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Tuberculosis

1. Key messages

In 2017, 972 new cases of tuberculosis were reported in Belgium.
Belgium is a low-incidence country with 8.6 new cases of tuberculosis per 100,000 inhabitants. There are however important geographical differences: the incidence is 3.9 and 4.7 times higher in the Brussels-Capital Region (27.8 cases/100,000), when compared with Wallonia (7.1 cases/100,000) and Flanders (5.9 cases/100,000). Big cities report more cases since there is a higher concentration of risk groups. Brussels is the city with the highest incidence.
The incidence of tuberculosis is higher in men, whatever the age, region or nationality.
In Belgium, in 2017, 52.1% of the tuberculosis cases occurred among people who did not have a Belgian nationality. This proportion was higher in Brussels (63.8%) than in the two other regions.

2. Background

Tuberculosis is a disease caused by a bacterium called Mycobacterium tuberculosis that usually affects the lungs.

According to the World Health Organization (WHO), there were 10 million new cases of tuberculosis in 2017. This disease is one of the top 10 causes of death worldwide. Belgium is situated among the “low-incidence countries” with less than 10 new cases of tuberculosis per 100,000 inhabitants per year [1].

Tuberculosis can nowadays be effectively treated with a success rate of 83.7% in 2016. In Belgium, treatment is free of charge for the entire population (even for people without health insurance). However, 8.7% of tuberculosis patients still die before the end of treatment (half of these deaths are due to comorbidity) [2].

The main risk factors for tuberculosis are contacts of infected people, poverty, poor nutritional status and immunodeficiency. Some people are more likely to get infected with tuberculosis since they are more exposed to the risk factors, like health care professionals and vulnerable populations such as homeless people, prisoners and migrants originating from countries with high tuberculosis prevalence.

Data presented in this chapter are extracted from the Belgian tuberculosis registry 2017 report written by the Fonds des Affections Respiratoires (FARES) [2] and the Vlaamse Vereniging voor Respiratoire Gezondheidszorg en Tuberculosebestrijding (VRGT) [3].

3. Tuberculosis incidence

Belgium

  • In 2017, 972 new cases of tuberculosis were reported in Belgium (8.6 cases/100,000 inhabitants).
  • Men are more often affected by the disease than women, with 65.5% of new cases occurring among men in 2017 in Belgium. The sex ratio is 1.9.
  • 40% of the tuberculosis patients diagnosed in 2017 were aged 25-44 years.

Trends and regional differences

40% of tuberculosis cases are registered in Flanders (n=386), 34% in Brussels (n=331) and 26% in Wallonia (n=255). When related to the number of inhabitants, the incidence rate is 3.9 times higher in Brussels (27.8 cases/100,000) as compared to Wallonia (7.1 cases/100,000) and 4.7 times higher as compared to Flanders (5.9 cases/100,000).

The number of new cases of tuberculosis is decreasing since more than 30 years, although the diminution is slowing down since the nineties and tends to stagnate the last few years. The incidence rate dropped below the level of 10 cases/100,000 inhabitants for the first time in 2007, ranking the country among low-incidence countries.

Since 1981, the incidence rate is decreasing in all three regions, with more variations in Brussels due to migration flows. In Wallonia, the incidence rate has decreased below the national average since 1987, except in 1991 and 1999. The incidence rate in Flanders is slightly lower than in Wallonia.

Tuberculosis incidence per 100,000, Belgium and regions, 1981-2017
Source: Belgian tuberculosis registry 2017, VRGT/FARES asbl, march 2019

Incidence in big cities

Tuberculosis occurs more frequently in big cities where people at risk are over-represented:

  • the incidence in Brussels is the highest (27.8/100,000 in 2017); it is more than 3 times higher than in Belgium as a whole (8.6 /100,000).
  • the incidence is also quite high in Antwerp and Liege (more than 20 new cases/100,000 in 2017), followed by Charleroi and Namur (more than 15 new cases/100,000).

At the opposite, the tuberculosis incidence is lower in the cities of Ghent and Bruges where the rates are below the national average (respectively 8.5 and 5.1 new cases/100,000 in 2017).

