknown. We independently investigated whether a variety of socio-economic factors, including maternal education and employment levels, were associated with intestinal parasite infection in rural school children.

Methods

This cross-sectional study was conducted in 12 rural communities in two Mexican states. The study sites and populations were selected on the basis of the following traits: a) presence of activities by the national administration of albendazole, b) high rates of intestinal parasitism, c) little access to medical examination, and d) a population having less than 2,500 inhabitants. A total of 507 schoolchildren (mean age 8.2 years) were recruited and 1,521 stool samples collected (3 per child). Socio-economic information was obtained by an oral questionnaire. Regression modelling was used to determine the association of socio-economic indicators and intestinal parasitism.

Results

More than half of the schoolchildren showed poliparasitism (52%) and protozoan infections (65%). The prevalence of helminth infections was higher in children from Oaxaca (53%) than in those from Sinaloa (33%) (p < 0.0001). Giardia duodenalis and Hymenolepis nana showed a high prevalence in both states. Ascaris lumbricoides, Trichuris trichiura and Entamoeba hystolitica/dispar showed low prevalence. Children from lower-income families and with unemployed and less educated mothers showed higher risk of intestinal parasitism (odds ratio (OR) 6.0, 95% confidence interval (CI) 1.6–22.6; OR 4.5, 95% CI 2.5–8.2; OR 3.3, 95% CI 1.5–7.4 respectively). Defecation in open areas was also a high risk factor for infection (OR 2.4, 95% CI 2.0–3.0).

Conclusion

Intestinal parasitism remains an important public health problem in Sinaloa (north-western Mexico) and Oaxaca (south-eastern Mexico). Lower income, defecation in open areas, employment status and a lower education level of mothers were the significant factors related to these infections. We conclude that mothers should be involved in health initiatives to control intestinal parasitism in Mexico.

Immunity in human schistosomiasis

Field studies on immunity in human schistosomiasis are expensive, labour-intensive and extremely time-consuming, requiring many years to yield even provisional results. In this review, Anthony Butterworth and Paul Hagan summarize the need for such studies, the evidence for immunity in man, the immunological factors that may govern the expression of immunity, and the implications of such work for the development of new methods of control through vaccination.

Prevalence and intensity of intestinal parasitic infections in relation to nutritional status in Mexican schoolchildren

Undernutrition and intestinal parasitic infections affect childhood development and morbidity in many developing countries. Undernutrition may increase susceptibility to parasitic infections which in turn impair the nutritional status of the host. The relationship between intestinal parasitic infections and nutritional status in 400 Mexican schoolchildren was investigated. More than half of the children in the study showed intestinal parasites and polyparasitism. The prevalence of helminth infections was significantly higher in Oaxaca than in Sinaloa (P < 0.05). Z scores for weight-for-age (WA) and height-for-age (HA) were much lower in children of Oaxaca than in Sinaloa (P < 0.001). A significantly higher Z score for weight-for-height (WH), WA, and HA were found in non-infected versus infected children (P < 0.05). Higher prevalences of intestinal infections were found in children with lower HA and WA than in normally nourished children (P < 0.05). Higher intensities of Ascaris lumbricoides and Trichuris trichiura were found in the schoolchildren of Sinaloa than in Oaxaca (P < 0.01). Negative and significant associations were found between Hymenolepis nana and T. trichiura infection (eggs per gram) and nutritional status. Intestinal parasitic infections may be regarded as main risk factors associated with poor nutritional status in Mexican schoolchildren.

Schistosomiasis control: keep taking the tablets

Despite the limited reports of praziquantel resistance, the relative success of chemotherapy-based control programmes for schistosomiasis has prompted overdue efforts to expand the use of cheap, generic, praziquantel in sub-Saharan Africa. The likely impact of such programmes on the development and spread of praziquantel resistance is uncertain, but this possibility reinforces the need for monitoring the spectrum of praziquantel sensitivity of schistosome populations and for an improved knowledge of the precise targets for the action of the drug. The search for alternatives to praziquantel and other tools for control of schistosomiasis must continue.

