AGES radar for infectious diseases - 25/04/2024


The flu epidemic of the 2023/24 season is over, and COVID-19 and RSV are hardly detected anymore. In this issue, we summarise the season of the most important respiratory infectious diseases.

The measles outbreak in Austria continues, although activity has continued to decline over the last four weeks. Since the last issue of the radar, 24 new cases have been recorded in the epidemiological reporting system. As of 21 May 2024, 425 cases have been reported for the current year. All federal states except Carinthia are affected.

The number of pertussis cases in Europe and also in Austria continues to rise, and there is a particular health risk for the vulnerable group of infants aged 0 to 6 months.

This month's topic is Campylobacter, the most common trigger of food-borne outbreaks. Especially in the barbecue season, infections can be prevented with consistent kitchen hygiene.

Studies provide new insights into avian influenza in the USA.

Situation in Austria

In the second half of 2023, there was an increase in the SARS-CoV-2 viral load in wastewater monitoring, which culminated in an all-time high in mid-December. This increase in SARS-CoV-2 detections in wastewater was followed by a rapid decline. From February 2024, the virus was only detected to a small extent. A similar trend was observed in inpatient hospital admissions: after peaking in mid-December with 1,501 COVID-19 admissions to normal wards, there was a decline to the level of September 2023 within a month.

From autumn 2023 to spring 2024, the BA.2.86 variant prevailed and has accounted for the majority of SARS-CoV-2 samples sequenced by AGES in Austria since December 2023. The samples sequenced in recent weeks could only be assigned to the BA.2.86 daughter line JN.1. However, due to the low number of cases, only very few samples have been genetically analysed recently.

Coronavirus - AGES

The diagnostic influenza network DINÖ announced the end of the seasonal flu epidemic at the beginning of April. The estimated number of influenza and influenza-like illnesses has also returned to the low level of the start of the season in calendar week 40.

Compared to the 2022/23 season, the DINÖ registered a lower number of influenza cases in the current 2023/24 flu season. At the peak in early February, around 650 samples tested positive for influenza in one week. In the 2022/23 season, the peak occurred in December with over 1,200 influenza-positive samples in one week.

Hospital adm issions peaked in the first week of February with 631 admissions to normal wards. In the first week of May, only nine admissions to normal wards were recorded.

There was no wave of influenza B this year.

Influenza - AGES

Since mid-April 2024, none of the sentinel samples in the sentinel system of the Austrian RSV network have tested positive for respiratory syncytial virus.

The RSV wave started later in the current 2023/24 season than in the comparative year 2022/23. The number of laboratory-confirmed cases was also lower at just over 200 detections in one week at the peak at the end of January 2024 compared to just under 350 detections at the peak of the 2022/23 season.

Hospital admissions peaked at the beginning of February. No RSV-related admissions to intensive care units have been recorded since mid-April (as at 22 May 2024).

The majority of patients admitted were infants and young children aged 0 to 4 years.

Further information on the RSV vaccination can be found at Vaccination plan Austria 2023/2024 (


As of 21 May 2024, 425 confirmed cases have been reported in Austria for the current year, compared to 186 for the whole of 2023.

Who is infected?

The highest incidence rates are found in infants and in the 10 to 14 age group. Most cases have been reported so far this year in Lower Austria (105), Tyrol (85), Vienna (62) and Styria (53). In 2024, 79 (18.9%) of the 418 cases with relevant information have so far been registered as hospitalised, four of them in intensive care.

Of the 282 cases with information on vaccination status, 254 (90.1 %) were unvaccinated, eleven (3.9 %) had received a post-exposure vaccination, three (1.1 %) people had been vaccinated once and 14 (5 %) had been vaccinated twice against measles according to the documentation.

Measles is a highly contagious viral disease. Infections are characterised by flu-like symptoms with a high fever and a characteristic skin rash. Life-threatening complications such as inflammation of the lungs and brain can occur.

The combined vaccination against measles, mumps and rubella (MMR) offers long-lasting protection against severe courses and secondary diseases. Missed vaccinations against measles can and should be caught up on as soon as possible at any age. In order to protect infants who are still too young to be vaccinated but who are at a higher risk of a severe course and complications of a measles infection, it is crucial that the entire environment is immune. If older siblings have been vaccinated twice, it is extremely unlikely that they will bring the virus home with them, for example from school or kindergarten.

Further information on the measles-mumps-rubella vaccination can be found in the Austria 2023/2024 vaccination plan (

Measles - AGES

International outbreaks

The transmission of SARS-CoV-2 began to rise in late summer, with a significant increase observed up to calendar week 49. SARS-CoV-2 activity then declined again. The same process was observed for severe COVID-19 cases, which have been on a steady decline since calendar week 50. COVID-19 mainly affected people aged 65 and over. Activity is currently low in most EU/EEA countries.

