Multimorbidity healthcare expenditure in Belgium: a 4-year analysis (COMORB study)

BACKGROUND

The complex management of health needs in multimorbid patients, alongside limited cost data, presents challenges in developing cost-effective patient-care pathways. We estimated the costs of managing 171 dyads and 969 triads in Belgium, taking into account the influence of morbidity interactions on costs.

METHODS

We followed a retrospective longitudinal study design, using the linked Belgian Health Interview Survey 2018 and the administrative claim database 2017-2020 hosted by the Intermutualistic Agency. We included people aged 15 and older, who had complete profiles (N = 9753). Applying a system costing perspective, the average annual direct cost per person per dyad/triad was presented in 2022 Euro and comprised mainly direct medical costs. We developed mixed models to analyse the impact of single chronic conditions, dyads and triads on healthcare costs, considering two-/three-way interactions within dyads/triads, key cost determinants and clustering at the household level.

RESULTS

People with multimorbidity constituted nearly half of the study population and their total healthcare cost constituted around three quarters of the healthcare cost of the study population. The most common dyad, arthropathies + dorsopathies, with a 14% prevalence rate, accounted for 11% of the total national health expenditure. The most frequent triad, arthropathies + dorsopathies + hypertension, with a 5% prevalence rate, contributed 5%. The average annual direct costs per person with dyad and triad were €3515 (95% CI 3093-3937) and €4592 (95% CI 3920-5264), respectively. Dyads and triads associated with cancer, diabetes, chronic fatigue, and genitourinary problems incurred the highest costs. In most cases, the cost associated with multimorbidity was lower or not substantially different from the combined cost of the same conditions observed in separate patients.

CONCLUSION

Prevalent morbidity combinations, rather than high-cost ones, made a greater contribution to total national health expenditure. Our study contributes to the sparse evidence on this topic globally and in Europe, with the aim of improving cost-effective care for patients with diverse needs.

Development and operationalization of a data framework to assess quality of integrated diabetes care in the fragmented data landscape of Belgium

Background

To assess the quality of integrated diabetes care, we should be able to follow the patient throughout the care path, monitor his/her care process and link them to his/her health outcomes, while simultaneously link this information to the primary care system and its performance on the structure and organization related quality indicators. However the development process of such a data framework is challenging, even in period of increasing and improving health data storage and management. This study aims to develop an integrated multi-level data framework for quality of diabetes care and to operationalize this framework in the fragmented Belgium health care and data landscape.

Methods

Based on document reviews, iterative working group discussions and expert consultations, theoretical approaches and quality indicators were identified and assessed. After mapping and assessing the validity of existing health information systems and available data sources through expert consultations, the theoretical framework was translated in a data framework with measurable quality indicators. The construction of the data base included sampling procedures, data-collection, and several technical and privacy-related aspects of linking and accessing Belgian datasets.

Results

To address three dimensions of quality of care, we integrated the chronic care model and cascade of care approach, addressing respectively the structure related quality indicators and the process and outcome related indicators. The corresponding data framework is based on self-collected data at the primary care practice level (using the Assessment of quality of integrated care tool), and linked health insurance data with lab data at the patient level.

Conclusion

In this study, we have described the transition of a theoretical quality of care framework to a unique multilevel database, which allows assessing the quality of diabetes care, by considering the complete care continuum (process and outcomes) as well as organizational characteristics of primary care practices.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08625-8.

Workshop on the validation and regulatory acceptance of innovative 3R approaches in regulatory toxicology - Evolution versus revolution

At a joint workshop organized by RIVM and BfR, international experts from governmental institutes, regulatory agencies, industry, academia and animal welfare organizations discussed and provided recommendations for the development, validation and implementation of innovative 3R approaches in regulatory toxicology. In particular, an evolutionary improvement of our current approach of test method validation in the context of defined approaches or integrated testing strategies was discussed together with a revolutionary approach based on a comprehensive description of the physiological responses of the human body to chemical exposure and the subsequent definition of relevant and predictive in vitro, in chemico or in silico methods. A more comprehensive evaluation of biological relevance, scientific validity and regulatory purpose of new test methods and assessment strategies together with case studies that provide practical experience with new approaches were discussed as essential steps to build up the necessary confidence to facilitate regulatory acceptance.