Schistosomiasis vaccines

While there are many challenges in vaccine development, none is greater than that of developing vaccines against large metazoan parasites such as schistosomes, the parasitic worms that are responsible for schistosomiasis. Initial optimism stemming from the identification of the first vaccine candidate antigens that gave protection in animals has been dashed by the failure, as yet, of any of the vaccine candidate antigens to enter Phase III clinical trials. Now, despite an improved understanding of the biology of the parasites and of the immune responses they stimulate in naturally exposed populations, the vaccine effort is stalled. The control effort has switched heavily in favour of the wider use of conventional chemotherapy with praziquantel, which is now affordable by all but the poorest countries. Disagreements among researchers in the schistosome field as to whether or not a vaccine is needed have not helped convince funding agencies that schistosomiasis vaccines, rather than drugs, should be a priority. With the schistosome genome projects at an advanced stage plus the power of the proteomics, perhaps it is still too early to call time on schistosome vaccine development.

Leishmania mexicana H-line attenuated under pressure of gentamicin, potentiates a Th1 response and control of cutaneous leishmaniasis in BALB/c mice

An attenuated line of Leishmania mexicana (the L. mexicana H-line) has been established by culturing in vitro under gentamicin pressure. BALB/c mice infected with the L. mexicana H-line developed a CD4(+)Th1-like response, indicated by the cytokine profile of their splenocytes stimulated by L. mexicana wild-type (WT) promastigotes. This profile is sustained after these mice are challenged with L. mexicana WT. Control mice infected with L. mexicana WT alone developed a CD4(+)Th2-like cytokine profile. In mice immunized with L. mexicana H-line and then challenged with WT-line, were eliminated when immunizing H-line parasites persisted in the skin and draining popliteal lymph nodes (PLNs). In experiments in which mice were inoculated with attenuated and WT parasites at the same time, either at the same site or on separate sides of the mouse, growth of the WT parasites was significantly contained and controlled, indicating a possible therapeutic role for the attenuated parasites.

Contrasting cellular responses in Schistosoma haematobium infected and exposed individuals from areas of high and low transmission in Zimbabwe

The study compared cytokine profiles of individuals from two areas with different transmission patterns for Schistosoma haematobium. One area was a high transmission (HT) while the other was a low transmission (LT) area for S. haematobium. Observations on cellular immune responses were made on stimulated peripheral blood mononuclear cells (PBMC), which were collected pre-treatment, then at 12 and 18 months post treatment. Stimulation was with schistosome worm and egg antigens and a mitogen, phaetohaemaglutinin (PHA). Observations were made on PBMC proliferation and the profiles of cytokine produced over a 5-day incubation period. The two distinct areas showed significant differences on both levels of proliferation and cytokine production for all the measured classes (IL-4, IL-5, IL-10 and IFN-gamma). PBMC from individuals from the LT area had high levels of proliferation but low cytokine production to both antigen stimulants while PBMC from individuals from the HT area showed low levels of proliferation but high cytokine production levels. Prior to treatment, individuals not excreting schistosome ova in the HT area had higher levels of proliferation to the stimulants, than the infected individuals. However, after treatment re-infected individuals showed high levels of proliferation. Before treatment, both infected and uninfected groups showed low and similar ratios, respectively, of IL-4:IFN-gamma, IL-5:IFN-gamma and IL-10:IFN-gamma, while IFN-gamma was high in the infected individuals. After treatment the non re-infected had higher levels of IL-4, IL-5 and IL-10, with the infected having high levels of IFN-gamma. Th1-like response dominated during infection with the Th2-like responses dominating post treatment and in uninfected individuals. The results indicated that the cytokine balance determines, in part, susceptibility or resistance to S. haematobium infection.