In the course of the 2023/24 season, BA.2.86 and especially its subline JN.1* have prevailed and displaced XBB.1.5 variants.

You can find more detailed information on the international and Austrian variant situation at: Coronavirus - AGES

Mid-December marked the beginning of the seasonal flu epidemic. From the end of January 2024, a downward trend in influenza activity was observed. Compared to the trends of previous flu waves, seasonal influenza activity declined earlier this season. Severe influenza-related illnesses affected all age groups. Both type A and type B influenza viruses were detected. The A(H1)pdm09 viruses dominated in the first part of the season; from the end of March 2024, the B/Victoria lineage was detected more frequently, albeit to a very small extent overall.

RSV activity began to increase in October and peaked in mid-December. RSV had the greatest impact on children aged 0 to 4 years.

Communicable disease threats report, 28 April - 4 May 2024, week 18 (

From 2023 to April 2024 inclusive, the number of pertussis cases increased tenfold compared to 2021 and 2022: almost 60,000 infections were reported in the EU/EEA.

According to the ECDC, there are several reasons for this sharp increase: Pertussis generally occurs in waves, with peaks every three to five years; the COVID-19 pandemic had an impact on the incidence of infection due to infection control measures, but also contributed to the fact that vaccination programmes could not be carried out.

Severe cases mainly affect infants under six months of age. Five children have already died in the UK in 2024. The aim of vaccination against pertussis is generally to protect this vulnerable group.

In Austria, 4,943 cases have been reported so far in 2024 (as of 20 May 2024).

The vaccination is included in the free vaccination programme in Austria. Basic immunisation in infants should be refreshed at school age. Thereafter, the vaccination should also be regularly boostered in adulthood to maintain immunisation protection. The pertussis vaccination is recommended for everyone.

In order to protect infants in the first months of life, pregnant women in the third trimester in particular are recommended to be vaccinated, regardless of the interval between the last pertussis vaccination.

Further information on the pertussis vaccination can be found in the Austria 2023/2024 vaccination plan (


Avian influenza in dairy cows - USA

As of 22 May 2024, the US Department for Agriculture (USDA) has confirmed 49 cases of highly pathogenic avian influenza (HPAI) in dairy cows in nine US states . Since the publication of the 8th edition of the AGES Infectious Disease Radar on 25 April 2024, in which we discussed avian influenza in the Topic of the Month, 14 new cases have been reported in cows, including two in Colorado for the first time.

In addition, on 22 May 2024, the second human avian influenza case in the USA was confirmed in connection with the current outbreak in dairy cows. As with the first case, this was a worker on a dairy farm, this time in the state of Michigan. As with the first confirmed case, the patient has conjunctivitis.

A report published at the beginning of May by researchers from the USDA, among others, shows that the virus has been circulating in cows since December 2023. Genomic analyses and epidemiological studies indicate that the current outbreak is likely to be based on a single transmission from a wild bird to a cow. The jump to cattle was made possible by a mixing or redistribution of genetic information within the avian influenza virus strains, technically known as a "reassortment event". The transport of asymptomatic cattle across the US may have subsequently played a role in the spread of the HPAI virus in the country's dairy herds.

Another study found that both avian and human influenza A virus receptors can be found in the mammary glands of cows. This means that cows are susceptible to the virus at this point. This explains the high levels of H5N1 viruses in the milk of infected cows. Due to the combination of avian and human influenza A virus receptors in their mammary glands, dairy cows would have the potential to act as a "mixing vessel" for new AI virus variants.

Both studies still have to undergo an evaluation by independent experts, the peer-reviewing process.

A possible infection of cattle with the HPAI virus through the feeding of by-products from poultry farming (e.g. litter, faeces, scattered feed) is also being discussed. The American Feed Industry Association (AFIA) issued a statement in early May denying this possibility.

US health authorities currently consider the risk to the general population to be low (as of 8 May 2024). The situation is being closely monitored, sampling along the food chain and testing of cattle and contact persons is being carried out. The virus genome has been detected in samples of pasteurised milk from retail outlets. The viruses are no longer infectious after pasteurisation. The FDA and CDC advise against the consumption of raw milk. The HPAI virus was also detected in the lung tissue of an asymptomatic cow from an affected herd. No virus has yet been detected in commercial meat samples. A study by the USDA showed that heating meat to 60 to 70 degrees Celsius (145 to 160 degrees Fahrenheit) kills the virus.

There are no cases of AI in cattle in Europe. The number of reported outbreaks in birds and poultry in Europe is currently the lowest it has been since 2020. In order to reduce pathogens in general, it is recommended to adhere to the basic rules of kitchen hygiene, to heat meat and eggs sufficiently and not to consume raw milk: Cook safely - AGES

Further information on avian influenza in Austria can be found in the Animal Disease Radar.