Repeated nipple fluid aspiration: compliance and feasibility results from a prospective multicenter study

BACKGROUND

Despite intensive surveillance, a high rate of interval malignancies is still seen in women at increased breast cancer risk. Therefore, novel screening modalities aiming at early detection remain needed. The intraductal approach offers the possibility to directly sample fluid containing cells, DNA and proteins from the mammary ductal system where, in the majority of cases, breast cancer originates. Fluid from the breast can non-invasively be obtained by oxytocin-assisted vacuum aspiration, called nipple fluid aspiration (NFA). The goal of this feasibility study was to evaluate the potential of repeated NFA, which is a critical and essential step to evaluate its possible value as a breast cancer screening method.

METHODS

In this multicenter, prospective study, we annually collected nipple fluid for up to 5 consecutive years from women at increased breast cancer risk, and performed a questionnaire-based survey regarding discomfort of the aspiration. Endpoints of the current interim analyses were the feasibility and results of 994 NFA procedures in 451 women with total follow-up of 560 person years of observation.

RESULTS

In this large group of women at increased risk of breast cancer, repetitive NFA appeared to be feasible and safe. In 66.4% of aspirated breasts, nipple fluid was successfully obtained. Independent predictive factors for successful NFA were premenopausal status, spontaneous nipple discharge, smaller breast size, bilateral oophorectomy and previous use of hormone replacement therapy or anti-hormonal treatment. The procedure was well tolerated with low discomfort. Drop-out rate was 20%, which was mainly due to repeated unsuccessful aspiration attempts. Only 1.6% of women prematurely declined further participation because of side effects.

CONCLUSIONS

Repeated NFA in women at increased breast cancer risk is feasible and safe. Therefore, NFA is a promising method to non-invasively obtain a valuable source of potential breast cancer specific biomarkers.

An indicator based 'traffic light' model to pro-actively assess the occurrence of mycotoxins in tree nuts

This paper proposes an indicator based 'traffic light' model as a tool to pro-actively assess the occurrence of mycotoxins in tree nuts. The model is built using a holistic approach and, consequently, uses indicators from inside and outside the tree nut production chain as the basic elements. Temperature and relative humidity (pre-harvest), harvest and drying, storage and transport conditions, crop variety and crop damage were selected as indicators. For these indicators, measurable sub-indicators (model parameters) and risk categories were defined. With these insights, a 'traffic light' model was proposed that indicates the possible risk of occurrence of mycotoxins with colour signals; 'red' indicates high risk, 'yellow' medium risk, and 'green' low risk. The current model is specified for aflatoxins in hazelnuts but can easily be adapted for other mycotoxins and/or tree nuts. Governmental organisations and the commercial sector may use such a model to anticipate on the potential presence of mycotoxins by proactive risk management.

Characterization and molecular epidemiology of rotavirus strains recovered in Northern Pretoria, South Africa during 2003-2006

Rotavirus infection is the most common cause of severe dehydrating gastroenteritis in infants and young children and remains a significant clinical problem worldwide. The severity and the burden of rotavirus disease could be reduced through the implementation of an effective vaccine. The aim of this study was to characterize rotavirus strains circulating in the local community as part of an ongoing hospital burden of disease study when a G1P[8] rotavirus vaccine candidate was being evaluated in the same community. From 2003 through 2006, 729 rotavirus-positive stool specimens were collected from children <5 years of age who were treated for diarrhea at Dr George Mukhari Hospital, Ga-Rankuwa, South Africa. Molecular characterization of the strains was performed by polyacrylamide gel electrophoresis and genotyping of the VP4 and VP7 alleles using well-established seminested multiplex reverse-transcription polymerase chain reaction methods. In 2003, 62% of strains exhibited the short rotavirus electropherotype, and the most common rotavirus strain was G2P[4]. In subsequent years, predominant rotavirus strains included G1P[8] and G1P[6] in 2004, G3P[8] and G3P[6] in 2005, and G1P[8] in 2006. For the 4 years of the study, rotavirus strains with P[6] genotype were detected in 25% of all rotavirus-positive specimens. In addition, unusual G12P[6] and G8 strains were detected at a low frequency. These results reflect the diversity of rotavirus strains circulating in South African communities.

