Contribution of respiratory pathogens to influenza-like illness consultations.

Influenza-like illnesses (ILIs) are caused by several respiratory pathogens. These pathogens show weak to strong seasonal activity implying seasonality in ILI consultations. In this paper, the contribution of pathogens to seasonality of ILI consultations was statistically modelled. Virological count data were first smoothed using modulation models for seasonal time series. Second, Poisson regression was used regressing ILI consultation counts on the smoothed time series. Using ratios of the estimated regression parameters, relative measures of the underreporting of pathogens were obtained. Influenza viruses A and B, parainfluenza virus and respiratory syncytial virus (RSV) significantly contributed to explain the seasonal variation in ILI consultations. We also found that RSV was the least and influenza virus A is the most underreported pathogen in Belgian laboratory surveillance. The proposed methods and results are helpful in interpreting the data of clinical and laboratory surveillance, which are the essential parts of influenza surveillance.

Hantavirus outbreak in Western Europe: reservoir host infection dynamics related to human disease patterns.

Within Europe, Puumala virus (PUUV) is the causal agent of nephropathia epidemica (NE) in humans, a zoonotic disease with increasing significance in recent years. In a region of Belgium with a historically high incidence of NE, bank voles (the PUUV reservoir hosts), were monitored for PUUV IgG antibody prevalence in nine study sites before, during, and after the highest NE outbreak recorded in Belgium in 2005. We found that the highest numbers of PUUV IgG-positive voles coincided with the peak of NE cases at the regional level, indicating that a PUUV epizootic in bank voles directly led to the NE outbreak in humans. On a local scale, PUUV infection in voles was patchy and not correlated to NE incidence before the epizootic. However, during the epizootic period PUUV infection spread in the vole populations and was significantly correlated to local NE incidence. Initially, local bank-vole numbers were positively associated with local PUUV infection risk in voles, but this was no longer the case after the homogeneous spreading of PUUV during the PUUV outbreak.

[Incidence of Neisseria gonorrhoeae infections in Belgium: trends 2000-2006]. / Incidence des infections à Neisseria gonorrhoeae en Belgique: tendances 2000-2006.

In Belgium, three registration systems collect epidemiological information on N. gonorrhoeae infections. The descriptive analysis of the data presented in this article allows describing the epidemiology of N. gonorrhoeae infections in Belgium in terms of trends in time, describing the characteristics of the patients, and providing information on resistance to antibiotics. The results on the incidence of N. gonorrhoeae infections show an important increase since the year 2000, and this increase is even more pronounced between 2005 and 2006. The majority of the patients reside in big cities, mainly in the district of Antwerp and in the Brussels-Capital region. Among the N. gonorrhoeae specimens that were sent to the reference laboratory, the proportion of specimens resistant to ciprofloxacine increases each year; this proportion reaches 61.4% in 2006. The increase in the incidence of N. gonorrhoeae infections and in antimicrobial resistance is also observed in other European countries. The increase in incidence may be partly related to the important increase of resistance to ciprofloxacine. It is very important to continue the surveillance of antimicrobial resistance, to adapt treatment in function of the recent evolutions and to inform physicians at a regular basis. The results show that homo- and bisexual men are most at risk for N. gonorrhoeae infections. The prevention campaigns for sexually transmitted infections and screening policy have to be reinforced, particularly among homo- and bisexual men.

Haemorrhagic Fever with Renal Syndrome: an analysis of the outbreaks in Belgium, France, Germany, the Netherlands and Luxembourg in 2005.

This article aims to describe the Haemorrhagic Fever with Renal Syndrome (HFRS) situation in 2005 in five neighbouring countries (Belgium, France, Germany, the Netherlands and Luxembourg) and define the most affected areas. The 2005 HFRS outbreaks in these countries were the most significant in the region since 1990, with a total of 1,114 confirmed cases. The main feature of the epidemic was the extension of the known endemic area in several of the affected countries, with the involvement of urban areas for the first time. A significant increase in the number of cases was noted for the first time in the province of Liège in Belgium and in the Jura department in France.

The relationship between blood pressure and environmental exposure to lead and cadmium in Belgium.