Tuberculosis incidence per 100,000 in cities >100,000 inhabitants, Belgium, 2017
Source: Belgian tuberculosis registry 2017, VRGT/FARES asbl, march 2019

Tuberculosis distribution by nationality

In 2017, in Belgium, 52.1% of new tuberculosis cases occurred among people with a foreign nationality: 91.5% of those come from countries with high prevalence of the disease (mostly from Eastern Europe, Africa and South Asia countries). This proportion is higher in Brussels (63.8% of the new tuberculosis cases among people with foreign origin) than in Wallonia and Flanders (respectively 47.5% and 45.1%).

Among Belgians, the incidence rate is more than 4 times higher in Brussels compared to Flanders, and 3.8 times higher than in Wallonia.

Among non-Belgians, the incidence rate of tuberculosis is also higher in Brussels when compared with the two other Regions but the difference is less pronounced than for Belgian people: the incidence rate is respectively 1.6 and 1.5 times higher than in Flanders and in Wallonia.

Flanders has the lowest incidence rate, regardless of nationalities.

  • Crude rate
  • Number of cases

Tuberculosis incidence per 100,000 by nationality and by region, Belgium, 2017
Source: Belgian tuberculosis registry 2017, VRGT/FARES asbl, march 2019

New cases of tuberculosis by nationality and by region, Belgium, 2017
Source: Belgian tuberculosis registry 2017, VRGT/FARES asbl, march 2019

The distribution of the incidence by age and sex is different according to nationality:

  • among Belgians, the incidence is higher in age groups 30-44 years and 60-74 years.
  • among non-Belgians, the incidence is higher in age group 15-29 years and lower in upper age groups.

Among Belgians, the sex ratio is 1.7. It tends to increase with age: the incidence rate is 4 times higher in men among people over 75 years.

If the number of new cases increases with age among men, it is not the case among women: the incidence is higher in age group 15-29 years and gradually decreases after 29 years.

Among non-Belgians, the sex ratio is 2. The incidence rate is more than 2 times higher in men in age groups 15-29 years, 30-44 years and over 75 years.

  • Belgians
  • Non-Belgians

Tuberculosis incidence per 100,000 by age and sex, Belgian people, 2017
Source: Belgian tuberculosis registry 2017, VRGT/FARES asbl, march 2019

Tuberculosis incidence per 100,000 by age and sex, non-Belgian people, 2017
Source: Belgian tuberculosis registry 2017, VRGT/FARES asbl, march 2019

International comparison

In 2017, according to WHO [4], estimated incidence rate in Belgium is above the EU-15 mean, ranking the country third among the countries with the highest incidence rate after Portugal and Spain.

International comparisons made on reported data must be interpreted with caution, since methods for collecting data can be very different depending the country. That is why the WHO Global Task Force on TB Impact Measurement [1] has developed a methodology to take into account underreporting, over and under-diagnosis in tuberculosis estimates. This explains why the incidence rate in Belgium presented in this international comparison is different compared to the incidence rate extracted from the Belgian tuberculosis registry publication.

Tuberculosis incidence per 100,000, EU-15 countries, 2017
Source: WHO/ECDC 2019

4. Read more

View the metadata for this indicator

Vlaamse Vereniging voor Respiratoire Gezondheidszorg en Tuberculosebestrijding (VRGT)

Definitions

Tuberculosis case
According to the WHO-recommended definitions [5], a tuberculosis case is defined by a case of active tuberculosis clinically diagnosed by a clinician or other medical practitioner or bacteriologically confirmed. Clinically diagnosed cases include “cases diagnosed on the basis of X-ray abnormalities or suggestive histology and extrapulmonary cases without laboratory confirmation” [5].
EU-15
The EU-15 corresponds to all countries that belonged to the European Union between 1995 and 2004: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Spain, Sweden and the United Kingdom. We compare the Belgian health status to that of the EU-15 because these countries have similar socioeconomic conditions.