Energy Transduction by Anaerobic Ferric Iron Respiration in Thiobacillus ferrooxidans

Formate-grown cells of the obligately chemolithoautotrophic acidophile Thiobacillus ferrooxidans were capable of formate- and elemental sulfur-dependent reduction of ferric iron under anaerobic conditions. Under aerobic conditions, both oxygen and ferric iron could be simultaneously used as electron acceptors. To investigate whether anaerobic ferric iron respiration by T. ferrooxidans is an energy-transducing process, uptake of amino acids was studied. Glycine uptake by starved cells did not occur in the absence of an electron donor, neither under aerobic conditions nor under anaerobic conditions. Uptake of glycine could be driven by formate- and ferrous iron-dependent oxygen uptake. Under anaerobic conditions, ferric iron respiration with the electron donors formate and elemental sulfur could energize glycine uptake. Glycine uptake was inhibited by the uncoupler 2,4-dinitrophenol. The results indicate that anaerobic ferric iron respiration can contribute to the energy budget of T. ferrooxidans.

A Combined Immunofluorescence-DNA-Fluorescence Staining Technique for Enumeration of Thiobacillus ferrooxidans in a Population of Acidophilic Bacteria

An antiserum raised against whole cells of Thiobacillus ferrooxidans was allowed to react with a variety of acidophilic and nonacidophilic bacteria in an enzyme-linked immunosorbent assay and an indirect immunofluorescence assay. Both experiments demonstrated that the antiserum was specific at the species level. This preparation was used to evaluate the role of T. ferrooxidans in the microbial desulfurization process. Leaching experiments were performed, and the numbers of T. ferrooxidans cells and other bacteria were estimated by using a combined immunofluorescence-DNA-fluorescence staining technique that was adapted for this purpose. Nonsterile coal samples inoculated with T. ferrooxidans yielded high concentrations of soluble iron after 16 days. After this period, however, T. ferrooxidans cells could no longer be detected by the immunofluorescence assay, whereas the DNA-fluorescence staining procedure demonstrated a large number of microorganisms on the coal particles. These results indicate that T. ferrooxidans is removed by competition with different acidophilic microorganisms that were originally present on the coal.

Floating filters, a novel technique for isolation and enumeration of fastidious, acidophilic, iron-oxidizing, autotrophic bacteria

Nuclepore polycarbonate filters floating on a liquid, FeSO(4)-containing medium (pH 1.6) were used to isolate a moderately thermophilic bacterium from a pyrite-oxidizing enrichment culture. The isolate failed to grow on any of the conventional solid media tried. To test the general applicability of the method, the enumeration of a fastidious acidophilic organism, Thiobacillus ferrooxidans, was carried out and the results compared with those obtained with other filters, solid media, and the most probable number technique. T. ferrooxidans showed better viability on the floating polycarbonate filters and grew in a much shorter time (4 to 5 days) than with the other techniques.

Oxygen and carbon dioxide mass transfer and the aerobic, autotrophic cultivation of moderate and extreme thermophiles: a case study related to the microbial desulfurization of coal

Mass transfers of O(2), CO(2), and water vapor are among the key processes in the aerobic, autotrophic cultivation of moderate and extreme thermophiles. The dynamics and kinetics of these processes are, in addition to the obvious microbial kinetics, of crucial importance for the industrial desulfurization of high-pyritic coal by such thermophiles. To evaluate the role of the temperature on the gas mass transfer, k(L)a measurements have been used to supplement the existing published data. Oxygen mass transfer from gas (air) to liquid (5 mM H(2)SO(4) in water) phase as a function of the temperature has been studied in a laboratory-scale fermentor. At 15, 30, 45, and 70 degrees C, (k(L)a)(o) values (for oxygen) were determined under three different energy input conditions by the dynamic gassing in/out method. The (k(L)a)(o) was shown to increase under these conditions with increasing temperature, and straight lines were obtained when the logarithm of (k(L)a)(o) was plotted against the temperature. By multiplying the equilibrium concentration of O(2) in water with (k(L)a)(o) maximal, O(2) transfer capacities were calculated. It appeared that in finite of a decreased solubility of O(2) at elevated temperature in mechanically mixed fermentors the calculated transfer capacities showed only minor changes for the range between 15 and 70 degrees C. However, in an air-mixed fermentor the transfer capacity of O(2) decreased slowly but steadily.Carbon dioxide mass transfer was predicted by calculations on the basis of the data for oxygen transfer. The maximal CO(2) transfer capacity, calculated as the product of the equilibrium CO(2) concentration times (k(L)a)(c), decreased slowly as the temperature increased over the range 15-70 degrees C under all three energy input conditions. Subsequent process design calculations showed that for aerobic, autotrophic cultures, CO(2) limitation is more likely to occur than O(2) limitation.