Leishmania mexicana and Leishmania major: attenuation of wild-type parasites and vaccination with the attenuated lines

A method for attenuation of Leishmania species by culturing in vitro under gentamicin pressure has been used successfully with Leishmania mexicana, L. major, L. infantum, and L. donovani. The attenuated lines invaded but were unable to survive within bone marrow-derived macrophages in vitro, whereas wild-type parasites survived and multiplied. The attenuated lines of L. mexicana and L. major both failed to induce cutaneous lesions in the majority of BALB/c mice over a minimum 12-week observation period after subcutaneous injection of stationary phase parasites. The attenuated line of L. mexicana retained its properties in gentamicin-free medium over 40 subcultures. The attenuated lines of L. mexicana and L. major both induced significant protection in mice against challenge with wild-type parasites.

Chemotherapy-induced, age-related changes in antischistosome antibody responses

Humoral responses directed against Schistosoma mansoni soluble egg antigen were studied in Zimbabwean children before and after treatment with either praziquantel (PZQ) or oxamniquine (OXAM). Treated children showed a significant increase in the proportion producing IgE and IgG3 and in mean levels of IgE, IgM, IgG3 six weeks post-treatment. At 18 weeks post-treatment, the proportion of treated children producing IgA, IgE, and IgG3 increased while the proportion producing IgG1 and IgG4 decreased. Mean levels of IgA, IgE, and IgG3 were higher than pre-treatment levels while levels of IgG1, IgG4 and IgM were lower. Statistical analyses showed that the magnitude of change in levels of IgE, IgM and IgG3 at 6 weeks post-treatment and of IgE, IgG3 and IgG4 at 18 weeks post-treatment was significantly greater in treated compared to untreated children, and there were no significant differences in immune responses between children treated with praziquantel and those treated with oxamniquine. The magnitude of change in IgE at 6 and 18 weeks, IgM at 6 weeks and IgG3 at 18 weeks post-treatment were significantly associated with age in treated but not in untreated children, with the change being greater in younger children. This suggests that treatment induced a change in the age-antibody relationship for these isotypes, and that the age-antibody relationship is not robust to chemotherapy. Pre-treatment infection levels were significantly associated (positive correlation) with the magnitude of change for IgE and IgG3 at 18 weeks post-treatment. Taken together, these results indicate that the age-antibody relationship observed in these children is due, at least in part, to cumulative host experience of parasite antigens and not host age alone.

The importance of models of infection in the study of disease resistance

Models currently occupy the crucial first step in the research flow for the development of new drugs and vaccines. Some animal models are better at reflecting the host-pathogen interaction in humans than others; this depends on the pathogen and its host specificity. Data gathered from what are often poorly adapted models provide a mosaic of sometimes contradictory information, yet there is little incentive to better delineate the relevance of models or to exploit recent advances to develop improved ones. This review reports on three particularly intractable human pathogens - Mycobacterium, Plasmodium and Schistosoma - and reflects that the extent to which these model systems mimic infection and protection processes in humans might not be sufficiently well defined.

Detection of the parasitic dinoflagellate Hematodinium in the Norway lobster Nephrops norvegicus by ELISA

Norway lobsters Nephrops norvegicus from the coastal waters of Scotland are seasonally infected by a parasitic dinoflagellate of the genus Hematodinium. An enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of the parasite in the haemolymph of N. norvegicus. The ELISA is simple to perform with a detection limit of 5 x 10(4) parasites ml(-1) haemolymph. The ELISA is currently being used to study the prevalence and seasonality of Hematodinium infection in N. norvegicus and other crustacean hosts.

