Evaluation of the performance of a lateral flow device for quantitative detection of anti-SARS-CoV-2 IgG

INTRODUCTION

The AbC-19™ lateral flow immunoassay (LFIA) performance was evaluated on plasma samples from a SARS-CoV-2 vaccination cohort, WHO international standards for anti-SARS-CoV-2 IgG (human), individuals ≥2 weeks from infection of RT-PCR confirmed SARS-CoV-2 genetic variants, as well as microorganism serology.

METHODS

Pre-vaccination to three weeks post-booster samples were collected from a cohort of 111 patients (including clinically extremely vulnerable patients) from Northern Ireland. All patients received Oxford-AstraZeneca COVID-19 vaccination for the first and second dose, and Pfizer-BioNTech for the third (first booster). WHO international standards, 15 samples from 2 variants of concern (Delta and Omicron) and cross-reactivity with plasma samples from other microorganism infections were also assessed on AbC-19™.

RESULTS

All 80 (100%) participants sampled post-booster had high positive IgG responses, compared to 38/95 (40%) participants at 6 months post-first vaccination. WHO standard results correlated with information from corresponding biological data sheets, and antibodies to all genetic variants were detected by LFIA. No cross-reactivity was found with exception of one (of five) Dengue virus samples.

CONCLUSION

These findings suggest BNT162b2 booster vaccination enhanced humoral immunity to SARS-CoV-2 from pre-booster levels, and that this antibody response was detectable by the LFIA. In combination with cross-reactivity, standards and genetic variant results would suggest LFIA may be a cost-effective measure to assess SARS-CoV-2 antibody status.

An apple a day: an outbreak of cryptosporidiosis in Norway associated with self-pressed apple juice

In the autumn of 2018, an outbreak of cryptosporidiosis affected adult employees from the same company in Western Norway. The organism was Cryptosporidium parvum, GP60 subtype IIaA14G1R1. All those infected had drunk from the same container of self-pressed apple juice. Incubation period (1 week) and clinical signs were similar among those infected, although some experienced a more prolonged duration of symptoms (up to 2-3 weeks) than others. The infections resulted after consumption from only one of 40 containers of juice and not from any of the other containers. It seems that although Cryptosporidium oocysts were detected in a sample from another container, the contamination did not affect the whole batch. This is perhaps indicative of a restricted contamination event, either from contaminated ground in the orchard, or during collection of the fruit, or during processing. Although outbreaks of food-borne cryptosporidiosis have previously been associated with consumption of contaminated apple juice, most of the more recent outbreaks of food-borne cryptosporidiosis have been associated with salad vegetables or herbs. This outbreak, the first outside USA reported to be associated with apple juice, is a timely reminder that such juice is a suitable transmission vehicle for Cryptosporidium oocysts, and that appropriate hygienic measures are essential in the production of such juice, including artisanal (non-commercial) production.

Giardia duodenalis in primates: Classification and host specificity based on phylogenetic analysis of sequence data

Giardia duodenalis colonizes the gastrointestinal tract of a wide range of hosts, including humans and other primates. It is grouped into eight different Assemblages and, beyond that, into a number of sub-Assemblages, defined ad hoc on the basis of genetic differences; these various groups are often considered to be associated with a specific restricted host range. The aim of this study was to use publicly available genotyping data to investigate the relatedness of human and non-human primate (NHP) Giardia isolates in order to evaluate the usefulness of current taxonomic classification and to assess whether there is potential for zoonotic transmission between humans and NHP. Our final data set consisted of sequence data from 165 isolates, 111 from NHP and 54 from humans. Assemblages were well defined, but sub-Assemblages across Assemblage B were not resolved. Although sub-Assemblages AI and AII were resolved, the terms were not found to capture any useful molecular or host/deme properties. In the phylogenetic tree, NHP isolates were scattered among human isolates across Assemblages A and B, and were even found in Assemblage E. We conclude that there does not appear to be significant molecular distinction between human and NHP Giardia isolates across these four molecular markers. Thus, on the basis of these markers, we cannot exclude a risk for zoonotic and anthropozoonotic transmission of Assemblages A and B isolates, irrespective of sub-Assemblage classification. We further evaluated the relative merit of the four genes used in genotyping studies. The tpi, gdh and bg genes gave relatively congruent tree topologies, but the SSU gene did not resolve Assemblages according to the current classification. Future genotyping efforts should aim for multilocus or whole-genome approaches and, in particular, use of the SSU gene as the sole marker should be avoided when possible.

Molecular identification of Neospora caninum from calf/foetal brain tissue and among oocysts recovered from faeces of naturally infected dogs in southern Ethiopia

This study sought to confirm and investigate further recently published information regarding the occurrence of Neospora caninum in cattle in Ethiopia and investigate infection in dogs, the canine definitive host, in this region. Faecal samples from 383 dogs in Hawassa, Ethiopia were examined by microscopy for Neospora-like oocysts, and positive samples then analysed by a molecular approach (DNA isolation, PCR and sequencing at the ITS1 gene). Brain tissue samples from four late term aborted foetuses, one congenitally defective calf (hind leg arthrogryposis) and placental tissue from cattle in the same area were also examined by the same molecular approach. All foetal, calf and placental tissue were associated with Neospora seropositive dams. A high prevalence of Neospora-like oocysts (11.5 μm±1.5 μm diameter) was observed in faecal samples from dogs (37 positive samples; 9.7% prevalence), and in 17 of these the identification was confirmed by PCR, giving a prevalence of confirmed infection of 4.4%. N. caninum DNA was also detected in all foetal and calf brain tissue samples. Sequencing revealed only minor differences among all PCR products, whether from oocysts or from brain tissue samples. These data provide molecular evidence of the presence of N. caninum infection in both dog and cattle in this region of Ethiopia. Moreover these findings highlight the role of dogs in maintaining and spreading the infection horizontally in the study area. The high frequency of N. caninum infection in household dogs as well as farm dogs is worthy of further investigation.

