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Biomedical subjects

B Swennen

Publications and source records attributed to B Swennen.

At least 19 recordsLinked to original sources
PubMed2006

[Vaccine prevention of Rotavirus infection].

Two new life attenuated vaccines have been granted this year a marketing authorization by European and American regulatory agencies. One, Rotarix, is a monovalent vaccine derived from a human strain and takes advantage of the cross-reactivity between human Rotavirus strains. The other, RotaTeq, is a pentavalent human-bovine reassortant. These 2 vaccines have been shown to have an excellent safety profile in clinical trials and are highly effective in protecting infants against severe manifestations of Rotavirus gastroenteritis. In industrialized countries, the incidence of Rotavirus infection has not been reduced by the improvement of economic and sanitary conditions and are still associated with severe morbidity and an important economic impact. When they are administered at the same time as DTPa-VHB-IPV/Hib and Pn7V vaccines, they do not interfere with the immune response against the 7 valencies included in these vaccines. The widespread use of these vaccines should allow to control Rotavirus infections in the European context.

Humans↗
PubMed2004

[Hexavalent combined vaccination].

Since January 2004, hexavalent combined vaccines are available in Belgium. They protect children simultaneously against 6 diseases (poliomyelitis, diphtheria, tetanus, pertussis, invasive infections with Haemophilus influenzae type b and hepatitis B) and reduce the number of needed injections. Acellular pertussis vaccine is the corner-stone of the combination. Theoretically, only 5 visits and 6 injections are needed to complete the vaccination of the children. In addition to the reduction of injections and consequently a better comfort for the child, Hexavalent vaccination favours an increase of immunization coverage, alleviation of the burden of diseases evitable by vaccination, simplification of immunisation programme and diminution of their cost. However an increased surveillance of the incidence of the diseases, particularly for pertussis and invasive Haemophilus influenzae type b disease is needed. As always for a new product, pharmacovigilance has to be able to detect any severe adverse event. Parent's information must be strengthened to maintain confidence in the immunization programme. Medical practice will have to adapt to the new vaccine because it reduces individual flexibility and modifies the catch-up immunization schedule.

Child, Preschool↗
PubMed2004

[Pneumococcal conjugate vaccine in children].

Streptococcus pneumoniae is one of the major causes of severe invasive infections in young children. As purified polysaccharide are not immunogenic in infants, vaccines containing the bacterial polysaccharide conjugated to a carrier protein have been developed according to the model that has proved to be effective for Haemophilus influenzae b and group C meningococcus. A conjugate vaccine containing the 7 serotypes responsible for about 90% of the invasive infections occuring in children in the United States has been shown to have a 97% protective efficacy against infections caused by vaccine serotypes. Pneumococcal conjugate vaccines are also protective, although to a lesser extent, against otitis media caused by vaccine serotypes, but the global impact of these vaccines on the total number of otitis media remains limited. The large scale use of this vaccine has demonstrated its epidemiological impact on the burden of invasive pneumococcal disease in the age group targeted by vaccination as well as among the adult contacts of the vaccines. On the basis of these informations, the conjugate pneumococcal vaccine has been included in the recommended vaccination schedule in Belgium. However, repeated vaccine shortages as well as the high cost of the product make the implementation of this recommendation uncertain.

Child, Preschool↗
PubMed2004

[Pertussis vaccine in adolescents and adults].

Despite high immunisation rates in infancy, Bordetella pertussis is still circulating in industrialised countries, causing severe infections in infants too young to be vaccinated, as well as an important number of long lasting cough episodes in older children, adolescents and young adults. The limited duration of the protection resulting from vaccination in the 2 first years of life is probably responsible for the insufficient control of the disease. The development of acellular pertussis vaccines has allowed immunisation of school age children, and an adult formulation is now available. The indications of this vaccine will be discussed.

Adolescent↗
PubMed2002

[Conjugated vaccines].