P38 mitogen-activated protein kinase influence on the production of IL-10 in human schistosomiasis mansoni

Schistosomiasis mansoni remains a significant public health problem in many parts of the tropics and subtropics. Clinical manifestations range from the asymptomatic intestinal form through to the hepatosplenic form of the disease, a potentially lethal clinical condition in a subsection of the exposed population. In this study, we investigated the mechanisms by which interleukin (IL)-10 production could be differentially controlled in patients with the intestinal and hepatosplenic forms of the disease, as IL-10 may play a fundamental role in the development of the hepatosplenic disease state. It is reported that p38 mitogen-activated protein (MAP) kinase signalling, and in particular p38 MAPK activation, is central to IL-10 production of cells from patients with schistosomiasis. Furthermore, the difference in the levels of activated p38 MAPK and the activation transcription factor (ATF-2), may explain the difference in the amount of IL-10 produced by cells from intestinal and hepatosplenic patients. We suggest that the type of immune response triggered in patients with hepatosplenomegaly could be influenced by the levels of phosphorylated p38 MAPK.

A novel and sensitive method to monitor helminth infections by faecal sampling

The Kato-Katz technique is the method routinely used for diagnosing human schistosomiasis mansoni by estimating faecal egg burdens. To improve the sensitivity of faecal diagnosis, we established and validated a novel separation technique based upon the greater density of viable schistosome eggs relative to faecal material. Subsequently, it was used for faecal examination of 27 schistosomiasis patients in El-Sharkia, Egypt, with Kato-Katz smears as criterion standard. Low intensity infections (<100 eggs/g) were only detected by our technique. Moreover, triple Kato-Katz analysis on consecutive samples still missed 7.4% of all human patients, whereas the new method diagnosed 100% of samples correctly on second analysis. We conclude that in endemic areas many patients are being systematically missed by routine diagnosis. Moreover, the sensitivity of our method allows its use in proposed pre-clinical and clinical vaccine trials in non-human primates and humans, where reliable estimates of faecal egg counts are essential.

T cell clones from Schistosoma haematobium infected and exposed individuals lacking distinct cytokine profiles for Th1/Th2 polarisation

T cell clones were derived from peripheral blood mononuclear cells of Schistosoma haematobium infected and uninfected individuals living in an endemic area. The clones were stimulated with S. haematobium worm and egg antigens and purified protein derivative. Attempts were made to classify the T cell clones according to production of the cytokines IL-4, IL-5 and IFN-gamma. All the T cell clones derived were observed to produce cytokines used as markers for the classification of Th1/Th2 subsets. However, the 'signature' cytokines marking each subset were produced at different levels. The classification depended on the dominating cytokine type, which was having either Th0/1 or Th0/2 subsets. The results indicated that no distinct cytokine profiles for polarisation of Th1/Th2 subsets were detected in these S. haematobium infected humans. The balance in the profiles of cytokines marking each subset were related to infection and re-infection status after treatment with praziquantel. In the present study, as judged by the changes in infection status with time, the T cell responses appeared to be less stable and more dynamic, suggesting that small quantitative changes in the balance of the cytokines response could result in either susceptibility or resistant to S. haematobium infection.

The impact of repeated treatment with praziquantel of schistosomiasis in children under six years of age living in an endemic area for Schistosoma haematobium infection

Praziquantel was given every eight weeks for two years to children aged under six years of age, living in a Schistosoma haematobium endemic area. Infection with S. haematobium and haematuria were examined in urine and antibody profiles (IgA, IgE, IgM, IgG1, IgG2, IgG3, and IgG4) against S. haematobium adult worm and egg antigens were determined from sera collected before each treatment. Chemotherapy reduced infection prevalence and mean intensity from 51.8% and 110 eggs per 10 ml urine, respectively, before starting re-treatment programme to very low levels thereafter. Praziquantel is not accumulated after periodic administration in children. Immunoglobulin levels change during the course of treatment with a shift towards 'protective' mechanisms. The significant changes noted in some individuals were the drop in 'blocking' IgG2 and IgG4 whereas the 'protecting' IgA and IgG1 levels increased. The antibody profiles in the rest of the children remained generally unchanged throughout the study and no haematuria was observed after the second treatment. The removal of worms before production of large number of eggs, prevented the children from developing morbidity.