The question whether in the general population environmental exposure to lead and cadmium influences blood pressure after controlling for confounding factors remains debated. The environmental exposure of the Belgian population to both lead and cadmium is high as compared with other countries. The Cadmibel Cooperative Study was therefore designed to elucidate whether environmental exposure to lead and cadmium has any effect on blood pressure and renal function in the population at large. Before embarking on the large Cadmibel project, a small study was conducted. Blood pressure and the 24-hr urinary excretion of cadmium (CdU) and lead (PbU) were determined in a random 4% sample of the population of a small Belgian town. CdU averaged 0.27 micrograms/24 hr in 46 youths (mean age 14 +/- 3 years, +/- SD), increased with age, and was higher in 57 adult men (age 41 +/- 14 years), as compared with 59 adult women (age 39 +/- 14 years) (1.05 vs. 0.81 micrograms/24 hr; p less than 0.01). PbU averaged 5.8 micrograms/24 hr in youths and similarly increased with age; adult men excreted more lead than women (13.3 vs. 8.3 micrograms/24 hr; p less than 0.001). Among men, manual workers excreted more cadmium (1.4 vs. 0.8 micrograms/24 hr; p less than 0.05) but a similar amount of lead (7.0 vs. 6.9 micrograms/24 hr) as compared with office workers. In simple regression analysis, CdU was positively correlated with both systolic (r = 0.30; p less than 0.05) and diastolic (r = 0.38; p less than 0.01) blood pressure in women.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of serum zinc in a random population sample of four Belgian towns with different degrees of environmental exposure to cadmium.

This report investigated the distribution of serum zinc and the factors determining serum zinc concentration in a large random population sample. The 1977 participants (959 men and 1018 women), 20-80 years old, constituted a stratified random sample of the population of four Belgian districts, representing two areas with low and two with high environmental exposure to cadmium. For each exposure level, a rural and an urban area were selected. The serum concentration of zinc, frequently used as an index for zinc status in human subjects, was higher in men (13.1 mumole/L, range 6.5-23.0 mumole/L) than in women (12.6 mumole/L, range 6.3-23.2 mumole/L). In men, 20% of the variance of serum zinc was explained by age (linear and squared term, R = 0.29), diurnal variation (r = 0.29), and total cholesterol (r = 0.16). After adjustment for these covariates, a negative relationship was observed between serum zinc and both blood (r = -0.10) and urinary cadmium (r = -0.14). In women, 11% of the variance could be explained by age (linear and squared term, R = 0.15), diurnal variation in serum zinc (r = 0.27), creatinine clearance (r = -0.11), log gamma-glutamyltranspeptidase (r = 0.08), cholesterol (r = 0.07), contraceptive pill intake (r = -0.07), and log serum ferritin (r = 0.06). Before and after adjustment for significant covariates, serum zinc was, on average, lowest in the two districts where the body burden of cadmium, as assessed by urinary cadmium excretion, was highest. These results were not altered when subjects exposed to heavy metals at work were excluded from analysis.

Health effects of environmental exposure to cadmium: objectives, design and organization of the Cadmibel Study: a cross-sectional morbidity study carried out in Belgium from 1985 to 1989.

Cadmium is a cumulative environmental pollutant. For the general population mainly exposed by the oral route and through tobacco smoke inhalation, the kidney is the critical organ. Belgium is the principal producer of cadmium in Europe, and certain areas of the country are polluted by cadmium mainly because of past emissions from nonferrous industries. Preliminary studies carried out in one polluted area have suggested that environmental pollution might lead to an increased uptake of cadmium by the human body and possibly to health effects. Thus, a large-scale morbidity study has been initiated to assess the validity of this hypothesis. The present paper describes the protocol of this study. Its main objectives are to determine to what extent environmental exposure to cadmium resulting from industrial emissions may lead to accumulation of the metal in the human organism; to establish whether or not environmental exposure may induce renal changes and/or influence blood pressure; and to assess the acceptable internal dose of cadmium for the general population. The study design takes advantage of the fact that biological indicators of exposure, body burden, and early nephrotoxic effects of cadmium are available, which increase the likelihood of detecting a cause-effect relationship.

The association between blood pressure, calcium and other divalent cations: a population study.