H5N1 Bird Flu: Current Situation Summary | Avian Influenza (Flu) (

Hepatitis E

In its "Disease Outbreak News" of 8 May 2024, the WHO reports a hepatitis E outbreak in the eastern province of Ouaddai in Chad, Central Africa. Many people from Sudan have fled to the province of Ouaddai since April 2023. Between 2 January and 28 April 2024, a total of 2,092 suspected cases of hepatitis E were reported, including seven deaths. The age groups most affected are 6 to 17 years (53.2% of all cases) and 18 to 59 years (23.9% of all cases). Most cases are reported in the André district, where three refugee camps and a temporary refugee centre have been set up to accommodate around 300,000 people. Limited access to clean drinking water and inadequate sanitary facilities and hygiene increase the risk of hepatitis E outbreaks. The WHO considers the risk to be high at a national level and low at a global level.

In Austria, the situation is not comparable with the current outbreak in Chad or serious outbreaks in South East and Central Asia, the Middle East and Mexico, among others. In industrialised countries, including Austria, hepatitis E is mainly transmitted through the consumption of undercooked pork or game meat. In Europe, hepatitis E is mainly caused by genotype 3, while genotypes 1 and 2 are predominant in African countries.(RKI, status: 17/05/2024)

In Austria, 63 cases of hepatitis E were reported in 2023 and 20 cases have been identified so far in 2024 (as of 21 May 2024).

Hepatitis E - Chad (

Topic of the month

The barbecue season is open and guests are chatting about recipes, the weather, other guests and often about the barbecue itself over gas, coal and wood flames. Should you pour beer over the meat, do professionals only grill with a lid and how raw should the steak be?

Food hygiene rarely makes it onto the list of popular small talk topics. Yet food-borne illnesses are in high season during the warmer months. One reason for this is bacteria of the genus Campylobacter. They are among the most important pathogens of bacterial intestinal infections in humans and can cause mild to severe diarrhoea. They usually make their appearance at barbecues thanks to poultry meat. Around 6,000 infections are reported in Austria every year, with 1,881 reported so far in 2024 (as of 21 May 2024).

Safely through the barbecue season

This does not mean you have to give up poultry, but it is a good reason to adhere to hygiene rules. It is important to heat potentially contaminated food sufficiently and prevent cross-contamination.

Cross-contamination is the unintentional transfer of bacteria or other microorganisms from one substance or object to another. In the area of food safety, this refers to the transfer of harmful bacteria, such as Campylobacter, usually from raw meat to ready-to-eat foods such as salads, fruit and already cooked dishes. This is the reason why chicken meat should not be washed before preparation: Washing runs the risk of spreading the germs over a wide area and ultimately ending up on other foods. The bacteria are reliably killed by the heat during preparation, so it is not necessary to wash the meat.

Good kitchen hygiene also includes cleaning hands, utensils and work surfaces with hot water and soap after coming into contact with raw meat. Especially during the barbecue season, avoiding cross-contamination is crucial to prevent foodborne illnesses.

A special feature of Campylobacter is that even very small amounts of germs are sufficient to cause an infection in humans: 500 germs are enough, and up to 10,000 germs can be detected on one gram of poultry skin alone. Accordingly, poultry should be handled cleanly.

Here are some key tips on hygiene practices to significantly reduce the risk of foodborne illnesses at home:

  • Hand washing: Wash your hands with soap and water before and after touching raw food.
  • Separate utensils and surfaces: Use separate cutting boards and knives for raw and ready-to-eat foods.
  • Correct storage: Store raw and ready-to-eat food separately, preferably in sealed containers.
  • Cooking temperatures: Ensure that poultry is brought to the correct internal temperature (at least 70 degrees Celsius) - a thermometer is helpful here.
  • Cleanliness: Clean and disinfect kitchen surfaces, grills and utensils regularly.

The seasonality of foodborne illnesses

The number of food-borne infections increases in the warmer months of the year. Many bacteria thrive better at high temperatures. This is particularly true for Campylobacter. They hardly multiply at temperatures below 30 degrees Celsius, so they do not multiply in food either - unlike salmonella. When it gets really warm, the bacterial load in broiler chickens increases and so the risk of humans catching diarrhoea from contaminated meat also increases.

Rare dangerous cases

Campylobacteriosis is not always harmless. In rare cases, the disease can trigger reactive arthritis or lead to Guillain-Barré syndrome.

Eight deaths occurred in Austria in 2023.