Conjugate vaccines extend the vaccinal prevention for children to more diseases. Conjugating the capsular polysaccharide to a carrier protein transforms a T-independent antigen in a T-dependent, allowing protection of the children (before 2 years of age) against Haemophilus influenzae type b, meningococcal C and pneumococcal infections. This article reviews the 3 conjugate vaccines and their results with focus on some questions: antigens interference in the immunological response, serological subrogate for protection, herd immunity and replacement of circulating serotypes.

B-Lymphocytes↗
PubMed2002

[Conjugate vaccines].

Conjugate vaccines extend the vaccinal prevention for children to more diseases. Conjugating the capsular polysaccharide to a carrier protein transforms a T-independent antigen in a T-dependent, allowing protection of the children (before 2 years of age) against Haemophilus influenzae type b, meningococcal C and pneumococcal infections. This article reviews the 3 conjugate vaccines and their results with focus on some questions: antigens interference in the immunological response, serological subrogate for protection, herd immunity and replacement of circulating serotypes.

Adult↗
PubMed2001

Analysis of factors influencing vaccine uptake: perspectives from Belgium.

METHODS AND OBJECTIVES: To estimate the infant vaccination coverage in Belgium, a random cluster sample according to the expanded program on immunization (EPI) cluster sampling technique was performed in 1999 in the Flemish (Flanders) and French (Wallonia) speaking community of Belgium. The objective was to document the infant vaccination coverage retrospectively in 18-24-month-old children. In addition, the study offered the opportunity to assess some factors influencing vaccine uptake in infants. RESULTS: In the Flemish community infant vaccination coverage could not be associated with any of the socio-demographic factors, with two exceptions: the province (county) and the hepatitis B (HepB) vaccination. The main reason for not complying with the vaccination schedule was mainly carelessness on either parent's or physician's side. In the French speaking community parents feel mostly themselves responsible for the non-vaccination or incomplete vaccination of their child, except for pertussis. For all vaccines, the attitude of the physician is mentioned as being very influential in the decision to vaccinate a child. Most of the socio-demographic factors showed no association with the infant vaccination coverage. CONCLUSION: The surveys in Flanders and Wallonia stress the importance of having information made available, and underline the role parents as well as physicians (and nurses) play in the infant immunization coverage.

Belgium↗
PubMed2001

Oral poliomyelitis vaccine: time to change?

For 3 decades, vaccination against poliomyelitis has rested mainly on the use of the oral attenuated vaccine (OPV). In countries where wild type poliomyelitis has been successfully controlled by OPV, the rare cases of poliomyelitis that can still be identified occur in vaccinees or their contacts and are caused by vaccine related strains. Over years, data indicating that the inactivated vaccine (IPV) also has the potential to control poliomyelitis and that there are no known risks associated with the use of this vaccine have accumulated. The reasons for changes in vaccine policy in industrialised countries and the situation of the global effort of poliomyelitis immunisation are described. Some of the issues and challenges for the future are reviewed.

Health Policy↗
PubMed2000

Epidemiological survey of workers exposed to inorganic germanium compounds.

OBJECTIVES: To assess occupational exposure to inorganic germanium (Ge) in workers from a producing plant, and to assess the health of these workers, with a special focus on respiratory, kidney, and liver functions. METHODS: Cross sectional study of 75 workers exposed to Ge and 79 matched referents. Exposure was characterised by measuring air and urine concentrations of the element during a typical working week, and health was assessed by a questionnaire, clinical examination, lung function testing, chest radiography, and clinical chemistry in serum and urine, including high and low molecular weight urinary proteins. RESULTS: Airborne concentrations of Ge (inhalable fraction) ranged from 0.03 to 300 micrograms/m, which was reflected by increased urinary excretion of Ge (0.12-200 micrograms/g creatinine, after the shift at the end of the working week). Lung, liver, and haematological variables were not significantly different between referents and workers exposed to Ge. A slightly higher urinary concentration of high molecular weight proteins (albumin and transferrin) was found in workers exposed to Ge, possibly reflecting subclinical glomerular changes. No relation was found between the intensity or duration of exposure and the urinary concentration of albumin. No difference between referents and workers exposed to Ge was found for other renal variables. CONCLUSIONS: Measurement of urinary Ge can detect occupational exposure to inorganic Ge and its compounds. It is prudent to recommend the monitoring of renal variables in workers exposed to Ge.