This report investigated the associations between blood pressure and the levels of various divalent cations in blood and urine in the population at large. The 1,982 participants (963 men and 1019 women; mean age 48 years) constituted a stratified random sample of the population of 4 Belgian districts. Systolic/diastolic pressure averaged 133/78 mmHg in men, and 128/76 mmHg in women. Serum total calcium (2.37 mmol/l), serum magnesium (1.00 mmol/l) and blood cadmium (10.0 nmol/l) were on average similar in the two sexes. By contrast, serum zinc (13.1 and 12.6 mumol/l, respectively), blood lead (0.56 and 0.36 mumol/l) and the urinary excretions of calcium (4.86 and 3.95 mmol/24h), copper (0.16 and 0.13 mumol/24h), and cadmium (9.4 and 7.2 nmol/24h) were significantly higher in men than in women. After adjustment for significant blood pressure covariates (age, body mass index, pulse rate, log gamma-glutamyltranspeptidase, smoking habits, and in women the contraceptive pill), serum total calcium was independently and positively correlated with systolic pressure in both sexes, and with diastolic pressure in women. After similar adjustments systolic pressure was positively correlated with urinary copper in men and women. In addition, systolic pressure and blood lead, and diastolic pressure and urinary cadmium were negatively correlated in men. In conclusion, this population study demonstrated a positive relationship between systolic blood pressure and both serum total calcium and urinary copper.

Pharmacoeconomics of immunisation: a review.

The effects of immunisation programmes that have existed for several decades in developed countries are demonstrated by the decrease and even eradication of smallpox, poliomyelitis, measles, mumps and hepatitis B. Cost, health policy and spontaneous evolution in the incidence of communicable diseases have a decisive influence on the use of a vaccine. Investment in vaccination policy has to be encouraged to maintain this progress made in the control of infectious diseases and to meet new challenges. Studies re-evaluating ongoing immunisation programmes are scarce. Nevertheless, it can be concluded that for vaccination against hepatitis B in professionally exposed at-risk populations, arguments for positive returns are consistent. The same holds for vaccination against S. pneumoniae and for influenza virus in the elderly. The results of the economic evaluation of revaccination against measles, when insufficient coverage exists, are inconclusive. Universal vaccination of children against Haemophilus influenzae type b (Hib) and of children of hepatitis B-positive mothers against hepatitis may require costs to be paid in order to gain extra health benefits.

Recent syphilis trends in Belgium and enhancement of STI surveillance systems.

Over the past five years, a series of syphilis outbreaks mainly occurring among gay men have been observed in Europe. One of these outbreaks was reported in the city of Antwerp, Belgium, during the first quarter of 2001. This outbreak is still ongoing in 2004. Furthermore, active syphilis diagnoses reported by the Sentinel Laboratory Network rose by 89% in the country during the fourth quarter of 2003. An increase in Brussels was also observed during the same quarter (+300%; 24 cases reported). Overall, the sentinel network of clinicians reported that 93.4% of patients were male; among them, 79.9% were men having sex with men (MSM). The overall proportion of patients co-infected with HIV was 50.5% (MSM: 58.6%; male heterosexuals: 23.8%; females: 8.3%); 76.1% of co-infected patients were already aware of their HIV infection at the time they were diagnosed with syphilis.

Recent syphilis trends in Belgium and enhancement of STI surveillance systems.

Over the past five years, a series of syphilis outbreaks mainly occurring among gay men have been observed in Europe. One of these outbreaks was reported in the city of Antwerp, Belgium, during the first quarter of 2001. This outbreak is still ongoing in 2004. Furthermore, active syphilis diagnoses reported by the Sentinel Laboratory Network rose by 89% in the country during the fourth quarter of 2003. An increase in Brussels was also observed during the same quarter (+300%; 24 cases reported). Overall, the sentinel network of clinicians reported that 93.4% of patients were male; among them, 79.9% were men having sex with men (MSM). The overall proportion of patients co-infected with HIV was 50.5% (MSM: 58.6%; male heterosexuals: 23.8%; females: 8.3%); 76.1% of co-infected patients were already aware of their HIV infection at the time they were diagnosed with syphilis.

Decrease in blood cadmium levels over time in Belgium.