References

  1. Global tuberculosis report 2018. Geneva: World Health Organization; 2018. https://www.who.int/tb/publications/global_report/en/
  2. Registre belge de la tuberculose 2017, FARES asbl, mars 2019. https://www.fares.be/static/front/upload/1/upload/files/tuberculose/registres/Regtbc2017.pdf
  3. Tuberculoseregister België 2017, Vlaamse Vereniging voor Respiratoire Gezondheidszorg en Tuberculosebestrijding VRGT vzw. https://tuberculose.vrgt.be/sites/default/files/Tuberculoseregister%20België%202017.pdf
  4. WHO Regional Office for Europe/European Centre for Disease Prevention and Control.
    Tuberculosis surveillance and monitoring in Europe 2019 – 2017 data. Copenhagen: WHO Regional Office for Europe; 2019. https://ecdc.europa.eu/sites/portal/files/documents/tuberculosis-surveillance-monitoring-Europe-2019-20_Mar_2019.pdf
  5. Definitions and reporting framework for tuberculosis – 2013 revision, updated December 2014. Geneva: World Health Organization; 2015. https://www.who.int/tb/publications/definitions/en/

 

HIV and other sexually transmitted infections

1. Key messages

Despite a recent decrease, the total number of new HIV diagnoses remains high. This calls for a more intensive implementation of the combined preventive strategies available in Belgium.

The HIV epidemic in Belgium mainly affects two populations: men who have sex with men (MSM), mainly of Belgian or other European nationality, and men and women who have contracted the virus through heterosexual relations, mainly from sub-Saharan Africa. The rate of new HIV diagnosis is higher in Brussels than in the other regions, reflecting the fact that HIV is mainly an urban phenomenon. 69% of the new HIV cases were diagnosed in men. Most HIV cases were diagnosed in the 25-49 age group.

Chlamydia is the most common sexually transmitted Infection (STI) in Belgium, followed by gonorrhea and syphilis. The number of reported cases of these three STIs has increased almost threefold in the past 10 years, reflecting more an increase in testing and screening practices, than an increase in incidence. However, there has been an increase in unsafe sexual practices, which is more pronounced among certain groups such as MSM, possibly resulting in some increase in the number of STI cases.

2. Background

Sexually transmitted infections (STIs) are spread primarily through person-to-person sexual contact. Some STIs, particularly HIV can also be transmitted through blood products and tissue transfer, and from mother to child during pregnancy.

Several STIs, such as HIV, chlamydia, and syphilis, can be present without symptoms, which can facilitate their transmission. STIs may however also lead to severe long-term consequences: HIV is one of the most serious communicable diseases in Europe. It is an infection that can lead to serious morbidity (AIDS) and high costs of preventive treatment and care. Chlamydia and gonorrhea may lead to complications such as infertility, chronic inflammation, and ectopic pregnancy. Untreated syphilis can damage any organ and cause severe neurological complications.

HIV and other STIs are avoidable infections since the transmission is largely preventable by behavioral measures (safe sex, safe injection). Therefore their incidence in a defined population is an indicator of the success/failure of control strategies. Since 2017, the use of pre-exposure prophylaxis to HIV (PrEP) is reimbursed in Belgium. While this may have a positive effect on the incidence of HIV, it may lead to an increase in the incidence of other STIs due to relaxing of vigilance.

The modes of epidemiological surveillance of HIV and other STIs are different, and are therefore described separately.

The epidemiological surveillance of HIV and AIDS in Belgium dates from 1985 and is carried out by Sciensano on the basis of the registration of the new HIV and AIDS diagnoses. These data come from two sources: on the one hand the registration and reporting of the AIDS patients by the clinicians, and on the other hand the registration of the HIV diagnoses by one of the seven AIDS reference laboratories that perform the confirmation tests. In addition to recording the number of newly diagnosed HIV positive, the laboratories also collect basic epidemiological data on gender, age, nationality, possible route of infection, and clinical stage at the time of diagnosis.

The slow progressive nature of the disease allows the existence of a "hidden" epidemic consisting of undiagnosed people living with HIV. Sciensano therefore also estimates the number of people living with HIV, including those who have not yet been diagnosed [1]. For this, it uses an instrument developed by the European Center for Disease Prevention and Control (ECDC), called the ECDC HIV Modeling Tool [2].

ECDC and the WHO Regional Office for Europe jointly coordinate HIV/AIDS surveillance in Europe. The surveillance data on HIV and AIDS diagnoses are collected and submitted annually by the national HIV/AIDS surveillance programs in the Member States to The European Surveillance System (TESSy). The international comparability is however poor, since the national surveillance systems in different countries may differ in levels of underreporting and reporting delay.

