The number of pertussis cases in Austria and many European countries rose massively in 2024, even in countries with high vaccination coverage rates. We presented details on this in the AGES Radar from 28/03/2024.

While 2,791 cases were reported in Austria in the previous year as a whole, there have been 13,441 cases of pertussis so far this year (as of 29 October 2024). The cases per 100,000 inhabitants for each province for 2024 are shown in Figure 1. The age distribution (Figure 2) shows how young children are particularly affected.

Even with a high vaccination rate, illnesses must be expected. The primary purpose of vaccination is to protect infants and young children from a severe course and death, as high vaccination coverage rates also protect non-immune individuals. This includes infants before the age of 3 months, who cannot yet be immunised and have a particularly high risk of a severe, potentially fatal, course of the disease.

The vaccination is included in the free vaccination programme for children in Austria. Due to the current situation, the vaccination schedule has been changed: The new vaccination schedule from 1 October 2024 states: 'The vaccination ... is vaccinated as part of the 6-fold vaccination according to the 2+1 schedule in the 3rd, 5th and 11th-12th month of life. Due to the frequent occurrence of whooping cough and its severe course in infancy, the vaccination series should be started as early as possible, i.e. immediately on completion of the 2nd month of life. Due to the current epidemiological situation, the first booster vaccination should be given at the age of 6 (from the age of 5). The booster vaccination should preferably be given before starting school ... " The 2nd booster vaccination is currently recommended five years after the 1st booster vaccination, but at the latest at the age of 14 or 15. Thereafter, booster vaccinations against whooping cough are currently recommended every five years.

In order to protect infants in the first months of life, pregnant women in particular are advised to be vaccinated in the last trimester of pregnancy, regardless of the interval between the last pertussis vaccination. This gives newborn babies protection through maternal antibodies.

Further information on the pertussis vaccination can be found in the vaccination plan Austria 2023/2024 version 2.0 (sozialministerium.at).

Whooping cough (pertussis) - AGES

On 19 August, a cluster of cases caused by Salmonella Umbilo was reported in Germany. Within a few weeks, further cases occurred in eight European countries. In the case of foodborne outbreaks, it is crucial to find the source as quickly as possible in order to remove the contaminated food from circulation. AGES employees played a key role in this outbreak investigation and were ultimately able to detect the outbreak strain of Salmonella Umbilo in rocket.

Between July and September, 19 cases occurred in Austria and two people had to be hospitalised. All 19 were questioned about their food consumption in order to trace the source of the infection. Thanks to the excellent cooperation with food authorities in Austria, Salmonella Umbilo was detected in two rocket samples on 20 September. The distribution channels were traced and control measures were immediately initiated at the manufacturer in Italy to withdraw the goods from circulation. There have been no new cases in Austria since mid-September and the outbreak is considered to have been clarified.

Salmonella - AGES

World Polio Day is held annually on 24 October to raise awareness of the disease poliomyelitis (polio) and to remind people that the declared goal of eradicating poliomyelitis worldwide can only be achieved with further global vaccination efforts.

A disease with a history

Poliomyelitis (polio for short) is an infectious disease that was widespread throughout the world and probably first appeared in ancient Egypt. In its full form, the disease is accompanied by acute flaccid paralysis, which can lead to death. Before the first vaccination was introduced in 1955, it was so widespread, particularly under poor hygienic conditions, that the disease was already present in early childhood, hence the name "polio". Until the middle of the 20th century, polio was responsible for an estimated half a million deaths per year, and this pandemic could only be stopped by the introduction of vaccination. As the vaccines are very effective and humans are the only reservoir for the virus, it is in principle possible to eradicate the disease. In the 1980s, the WHO set the goal of completely eliminating poliomyelitis. Thanks to international vaccination programmes, this has almost been achieved: While there were still more than 350,000 cases worldwide in 1988, there were only twelve cases in 2023 and 54 so far in 2024. These have all occurred in Afghanistan and Pakistan - the last two countries where polio is still endemic. Apart from the Asian continent, all other continents are considered polio-free (Europe, for example, since 2002). Two of the three wild strains have also been completely eradicated. However, inadequate immunisation rates, partly due to the increased occurrence of hotspots and vaccination fatigue observed in some countries, are jeopardising this success.

Polioviruses

Poliomyelitis is caused by polioviruses 1-3 (wild type), which belong to class C of the enteroviruses. They are highly infectious and very resistant to environmental influences, including common disinfectants. They are only found in the nasopharynx or intestinal tract of humans and their peak season is in the warmer months. They are mainly transmitted directly from person to person, for example via contaminated hands of infected people. However, indirect transmission via contaminated surfaces (utensils) or contaminated drinking/bathing water is also possible. The viruses are absorbed via the mucous membranes of the respiratory tract or the digestive tract. Infected persons can excrete the viruses in their faeces for weeks and thus represent a source of infection.

Disease

The majority of infections (>90 %) are asymptomatic. Otherwise, after an incubation period of approx. one week (3-35 days), various forms of the disease can develop: From symptoms of a mild flu-like infection ("abortive poliomyelitis"), to meningitis ("non-paralytic poliomyelitis"), in less than one per cent it progresses to the full-blown "paralytic poliomyelitis". This is accompanied by acute symptoms of flaccid paralysis, which primarily affect the legs, but also the arms, abdomen or chest, including the respiratory muscles. These paralyses only partially recover. Severe paralysis of the respiratory system or the heart can lead to death. Even years after falling ill, the symptoms can increase again, known as "post-polio syndrome".
There is no causal therapy available for poliomyelitis; treatment is purely symptomatic. Long rehabilitation programmes are often necessary, and if the respiratory muscles are affected, patients may have to be ventilated. The most effective measure to prevent the disease is and remains vaccination.