European doctorate in biotechnology: Added value for european academia and industry

It has long been recognized that educational programs and degrees are not equivalent across Europe. Add to this the fact that Europe consists of many different cultures and languages, then it is not surprising that the free circulation of scientists and their job market in the European Union is severely restricted. This is one of several debated causes for the crisis in European biotechnology, which is in danger of succumbing to the competition of North America, Japan, and some of the developing countries. The Universities (even those tradition-ridden), the European University Association, and the European Commission are aware of the danger and plans are in preparation for sweeping organizational and cultural changes. The problem is how long will it take and how long can we afford to wait? A number of biotechnologists and scientists from several institutions and many countries decided, instead of waiting, to make a preliminary move in the right direction. With the help of the European Commission and using European Molecular Biology Organization, European Federation of Biotechnology, and the European University Rectors as references, the European Association for Higher Education in Biotechnology was founded in 1995 by representatives of universities and research institutes. It awards the additional title of European Doctor to PhD graduates showing excellence in biotechnology and/or related Life Science subjects and who are willing to fulfil a program of studies that is both international and interdisciplinary. The present article reports on the first 9 years of this adventure.

Anticipating rotavirus vaccines: epidemiology and surveillance of rotavirus in South Africa

Rotavirus infection is associated with acute infantile gastroenteritis in infants and young children globally. In South Africa, rotavirus infection has been shown to be associated with approximately one-quarter of all diarrhoeal admissions to hospital. Rotavirus infection predominantly occurs in infants less than 12 months of age (75%) and has a peak of shedding during the cooler, drier months of the year. A secondary peak during the spring has been observed. Multiple infections with rotavirus and at least one other microbial agent are common. The circulating VP7 serotypes and VP4 genotypes have been determined in various regions of South Africa and show a geographic specific distribution. A decade previously, P[8]G1 or G4 strains predominated, and P[4]G2 strains occurred in an epidemic pattern in one region. More recently, rotavirus strains with P[6] genotype have become common and novel VP7/VP4 genotype combinations are occurring across the country. G9 strains have been reported from Cape Town to Vendaland. The circulating rotavirus types observed in this study add to the knowledge of the natural history of rotavirus infection and provide the groundwork to consider future vaccine strategies.

Seroresponses to virus-like particles of human papillomavirus types 16, 18, 31, 33, and 45 in San people of Southern Africa

Virus-like particles (VLPs) of the high-risk human papillomavirus (HPV) types 16, 18, 31, 33, and 45 were used as antigen in enzyme-linked immunosorbent assay (ELISA) to determine the prevalence of serum IgG in a group of San people originally from Namibia, now residing in South Africa. The San children had low seroprevalence to all VLP types, but 26/115 (22.6%) of the children were seropositive to at least 1 VLP type. Among the adults, seroprevalence was significantly higher. The seroprevalence of antibodies in 101 San women to VLP-16 was 16.8%, VLP-18 18.8%, VLP-31 12.9%, VLP-33 17.8%, and VLP-45 22.8%. Five of the 11 men were seropositive: 2 for VLP-31, 1 for VLP-18, 1 for VLP-33, and 1 for VLP-45. Seroreactivity appeared to be type specific, except possibly to VLP-18 and -45. Of the adults, 50.5% were seropositive to at least 1 VLP type and 24.8% were seropositive to >1 VLP type. From this study, it is concluded that the San people are exposed to HPV-16, -18, -31, -33, and -45, with antibodies to VLP-45 being the most prevalent.

Seroepidemiological study of genogroup I and II calicivirus infections in South and southern Africa

Diarrhoea is associated with the daily death of between 180 and 200 children under the age of 5 years in South Africa. Until recently, many cases and outbreaks of diarrhoea were not associated with a known aetiologic agent. Previous studies using baculovirus-expressed Norwalk virus (NV) and Mexico virus (MxV) capsid antigens have shown that human calicivirus infection is common in South Africa. In this study, our surveillance was extended to different populations, as well as to four other southern African countries: Namibia, Angola, Zimbabwe, and Mozambique. More than 1,700 specimens, some involved in previous cohort studies of infectious diseases, were enrolled in the surveillance. The overall seroprevalence of antibody against NV was >90% for all cohorts except for Mozambican refugees that had 83. 8% sero-positivity. The MxV antibody prevalence was higher than NV, with >95% positivity for all cohorts, except for one in Namibia that had 81% exposure. This study is one of only a few reporting on the concurrent incidence of NV and MxV infections in a cohort study, and has determined that small round structured viruses are prevalent in the local populations of South and Southern Africa. These agents may account for a number of previously unknown or unidentified causes of diarrhoeal illness, in both adults and children, in southern Africa.