Seroprevalence of Neospora caninum and associated risk factors in intensive or semi-intensively managed dairy and breeding cattle of Ethiopia

A cross-sectional study of Neospora caninum infection was conducted in major milksheds of Ethiopia. Cattle (n=2334) from 273 farms were bled and the sera screened for antibodies against N. caninum using a commercial ELISA kit. Herd and individual animal level data were collected from farm records and a semi-structured questionnaire format. The overall animal level seroprevalence was 13.3%, while the prevalence at farm level was 39.6%. In urban and peri-urban smallholder dairy farms, the seroprevalence was 14.9%, while 12.9% and 9.8% reactors were found among commercial dairy farms and breeding cattle, respectively. At farm level, 35.7% of urban and peri-urban farms, 47.5% of the commercial farms and five of the breeding farms were found to have at least one infected animal. Purchased cows (OR: 2.3) and cows with history of maternal reproductive disorders (OR: 2.1) were associated with seropositivity at the individual animal level. Crossbred cattle (Holstein-Friesian crossed with indigenous zebu) were associated with lower risk than pure breeds (OR: 0.6). A trend of prevalence increment was observed for large herd sizes (OR: 1.8). Other factors that were associated with seropositivity were: presence of farm dogs for more than 5 years (OR: 1.9), access to farm by wild carnivores (OR: 3.1) and compromised farm hygienic status (OR: 3.4). Abortion, retention of foetal membrane and metritis were the most frequently reported clinical reproductive disorders among seropositive cattle. Together, these finding indicate that N. caninum infection is highly prevalent, widely distributed and clinically important in dairy and breeding cattle of Ethiopia. N. caninum should be considered an important infectious cause of reproductive disorders in Ethiopian cattle, and the risk factors for exposure identified here should be used as basis for implementing control measures that could limit the transmission of this infection.

European pet travel: misleading information from veterinarians and government agencies

Inter-country travel of companion animals provides an opportunity for introduction of zoonotic pathogens, such as rabies virus and Echinococcus spp. Regulations are in place to control this threat, but Schengen Agreements mean that border controls between some European countries are minimal, and animals may enter countries without any checks that they have been appropriately treated. Veterinarians provide an important source of information for people intending to travel with their pets. We conducted a telephone survey to investigate provision of correct advice to someone intending to travel with their dog to Norway. Mainland Norway is considered free of both rabies and E. multilocularis and is a signatory to the Schengen Agreement. Ten randomly selected veterinary clinics were surveyed in Austria, Belgium (Wallonia), Finland, France, Germany, Norway, Sweden, Switzerland and United Kingdom. The information provided was scored as correct, incorrect or incomplete. The information provided by secondary information sources (website or government agency), which the clinic had referred the caller to, was also assessed (correct, incorrect, incomplete). Whilst the majority of clinics provided appropriate information regarding rabies, many clinics did not provide correct information regarding treatment for E. multilocularis. Less than one in 10 clinics provided the correct information regarding both pathogens directly at the time of calling. The correct information was obtained, once taking into account secondary sources, just 62% of the time. Countrywise, most clinics in Finland provided correct advice, either directly or indirectly via referring the caller to another source, whilst the majority in Belgium, Germany and France did not. The apparent paucity of readily accessible, correct advice for owners intending to travel with their dogs is concerning. The compulsory treatment regulations are only as good as the checks that ensure compliance, and this is also lacking in some countries.

Unexpected results from large-scale cryptosporidiosis screening study in calves in Tanzania

A study was undertaken to investigate Cryptosporidium infection in crossbreed dairy calves in two districts in Tanzania. A total of 943 fecal samples from 601 dairy calves were included in the study, with calves from both smallholder dairy farms and from large-scale and medium-scale dairy farms. The modified Ziehl-Neelsen (mZN) technique was used to examine 710 samples, and 13 of these were considered to be positive for Cryptosporidium. These 13 samples considered positive by mZN, along with the remaining 233 samples, were analysed by immunofluorescent antibody test (IFAT). Of these 246 samples examined by IFAT, 15 samples, 10 of which were considered positive by mZN, were also examined by the auramine phenol technique, and 5 samples, all of which were considered positive by mZN, were analysed by PCR. The results from the IFAT, auramine phenol and PCR analyses demonstrated that none of the samples contained Cryptosporidium oocysts, indicating that, cryptosporidiosis is currently not a problem in dairy calves in these regions of Tanzania. These unexpected results are discussed with respect to other reports on cryptosporidiosis in calves that suggest that this parasite is a serious calf disease globally, and particularly in relation to studies from Tanzania. We suggest that results from studies of cattle in Tanzania, in which mZN has been used as the sole analytical method, should be treated with caution.

Effects of Preservatives on Viability of Cryptosporidium parvum Oocysts

Potassium dichromate and formalin reduced the viability of Cryptosporidium parvum oocysts as assessed by inclusion or exclusion of 4',6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI) and excystation. Some formalin-treated oocysts containing dead sporozoites excluded PI; that this fluorogenic assay relies not solely upon exclusion of PI but also upon highlighting of sporozoite nuclei by DAPI is reiterated.

Development and use of a pepsin digestion method for analysis of shellfish for Cryptosporidium oocysts and Giardia cysts

Investigation of shellfish for Cryptosporidium oocysts and Giardia cysts is of public health interest because shellfish may concentrate these pathogens in their bodies, and because shellfish are frequently eaten raw or lightly cooked. To date, the methods used for the analysis of shellfish for these parasites are based on those originally designed for water concentrates or fecal samples; the reported recovery efficiencies are frequently relatively low and the amount of sample examined is small. Here, we describe the development and use of a pepsin digestion method for analyzing shellfish samples for these parasites. The conditions of the isolation method did not affect subsequent parasite detection by immunofluorescent antibody test, and allowed examination of 3-g samples of shellfish homogenate, with recovery efficiencies from blue mussel homogenates of between 70 and 80%, and similar recoveries from horse mussel and oyster homogenates. Although exposure of the parasites to the conditions used in the technique affected their viability, as assessed by vital dyes, the maximum reduction in viability after 1-h incubation in digestion solution was 20%. In a preliminary survey of shellfish collected from the Norwegian coast, Cryptosporidium oocysts were detected in blue mussel homogenates in 6 (43%) of 14 batches and Giardia cysts in 7 (50%) of these batches. However, this relatively high occurrence, compared with other surveys, may be due to the higher recovery efficiency of the new method, and the relatively large sample size analyzed. A more comprehensive study of the occurrence of these parasites in shellfish would be of pertinence to the Norwegian shellfish industry.