Adult↗
PubMed1994

Acute and subacute inhalation toxicity of germanium dioxide in rats.

Two acute (4 hr) and one subacute (4 wk) inhalation toxicity studies on germanium dioxide (purity > or = 99%, mean particle size 1.7-2.6 microns) were conducted in young adult Wistar rats. In the acute studies, exposure of two groups of five rats of each sex to maximum attainable concentrations of either 3.10 g amorphous or 1.42 g hexagonal germanium dioxide/m3 for 4 hr was not lethal. In the subacute study, four groups of five rats of each sex were exposed to 0, 16, 72 and 309 mg hexagonal germanium dioxide/m3 for 6 hr/day, 5 days/wk during 4 wk. Two additional groups of 5 rats per sex, exposed either to 0 or to 309 mg/m3, were kept for a 33-day post-exposure period. At the end of the treatment period, changes were observed only in rats of the high concentration group: these changes were decreased body weight gain (both sexes), decreases in haematocrit (females) and thrombocyte count (both sexes), and increases in neutrophil count (both sexes) and white blood cell count (females). On clinical chemistry evaluation, decreased fasting blood glucose (females), decreased total protein concentration (both sexes), increased plasma alanine aminotransferase and aspartate aminotransferase activities (females), increased plasma urea nitrogen (males) and increased plasma bilirubin level (females) were observed. In addition, urinary volume was elevated, and urine density and pH were lowered in both sexes. Relative weights of kidneys, spleen, heart and lungs were higher than in controls. Microscopic examination revealed effects on renal tubular epithelium. Effects on growth, kidneys, and liver were still present at the end of the 33-day recovery period. It was concluded that the 4-hr LC50 value of amorphous germanium dioxide was greater than 3.10 g/m3 and that of the hexagonal form greater than 1.42 g/m3. The no-adverse-effect-level in the 4-wk study using hexagonal germanium dioxide was 72 mg/m3.

Administration, Inhalation↗
PubMed1994

Biological monitoring of workers exposed to cobalt metal, salt, oxides, and hard metal dust.

OBJECTIVE: The aim was to examine the relation between environmental and biological (blood and urine) indices of exposure to different chemical forms of cobalt. METHODS: A cross sectional study was undertaken in workers exposed to cobalt metal, oxides, and salts in a refinery and to a mixture of cobalt and tungsten carbide in a hard metal producing plant. RESULTS AND CONCLUSION: Although biological monitoring of workers exposed to cobalt oxides showed higher blood and urine concentrations than in non-exposed subjects, these indices poorly reflected the recent exposure level. By contrast, when exposure was to soluble cobalt compounds (metal, salts, and hard metals), the measurement of urine or blood cobalt at the end of the workweek could be recommended for the assessment of recent exposure. An eight hour exposure to 20 or 50 micrograms/m3 of a soluble form of cobalt would lead to an average concentration in a postshift urine sample collected at the end of the workweek of 18.2 or 32.4 micrograms of cobalt/g creatinine, respectively.

Adult↗
PubMed1993

The epidemiology of iodine-deficiency disorders in relation to goitrogenic factors and thyroid-stimulating-hormone regulation.