Characterization of VP6 subgroup, VP7 and VP4 genotype of rotavirus strains in Lusaka, Zambia

In a previous study, rotavirus infection was determined in young children at the University Teaching Hospital in Lusaka. In this study, selected rotavirus strains were characterized by monoclonal antibody assay to the VP6 subgroup antigen present and by hybridization analysis of the VP7 and VP4 genes carried by the virus. The majority of the strains were characterized as a VP6 subgroup II, VP7 serotype G1 strain with a long electropherotype and bearing the VP4 P8 genotype. A further four minor rotavirus strains with a long RNA electropherotype and subgroup II antigen were also observed to be circulating bearing G1 or G4 VP7 genes and the VP4 P8 genotype. Two electrophoretic strains with differing short RNA electropherotypes and subgroup I antigenicity were also present. These strains hybridized to the VP7 type G2 and VP4 P4 genotype probes.

Isolation of the tetrathionate hydrolase from Thiobacillus acidophilus

An enzyme capable of hydrolysing tetrathionate was purified from cell-free extracts of Thiobacillus acidophilus. The purified enzyme converts tetrathionate into thiosulfate, sulfur and sulfate. In addition, pentathionate could also be converted by the same enzyme. Measurement of the enzyme activity during purification is based on the absorbance of the initial intermediates formed from tetrathionate in the ultraviolet region, which have not been identified. Enzyme activity could also be measured by the scattering of insoluble sulfur in the visible region. The purified enzyme has a pH optimum of 2.5 and a temperature optimum of 65 degrees C. Enzyme activity is strongly stimulated by the presence of sulfate ions. The purified enzyme is a dimer with two identical subunits of 48 kDa. The ultraviolet-visible absorption spectra and denaturation experiments indicate the presence of an organic cofactor.

Monitoring of rotavirus infection in a paediatric hospital by RNA electrophoresis

During the spring of 1987 and the autumn of 1988, stool specimens were collected from infants and young children in the paediatric unit at H. F. Verwoerd Hospital, Pretoria, and examined for the presence of rotaviruses to assess the potential for hospital-acquired infection in the paediatric wards. Stool samples were also collected from children admitted to the hospital for causes unrelated to gastro-enteritis to investigate the possible asymptomatic carriage of rotavirus in this population. Hospital-acquired rotavirus infection was determined in only 9% of cases. Very little asymptomatic carriage of the virus was identified. Electrophoretic analysis of the rotavirus strains showed that the majority of the infections (20 of 42) were associated with a particular strain with a long RNA profile, while 7 minor strains co-circulated (5 with a long electrophoretype and 2 with a short one). An apparent small outbreak of nosocomial infection with a single strain was observed to occur in one of the paediatric wards during the spring and early summer.

Hepatitis B viral markers in Bushmen at Schmidtsdrift, South Africa: baseline studies for immunisation

In an effort to control hepatitis B virus (HBV), the prevalence rates of the virus need to be ascertained in different regions or populations. As a baseline for a hepatitis B immunisation programme, the seroprevalence of HBV markers was determined in 400 San Bushmen from a community who were translocated from Northern Namibia to South Africa. HBsAg was detected in 6.8% while 57.0% showed one or more markers of HBV infection. The balance of the population (43.0%) showed no evidence of previous exposure to HBV. The HBV exposure rate of 57.0% is intermediate to high with reference to internationally reported figures and protection of seronegative individuals through immunisation is recommended. Individuals without possible natural immunity against HBV such as those with anti-HBc or anti-HBs as a sole marker may provide insight into the circulation of HBV mutants in this community, since these sole markers could be seroconversion in response to a mutant HBV strain.

Sero-prevalence to hepatitis B and C virus infection in refugees from Mozambique in southern Africa

Serological markers for evidence of past exposure to hepatitis B virus (HBV) and hepatitis C virus (HCV) were investigated in a cohort of refugees from Mozambique. Serological markers for past exposure to HBV were detected in 56% of the population and, in addition, 13.2% carried the HBV surface antigen. Anti-HCV antibodies could be confirmed in 3.2% of the population and occurred mostly in the older individuals. Only one anti-HCV antibody positive individual was positive for HBsAg. Immunity to rubellavirus had reached 85% by 11 years of age.