Treatment-ladder and genetic characterisation of parasites in refractory giardiasis after an outbreak in Norway

OBJECTIVES

To evaluate the efficacy of a treatment ladder in metronidazole-refractory giardiasis, and to compare genetic characteristics of the parasites.

METHODS

A clinical observational study was carried out in 38 adult patients with metronidazole-refractory giardiasis, during an outbreak in Norway with more than 1200 cases. All patients were treated with albendazole in combination with metronidazole. Those who failed were treated with paromomycin. Those who failed on paromomycin were treated with quinacrine in combination with metronidazole. Giardia isolates from 17 patients were characterised by PCR and sequencing at two separate genes.

RESULTS

Metronidazole in combination with albendazole was effective in 30 (79%) out of 38 patients. Paromomycin was effective in three out of six patients. Quinacrine in combination with metronidazole was effective in 3 patients. Molecular characterisation of the Giardia isolates revealed that these parasites were identical at two different gene segments, while sequence profiles from isolates at the peak of the outbreak were more heterogenous.

CONCLUSIONS

Albendazole and quinacrine both in combination with metronidazole were effective in treating metronidazole-refractory giardiasis in this cohort. Paromomycin was less effective. Particular Giardia sub-genotypes may have been associated with the treatment-refractory giardiasis in these patients, although other undefined factors are probably also of importance.

Giardia cysts in sewage influent in Bergen, Norway 15-23 months after an extensive waterborne outbreak of giardiasis

AIMS

In autumn/winter 2004, a large outbreak of waterborne giardiasis occurred in Bergen, Norway. Over 1 year later, the concentrations and genotypes of Giardia cysts occurring in sewage influent were studied to investigate the impact of the outbreak event on Giardia infections in the community.

METHODS AND RESULTS

Sewage influent samples from four sewage treatment works (STW) serving Bergen were analysed for Giardia cysts on four occasions between 15 and 23 months after the outbreak. Cysts genotypes were investigated at one to three genes. Data from influent analysis from one of the STW before the outbreak, and from patient faecal samples analysed during the outbreak, provided baseline comparative data. Relatively high concentrations of Giardia cysts of diverse genotypes, both from Assemblages A and B, were detected at all STW.

CONCLUSIONS

Comparison of data suggests that although Giardia cyst concentrations in sewage influent returned to pre-outbreak levels within 18 months after the outbreak peak, the genetic composition of the isolates remained significantly influenced by the Assemblage B isolate associated with the outbreak.

SIGNIFICANCE AND IMPACT OF THE STUDY

Genotypes associated with an extensive outbreak of giardiasis continued to occur in Giardia infections in Bergen's population many months after the outbreak was considered to be over.

Molecular characterisation of Giardia isolates from clinical infections following a waterborne outbreak

OBJECTIVES

During autumn/winter 2004/2005 an outbreak of waterborne giardiasis occurred in Bergen, Norway. Genetic characterisation at 2 genes of Giardia duodenalis isolates from samples from the outbreak peak showed significant variations between isolates. Characterisation of further isolates from patients diagnosed in the subsequent months was conducted to determine whether isolates with particular sequences might predominate, or whether the sequence variation would continue.

METHODS

Genetic characterisation was conducted on 63 isolates from patients diagnosed in the 12 months subsequent to the outbreak peak.

RESULTS

At the beta-giardin gene and glutamate dehydrogenase gene, particular isolate sequences within Assemblage B, gradually predominated over time. These sequences had not been the most frequently identified amongst 21 isolates from the outbreak peak. Nor were they apparently associated with a particular sequence at the triose phosphate isomerase gene.

CONCLUSIONS

The predominance of particular sequences at the beta-giardin gene and glutamate dehydrogenase gene over time suggests that these sequences may be associated with enhanced transmission characteristics such as higher virulence, greater cyst environmental resistance, increased proliferation, or a combination of these factors. Alternatively greater association with clinical disease may have led to increased submission of samples with these sequences. Whether these sequences may be associated with particular symptom characteristics such as overt clinical disease, infection persistence or unresponsiveness to treatment warrants further study.

Fate of Cryptosporidium oocysts and Giardia cysts in the Norwegian aquatic environment over winter

We investigated the survival of Cryptosporidium oocysts and Giardia cysts during winter in an aquatic environment (approximate temperature measurements between 1 and 7 degrees C) in Norway, using morphology and uptake of dyes as indicators of viability. Previous research has shown that in the terrestrial environment, shear forces caused by freeze and thaw cycles probably cause the parasites to be inactivated. Such forces occurred infrequently in the aquatic environment, as freezing of the water around the parasites was not observed during the study period (although freezing of the water surface did occur). The rate of decline in viability (log(10) N (t)/N (0)) was similar in control and experimental environments for both parasites; no Cryptosporidium oocysts with viable morphology were detected after approximately 20 weeks and no Giardia cysts with apparently viable morphology could be detected after 1 month. These results suggest that infection with these parasites in Norway is not usually from transmission stages that have over-wintered in the Norwegian environment.

Occurrence of Cryptosporidium oocysts and Giardia cysts in sewage in Norway

Samples of sewage influent from 40 sewage treatment works (STW) throughout Norway were examined for Cryptosporidium oocysts and Giardia duodenalis cysts. Both parasites were detected frequently (80% of STW were Cryptosporidium positive; 93% of STW were Giardia positive) and at maximum concentrations of > 20,000 parasites/liter. The data suggest giardiasis is more widespread, and/or occurs with greater infection intensity, than cryptosporidiosis in Norway. STW serving higher person equivalents were more likely to be positive and had higher parasite concentrations. Parasite concentrations were used to estimate the proportion of contributing populations that could be clinically infected. For Cryptosporidium, the highest estimates were up to 5 per 100,000 individuals for two populations in eastern Norway. For Giardia, the highest estimate was 40 infected per 100,000 persons (approximately five times the usual national annual average) contributing to an STW in western Norway. As this population experienced a large waterborne giardiasis outbreak 6 months after sampling, it can be speculated that regular challenge with Giardia may occur here. Most Giardia isolates in sewage influent were assemblage A, although some assemblage B isolates were detected. There was substantial heterogeneity, but most samples contained isolates similar to genotype A3. Removal efficiencies at two STW with secondary treatment processes were estimated to be approximately 50% for Cryptosporidium and > 80% for Giardia. An STW with minimal treatment had negligible removal of both parasites. Many STW in Norway have minimal treatment and discharge effluent into rivers and lakes, thus, risk of contamination of water courses by Cryptosporidium and Giardia is considerable.

