Management of potential human cases of influenza A/H5N1: lessons from Belgium.
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Belgium↗
Biomedical subjects
R Snacken
Publications and source records attributed to R Snacken.
Pandemic planning.
During the previous century, three influenza A pandemics occurred with a variable severity. The two latter were explained by a genetic re-assortment and false alarms without pandemic spread were observed later by the same mechanism or by direct animal infection. The likelihood that such an event occurs again is high and each country has to be prepared for facing what could be a catastrophe. The last event in Hong Kong in 1997 where six persons died, has allowed refining the definitions and phasing a pandemic threat from the moment that a novel virus is discovered. WHO implemented 50 years ago a large network of surveillance with five collaborating centres, including the animal influenza centre of Memphis, and 110 national influenza centres. These centres are encouraged to prepare or improve a national contingency plan that could reduce importantly medical and socio-economic consequences of an influenza A pandemic. Countries or regions are recommended to use these guidelines that provide a framework for preparing an appropriate and proportionate response.
Health Planning↗
[Influenza: prevention and treatment].
Prevention of influenza for persons at risk with inactivated vaccine remains the best way for attenuating the impact of influenza epidemics if persons to be vaccinated are correctly identified. In current recommendations, the lower cut off age is controversial, but new arguments on mortality associated with influenza suggest to lower the age to 45 for vaccination. Moreover immunization of health care workers is essential by decreasing transmission to susceptible patients and by reducing absenteeism of essential people during epidemics. Intranasal attenuated live vaccine seems to be of particular importance essentially in children and could replace the current vaccine in a near future. The role of chemoprophylaxis by inhibitors of neuraminidase needs further studies, but preliminary controlled trials have demonstrated a certain efficacy by controlling outbreaks in health care institutions. Treatment of influenza by these latter antivirals already has defined indications and a larger use currently lies on convincing arguments. By reducing inappropriate use of antibiotics, an extended use of neuraminidase inhibitors is of particular interest even if it is not a valuable argument, stricto sensu, for good medical practices.
Absenteeism↗
Control of influenza. Public health policies.
The control and management of influenza are currently based on the surveillance, prevention and treatment of the disease. Almost all European countries have influenza immunization policies for populations considered as being at-risk, but there are large disagreements about the meaning of "risk", and the levels of vaccine use vary greatly country by country. In the near future, new vaccines and specific anti-viral drugs will need to adapt and to extend current recommendations, but meanwhile increasing vaccination coverage, improving and up-dating national policies and their achievement are the only ways to reduce the recurrent burden of influenza epidemics for both individuals and society.
Antiviral Agents↗
European Influenza Surveillance Scheme on the Internet.
In 1995, The European Influenza Surveillance Scheme was created with the participation of eight networks from seven countries. The main objectives were to continue the previous CARE Telematics Network and to adapt the project to the Internet environment as well as to improve substantially the quality of the surveillance according to new epidemiological requirements. Clinical and virological data from the general population and hospitals are collected in an interactive real-time database which can then be used for data entry, queries and consultations. Research programmes have been undertaken in various fields such as standardisation of clinical data and comparability between countries. Validation and security processes guarantee the quality assurance as well as regular assessment by the steering committee. Two additional countries will participate during the next influenza season (1997-98). This will represent an early warning system in a region of approximately 264 million inhabitants.
Cross-Sectional Studies↗
Mortality in the elderly and ambient ozone concentration during the hot summer, 1994, in Belgium.
Extensive investigations were carried out to study the relationship between daily mortality in the elderly, outdoor air temperature, and ozone concentration observed in Belgium during the hot summer, 1994. The two environmental variables were assessed through mean daily temperature and 24-hr ozone concentration, both measured the day before and averaged over the country. Data were stratified by terciles of mean daily temperature in order to reduce the degree of collinearity between the investigated environmental variables. In the first stratum, which ranged from 9.9 to 15.4 degrees C (41 days), mean daily temperature and 24-hr ozone concentration were not correlated while the mean number of daily deaths was higher when 24-hr ozone concentration increased from 45 to 55 micrograms/m3 (P < 0.05). In the second stratum, which ranged from 15.6 to 20.3 degrees C (42 days), mean daily temperature and 24-hr ozone concentration were strongly correlated (r = 0.54, P < 0.0001). In this stratum, the number of daily deaths did not depend on the mean daily temperature but increased linearly with 24-hr ozone concentration within the range 25 to 85.5 micrograms/m3 (P < 0.001). After having examined the possible confounding effect of sulfur dioxide, nitrogen dioxide, fine particulates, and humidity, ozone was found to be the only investigated variable contributing to the increased daily mortality. In the third stratum, which ranged from 20.4 to 27.6 degrees C (40 days), mean daily temperature and 24-hr ozone concentration were also strongly correlated (r = 0.71, P < 0.0001). Daily mortality, in this stratum, was correlated more with mean daily temperature (r = 0.68, P < 0.001) than with 24-hr ozone concentration (r = 0.55, P < 0.001). Nonparametric regression analyses were performed to model the number of daily deaths in the whole range of temperatures. These analyses confirmed the effect of 24-hr ozone concentration on daily mortality already uncovered by the least-squares regression analysis in the second stratum of mean daily temperature. In addition, at levels exceeding 20 degrees C, the effect of ozone concentration on daily mortality was enhanced by temperature owing to a positive interaction between these two variables. The present study thus demonstrated a statistical association between daily mortality, observed in the elderly during the hot summer, 1994, in Belgium, and ambient ozone concentration. This relationship was dependent on the range of temperatures.