The surveillance of other STIs in Belgium is mainly done via the Sciensano's sentinel network of medical laboratories, which covers about 50% of the laboratories. Since the surveillance of STIs is based on reported cases, the trends do not represent the true incidence. Indeed, since STIs are often asymptomatic, only a part of them are detected and notified. As a result, changes in notification rates can be affected by changes in both the underlying incidence and the proportion of cases being detected (due to an intensification of the screening or to more performant tests). To help interpret these trends, Sciensano compares the evolution of the number of reported cases of chlamydia and gonorrhea to that of the total number of tests for these STIs reimbursed by National Institute for Health and Disability Insurance (RIZIV-INAMI).

The routine surveillance of the laboratory network is completed by the clinical sentinel network to identify the most important behavioral risk factors and evaluate the impact of prevention campaigns. This clinical network is not suited to follow the evolution of the number of cases of the predominant STIs, but can help to describe factors that influence the transmission of STIs.

3. HIV

Situation in 2018

Belgium

In 2018, 882 new diagnoses of HIV infections were made in Belgium (7.8 new diagnoses per 100,000 inhabitants, or on average 2.4 cases a day). Among those, 69% were men. 68% of the HIV cases were diagnosed in people aged 25-49.

In 2018, 49 cases of AIDS were notified. 59 deaths were notified among the people living with HIV. This number includes deaths from any cause (not only related to HIV); from the cause of death register, it appears that HIV is mentioned as underlying cause of deaths in about two-thirds of the deaths where an HIV infection was mentioned.

Number of new reported HIV diagnoses by age and sex, Belgium, 2018
Source: Epidémiologie du SIDA et de l’infection à VIH en Belgique, Sciensano, 2019 [1]
Regional specificities

In 2018, of the 882 new diagnoses, 235 were reported in Brussels, 414 in Flanders, 170 in Wallonia, and 63 cases were of unknown residence.

When related to the number of inhabitants, the diagnostic rates in Flanders and Wallonia are quite comparable, while the one in Brussels is much higher. This difference is not surprising, since a high HIV prevalence is typically an urban phenomenon. The Brussels Capital Region can indeed be considered as a big city – with the socio-cultural characteristics of an urban context – while the two other regions mix rural, semi-urban, and urban contexts.

Rate of new HIV diagnoses per 100,000 by region, Belgium, 2018
Source: Own calculations from Epidémiologie du SIDA et de l’infection à VIH en Belgique, Sciensano, 2019 [1]

Trends

Belgium

In 2018, the number of new HIV diagnosis has decreased by 2% compared to 2017 and by 28% compared to 2012.

Between the start of the outbreak in the early 1980s and the end of 2018, a total of 31,695 persons were diagnosed with HIV, a total of 5091 cases of AIDS were reported, and 2751 people had died with HIV. Not all of those deaths were due to HIV. From the cause of death register, it appears, that since 1998, about 1000 deaths were declared having HIV as the direct cause of death (the code of death for HIV did not exist before).

Number of new diagnoses of HIV, AIDS, and deaths reported, Belgium, 1982-2018
Source: Epidémiologie du SIDA et de l’infection à VIH en Belgique, Sciensano, 2019 [1]
Regional specificities

Between 2012 and 2018, the number of new HIV diagnoses decreased in Flanders and Wallonia, but remained quite stable in Brussels. However, it should be noted that the availability of information on region of residence of HIV cases has greatly improved in recent years, from 75% in 2015 to 93% in 2018. The large number of cases with unknown region or residence in the past has resulted in an underestimation of the number of cases in each region, which complicates interpretation of trends.

Number of new HIV diagnoses by region, Belgium, 2009-2018
Source: Epidémiologie du SIDA et de l’infection à VIH en Belgique, Sciensano, 2019 [1]

Modes of infection

The HIV epidemic in Belgium mainly affects two populations: men who have sex with men (MSM), mainly of Belgian or other European nationality, and men and women who have contracted the virus through heterosexual relations (95% of the HIV-infected women and 28% of the men), mainly from sub-Saharan Africa.