Occurrence of Cryptosporidium oocysts and Giardia cysts in sewage in Norway

Samples of sewage influent from 40 sewage treatment works (STW) throughout Norway were examined for Cryptosporidium oocysts and Giardia duodenalis cysts. Both parasites were detected frequently (80% of STW were Cryptosporidium positive; 93% of STW were Giardia positive) and at maximum concentrations of > 20,000 parasites/liter. The data suggest giardiasis is more widespread, and/or occurs with greater infection intensity, than cryptosporidiosis in Norway. STW serving higher person equivalents were more likely to be positive and had higher parasite concentrations. Parasite concentrations were used to estimate the proportion of contributing populations that could be clinically infected. For Cryptosporidium, the highest estimates were up to 5 per 100,000 individuals for two populations in eastern Norway. For Giardia, the highest estimate was 40 infected per 100,000 persons (approximately five times the usual national annual average) contributing to an STW in western Norway. As this population experienced a large waterborne giardiasis outbreak 6 months after sampling, it can be speculated that regular challenge with Giardia may occur here. Most Giardia isolates in sewage influent were assemblage A, although some assemblage B isolates were detected. There was substantial heterogeneity, but most samples contained isolates similar to genotype A3. Removal efficiencies at two STW with secondary treatment processes were estimated to be approximately 50% for Cryptosporidium and > 80% for Giardia. An STW with minimal treatment had negligible removal of both parasites. Many STW in Norway have minimal treatment and discharge effluent into rivers and lakes, thus, risk of contamination of water courses by Cryptosporidium and Giardia is considerable.

Cryptosporidium parvum infections in Bergen, Norway, during an extensive outbreak of waterborne giardiasis in autumn and winter 2004

During a large waterborne giardiasis outbreak in Norway, many diarrheic patients were found to have Cryptosporidium infections. Gene sequencing identified these infections as Cryptosporidium parvum infections, although they were not identical. Whether these infections were due to a simultaneous outbreak of waterborne cryptosporidiosis or reflected background levels not normally detected is discussed.

Application of genotyping during an extensive outbreak of waterborne giardiasis in Bergen, Norway, during autumn and winter 2004

During the autumn and winter of 2004 and 2005, an extensive outbreak of waterborne giardiasis occurred in Bergen, Norway. Over 1,500 patients were diagnosed with giardiasis. Analysis of water from the implicated source revealed low numbers of Giardia cysts, but the initial contamination event probably occurred up to 10 weeks previously. While sewage leakage from a residential area is now considered to be the probable source of contamination, during the episode waste from one particular septic tank was thought to be a possible source. Genotyping of cysts from the septic tank demonstrated that they were assemblage A cysts, although the sequences were not identical to any previously published sequences. For the beta-giardin gene, the closest published subgenotype was subgenotype A3; for the gdh gene, the closest published subgenotype was subgenotype A2. Genotyping of cysts from 21 patient samples revealed that they were assemblage B cysts; thus, the septic tank was unlikely to be the contamination source. Sequencing of the beta-giardin and gdh genes from patient samples and a comparison of the sequences gave complex results. For the beta-giardin gene, three isolates had sequences identical to subgenotype B3 sequences. However, other isolates had between one and four single-nucleotide polymorphisms (SNPs). For the gdh gene, none of the sequences were identical to the sequence published for subgenotype B3, and the sequences had between one and three SNPs. One isolate, which was identical to subgenotype B3 at the beta-giardin gene, was more similar to subgenotype B2 at the gdh gene. Grouping the isolates on the basis of SNPs resulted in different groups for the two genes. The results are discussed in relation to giardiasis in Norway and to other Giardia genotyping studies.

The potential for acquiring cryptosporidiosis or giardiosis from consumption of mung bean sprouts in Norway: a preliminary step-wise risk assessment

The current work evolved from a microbial survey of fruits and vegetables conducted in Norway between 1999 and 2001. This survey found that mung bean sprouts were more likely to be contaminated with Cryptosporidium and Giardia than the other produce included in the survey. To support this observation and to demonstrate to public health officials that this might be a risk warranting further attention, a simple risk assessment was initiated. Assuming that 60,000 people in Norway consume a single serving of bean sprouts per week, and contamination levels are similar to those found in the survey, it was calculated that there could be in the order of 20 cases of Giardia or Cryptosporidium infection per 100,000 population attributable to consumption of mung bean sprouts. A number of assumptions were made for the calculations, including parasite factors (e.g. viability, genotype), product factors (e.g. extent of product contamination) and host factors (e.g. composition and extent of consumer group). These assumptions and areas of uncertainty, where further data would improve the risk assessment, are highlighted throughout. Not only does the risk assessment identify new areas of research, but it also demonstrates how risk assessment can be used as a tool to try to influence public health surveillance.

'On Track' – an educational resource to support dental SHO training

This paper describes the development, implementation and evaluation of an educational resource, "On Track", designed to support dental SHOs throughout their time in post, thereby helping them gain optimum benefit from this important stage in their early postgraduate training. The need for such a resource was highlighted by a previous study undertaken by the paper's key authors with SHOs and their trainers in a UK dental school. Among several areas of change identified by both trainers and trainees were the needs to develop the SHO experience into more than an apprenticeship by improving the trainer/trainee relationship, and to encourage trainee-centred learning and self-appraisal. The key aims of "On Track" were therefore to define the outcomes of SHO training, to facilitate the relationship between SHO and educational supervisor (trainer), and to encourage the SHO in reflective learning and self-appraisal."On Track" was subject to developmental testing with both trainers and trainees to ensure that it could achieve these aims and the resultant resource is described, along with its implementation and evaluation. "On Track" met with mixed success and the reasons behind this and conclusions drawn for the introduction of any future similar resources are outlined.