Aged↗
Influenza vaccination in 22 developed countries: an update to 1995.
This study expands and updates through 1995 our earlier report on influenza vaccine use in 18 developed countries. Five of the six countries with high levels of vaccine use in 1992 (> or = 130 doses/1000 population) showed little change or slight declines over the subsequent 3 years. The exception was the United States, where a new federal program for vaccination reimbursement for the elderly helped to increase vaccine distribution from 144 to 239 doses/1000 population. The six countries with medium levels of vaccine use in 1992 (76-96 doses/1000 population) increased to > or = 100 doses/1000 population by 1995. Among the six low-use countries in 1992 (< or = 65 doses/1000 population), only Finland showed substantial improvement (96 doses/1000 population) in 1995. Four new countries were added to the study. In Germany, vaccine use increased to 80 doses/1000 population in 1995, but in Ireland it remained at a low level (48 doses/1000 population). In Korea, vaccine use increased from 17 to 95 doses/ 1000 population during the period 1987-1995. In Japan, very high levels of vaccine use (approximately 280 doses/1000 population) in the early 1980s were associated with vaccination programs for school children. However, vaccine use fell precipitously when these programs were discontinued, and only 2 and 8 doses/1000 population were used in 1994 and 1995, respectively. In all 22 countries, higher levels of vaccine use were associated with vaccination reimbursement programs under national or social health insurance and were not correlated with different levels of economic development. Excluding Japan, in 1995 there was still a greater than fourfold difference between the highest and lowest levels of vaccine use among the other 21 countries in the study. Given its well established clinical effectiveness and cost-effectiveness, none of these countries has yet achieved the full benefits of its programs for influenza vaccination.
Developed Countries↗
Weekly monitoring of influenza impact in Belgium (1993-1995).
The primary objectives of an influenza monitoring programme are early detection of an epidemic and the identification of the viruses responsible. The healthcare impact of the disease is often some time after the epidemic. In Belgium data on the consequences of influenza are recorded weekly, which provides an early estimate of the severity of the epidemic. Data collected during 3 influenza seasons (1993-95) showed that during the peak of the very moderate influenza A/H3N2 outbreak in 1993-94, general practitioner consultations for acute respiratory infections increased by 100%, work absenteeism by 56%, total sales of pharmaceuticals by pharmacists by 26% and overall mortality by 14%. From these data, we estimated that 498,400 working days were lost during the peak week in Belgium in 1993, and 848 excess deaths were observed during the whole of the 1993-94 epidemic. 12% of those who died were aged less than 60 years. Hospitalisation data must be included in the future in order to complete the information that is essential for formulating public health policies on influenza vaccination.
Belgium↗
[Which response against the next influenza pandemic?].
An influenza pandemic is caused by the emergence or the reoccurrence as well as the explosive spreading of a new influenza A virus in an immunologically unprotected population. During this century, three severe pandemics occurred: the Spanish Flu in 1918, the Asian Flu in 1957 and the Hong Kong Flu in 1968. The first one was responsible for 20 millions deaths. A future pandemic is very likely to occur but we cannot predict when it will happen. The mechanism of emergence of a new virus is totally different of the one observed during the annual interpandemic outbreaks. Since the severity of a pandemic virus is unpredictable, action plans must be designed to avoid over-reaction to harmless influenza viruses and at the same time to be adequate in dealing with a threatened new pandemic. Thus these two situations need different control and prevention plans.
Belgium↗
Temperature, ambient ozone levels, and mortality during summer 1994, in Belgium.
The number of daily deaths, temperature, relative humidity, and 24-hr concentrations of main air pollutants observed during a heat wave (June 27-August 7, 1994) in Belgium were compared with those recorded before and after this heat wave. All these variables were averaged over the country. Expected mortality was calculated from daily deaths observed during the summers of 1985-1993. The influence of meteorological and air pollution variables on daily mortality was analyzed using generalized least-squares method. Mortality recorded during the heat wave was higher than expected: it increased by 9.4% in the age group 0-64 years (236 excess deaths; P < 0.001) and by 13.2% in the elderly (1168 excess deaths; P < 0.001). After the heat wave, mortality in the elderly was lower than expected (178 deficit deaths; P< 0.05); the net excess of mortality in the whole population amounted to 1226 deaths when accounting for this deficit. This increased mortality was associated with unusually high outdoor temperatures (range of daily mean: 15.3-27.5 degrees C) and elevated ozone levels (range of 24-hr concentration: 34.5-111.5 microg/m3). The duration of the ozone overexposure during the heat wave was also uncommon: half-hour concentrations of ozone exceeded, on an average, 100 microg/m3 for 8 consecutive hr. The number of daily deaths was mostly correlated with the mean daily temperature and 24-hr ozone concentration, both measured the day before. A synergy between temperature and ozone in their effects on mortality was also highlighted in both age groups. The product of the logarithm of temperature by the logarithm of ozone concentration, both measured the day before, contributed to 39.5% of the variance of the logarithm of daily deaths in elderly and to 4.5% in the age group 0-64 years. In conclusion, elevated outdoor temperatures combined with high ozone concentrations were assumed to be the likely cause of the important excess mortality observed in Belgium during the summer, 1994.