Acidic vesicles of Schistosoma mansoni

The fluorescent probe LysoTracker Red was used to examine for the presence of acidic vesicles in cercariae and schistosomula of Schistosoma mansoni. Acidic vesicles were widely distributed throughout the body of freshly transformed schistosomula and 24-h-old schistosomula but were absent from cercariae. The vesicles of freshly transformed schistosomula were undetectable after incubation with drugs that affect the functionality of acidic vesicles including monensin, ouabain, primaquine, and amiloride. In 24-h transformed schistosomula, the same effect was observed with monensin but not with ouabain, primaquine or amiloride. Praziquantel also affected the acidic vesicles of the schistosomula. We suggest that these acidic vesicles could be large lysosome-like organelles.

Cytokine responses to mitogen and Schistosoma haematobium antigens are different in children with distinct infection histories

Prevalence of Schistosoma haematobium infection in children from two neighbouring villages in Zimbabwe was 77.1% and 40.3%, respectively. The age-intensity data indicated peak intensities of infection at a lower age in the high prevalence village. This study investigated whether the difference in infection histories was reflected in a difference in cytokine profiles between children resident in these two villages. Blood samples were taken to assay for cytokine secretion 1 year after treatment for schistosomiasis. They were cultured with phytohaemagglutinin (PHA), schistosome egg antigens (SEA) or cultured without stimulant and tested for the presence of interleukin (IL)-4, IL-5, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-gamma. Blood samples from children from the low prevalence village were more likely to produce IL-4 (P < 0.0001) and produced higher levels of IFN-gamma (P < 0.02) and GM-CSF (P < 0.03) when cultured with PHA for 24 h. Residence in the high prevalence village was associated with production of IL-10 (P < 0.006) and GM-CSF (P < 0.04) in response to culture with SEA and IL-5 (P < 0.02) with PHA for 48 h. The interaction between age and village was not significant for these results; however, there was a significant interaction between age and village for IL-5 detected in blood samples cultured with PHA for 24 h (P < 0.01). These results concur with previous observations that major patterns of cytokine production can be related to immunosuppression, but also indicate an underlying pattern which reflects the importance of history of infection to the immune response.

Dissociation of interleukin-4 and interleukin-5 production following treatment for Schistosoma haematobium infection in humans

Infection with Schistosoma haematobium, the causative agent of urinary schistosomiasis is characterized by high levels of specific immunoglobulin (Ig) E and eosinophilia. The primary cytokines driving production of IgE and eosinophilia are IL-4 and IL-5, respectively. In this study, IL-4 and IL-5 production in children from a schistosome endemic area of Zimbabwe were investigated. Blood samples were taken, stimulated in vitro with either mitogen or schistosome antigens and assayed for IL-4 and IL-5 production. These samples produced either IL-4 or IL-5 but rarely both cytokines when blood was cultured in vitro for 24 or 48 h. After 72 h culture in vitro, both cytokines were detected in most samples. These data imply that while IL-4 and IL-5 are both produced by schistosome infected people, they are not necessarily coproduced.

Anti-schistosome antibody responses in children coinfected with malaria

People residing in schistosome endemic areas are often infected with other parasites. The interaction of the parasites in the host has important implications in the development of acquired immunity to schistosomiasis, and schistosome immuno-epidemiology. An analysis of specific anti-schistosome egg responses in children coinfected with schistosomiasis and malaria shows that malaria positive children produce significantly more anti-schistosome IgE and IgG3 than schistosome infected children who are negative for malaria.