In children aged 5-7 y from goiter-endemic areas in Ubangi, Zaire, and Ntcheu, Malawi, mean serum thyroxin (T4) concentrations were 53 +/- 49 vs 81 +/- 33 nmol/L (P < 0.05), and thyroid-stimulating hormone (TSH) values were 24.3 +/- 9.6 vs 4.5 +/- 3.3 mU/L respectively (P < 0.01); mean urinary iodine concentrations were 0.14 +/- 0.02 vs 0.09 +/- 0.02 mumol/L, and mean thiocyanate concentrations were 0.33 +/- 0.05 vs 0.17 +/- 0.05 nmol/L, respectively (P < 0.05). Mean serum selenium concentrations were 0.343 +/- 0.176 mumol/L in Ubangi and 0.437 +/- 0.178 mumol/L in Ntcheu (P < 0.05). In two groups of 11 adolescent girls from Ubangi, the mean values for excretion of urinary iodine were 1.31 +/- 0.14 and 0.58 +/- 0.17 mumol/L (P < 0.05) after a meal of cassava or a control meal of rice, respectively. In euthyroid subjects from Ubangi, mean serum TSH for a given serum T4 was approximately twice as high for children aged < 15 y than for those aged 16-25 y. The high frequency of myxedematous cretins observed in Ubangi very probably result from both severe iodine and selenium deficiency together with thiocyanate overload.

Adolescent↗
PubMed1993

Epidemiological survey of workers exposed to cobalt oxides, cobalt salts, and cobalt metal.

Several organs (lung, skin, thyroid, heart, bone marrow) are potential targets of cobalt (Co). Whereas there is no doubt that inhalation of Co alone may cause bronchial asthma, its role in the occurrence of hard metal disease is still controversial because most cases were reported in workers exposed not only to Co but also to other substances such as tungsten carbide, titanium carbide, iron, silica and diamond. To assess whether exposure to pure Co dust (metal, oxides, or salts) may lead to adverse health effects a cross sectional study was carried out among 82 workers in a Co refinery. The results were compared with those in a sex and age matched control group. The Co group had been exposed for 8.0 years on average (range 0.3-39.4). The geometric mean time weighted average exposure assessed with personal samplers (n = 82) was about 125 micrograms/m3 and 25% of the values were higher than 500 micrograms/m3. The concentrations of Co in blood and in urine after the shift were significantly correlated with those in air. Concentration of Co in urine increased during the workweek. A slight interference with thyroid metabolism (decreased T3, T4, and increased TSH), a slight reduction of some erythropoietic variables (red blood cells, haemoglobin, packed cell volume) and increased white cell count were found in the exposed workers. The exposed workers complained more often of dyspnoea and wheezing and had significantly more skin lesions (eczema, erythema) than control workers. Within the exposed group a dose-effect relation was found between the reduction of the forced expiratory volume in one second/vital capacity and the intensity of current exposure to Co assessed by the measurement of Co in air or in urine. The prevalence of dyspnoea was related to the dustiness of the workplace as reflected by statistically significant logistic regression between this symptom and the current levels of Co in air and in urine. No difference between lung volumes, ventilatory performances, carbon monoxide diffusing capacity, and serum myocardial creatine kinase and procollagen III peptide was found between the Co and control groups and no lung abnormalities were detected on the chest radiographs in both groups. The results suggest that exposure to high airborne concentrations of Co alone is not sufficient to cause pulmonary fibrosis. This finding is compatible with experimental studies indicating that interaction of other airborne pollutants with Co particles play a part in the pathogenesis of parenchymal lung lesions.

Adult↗
PubMed1989

[The Communauté française' eradication plan for measles, mumps and rubella].

The combined vaccine against measles, mumps and rubella provides an efficient tool for the elimination of these three diseases in a community. In the French Community of Belgium the MMR vaccine is commercially available since 1984 and was officially included in the immunization schedule in 1985. The present coverage rate is estimated at 60% of the children under 24 month. To improve the situation, the "Conseil Consultatif Communautaire de Prévention pour la Santé" of the French Community of Belgium has proposed a programme of MMR immunization promotion based on a coordinated mobilization of the various structures involved i.e. MCH organization, school medicine, general practitioners, pediatricians, Faculties of medicine and Health Administration. The programme has been adopted by the political authority and has started on February 1st 1989.

Belgium↗
PubMedDate not supplied

Iodine deficiency, other trace elements, and goitrogenic factors in the etiopathogeny of iodine deficiency disorders (IDD).