A decrease in the number of new HIV diagnoses occurred in both key populations. The proportion of new infections in injecting drug users (IDUs) is limited and tends to decrease further. Finally, it is also important to note that there is a significant proportion of new infections for which the mode of transmission is unknown (25% in 2018).

Number of new HIV diagnoses by probable mode of infection, Belgium, 1999-2018
Source: Epidémiologie du SIDA et de l’infection à VIH en Belgique, Sciensano, 2019 [1]
Nationality by mode of infection

In 2018, 50% of the HIV cases diagnosed among MSM were of Belgian nationality. This proportion has strongly decreased in the last few years (73% in 2009 and 62% in 2016 and 2017). Among people infected by heterosexual contact, 43% were of sub-Saharan nationality in 2018 (compared to 61% in 2009 and 50% in 2017).

  • MSM
  • Heterosexuals

Number of new HIV diagnoses in MSM by nationality, Belgium, 1995-2018
Source: Epidémiologie du SIDA et de l’infection à VIH en Belgique, Sciensano, 2019 [1]

Number of new HIV diagnoses in heterosexuals by nationality, Belgium, 1995-2018
Source: Epidémiologie du SIDA et de l’infection à VIH en Belgique, Sciensano, 2019 [1]

Estimation of the HIV prevalence in Belgium

Sciensano estimates the prevalence of HIV in Belgium based on a tool developed by ECDC [1,2]. The number of people living with HIV in Belgium in 2018 was estimated at 19,213. Among those, 1747 were not diagnosed. This implies that 9.1% of all people living with HIV in Belgium are not aware of their seropositivity.

Note: the prevalence estimated by the model is lower than the total number of people diagnosed with HIV since the beginning of the epidemic (31,695). This difference is mainly due to deaths and people who have left the territory. In addition, some duplication cannot be excluded due to the old personal identifier. Finally, it should be noted that these estimates have been calculated on the basis of available data, and that missing data may affect accuracy.

4. Other sexually transmitted infections

Situation in 2018

Belgium

Chlamydia is the most common STI in Belgium with 80 reported cases per 100,000 in 2018. Chlamydia infections are more frequent in women, with the highest notification rate among women aged 20-24.

Gonorrhea and syphilis are less common, with respectively 19 and 14 reported cases per 100,000 in 2018. Most gonorrhea and syphilis cases are registered among men, especially among men who have sex with men (MSM). The highest number of gonorrhea and syphilis cases are reported among men aged 25-29 and 30-39, respectively.

  • Chlamydia
  • Gonorrhea
  • Syphilis

Reported cases of chlamydia by age and sex, Belgium, 2016
Source: Surveillance des infections sexuellement transmissibles, Sciensano, 2020 [4]

Reported cases of gonorrhea by age and sex, Belgium, 2016
Source: Surveillance des infections sexuellement transmissibles, Sciensano, 2020 [4]

Reported cases of syphilis by age and sex, Belgium, 2016
Source: Surveillance des infections sexuellement transmissibles, Sciensano, 2020 [4]

Trends

Between 2002 and 2018, the chlamydia notification rates increased from 9.5 cases/100,000 in 2002 to 80.2 cases/100,000 in 2018, while the notification rates of gonorrhea and syphilis increased to a lesser extent.

A similar increase is observed in the test intensity for chlamydia and for gonorrhea, (except in 2015 where the testing rate of gonorrhea evolved faster than the reported rate of the cases). These similar evolutions in both the testing rates and the reported infections suggest that the apparent rise in reported cases could be a consequence of an intensified testing rather than an increase in incidence. Indeed, for chlamydia infection, it is generally accepted that the actual incidence has remained stable over time. Also for gonorrhea, the incidence does not seem to have increased at the level of the general population. However, additional information provided by the STI clinical network suggests that unsafe sexual practices have become more common in certain population groups (especially MSM), leading to a focused increase in the incidence and reinfections with gonorrhea and syphilis in this group.