Serologic markers for hepatitis B virus and hepatitis A virus in Bushmen in West Caprivi, Namibia

A community based sero-epidemiological study was undertaken to determine the age specific prevalence rates of hepatitis A virus (HAV) and hepatitis B virus (HBV) infection in a band of Bushmen in the West Caprivi, Namibia. All children tested and all but two of the adults tested showed the presence of anti-HAV antibodies. Nineteen individuals (18%) were positive for HBsAg and 65 (61%) individuals had serologic evidence of past exposure to HBV infection.

Prevalence of antibodies to rubella, herpes simplex 2 and cytomegalovirus in pregnant women and in neonates at Ga-Rankuwa

Blood samples were collected from 917 women attending the Obstetrics and Gynaecology Department at Ga-Rankuwa Hospital during a one year period. Each woman presented with an unfavourable outcome to pregnancy. Blood was also obtained from 99 newborn babies who were jaundiced, or who died within a few days of birth or who showed gross congenital abnormalities. IgM antibodies to cytomegalovirus (CMV), Herpes simplex virus type 2 (HSV-2) and rubella virus were determined by commercial ELISA. CMV was found to be the most prevalent infection in both groups of women (19.2 pc) and in the babies (24.2 pc) indicating the importance of this virus in intra-uterine infection in this community. Rubella and HSV-2 infection were identified in the population sample but seemed to play a much less significant role than CMV.

Low prevalence of human T lymphotropic virus type I in !Kung San in Bushmanland, Namibia

Antibodies to human immunodeficiency virus 1 (HIV-1) and human T lymphotropic virus type 1 (HTLV-I) have been identified in various population groups living in southern and central Africa. Sera from 291 !Kung Bushmen in Bushmanland, Namibia were examined for the presence of antibodies to HIV-1 and HIV-2 and to HTLV-I. Initial screening for HIV-1/2 by two enzyme-linked immunosorbent assays (ELISAs) revealed evidence of past exposure in four individuals. However, no HIV-1/2 infection could be confirmed by a particle agglutination assay, a recombinant ELISA, or by Western blot for HIV-1 and HIV-2. Indeterminate Western blot profiles (with a p55 for each and either a p25 or p18 band) existed for all four HIV-1-reactive sera. Eight sera were reactive in the HTLV-I ELISA, although only five were positive on a second ELISA. Only three of the five HTLV-I-reactive sera could be confirmed by Western blot.

Comparison of two rapid enzyme immunoassays with standard enzyme immunoassay and latex agglutination for the detection of human rotavirus in stools

We evaluated the performance of six commercially available immunoassays for their ability to detect rotaviruses in stool specimens. Four of the assays were enzyme-linked immunosorbent assays (ELISA), including two rapid enzyme immunoassays (Testpack, Abbott Laboratories, Chicago and Pinpoint, Cambridge Biomedical, UK), and the remaining two were latex agglutination tests. A total of 100 specimens from children with gastroenteritis were tested with the commercial immunoassays and compared with electron microscopy (EM) and polyacrylamide gel electrophoresis (PAGE) as reference tests for the detection of rotavirus. Discordant results were further evaluated by a standard blocking ELISA. The rapid EIAs were found to be highly sensitive (100% for the Testpack and 97% for the Pinpoint) and more sensitive than the other immunoassays tested. High specificity was also recorded with both rapid EIAs (96% and 100% for Testpack and Pinpoint, respectively). The rapid EIA tests were easy to perform, required no specialized equipment, and could yield a result in less than 15 min. The results show that each of the commercial assays evaluated could accurately detect rotavirus in the stools of children with gastroenteritis, although the suitability of choice of assay will ultimately depend upon the requirements of the individual laboratory.

Electrophoretic typing of nosocomial rotavirus infection in a general paediatric unit showing the continual introduction of community strains

During 1989 stool specimens from hospitalised children with gastroenteritis at Ga-Rankuwa Hospital in South Africa were examined for the presence of rotaviruses. Overall 16% of the children were positive for rotavirus. However, 43% of the rotavirus positive patients were infected in the hospital. Further characterisation of the rotavirus strains was performed by electrophoresis of the RNA genome and hybridisation analysis of the VP7 and VP4 genes present. The strains associated with nosocomial infection were similar to those strains acquired in the community. The majority of the strains, both community- or hospital-acquired, were associated with a serotype 1 strain with a long electrophoretype and bearing the Wa-like VP4 gene. Three minor rotavirus strains with a long electrophoretype were also observed to be circulating bearing serotype 1 or 4 VP7 genes and the Wa-like VP4 gene. Interestingly, a serotype 4 strain bearing the M37-like VP4 gene was identified to occur almost exclusively in neonates although the gene was associated with diarrhoea in these cases. Two strains with differing short RNA electrophoretypes were also observed, members of which hybridised to VP7 serotype 2 and VP4 DS-1 type probes.