Applying learning outcomes to dental education

Increasing emphasis is being placed in dentistry, as in other areas, on outcome-based education and on the specification of learning outcomes. An earlier paper by the same authors described the adaptation for dentistry of Harden's medical three-circle model to specify learning outcomes. This paper shows how learning outcomes can be applied in dental education, in particular in the areas of student selection, curriculum planning, teaching, learning and assessment.

Effects of the Norwegian winter environment on Giardia cysts and Cryptosporidium oocysts

The structural integrity of Cryptosporidium oocysts and Giardia cysts in the Norwegian winter environment was investigated. During winter 2001/2002, Cryptosporidium oocysts and Giardia cysts were placed in the upper layers of soil in different matrices contained in chambers and exposed to the Norwegian climate. Morphological characteristics and inclusion/exclusion of vital dyes were monitored and compared to refrigerated controls. Reduction in parasite numbers was recorded for all parasites, geographical locations, and matrices. Shear forces generated during freeze-thaw cycles are postulated to have disintegrated the parasites exposed to the Norwegian winter and retrospective laboratory studies support this theory. Increased dye inclusion, possibly indicative of viability loss, was also noted. The refrigerated control parasites exhibited no decline in numbers, and alteration in dye inclusion characteristics for refrigerated parasites was slower. Cryptosporidium oocysts were apparently more robust than Giardia cysts; differences between isolates were also noted. These results suggest Cryptosporidium oocysts and Giardia cysts do not persist in the Norwegian terrestrial environment over winter, and when detected, will have been excreted since the previous winter. Differences in the morphological characteristics, matrix effects, and the possible relationship of the dye data to parasite survival are discussed in relation to further studies.

The specification of learning outcomes in dentistry

Increasing emphasis is being placed in dentistry, as in other areas, on outcome-based education and on the specification of learning outcomes. This paper describes the adaptation for dentistry of the medical three circle model as described by Harden to specify learning outcomes. The model offers an effective and user-friendly format based on the three dimensions of the work of a dentist. What the dentist is able to do ('doing the right thing'), how the dentist approaches their practice ('doing the thing right'), and the dentist as a professional ('the right person doing it'). The model also facilitates curriculum and examination planning, reconciles tensions between vocational and academic education and is readily understood and accepted by students and teachers.

Occurrence of parasites on fruits and vegetables in Norway

Between August 1999 and January 2001, samples of various fruits and vegetables obtained within Norway were analyzed by published methods for parasite contamination. Neither Cyclospora oocysts nor Ascaris (or other helminth) eggs were detected on any of the samples examined for these parasites. However, of the 475 samples examined for Cryptosporidium oocysts and Giardia cysts, 29 (6%) were found to be positive. No samples were positive for both parasites. Of the 19 Cryptosporidium-positive samples. 5 (26%) were in lettuce, and 14 (74%) in mung bean sprouts. Of the 10 Giardia-positive samples, 2 (20%) were in dill, 2 (20%) in lettuce, 3 (30%) in mung bean sprouts, 1 (10%) in radish sprouts, and 2 (20%) in strawberries. Mung bean sprouts were significantly more likely to be contaminated with Cryptosporidium oocysts or Giardia cysts than the other fruits and vegetables. Concentrations of Cryptosporidium and Giardia detected were generally low (mean of approximately 3 [oo]cysts per 100 g produce). Although some of the contaminated produce was imported (the majority, if sprouted seeds are excluded), there was no association between imported produce and detection of parasites. Crvptosporidium oocysts and Giardia cysts were also detected in water samples concerned with field irrigation and production of bean sprouts within Norway. This is the first time that parasites have been detected on vegetables and fruit obtained in a highly developed. wealthy country, without there being an outbreak situation. These findings may have important implications for global food safety.

Factors affecting recovery efficiency in isolation of Cryptosporidium oocysts and Giardia cysts from vegetables for standard method development

While recently published techniques for recovering parasites from fruits and vegetables demonstrate a marked increase in efficiency and utility, there is still scope for further improvement in developing a standard method, particularly with difficult, but important, sample matrices such as bean sprouts. Herein, a number of parameters used in published techniques are investigated more closely. While sample size reduction may improve recovery efficiency because of a range of factors, it is important to keep the sample large enough for detection of low-level contamination. Age of sample is also important, and samples should be as fresh as possible. Elution procedures may contribute to losses of Giardia and should be more thoroughly investigated. Improved immunomagnetic separation techniques currently coming onto the market also have the potential to increase recovery efficiency substantially, even with difficult samples such as aged bean sprouts. However, merely increasing magnetic strength of the capturing magnet does not affect recovery efficiency, which must be reliant on a superior bead system, buffering system, or both.

Occurrence of Cryptosporidium oocysts and Giardia cysts in raw waters in Norway

AIMS

This paper reports the first investigation into the occurrence of Cryptosporidium and Giardia in Norwegian raw water sources.

METHODS

Between June 1998 and October 1999, 408 raw water samples, collected from 147 different sites across Norway, were analysed for these parasites. Analysis was based upon US EPA Method 1623.

RESULTS

In 305 samples (75%), parasites were not detected. In 55 samples (13.5%), Cryptosporidium only was detected. In 38 samples (9%), Giardia only was detected. In 10 samples (2.5%) both Cryptosporidium and Giardia were detected. Of the sites sampled, parasites were not detected at 100 (68%) of them, Cryptosporidium only was detected at 20 (13.5%). Giardia only was detected at 11 (7.5%), and both Cryptosporidium and Giardia were detected at 16 (11%). Concentrations of parasites were low; usually one cyst/oocyst detected per 10 litres of water.

CONCLUSIONS

Significant associations were demonstrated for these samples between the detection of these parasites and (a) turbidity > or =2.0 NTU, and (b) high numbers of domestic animals within the catchment area. No association between seasonality and the occurrence of these parasites could be detected. The results are discussed in relation to other studies and the potential public health implications for Norway.