Vaccination

Two different polio vaccines have been available since 1955 and 1960 respectively - an inactivated polio vaccine (IPV or Salk vaccine) and a live vaccine (oral polio vaccine, OPV or Sabin vaccine). IPV is used in many countries where polio no longer occurs. This vaccine is safe and effective, providing almost 100 per cent protection against the disease after two vaccinations. However, after vaccination with IPV, people are not protected against becoming infected with polioviruses (without falling ill) and excreting them. In Austria, IPV is included in the free vaccination programme, infants should receive three partial vaccinations, followed by two booster vaccinations (see Pertussis). Thereafter, further booster immunisations against polio are only recommended if indicated.
In contrast to IPV, OPV can be administered as an oral vaccine and is therefore used where large areas need to be immunised quickly and cheaply, including in areas that are difficult to reach or where few resources are available.

Is polio back?

In addition to outbreaks with the wild poliovirus, which mainly occur in Afghanistan and Pakistan, there may be outbreaks with mutated vaccine strains, which have become increasingly important in recent years. The virus strain from the OPV that has been rendered harmless can re-mutate and thus regain its ability to cause poliomyelitis. For this to happen, however, there must be enough susceptible, i.e. non-immune, individuals in whom the virus can circulate and mutate. This is particularly problematic in populations with low immunisation rates. The majority of polio cases worldwide are now caused by such strains, with several hundred per year in 2018-2023, mainly affecting parts of Africa and Indonesia. Due to the emergence of vaccination gaps, there is a risk of such outbreaks in all parts of the world. This worrying development has recently become clear time and again: in order to recognise the circulation of vaccine-derived strains at an early stage, wastewater is regularly screened in many parts of the world. In the Gaza Strip, samples repeatedly tested positive in 2024, and in August an unvaccinated infant contracted polio. In New York, one hundred wastewater samples tested positive for polio in 2022, and in the same year the first case of polio with a mutated vaccine strain occurred there since the OPV was discontinued. Europe is also affected; for example, a positive wastewater sample was discovered in Spain for the first time this year on 16 September, but no case of the disease has yet been reported.

Situation in Austria

Polio is a notifiable disease in Austria, and doctors are also obliged to report acute flaccid paralysis in children and to test these patients for polioviruses. In Austria, the last case of poliomyelitis caused by a wild strain occurred in 1980; as part of the refugee screening programme, mutated vaccine strains were occasionally detected in asymptomatic people in 2013-2015, but there have been no outbreaks to date. In order to prevent polio from circulating again in Austria, the aim is to achieve a 95% immunisation coverage rate for 1-year-olds (as is the case worldwide). Although this was achieved in Austria in 2023, this has not always been the case in recent years. Among other things, the COVID-19 pandemic has led to significant vaccination gaps. The vaccination coverage rate for booster vaccinations from primary school age is lower. It is estimated that 48,000 children aged 2-4 were not sufficiently protected against polio in 2023; among 10-16-year-old children, the figure was 79,500.

There is therefore a global risk, including in Austria, that poliomyelitis could be reintroduced and spread further - a disease that could have been eradicated long ago. To prevent this, targeted measures to increase the vaccination coverage rate are absolutely necessary in addition to ongoing surveillance.

Polio - AGES

World Polio Day (who.int)

The mild temperatures in autumn may contribute to a second peak in activity of Ixodes ticks, and if climatic conditions are favourable, this second wave may extend into December in Austria.

Climate change is influencing the vector landscape in Austria. The OH SURVector (One Health surveillance and Vector monitoring for cross-border pathogens) project focuses on monitoring programmes for mosquitoes and ticks. Due to milder winters and hotter summers, the annual occurrence of different tick species is also influenced and ticks can now be found in almost every month. This year, the first Ixodes ricinus tick("wood tick") was spotted in January, a month that is normally too cold for this tick species to find a host.

As part of a current research project, an Austria-wide tick monitoring programme is being set up. The Austrian population plays an essential role in this: they are called upon to send any ticks they find to AGES (by handing them in at AGES sites or sending them in). This allows data to be generated for the various regions of Austria.

As of 25.10.2024, a total of 1,221 ticks were analysed microscopically. The majority of ticks belonged to the genus Ixodes (common wood tick) (84.82 %), followed by Dermacentor ticks(alluvial tick) (12.64 %), Haemaphysalis ticks(relict tick) (1.78 %) and other tick species (0.76 %).

1,035 ticks have been tested for Borrelia so far. Of these, a total of 22.13 % were positive. The human-relevant Ixodes ticks showed an infection rate of 24.9 % - almost one in four ticks carries Borrelia.

In 2024, we received eleven reports from the population that we were able to confirm as Hyalomma ticks. The majority of these ticks were introduced from Croatia. Eight of these ticks have so far been sent to us for analysis and tested for Crimean-Congo haemorrhagic fever virus (CCHFV) and rickettsiae. CCHFV was not detected in any of them, but three (37.5 %) were positive for Rickettsia aeschlimannii.

If you discover a tick or two in the near future, please remember the project. Important: please indicate where you found them, otherwise the ticks cannot be utilised. You can find more information about the project and how to take part at Tick information - AGES.