Adolescent↗
Influenza immunization policies in Europe and the United States.
Influenza vaccination policies of 28 European countries were compared with those of the US Immunization Practices Advisory Committee. Twenty-four of 28 (86%) European countries had immunization policies for influenza. European and US recommendations were in complete agreement concerning immunization of those with heart and lung disease. Within Europe there was 81-86% agreement concerning immunization of the elderly, irrespective of their health status, and patients with diabetes, renal dysfunction and immunosuppression, and 71% agreement concerning those in residential care and occupational groups that can transmit influenza to high-risk patients. Unlike the US, 62-71% of European countries did not target those with haemoglobinopathies, children and teenagers taking salicylates or household members of those at high risk. Few recommendations were endorsed by relevant medical or patient organizations. The observed variation in vaccination policies in Europe and North America possibly reflect uncertainties concerning risks from influenza and benefits from vaccination, and differences in public health systems and attitudes towards preventive medicine.
Europe↗
The CARE telematics network for the surveillance of influenza in Europe.
Since the 1950s, national networks for the surveillance of influenza have been progressively implemented in several countries. New epidemiological arguments have triggered changes in order to increase the sensitivity of existent early warning systems and to strengthen the communications between European networks. The WHO project CARE Telematics, which collects clinical and virological data of nine national networks and sends useful information to public health administrations, is presented. From the results of the 1993-94 season, the benefits of the system are discussed. Though other telematics networks in this field already exist, it is the first time that virological data, absolutely essential for characterizing the type of an outbreak, are timely available by other countries. This argument will be decisive in case of occurrence of a new strain of virus (shift), such as the Spanish flu in 1918. Priorities are now to include other existing European surveillance networks.
Computer Communication Networks↗
Using Videotex in public health in Belgium.
In public health, access to information is more and more felt to be an urgent need. In this matter Videotex has shown to be a good working tool, though its utilisation in Belgium is not widespread yet. The Institute for Hygiene and Epidemiology has implemented EPITEL, a databank allowing for consultation of data on health and environment. The rationale for the choice of Videotex as a consulting tool is analysed here. Though very user-friendly, its high technicality allows for certain applications to function in real time mode, generate graphics, or even to consult an expert system, as the one used in the application on immunisations. In this way Videotex can also be a helpful tool in primary prevention, besides its data consulting function. This demonstration will present the five applications: health and travelling, health indicators, allergenic pollen, biological quality of the swimming waters at the coast, air pollution data. It shortly presents the hardware and software supporting the system, as well as a few results of a two-year experience running the system. Some shortcomings of the actual system may be highlighted, and possible evolutions might be discussed.
Belgium↗
Five years of sentinel surveillance of acute respiratory infections (1985-1990): the benefits of an influenza early warning system.
For the last five years, the Brussels Institute of Hygiene and Epidemiology has been involved in the surveillance of acute respiratory infections (ARI). The four indicators used (number of encounters of ARI by GP's/100 encounters, virus isolations, absenteeism and mortality) are discussed. A regression procedure is applied to the data collected by a sentinel network of general practitioners (GP's). This procedure permits the baseline to be visualized and an epidemic threshold to be determined in order to recognize early an influenza outbreak. The traditional use of flu-like illnesses as an indicator might be improved by the addition of non-specific ARI which are more precocious, especially in children. The criteria for an accurate definition of an influenza epidemic are discussed. The same mathematical model can be used for the analysis of mortality linked with an outbreak. It shows that the last epidemic in the winter 1989-1990 was responsible for about 4900 deaths directly or indirectly related to influenza.
Absenteeism↗
The next influenza pandemic: lessons from Hong Kong, 1997.
The 1997 Hong Kong outbreak of an avian influenzalike virus, with 18 proven human cases, many severe or fatal, highlighted the challenges of novel influenza viruses. Lessons from this episode can improve international and national planning for influenza pandemics in seven areas: expanded international commitment to first responses to pandemic threats; surveillance for influenza in key densely populated areas with large live-animal markets; new, economical diagnostic tests not based on eggs; contingency procedures for diagnostic work with highly pathogenic viruses where biocontainment laboratories do not exist; ability of health facilities in developing nations to communicate electronically, nationally and internationally; licenses for new vaccine production methods; and improved equity in supply of pharmaceutical products, as well as availability of basic health services, during a global influenza crisis. The Hong Kong epidemic also underscores the need for national committees and country-specific pandemic plans.
Animals↗
What can be done in Belgium for fighting against hepatitis C?
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Belgium↗
[Avian flu: what kind of danger for public health?].
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Animals↗
[Concern about vaccination: which vaccine in the event of pandemic influenza?].
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Disease Outbreaks↗