Isolation of Cyclospora oocysts from fruits and vegetables using lectin-coated paramagnetic beads

Published techniques for recovering parasites from fruit and vegetables are generally inadequate, with low and variable recovery efficiencies. Herein, we describe an improved method for analyzing fruit and vegetables for Cyclospora oocysts. The technique includes washing procedures, sonication, and separation using lectin-coated paramagnetic beads. Identification is by microscopy (differential interference contrast and fluorescence). Oocyst recovery efficiencies from mushrooms, lettuce, and raspberries were approximately 12%. Recovery efficiencies from bean sprouts were approximately 4%. Although no significant difference in recovery efficiency could be detected between samples processed using the lectin-coated beads and samples processed without this procedure, distinct advantages were apparent when the lectin-coated beads were used. A considerably smaller, cleaner final volume remained for microscopy, which increases the sensitivity of the technique and reduces operator time.

Isolation and enumeration of Giardia cysts, cryptosporidium oocysts, and Ascaris eggs from fruits and vegetables

Published techniques for recovering parasites from fruit and vegetables are generally inadequate, with low and variable recovery efficiencies. Here we describe an improved methodology for analyzing fruit and vegetables for Giardia cysts, Cryptosporidium oocysts, and Ascaris eggs. The method includes washing procedures, sonication, and, for Giardia and Cryptosporidium, immunomagnetic separation. Identification is by immunofluorescence (Giardia and Cryptosporidium) or brightfield microscopy (Ascaris). Recovery efficiencies from lettuce, Chinese leaves, and strawberries were found to be approximately 67% for Giardia, 42% for Cryptosporidium, and 72% for Ascaris. Recovery efficiencies from bean sprouts tended to be more variable and lower. This could be due to material removed with the parasites during the washing procedures, which, in turn, appeared related to the age of the bean sprouts. It is therefore recommended that fruit and vegetables should be as fresh as possible when analyzed for parasites.

Effect of sample holding time on recovery of Cryptosporidium oocysts and Giardia cysts from water samples

U.S. Environmental Protection Agency methods for analysis of water for Cryptosporidium and Giardia stipulate maximum sample holding times which are not always practical to comply with. A spiking experiment indicated that holding times of up to 2 weeks had no significant effect on recovery of these parasites from 10-liter samples of raw water in plastic carboys.

Factors affecting patient radiation exposure during routine coronary angiography in a tertiary referral centre

Cardiac catheterization is carried out by an increasing number of operators from district hospitals as well as tertiary referral centres. Procedures are not standardized and are at the discretion of individual operators. The purpose of this study was to describe the pattern of patient radiation dose and screening times associated with diagnostic cardiac catheterization, and explore determinants of radiation dose to patients and staff. Data were collected from 1337 diagnostic procedures carried out in two cardiac catheterization laboratories from January to June 1998. Screening time and radiation dose measured by dose-area product (DAP) meter were recorded. Status of the operator and type of investigation were determined. 22 operators had performed at least 15 left ventriculograms with coronary angiography (total 944 procedures). The average (+/- SD) was 40 (+/- 22) per operator. Screening times for individual operators varied from 2.0 (+/- 1.3) min to 5.0 (+/- 4.3) min with no relationship between time and number of cases. Consultants and visiting physicians had longer screening times and greater patient DAP readings. In comparison with 115 cases of coronary angiography alone, left ventriculography increased DAP reading from 14.24 (+/- 11.7) Gy cm2 to 20.26 (+/- 0.47) Gy cm2 (p < 0.0001). In 106 cases of coronary artery bypass graft angiography, an aortogram (n = 53) did not add significantly to radiation dose or screening time. A right heart catheter added approximately 5 min to screening time (9.13 (+/- 0.63) min with right heart (n = 83) vs 3.96 (+/- 0.12) min without right heart (n = 1234)), but did not affect radiation dose significantly. There is a wide range of screening times and radiation doses related to diagnostic cardiac catheterization. Visiting and consultant staff use greater radiation doses. Left ventriculography adds significantly to patients' radiation exposure. Aortography does not add significantly to radiation dose in cases of graft angiography.

Severe giardiasis and cryptosporidiosis in Scotland, UK

Hospital discharge data from 1990-4 for 26 hospitals were used to estimate and compare the cost and describe the epidemiology of severe giardiasis and cryptosporidiosis in Scotland, UK. The incidence of severe cryptosporidiosis was almost double that of severe giardiasis and the median duration of hospitalization was longer for cryptosporidiosis than giardiasis. Impaired immunity was frequently listed as co-diagnosis with cryptosporidiosis and associated with extended hospitalization. Although both infections were associated with infants, the median age was lower for cryptosporidiosis (5 years compared with 30 years). Whereas hospitalization was not significantly longer for infants with cryptosporidiosis, hospitalization for this age group with giardiasis was longer (4 days compared with 3 days). Comparison with similar data for giardiasis from USA revealed various differences and similarities. These points are discussed in relation to the epidemiology of these infections and published data were used to estimate costs of hospitalization.

Detection of Cryptosporidium parvum oocysts in faeces: comparison of conventional coproscopical methods and the polymerase chain reaction

Conventional and coproscopical methods were compared with the polymerase chain reaction (PCR) for the detection of Cryptosporidium oocysts in bovine faeces. Oocysts were not detected in samples seeded with 10,000 oocysts following formol ether sedimentation and examination using auramine phenol (AP) or by immunofluorescent (IF) staining. When oocysts were concentrated using sucrose flotation the threshold of detection was 4000 oocysts per gram for both staining methods. Following salt flotation 4000 oocysts per gram could be reliably detected by AP staining but the detection limit was increased to 6000 oocysts per gram using IF staining. The recovery of oocysts was significantly less than expected for all techniques. A specific PCR coupled with immunomagnetic particle separation (IMS) of samples detected five oocysts per ml of diluted faeces, which corresponds to 80-90 oocysts per gram. Even allowing for the dilution of formed faecal samples, required for IMS, this represents an increase in sensitivity of several orders of magnitude over the conventional corpodiagnostic methods.

From asps to allegations: biological warfare in history

Biological warfare has been waged intermittently for nearly 2,500 years. The techniques of delivery and weaponization of biological warfare agents have gradually evolved from the catapulting of plague victims to the deliberate use of infected clothes, insect vectors, and specialized weapon systems. Despite advances in immunotherapy and chemotherapy, the threat of biological warfare is increasing, and military health personnel should be acquainted with this area. This paper reviews the history, often controversial, of biological warfare from the Scythian archers through the Russian offensive program in 1994.