Exposure, infection and immune responses to Schistosoma haematobium in young children

Behavioural, parasitological and immunological data were obtained from 48 children up to 6 years old, resident in a Schistosoma haematobium endemic area in Zimbabwe. The children averaged more than 1 contact with infective water bodies every 3 days and all showed immunological evidence of exposure (an anti-cercarial and/or anti-egg antibody response). IgM was the dominant isotype and appeared in the youngest children, followed by IgA, IgE and IgG3. However, only 38 children showed evidence of infection (an anti-egg response or eggs in urine) and only 14 were excreting eggs. The best estimates from these data are that less than 1 in 100 contacts results in infection and less than 1 in 1000 result in egg output. This suggests that there may be substantial attrition of invading cercaria even in naïve individuals.

Seeking the ghost of worms past

The mechanisms of protective immunity to parasite infections in humans are still elusive. Here, Woolhouse and Hagan discuss new evidence suggesting that the extremely slow development of acquired immunity to human schistosomes may depend on exposure to antigens from these worms after they die.

Ultrastructural localization of Sm15 and Sm25, two major tegumental adult worm antigens of Schistosoma mansoni

Sm15 and Sm25 are two of the principal tegumental antigens recognized by antibodies from mice protectively vaccinated with adult worm tegumental membranes and may therefore be potential vaccine candidate antigens. Using antibodies affinity purified from anti-tegumental membrane anti-sera, and antibodies raised against the recombinant antigens, Sm15 and Sm25 were shown to be located specifically in the tegument of adult worms being distributed throughout the syncitium but not associated with the outer membrane.

A comparison of re-infection rates with Schistosoma haematobium following chemotherapy in areas with high and low levels of infection

Two groups of children (6-15 years) from a Schistosoma haematobium endemic area were followed for 9 months after praziquantel treatment. Seventy-three children came from an area of high infection while 67 children came from an area of low infection. Pre-treatment infection prevalence in the high infection area (76.6%) was significantly higher than that in low infection area (36.3%). Levels of anti-SEA immunoglobulin (Ig)A and IgM were significantly higher and levels of IgG3 significantly lower in children from the low infection area. Nine months after treatment, infection prevalence was significantly higher in the high infection area (29.0%) (where re-infection rates were higher) than in the low infection area (12.9%). Children from the high infection area were six times more likely to get re-infected than those from the low infection area, while younger children were 30 times more likely to get re-infected than older children. These results are discussed in relation to differences in transmission and the development of acquired immunity. Pre-treatment levels of IgM and the difference between IgE and IgG4 were positively associated with re-infection in the high infection area. These results are discussed in relation to the interpretation of simple correlations between infection and some antibody levels and the inference of causal relationships between observed epidemiological and immunological patterns.

Changes in specific anti-egg antibody levels following treatment with praziquantel for Schistosoma haematobium infection in children

Fifty-seven children 6-15 years old resident in a Schistosoma haematobium endemic area in eastern Zimbabwe were treated with praziquantel at 40 mg/kg body weight. Levels of IgA, IgE, IgG1, IgG2, IgG3, IgG4, and IgM antibodies against soluble egg antigen (SEA) were assayed by ELISA before treatment and at 18 and 36 weeks following treatment. Prevalence of infection (as determined by urine egg counts) was 65% before treatment, all children were confirmed egg negative six weeks after treatment, and reinfection prevalence was 4% at 18 weeks and 21% at 36 weeks after treatment. At 18 weeks after treatment, there was a massive increase in IgG1 levels and significant increases in IgE and IgG4 levels and significant decreases in IgA and IgG2 levels. Similar patterns occurred at 36 weeks after treatment. Egg positive children showed a more marked increase in IgG1 and (for older children) a more marked decrease in IgG2 levels. There were no other effects of age or sex. IgA and IgG1 levels fell significantly between 18 and 36 weeks following treatment but not to pretreatment levels. The results show that specific anti-egg antibody responses are highly sensitive to the effects of praziquantel treatment. A possible consequence is that the susceptibility of children to infection with S. haematobium is altered by chemotherapy; this requires further investigation.