During the time period from 1984 to 1988, blood cadmium concentration decreased by 56% in 31 males who were not occupationally exposed to cadmium and who lived in a Belgian urban area where there existed nonferrous industries. A 40% decrease in blood cadmium concentration was also observed in an independent cross-sectional survey conducted in 1985 and 1988 among 412 subjects who lived in a rural area. This latter decrease persisted when the main determinants of blood cadmium concentration--gender, age, and tobacco--were allowed for. The results presented are consistent with a decrease in environmental cadmium exposure in Belgium.

Impact of environmental cadmium pollution on cadmium exposure and body burden.

The body burden of cadmium, as estimated from 24-h urine cadmium levels, was determined in 1,523 subjects who were not occupationally exposed and who lived in five areas of Belgium. Urinary cadmium levels differed significantly with place of residence. These differences persisted after standardization for the other significant determinants (i.e., age, body mass index, smoking habits, social class, alcohol consumption, and menopause). The highest 24-h urine cadmium levels were found in subjects who lived in areas that contained cadmium-polluted soils. The body burden overload has been attributed mainly to the consumption of locally grown vegetables and the use of contaminated well water for cooking and drinking. Blood cadmium levels were also dependent on place of residence. However, the geographical differences in blood cadmium did not parallel those of urine cadmium. Blood cadmium is more influenced by recent exposure; therefore, this latter observation might reflect the recent implementation of preventive measures in some areas.

Chronic lead exposure and pregnancy.

The objective of the study was to determine the effect of chronic lead exposure on pregnancy and the newborn. Cord blood was assayed for blood lead levels (PbB) in a randomly selected group of 82 Maltese newborns. Twenty-eight (34.1%) neonates had a PbB level greater than 200 µg/l. Two trends appeared with increasing blood lead levels suggesting a decrease in newborn birth weight (r=-0.1445, P=0.207) and an increase in the duration of the first stage of spontaneous labour (r=0.1385, P=0.3043). There appeared to be no mean differences in maternal third trimester haemoglobin, duration of gestation, and previous pregnancy loss in infants with high PbB levels compared to infants with low PbB. Through its properties of inhibiting enzymatic function and its competitiveness with other minerals, calcium and zinc, chronic sub-toxic lead exposure during pregnancy may cause adverse effects on the neonate and pregnancy.

Hantavirus disease (nephropathia epidemica) in Belgium: effects of tree seed production and climate.

Recently, human cases of nephropathia epidemica (NE) due to Puumala virus infection in Europe have increased. Following the hypothesis that high reservoir host abundance induces higher transmission rates to humans, explanations for this altered epidemiology must be sought in factors that cause bank vole (Myodes glareolus) abundance peaks. In Western Europe, these abundance peaks are often related to high tree seed production, which is supposedly triggered by specific weather conditions. We evaluated the relationship between tree seed production, climate and NE incidence in Belgium and show that NE epidemics are indeed preceded by abundant tree seed production. Moreover, a direct link between climate and NE incidence is found. High summer and autumn temperatures, 2 years and 1 year respectively before NE occurrence, relate to high NE incidence. This enables early forecasting of NE outbreaks. Since future climate change scenarios predict higher temperatures in Europe, we should regard Puumala virus as an increasing health threat.

Lowering time trend of blood lead levels in Belgium since 1978.

Since 1978, the biological screening of the Belgian population was regularly monitored by measuring blood lead levels. Over 11 years, 6070 samples were analyzed in urban, rural, and industrial areas. The median values of blood lead concentration dropped from 170 to 78 micrograms/liter of blood, i.e., a lowering of about 55%. The trend persists when taking into account some individual characteristics which influence blood lead levels such as gender, age, tobacco, and areas. These influences and the possible environmental causes of the observed trend are discussed.

Analytical quality control of cadmium and lead in blood and cadmium in urine: results of its implementation during a five-year epidemiological study.