The effect of sewage sludge treatment processes on oocysts of Cryptosporidium parvum

The effect of common sewage sludge treatment processes on oocysts of the coccidian protozoan Cryptosporidium was evaluated in laboratory simulations. The ability of primary sewage sedimentation to remove Cryptosporidium oocysts was found to be poor. Thermophilic (55 degrees C) aerobic digestion and sludge pasteurization at the same temperature were found to be effective treatments to inactivate Cryptosporidium oocysts. Approximately 10% of the oocyst population were found to be viable after 18 d exposure to mesophilic (35 degrees C) anaerobically digesting sludge. The viability of Cryptosporidium oocysts decreased within the range 20-40% in sludge-treated soil mesocosms over 30 d. The survival results obtained, however, indicated that oocysts would survive well beyond this period.

p53 expression in normal and dysplastic bronchial epithelium and in lung carcinomas

Bronchial epithelial dysplasia is thought to be a premalignant stage in the evolution of lung cancers. Using the CM-1 polyclonal antibody, we have examined the expression of the p53 protein in a larger series of bronchial dysplasias (n = 60) than hitherto investigated. The p53 protein was detected in 14% of mild, 25% of moderate and 59% of severe dysplasias; increased p53 expression correlated with the severity of dysplasia. p53-positive dysplasias had greater PCNA indices than p53-negative dysplasias. p53 expression in dysplastic tissues was compared with that in two groups of histologically normal epithelium: 14 bronchial biopsies from non-cancer patients of which all but one were negative and 32 bronchial margins from resected carcinomas, of which 17 showed infrequent solitary cells with p53-positive nuclei in predominantly basal locations scattered throughout the epithelium. These results for resection margins were confirmed by use of a second antibody, DO-1. Sixty-nine per cent of the corresponding carcinomas were p53 positive, but in 15 cases the p53 reactivity differed from resection margins. No correlation between p53 expression and any of the clinicopathological characteristics of these tumours was found. This study supports the observation that abnormal p53 expression may be an early but not obligatory event in malignant transformation in lung.

Malignant astrocytoma of the cervico-medullary junction masquerading as Guillain-Barré syndrome

Brainstem gliomas are rare primary brain tumours which most commonly occur in the midbrain and pons. Malignant gliomas and tumours at the cervico-medullary junction are particularly unusual. The diagnosis of tumours at this site is particularly difficult using computed tomographic (CT) scanning owing to artifacts around the base of the skull. Intrinsic tumours of the cervico-medullary junction may lead to a dissociated motor deficit and the onset of symptoms can be rapid. We describe a patient in whom an isolated ascending motor deficit in association with a raised cerebrospinal fluid protein and a normal CT scan led to an erroneous diagnosis of Guillain-Barré syndrome. The patient was treated on the intensive care unit for an 8-week period before further investigation demonstrated a malignant glioma of the cervico-medullary junction. We recommend confirmation of the diagnosis of polyradiculopathy by nerve conduction studies wherever possible.

Induction of folds or sutures on the walls of Cryptosporidium parvum oocysts and their importance as a diagnostic feature

The proportion of oocysts of Cryptosporidium parvum showing a fold on oocyst walls when incubated with either fluorescent monoclonal antibody or a surface-reactive fluorescent dye was increased by incubating suspensions of oocysts with dimethyl sulfoxide, sucrose, or Hanks' balanced salt solution. Further incubation of sucrose-incubated oocysts with water showed this to be a reversible phenomenon. Oocysts demonstrating this fold after incubation in dimethyl sulfoxide were of the same viability as control oocysts and followed the same excystation dynamics. Despite this fold having been previously described as a suture, we were unable to find any evidence that this pattern of fluorescence highlighted the same suture that has been described in ultrastructural studies. Furthermore, oocysts were observed in which this fold was not always continuous with the gape in the oocyst wall through which the sporozoites had emerged. We propose that this fluorescently highlighted region or fold should no longer be described as a suture and question its validity as a diagnostic feature. When environmental and other samples are being examined for the presence of C. parvum oocysts, objects of appropriate size, shape, and fluorescence which do not demonstrate a surface fold should not necessarily be excluded.

Glutathione S-transferase expression in benign and malignant ovarian tumours

Glutathione S-transferase sub-types alpha, mu and pi were assessed by immunocytochemistry in 109 biopsies of ovarian tissue, comprising malignant epithelial tissue in 86 cases and tissue of ovarian origin considered to be normal in 23. Glutathione S-transferase pi was the most prevalent, being present in all except one malignant epithelium studied and 83% of non-malignant tissue. There were no significant differences in the overall distribution of positive staining for alpha, mu and pi in the malignant and non-malignant biopsies, although the intensity of staining was greater in the malignant epithelium. Stromal staining was in general more pronounced in the malignant biopsies, and this was particularly prominent in the case of the alpha sub-type. Positive staining was seen more frequently in the less well-differentiated tumours, and a diffuse cytoplasmic pattern was the most common observation in tumours of moderate and poor differentiation. There was no significant association between survival and the presence or absence of sub-type staining of alpha and mu sub-type. For the sub-type pi, patient survival was found to correlate with the intensity of staining (on a 0-(+++) scale). Those patients showing resistance to cytotoxic chemotherapy were found to have a higher intensity of staining for GST pi than responding patients.

The Nithsdale schizophrenia surveys. XI: Relatives' expressed emotion. Stability over five years and its relation to relapse

The level of expressed emotion (EE) in 32 relationships between relatives and schizophrenic patients was assessed on three separate occasions over five years. EE was high on all three occasions in 25% of relatives, low on all three in 38%, and fluctuating in 38%; that is, in the majority of relatives (63%) the level of EE was stable over time. Three relatives who had previously shown high EE had evidence of dementia at the time of the third assessment, and showed low EE. Fourteen patients relapsed at least once over five years; patients who relapsed were evenly spread throughout those living in a home in which EE was consistently high, consistently low, or fluctuating. However, patients living in low-EE homes who did relapse did so significantly less often than those who relapsed and were living in homes in which EE was high or fluctuating. At the time of relapse, EE was not consistently high, and some patients in consistently high-EE homes did not relapse at all over five years.