Purification and partial characterization of a thermostable trithionate hydrolase from the acidophilic sulphur oxidizer Thiobacillus acidophilus

Cell-free extracts of Thiobacillus acidophilus catalysed the quantitative conversion of trithionate (S3O6(2-) to thiosulphate and sulphate. A continuous assay for quantification of experimental results was based on the difference in absorbance between trithionate and thiosulphate at 220 nm. Trithionate hydrolase was purified to near homogeneity from cell-free extracts of T. acidophilus. The molecular masses of the native enzyme and the subunit were 99 kDa (gel filtration) and 34 kDa (SDS/PAGE). The purified enzyme has a pH optimum of 3.5-4.5 and a temperature optimum of 70 degrees C. Enzyme activity was stimulated by sulphate. The stimulation of the enzyme activity by sulphate was half maximal at a concentration of 0.23 M. The Km for trithionate is 70 microM at 30 degrees C and 270 microM at 70 degrees C. Enzyme activity was lost after 36 days at 0 degrees C, 27 days at 70 degrees C; but after 97 days at 30 degrees C, 40% of the initial activity was still present: The enzyme activity was inhibited by mercury chloride, N-ethylmaleimide, thiosulphate and tetrathionate. Tetrathionate S4O6(2-) was not hydrolysed by trithionate hydrolase.

Further characterisation of human rotaviruses isolated from asymptomatically infected neonates in South Africa

Stool specimens were collected from healthy neonates at Ga-Rankuwa Hospital in the winters of 1984 and 1986 and tested for the presence of rotavirus infection. Asymptomatic excretion was found to occur in 25% of the newborn babies analysed. Gel electrophoresis of the rotavirus RNA genome revealed that a genomically stable strain of rotavirus was endemic in the ward at the time intervals examined. Hybridisation analysis of the VP4 and VP7 rotavirus genes, which encode the outer capsid neutralization proteins of the virus, was conducted. These results showed the presence of a serotype 4 rotavirus strain with an M37-like VP4 gene allele, which remained conserved in the nursery over the time period examined. Partial nucleotide sequences were obtained for a variable region of the VP7 gene and for the hyperdivergent region of the VP4 gene from 8 of these viruses and showed that remarkable conservation of these regions in the genes of the viruses occurred over time.

Anaerobic Growth of Thiobacillus ferrooxidans

The obligately autotrophic acidophile Thiobacillus ferrooxidans was grown on elemental sulfur in anaerobic batch cultures, using ferric iron as an electron acceptor. During anaerobic growth, ferric iron present in the growth media was quantitatively reduced to ferrous iron. The doubling time in anaerobic cultures was approximately 24 h. Anaerobic growth did not occur in the absence of elemental sulfur or ferric iron. During growth, a linear relationship existed between the concentration of ferrous iron accumulated in the cultures and the cell density. The results suggest that ferric iron may be an important electron acceptor for the oxidation of sulfur compounds in acidic environments.

The molecular epidemiology of rotavirus infection in Ga-Rankuwa, southern Africa

Rotaviruses were detected in 32.8 pc (96/292) of stool specimens collected from infants and young children with gastroenteritis attending the rehydration unit at Ga-Rankuwa Hospital between January and December 1989. A seasonal distribution was observed with an increase in numbers shedding the virus during the colder months of the year. Based on variations in the migration pattern of the RNA genome segments when passed through polyacrylamide gels, seven different RNA electrophoretypes were identified; 82 pc of the patients had virus with long patterns and 17 pc with short patterns. A mixed infection was observed in one case with both a long and a short virus. A single dominant long electrophoretype persisted throughout the 12 month study period, whereas the other minor types co-circulated at varying intervals.

Human T-lymphotropic virus type I-associated myelopathy. A case report

Tropical spastic paraparesis (TSP) has been reported from various parts of the world for several decades. Recently reports have emerged from Japan and also countries in tropical zones associating endemic TSP with abnormally high titres of antibodies to human T-lymphotropic virus type I (HTLV-I). Data indicate that this lymphotropic retrovirus is neuropathogenic, either by direct invasion or via immunopathological mechanisms. A South African man is described who met the diagnostic criteria of TSP. Both serum and cerebrospinal fluid were antibody-positive for HTLV-I. It is possible that HTLV-I infection may be implicated in the 'myelopathies of undetermined cause' that form a substantial subgroup of spinal cord disease occurring in black South Africans.