5. Read more

View the metadata for HIV

View the metadata for STI

Sciensano: HIV/AIDS surveillance

Sciensano: STI surveillance

Sciensano Epistat: Determinants of Sexually Transmitted Infections 

Definitions

HIV/AIDS
HIV infection and AIDS are the acronyms of "Human Immunodeficiency Virus" (HIV) infection and "Acquired Immune Deficiency Syndrome" (AIDS). Initial HIV infection is most often asymptomatic, while people may experience influenza-like symptoms. This is followed by a prolonged period with no symptoms. If the infection progresses, it interferes more with the immune system, increasing the risk of developing infections such as tuberculosis, as well as other opportunistic infections, and tumors which are rare in people who have normal immune function. These late symptoms of infection are referred to as AIDS. Since the late 1990s, efficient antiretroviral treatment exists that can slow down the progression of the disease.

References

[1] Epidémiologie du SIDA et de l’infection à VIH en Belgique. Situation au 31 décembre 2018. Brussels: Sciensano; 2019. https://doi.org/10.25608/k6sn-n789

[2] European Centre for Disease Prevention and Control. HIV Modelling Tool. 2015. https://www.ecdc.europa.eu/en/publications-data/hiv-modelling-tool

[3] European Centre for Disease Prevention and Control/WHO Regional Office for Europe. HIV/AIDS surveillance in Europe 2019 – 2018 data. Stockholm: ECDC; 2019. https://www.ecdc.europa.eu/sites/default/files/documents/HIV-annual-surveillance-report-2019.pdf

[4] Surveillance des infections sexuellement transmissibles. Données pour la période 2014-2016. Brussels: Sciensano; 2020. https://www.sciensano.be/sites/www.wiv-isp.be/files/surv_sti_1416_fr.pdf

Influenza and influenza-like illness

1. Key messages

On average, around 600,000 people are affected by influenza-like illness (ILI) each year in Belgium, i.e., about 5% of the total population. About 50-60% of these cases are actual influenza cases.
While ILI is in most cases a benign illness, about 2% to 3% of influenza cases require hospitalization. Of the hospitalized cases, 13% develop severe complications, including 6% who die in the course of hospital stay; usually more than 80% of these deaths occur in people of 65 years and over.
The Belgian flu epidemic of the 2018-2019 season lasted 8 weeks, which was average compared to previous seasons. An estimated 506,000 Belgians consulted their GP for flu-like symptoms. The severity indicators indicated that this flu epidemic was relatively no more serious than in previous seasons.

2. Background

Influenza-like illness (ILI) is a medical diagnosis of possible influenza or other illness causing a set of symptoms. These symptoms commonly include fever, shivering, chills, malaise, dry cough, loss of appetite, body aches, and nausea, typically in connection with a sudden onset of illness. In most cases ILI is a benign illness, but for elderly people, pregnant women and people with chronic diseases, the complications of flu can be dangerous.

ILI is caused by a variety of respiratory pathogens, including, amongst others, influenza virus, parainfluenza virus, adenovirus, RSV, and Mycoplasma pneumoniae. The influenza A(H1N1) and A(H3N2) viruses as well as the influenza B virus are the cause of seasonal influenza epidemics in Belgium and circulate every year to different extents. Vaccination remains the best way of preventing transmission, complications and hospitalization of flu.

Sciensano coordinates sentinel networks of general practitioners and hospitals to ensure the permanent surveillance of ILI and influenza activity, intensity and severity of epidemics and impact on the population. The epidemic threshold is the minimum number of GP consultations for flu-like symptoms per 100,000 inhabitants per week needed to officially speak of an epidemic. This number is calculated by the European Centre for Disease prevention and Control (ECDC), and varied between 135 and 157 GP visits/100,000 inhabitants over the last 5 years. Sciensano also hosts the National Reference Centre (NRC) for influenza virus.

At the international level, influenza surveillance and pandemic preparedness is coordinated by ECDC and the World Health Organization.

3. ILI season 2018-19

Incidence

The Belgian flu epidemic of the 2018-2019 season lasted 8 weeks, which was average compared to previous seasons. The epidemiological threshold was exceeded from week 4/2019 (January 21 to January 27, 2019) to week 11/2019 (March 11 until March 17, 2019). The epidemic was of medium activity.

Number of GP visits for flu-like symptoms per 100,000 inhabitants, Belgium, 2014-19
Source: Sciensano Sentinel GP Network [1]

From week 40/2018 to week 18/2019, respiratory samples from patients diagnosed with ILI were collected by the sentinel network of general practitioners and analyzed at the National Influenza Center. Of these samples, 53% were positive for influenza viruses.