In vitro excystation of Cryptosporidium parvum

Protocols for in vitro excystation of oocysts of Cryptosporidium parvum, including different chemical pre-incubation steps, were compared to examine some of the biochemical triggers involved in excystation and to define an in vitro excystation protocol of a reproducibly high efficiency. Pre-incubation steps which increased the permeability of the oocysts were found to enhance excystation dynamics and pre-treatment of oocysts with saliva was found to decrease the permeability and reduce excystation. Although excystation was maximal after incubation for 4 h, sporozoites tended to lyse over this period, and maximum sporozoite recovery occurred after 30 min. The results obtained are discussed in relation to excystation protocols adopted by different research groups and a number of recommendations are given for in vitro excystation of C. parvum oocysts.

Viability of Cryptosporidium parvum oocysts: correlation of in vitro excystation with inclusion or exclusion of fluorogenic vital dyes

A viability assay for oocysts of Cryptosporidium parvum based on the inclusion or exclusion of two fluorogenic vital dyes, 4',6-diamidino-2-phenylindole (DAPI) and propidium iodide, was developed by using several different isolates of oocysts. Correlation of this assay with viability measured by in vitro excystation was highly statistically significant, with a calculated correlation coefficient of 0.997. In this research, two similar excystation protocols were utilized, and no significant difference between excystation protocols was detected. Percent excystation of oocyst suspensions could be increased or reduced by inclusion of a preincubation treatment in either excystation protocol, and this alteration was also demonstrated in the viability assay. Oocysts which excluded both dyes would not excyst in vitro unless a further trigger was provided and were more resistant to acid or alkali treatment. The results of this research provide a reproducible, user-friendly assay which is applicable to individual oocysts and also provides a useful adjunct for identification of oocysts in water and environmental samples.

Survival of Cryptosporidium parvum oocysts under various environmental pressures

The survival of various isolates of Cryptosporidium parvum oocysts under a range of environmental pressures including freezing, desiccation, and water treatment processes and in physical environments commonly associated with oocysts such as feces and various water types was monitored. Oocyst viability was assessed by in vitro excystation and by a viability assay based on the exclusion or inclusion of two fluorogenic vital dyes. Although desiccation was found to be lethal, a small proportion of oocysts were able to withstand exposure to temperatures as low as -22 degrees C. The water treatment processes investigated did not affect the survival of oocysts when pH was corrected. However, contact with lime, ferric sulfate, or alum had a significant impact on oocyst survival if the pH was not corrected. Oocysts demonstrated longevity in all water types investigated, including seawater, and when in contact with feces were considered to develop an enhanced impermeability to small molecules which might increase the robustness of the oocysts when exposed to environmental pressures.

Haemoglobin concentrations and concomitant infections of hookworm and Trichuris trichiura in Panamanian primary schoolchildren

The blood haemoglobin concentrations and intestinal helminth infections were surveyed in 658 children aged between 6 and 12 years attending 4 primary schools in Coclé Province, Panama, in November 1987. 147 (22.3%) of the children were judged to have haemoglobin concentrations indicative of iron-deficiency anaemia. Blood haemoglobin concentrations were significantly lower in children with heavier Trichuris trichiura infections (> 5000 eggs/g) (P = 0.014), and in children with dual infections of both hookworm and T. trichiura (P = 0.005). Children with concomitant T. trichiura and hookworm infections were also significantly more likely to have blood haemoglobin levels indicative of anaemia than children who were uninfected or had single infections with either of these helminths (P < 0.005). In a longitudinal study involving 171 children selected from the original 658, blood haemoglobin concentrations were measured again in November 1988. Children who were considered to show an improvement in both hookworm and T. trichiura infections over this 12 month period showed a significantly greater increase in blood haemoglobin concentrations than children who had remained uninfected with either of these helminths throughout the study period (P < 0.05).

The Nithsdale schizophrenia surveys. X: Obstetric complications, family history and abnormal movements

Obstetric histories of 54 schizophrenic patients and 114 siblings were obtained from their mothers and scored using the Obstetric Complications Scale. There were no statistically significant difference in the proportion of schizophrenic patients (35%) and siblings (29%) who had at least one definite obstetric complication. There was no evidence that schizophrenic patients with a history of obstetric complications were less likely to have a first-degree relative with a history of psychiatric illness leading to in-patient care. Schizophrenic patients with a history of obstetric complications were more likely to have drug-induced Parkinsonism. There was a trend for tardive dyskinesia to be more common in those schizophrenic patients with no obstetric complications but a family history of schizophrenia.

The Nithsdale schizophrenia surveys. IX: Akathisia, parkinsonism, tardive dyskinesia and plasma neuroleptic levels

Of all known schizophrenics living in Nithsdale, south-west Scotland, 146 (88%) were examined for the presence of the three principal movement disorders secondary to antipsychotic medication, namely akathisia, tardive dyskinesia and Parkinsonism. Of these, 18% had akathisia, 5% pseudoakathisia, 29% tardive dyskinesia, 8% persistent tardive dyskinesia, and 27% Parkinsonism. No movement disorder was seen in 445, 36% had one and 20% had more than one movement disorder. Plasma neuroleptic levels at the time of clinical assessment were measured by the radioreceptor technique. Correlations between dose and plasma level were low; the ratio of mean plasma concentration to mean dose was greatest with fluphenazine decanoate and lowest for sulpiride. The concentration:dose ratio was higher in the elderly. There was no relationship between neuroleptic levels and akathisia, Parkinsonism or tardive dyskinesia. Additional psychotropic medication influenced neuroleptic levels. In 9% of patients receiving oral antipsychotic medication, no drug was detected in plasma.

Percutaneous inferior vena cava placement of tunneled silastic catheters for prolonged vascular access in infants

In infants and children requiring prolonged and multiple central venous catheterizations, conventional cannulation sites may become thrombosed or stenotic, making inability to gain vascular access a life-threatening problem. The technique we use for the percutaneous placement of inferior vena caval tunneled silastic catheters via the translumbar and transhepatic approaches is described. Three translumbar placements and one transhepatic placement in three children without immediate complications have been performed. We conclude that percutaneous inferior vena caval cannulation via the translumbar or transhepatic routes offers a viable alternative in these patients with difficult vascular access.