Growth of Thiobacillus ferrooxidans on Formic Acid

A variety of acidophilic microorganisms were shown to be capable of oxidizing formate. These included Thiobacillus ferrooxidans ATCC 21834, which, however, could not grow on formate in normal batch cultures. However, the organism could be grown on formate when the substrate supply was growth limiting, e.g., in formate-limited chemostat cultures. The cell densities achieved by the use of the latter cultivation method were higher than cell densities reported for growth of T. ferrooxidans on ferrous iron or reduced sulfur compounds. Inhibition of formate oxidation by cell suspensions, but not cell extracts, of formate-grown T. ferrooxidans occurred at formate concentrations above 100 μM. This observation explains the inability of the organism to grow on formate in batch cultures. Cells grown in formate-limited chemostat cultures retained the ability to oxidize ferrous iron at high rates. Ribulose 1,5-bisphosphate carboxylase activities in cell extracts indicated that T. ferrooxidans employs the Calvin cycle for carbon assimilation during growth on formate. Oxidation of formate by cell extracts was NAD(P) independent.

Varying antibody response in dental health care workers vaccinated with recombinant hepatitis B vaccine

Significance of the antibody levels to hepatitis B surface antigen (anti-HBs) as an indicator of protective immunity has recently been stressed. The aim of this study was to quantitatively evaluate the immune response in dental personnel vaccinated with Engerix B recombinant DNA vaccine (SK&F). The vaccine was administered to staff at the MEDUNSA Dental Hospital with either no immunity to HBV or with anti-HBs levels below 10 mIU/ml (n = 43). Anti-HBs was determined by AUSAB (Abbott) one, six and seven months after the start of vaccination and expressed in mIU/ml by comparison with a WHO standard. Only 29 per cent of seronegative subjects developed anti-HBs titers of greater than or equal to 10 mIU/ml after the first dose, while 94 per cent reached this level after the third dose. Results indicated that individuals with naturally acquired low anti-HBs were not protected against HBV before vaccination. All subjects previously vaccinated, but with anti-HBs below 10 mIU/ml, reacted with an anamnestic response and were therefore still immune. The overall antibody response after the third inoculation was good, with 95 per cent (41/43) acquiring a protective anti-HBs titer. However 6/43 were low responders with peak anti-HBs levels between 10-100 mIU/ml. Post-vaccination testing and quantitation of the immune response seems strongly advisable, both to identify non- and low responders and to give each vaccine a guideline to further vaccination.

Mixotrophic and Autotrophic Growth of Thiobacillus acidophilus on Glucose and Thiosulfate

Mixotrophic growth of the facultatively autotrophic acidophile Thiobacillus acidophilus on mixtures of glucose and thiosulfate or tetrathionate was studied in substrate-limited chemostat cultures. Growth yields in mixotrophic cultures were higher than the sum of the heterotrophic and autotrophic growth yields. Pulse experiments with thiosulfate indicated that tetrathionate is an intermediate during thiosulfate oxidation by cell suspensions of T. acidophilus . From mixotrophic growth studies, the energetic value of thiosulfate and tetrathionate redox equivalents was estimated to be 50% of that of redox equivalents derived from glucose oxidation. Ribulose 1,5-bisphosphate carboxylase (RuBPCase) activities in cell extracts and rates of sulfur compound oxidation by cell suspensions increased with increasing thiosulfate/glucose ratios in the influent medium of the mixotrophic cultures. Significant RuBPCase and sulfur compound-oxidizing activities were detected in heterotrophically grown T. acidophilus . Polyhedral inclusion bodies (carboxysomes) could be observed at low frequencies in thin sections of cells grown in heterotrophic, glucose-limited chemostat cultures. Highest RuBPCase activities and carboxysome abundancy were observed in cells from autotrophic, CO 2 -limited chemostat cultures. The maximum growth rate at which thiosulfate was still completely oxidized was increased when glucose was utilized simultaneously. This, together with the fact that even during heterotrophic growth the organism exhibited significant activities of enzymes involved in autotrophic metabolism, indicates that T. acidophilus is well adapted to a mixotrophic lifestyle. In this respect, T. acidophilus may have a competitive advantage over autotrophic acidophiles with respect to the sulfur compound oxidation in environments in which organic compounds are present.