Based on surveillance through the sentinel network of general practitioners, it was estimated that about 506,000 Belgians consulted their GP for flu-like symptoms and, if they were all systematically tested, about 307,000 of them would actually be infected with the flu virus.

All age groups were affected at the approximately same weeks during the epidemic, with peak incidences in weeks 7/2019 and 8/2019.

Number of GP visits for flu-like symptoms per 100,000 inhabitants, by age, Belgium, 2018-19
Source: Sciensano Sentinel GP Network [1]

Severity

Although there were many hospital admissions for a severe acute respiratory tract infection (SARI) during this intense season, the severity indicators of the confirmed flu cases (estimated through the network of 6 sentinel hospitals) indicated that this flu epidemic was relatively no more serious than in previous seasons.

The average length of stay for a serious flu infection during this season was 8.8 days (varying in age from 3.6 days in the age of 0-4 to 13.3 days in persons aged 85 years and older). This is comparable to the other seasons.

About 2% to 3% of people with influenza were hospitalized. Among those, 13% had serious complications, which were fatal in 6% of hospitalized patients; these indicators are however similar to those observed in the previous seasons. The vast majority of patients who suffered from severe complications had pre-existing comorbidity (91%).

Deaths were only observed in people aged 54 and over and 90% of these deaths were in patients with one or more comorbidities. The median age of death of patients without comorbidities was 87 years (range: 71-90 years) and the median age of death of patients with comorbidities was 79 years (range: 54-97 years).

International comparison

The observations in Belgium were in line with those in the rest of Europe.

At European level, influenza activity started in week 49/2018, peaked in week 7/2019 and returned to baseline levels in week 17/2019. Influenza viruses started circulating at high levels in week 52/2018 until week 12/2019.

Intensive care unit (ICU) cases were mainly aged 65 years and older, but in certain countries there was a substantial number of hospitalizations in persons aged 40–64 years.

Influenza intensity reported during the 2018-19 season, Europe
Source: European Centre for Disease Prevention and Control [2]

4. Comparison of the last ILI seasons

Incidence

Each year, between 300,000 and 900,000 people visit their GP because of influenza-like illness in Belgium. Among these, the annual number of influenza infections is estimated between 116,000 and 472,000.

Number of GP visits for influenza-like illness by age, Belgium, 2008-19
Source: Sciensano Sentinel GP Network [1]

Severity

Since 2012, between 11% and 15% of patient hospitalized with a confirmed influenza infection have developed severe complications, including 4% to 9% who have died in the course of hospital stay.

Severity indicators in patients with confirmed influenza infection, Belgium, 2011-19
Source: Sciensano network of sentinel hospitals [1]

5. Read more

View the metadata for this indicator

Influenza monitoring

Results of the surveillance of influenza and influenza-like illness in Belgium

Laboratory surveillance of influenza in Belgium

Definitions

Influenza-like illness (ILI)
ILI can be caused by a variety of microbial agents other than influenza viruses. Influenza infection causes a clinical syndrome not easily distinguished from other respiratory infections. ILI is defined by the World Health Organization as an acute respiratory infection with: measured fever of ≥ 38 C°; and cough; with onset within the last 10 days.
Severe acute respiratory tract infection (SARI)
SARI is defined by the World Health Organization as an acute respiratory infection with: history of fever or measured fever of ≥ 38 C°; and cough; with onset within the last 10 days; and requires hospitalization. The SARI definition aims to capture both the influenza-related pneumonias and influenza-related exacerbations of chronic illnesses such as asthma or heart disease.

References

  1. Bossuyt N, Bustos Sierra N, Thomas I, Barbezange C. Surveillance of influenza-like illness in season 2018-2019. Brussels: Sciensano; 2020. Available from https://epidemio.wiv-isp.be/ID/diseases/Pages/Influenza.aspx.
  2. Infographic: Influenza in Europe, Season 2018-2019. Stockholm: ECDC; 2019. Available from https://www.ecdc.europa.eu/en/publications-data/infographic-influenza-europe-season-2018-2019