Quality-control programmes are very important in assessing the reliability of biological analyses. Such programmes are essential if misleading results in epidemiological studies dealing with low levels of exposure to heavy metals present in the general environment (e.g., cadmium, lead) are to be avoided. Internal and external quality-control programmes for the measurement of cadmium and lead in blood and of cadmium in urine were implemented from 1985 to 1989 in support of a national epidemiological study, Cadmibel (2327 participants), conducted in Belgium to assess the effects of environmental exposure to cadmium and lead on the general population. Apart from these programmes, inter-comparisons between the two participating laboratories were carried out on 10% of the samples. The results of these quality-control programmes met external acceptability criteria, emphasizing the analytical proficiency of these measurements at the relatively low concentrations in the Cadmibel study.

Exposure to lead of the Belgian population.

According to the Council Directive of 29 March 1977 on biological screening of the population for lead, the blood-lead levels (PbB) were determined in samples of the Belgian population not occupationally exposed to this metal. Two campaigns of sampling were performed: the first one in 1979 (1678 samples analysed) and the second in 1981 (1000 samples analysed). Sampling was done in urban and industrial zones, as well as in areas where lead risk could be present. Concerning the urban and industrial areas, the results obtained seem to indicate that a particular lead risk does not exist for the adult population if we consider the reference levels of the CEE Directive. Moreover, the results of the second campaign of sampling showed a decreasing trend: the median PbB values dropped from 183 to 156 micrograms/l in Brussels and from 192 to 139 micrograms/l in Liège. This could be partly due to the limitation of the lead content of gazoline. On the other hand, the results of the surveys clearly demonstrated the existence of two areas where an obvious lead risk exists. In one of those, the lead risk is of industrial origin (lead smelter) and concerns mainly children: median PbB value 260 micrograms/l, percentile 90 and 98 respectively 390 and 430 micrograms/l. In the other one, the lead risk is from a hydric source and concerns adults and children: median PbB value 258 micrograms/l, percentile 90 and 98 respectively 370 and 520 micrograms/l.

Assessment and comparison of human exposure to lead between Belgium, Malta, Mexico and Sweden.

This is a follow-up study of UNEP/WHO Pilot Project on Assessment of Human Exposure to Lead and Cadmium through Biological Monitoring, carried out in 1983/1984. The main objectives of the follow-up study were: to study whether differences in blood-lead levels found between countries in the Biological Monitoring Project were confirmed and were primarily due to exposure via ingested lead (oral intake) or via inhaled lead; to make a preliminary survey, in selected areas, of the possible sources of high exposure (Malta, Belgium). Four countries participated: Belgium, Malta, Mexico, Sweden. To insure comparability between the populations, certain categories were monitored: teachers for socio-economic status, non smoking males, aged between 25 and 50 years old. The blood-lead concentration (PbB) was measured to determine the current exposure and the feces-lead excretion (PbF) was determined to find out the part of the exposure due to ingestion. Blood-lead levels and feces-lead excretion were very different between the four countries. Median values for PbB, in micrograms Pb/1, were, in decreasing values 247 in Malta, 188 in Mexico, 135 in Belgium and 53 in Sweden. Median values for PbF, in micrograms Pb/day, were 361 in Malta, 159 in Mexico, 82 in Belgium and 22 in Sweden. Oral intake seems to be the major exposure route in the four countries. The relationship between PbB and PbF is curvilinear. To investigate the possible source of high exposure, a preliminary survey was made in Malta and Belgium; lead in air suspended and sedimenting particles was monitored as well as the lead concentration in some food and street dust samples. Concerning the comparison of lead concentrations in these environmental samples between Belgium and Malta, no major differences were detected. The high internal exposure to lead in Maltese people, as measured by PbB, is probably due to a combination of several factors.

[Trends in pneumococcal infections in Belgium from 1986 to 1991]. / Evolution des infections à pneumocoques en Belgique de 1986 à 1991.

Streptococcus pneumoniae is one of the most frequent causes of pneumonia, meningitis, and otitis media. Persons at high risk are young children, elderly, and individuals with immunodeficiency or with an underlying disease. Thanks to a network ot 111 laboratories spread all over Belgium, the evolution of the number of deep isolates of S. pneumoniae has been followed from 1986 to 1991: the recorded frequency increased with a mean number of isolations per laboratory and per year rising from 3.6 in 1986 to 6.2 in 1991. The objectives of this paper are to study the evolution of age and sex distribution of the patients, and of the origin of the isolates, and to propose solutions for slowing down this evolution.