Campylobacter - AGES

World Food Safety Day 2024 (


The 2023 annual report on Clostridioides(C.) difficile was published by the National Reference Centre on 23.05.2024. C . difficile is a bacterium that can colonise the intestinal tract under certain circumstances and produce toxins there. It is therefore partly responsible for the majority of severe diarrhoeal diseases following antibiotic administration. In 2023, a total of 136 C. difficile samples were sent to the reference centre. At the same time, 511 severe C. difficile infections (CDI) were reported in Austria via the electronic reporting system; three CDIs were fatal.

The most frequently isolated PCR ribotype in Austria in 2023 was strain 014, which was already the most frequently detected strain in the years 2019 to 2021. The highly virulent PCR ribotype 027 was found in four (3.6%) of 112 isolates. Ribotype 955, which was recently discovered in the UK and is also classified as highly virulent, has not yet been detected in any of the samples submitted in Austria.

Clostridioides difficile - AGES

In April, the Cochrane Scientific Network published a review in which the release of Wolbachia-infected mosquitoes was examined as a strategy to combat dengue fever. The study concluded that this approach could help to reduce dengue cases.

Mosquitoes infected with the Wolbachia bacterium are largely immune to dengue and other viruses, which also reduces the likelihood of transmission to humans. Since the use of insecticides and the drying out of breeding waters have only had and continue to have a limited effect on mosquito density, a new approach is the release of mosquitoes artificially infected with Wolbachia (more on this project in the AGES Radar of 30 November 2023). A methodologically high-quality study from Indonesia found that people living in areas where Wolbachia-infected Aedes mosquitoes have been released have a significantly lower risk of contracting dengue than people living in areas where such mosquitoes have not been released.

One limitation of the evidence is that only one completed study is available so far and it is therefore not clear whether the results are also valid for other areas and countries. Further studies on this topic are already in progress.

Can dengue fever be controlled by releasing more mosquitoes? | Cochrane Germany

Wolbachia-carrying Aedes mosquitoes for the prevention of dengue infection - Fox, T - 2024 | Cochrane Library

World Hand Hygiene Day was held on 5 May. This has been held annually since 2009 under the motto "SAVE LIVES: Clean Your Hands". The campaign is primarily aimed at people who work in the healthcare sector. Maintaining hand hygiene can protect patients and healthcare staff from pathogens and plays a key role in the fight against antimicrobial resistance.

World Hand Hygiene Day (

World Hand Hygiene Day 2024 (

World Hand Hygiene Day 2024 (

Technical term epidemiology

The term has been used frequently during the COVID-19 pandemic and simply means "containment". In epidemiology, it refers to the strategy of isolating areas or processes with an increased risk potential at an early stage. This is intended to prevent an infection from spreading from its source or to contain its further spread.

Containment can be attempted through a variety of demarcation and barrier measures: Contact tracing and isolation of those affected are just as much a part of this as travel restrictions or lockdown vaccinations. Unprotected people in the vicinity of an outbreak are offered a vaccination as quickly as possible in order to stop the further spread of the infection.


About the radar

The AGES Radar for Infectious Diseases is published monthly. The aim is to provide the interested public with a quick overview of current infectious diseases in Austria and the world. The diseases are briefly described, the current situation is described and, where appropriate and possible, the risk is assessed. Links lead to more detailed information. The "Topic of the month" takes a closer look at one aspect of infectious diseases.

How is the AGES radar for infectious diseases compiled?

Who: The radar is a co-operation between the AGES divisions "Public Health" and Risk Communication.

What: Outbreaks and situation assessments of infectious diseases:

  • National: Based on data from the Epidemiological Reporting System (EMS), outbreak investigation and regular reports from AGES and the reference laboratories
  • International: Based on structured research
  • Topic of the week (annual planning)
  • Reports on scientific publications and events

Further sources:

Acute infectious respiratory diseases occur more frequently in the cold season, including COVID-19, influenza and RSV. These diseases are monitored via various systems, such as the Diagnostic Influenza Network Austria (DINÖ), the ILI (Influenza-like Illness) sentinel system and the Austrian RSV Network (ÖRSN). The situation in hospitals is recorded via the SARI (Severe Acute Respiratory Illness) dashboard.

Austrian laboratories send SARS-CoV-2 samples to AGES for sequencing. The sequencing results are regularly published on the AGES website.

For the international reports, health organisations (WHO, ECDC, CDC, ...) specialist media, international press, newsletters and social media are monitored on a route-by-route basis.

For infectious diseases in Austria, the situation is assessed by AGES experts, as well as for international outbreaks for which no WHO or ECDC assessment is available.

Disclaimer: The topics are selected according to editorial criteria, there is no claim to completeness.

Suggestions and questions

As the response to enquiries is also coordinated between all parties involved (knowledge management, INFE, risk communication), please be patient. A reply will be sent within one week.

The next AGES-Radar will be published on 23 May 2024.

Last updated: 24.05.2024

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