Severe goiter, cretinism, and the other iodine deficiency disorders (IDD) have their main cause in the lack of availability of iodine from the soil linked to a severe limitation of food exchanges. Apart from the degrees of severity of the iodine deficiency, the frequencies and symptomatologies of cretinism and the other IDD are influenced by other goitrogenic factors and trace elements. Thiocyanate overload originating from consumption of poorly detoxified cassava is such that this goitrogenic factor aggravates a relative or a severe iodine deficiency. Very recently, a severe selenium deficiency has also been associated with IDD in the human population, whereas in animals, it has been proven to play a role in thyroid function either through a thyroidal or extrathyroidal mechanism. The former involves oxidative damages mediated by free radicals, whereas the latter implies an inhibition of the deiodinase responsible for the utilization of T4 into T3. One concludes that: 1. Goiter has a multifactorial origin; 2. IDD are an important public health problem; and 3. IDD are a good model to study the effects of other trace elements whose actions in many human metabolisms have been somewhat underestimated.

Adolescent↗
PubMedDate not supplied

Safety and immunogenicity of an Haemophilus influenzae type b-tetanus toxoid conjugate (PRP-T) and diphtheria-tetanus-pertussis (DTP) combination vaccine administered in a dual-chamber syringe to infants in Belgium and Chile.

To document any unexpected differences in the immune response between study populations and to evaluate immunogenicity and safety of a simplified presentation (dual-chamber syringe) of an Haemophilus influenzae type b-tetanus toxoid conjugate (PRP-T) and diphtheria-tetanus-pertussis (DTP) combination vaccine, a multicentre, randomized, comparative study was conducted in Belgium and Chile. A total of 537 healthy infants, 270 in Chile and 267 in Belgium, received PRP-T and DTP vaccines combined in a dual-chamber syringe (D-Ch group, DTP/PRP-T, reconstituted by pressing the plunger of the syringe immediately before injection, n = 239) or combined in a single-chamber syringe (C-In group, DTP@PRP-T, reconstituted immediately before injection, n = 61) or in separate injections (S-In group, DTP + PRP-T, simultaneously injected at separate sites, n = 237) at 3, 4, and 5 months of age. Serum samples were collected before vaccination and at 6 months of age. In the D-Ch group, the incidence of adverse events was comparable to administration of DTP vaccine alone. Higher rates of local and systemic reactions were observed in the Chilean population, possibly due to differences in surveillance practice. The immune response to each vaccine component compared well to that of the separate administration of PRP-T and DTP vaccines, except for higher post-immunization anti-PRP geometric mean titre (GMT) values after separate injections (25.6 micrograms mL-1) than after combined injection with the dual-chamber syringe (17.6 micrograms mL-1) (p = 0.001). An unexpected 'syringe' effect was seen: a greater post-immunization anti-PRP GMT was observed in the D-Ch group (17.6 micrograms mL-1) than in the C-In group (7.7 micrograms mL-1) (p = 0.0001). Whereas pre-immunization GMTs of some antibodies were significantly lower in Chilean than in Belgian infants, the post-immunization GMTs of Chilean infants were two to three times greater for all of the antibodies studied (p < 0.005). Differences in reactogenicity and in the immune response between the study populations or the different vaccine presentations were striking, but are probably of no clinical relevance. The convenient dual-chamber syringe presentation of DTP and PRP-T vaccines is safe and highly immunogenic.

Antibodies, Bacterial↗
PubMedDate not supplied

Recommendations for the use of the 23-valent polysaccharide pneumococcal vaccine in adults: a Belgian consensus report.

A multidisciplinary expert panel, appointed by the High Council for Public Health, evaluated the scientific evidence on which the recommendations for the appropriate use of the pneumococcal vaccine was based and reviewed the studies that became available since previous reports. The conclusions of the working group, presented in this manuscript, resulted in an update of the Belgian recommendations for pneumococcal vaccination.

Adult↗