No 1/2 - 2018

Infectious diseases 2017

The childhood vaccination programme

In 2017, the coverage of the childhood vaccination programme rose to a historically high level. According to the latest report, 96% of all children born in 2016 have received the first vaccine of the childhood vaccination programme (DTaP-IPV/Hib), and the coverage of the initial MMR vaccination for children born in 2014 and 2015 has reached 92%. The cause of this increase may, in part, be owed to the lively public debate on the childhood vaccination programme, including the debate on the ethical issues associated with not having your children vaccinated. Additionally, Statens Serum Institut sends out reminders for parents informing them of any lacking vaccination of their children. It has been shown that the reminders - which are now sent out via e-Boks, EPI-NEWS 5/17 - produce a 4-5 percentage point increase in the coverage of the 4-year and 5-year vaccinations. Finally, correct registration of vaccinations in the Danish Vaccination Register has undoubtedly gained attention in the minds of stakeholders, thereby reducing any previous under-registration.

2017 was also the year when the WHO declared that measles had been eliminated in Denmark, EPI-NEWS 37/17. Elimination implies that we have been able to document that there has been no persistent circulation of measles virus in Denmark during the past 3 years. The definition does not exclude that limited further transmission from imported cases may occur. Thus, 2017 recorded four cases of measles in Denmark. Virological examination of the measles gene showed that the infection had originated abroad and no further transmission was detected in Denmark.
Thus, Denmark now belongs to the 42 European countries (from a total of 53) that have no endemic transmission of measles. Nevertheless, Europe still has quite a distance to go before measles is eliminated; in 2017, Europe experienced several major measles outbreaks with extensive transmission in countries like Germany, Italy, Belgium and Romania, EPI-NEWS 23/17.

The coverage of the HPV vaccination also increased in 2017, EPI-NEWS 41/17. The renewed confidence in the HPV vaccination programme may be attributed notably to the publication of several recent scientific studies supporting the vaccine’s safety and effect. Furthermore, the joint campaign “Stop HPV”, implemented by the Danish Health Authority, the Danish Cancer Society and the Danish Medical Association and supported by the SSI and a broad range of scientific societies, has had an impact, among others because it has a strong social media presence. Thereby the campaign reaches the target group of doubting or hesitant parents who may not seek information with their GP or at the authorities’ websites. The campaign has also been helpful in re-focusing attention to the main objective of HPV vaccination: preventing cervical cancer.

In November 2017, the 9-valent HPV vaccine was introduced into the childhood vaccination programme. This vaccine has a new and broader coverage than the one previously used, EPI-NEWS 42-43/17. Preliminary figures show that during the first two months after its introduction, a total of 6,951 girls initiated their HPV vaccination. That is more than twice the number who started in the corresponding period of 2016. This suggests that the new vaccine is in high demand, and it will therefore be interesting to follow the programme’s coverage in 2018.

In contrast to a few other European countries, e.g. England and Holland, meningococcal vaccination is not part of the Danish childhood vaccination programme. This is because of the very low incidence of meningococcal disease in Denmark. In 2017, the incidence remained historically low, with only 39 notified cases. However, an increase was observed in group W135 cases, EPI-NEWS 6/17 and 49/17, with a total of 13 cases in 2017. These cases were scattered across Denmark, and they were unrelated. Group W135 may have an atypical clinical presentation and a more aggressive course than the other groups of meningococci. The SSI is therefore very attentive to the development in the occurrence of this particular type.

Antimicrobial resistance

Antimicrobial resistance (AMR) is one of the world's greatest health threats because we risk losing the effect of our antibiotics, which would leave us unable to treat even trivial infections. AMR is mainly associated with a high and inexpedient use of antimicrobials, and one of the primary focus areas in the fight to curb AMR is therefore to reduce consumption of antimicrobials. Owing to a wide range of initiatives in this area, recent years have seen a trend towards a decline in the use of antimicrobials in Denmark, in primary healthcare as well as in hospitals. In 2017, the Danish Ministry of Health also launched an action plan on antimicrobials, which - for the first time ever - specified concrete objectives for the reduction of consumption of antimicrobials in the period leading up to 2020, to limit the spread of infection due to resistant bacteria.

Nevertheless, it is worrying that the 2016 DANMAP report detected a continued increase in the number of patients at Danish hospitals with findings of vancomycin-resistant enterococci (VRE) in invasive samples such as blood cultures. Since 2012, the number has risen from less than 50 annual cases to 434 in 2016. Additionally, the monitoring revealed a continued increase in findings of carbapenemase-producing organisms (CPO). In all, 115 CPO were isolated in a total of 99 patients in 2016, EPI-NEWS 44/17. Previously, CPO has been travel-associated. However, in recent years, the source of several of the CPO findings has remained unknown or been related to Danish outbreaks. A working group under the Danish Health Authority has prepared a guideline on prevention of the spreading of CPO. The guideline will now be submitted to a hearing before being published.

It is important that the Danish Health Authority’s recommendations are implemented rapidly at Danish hospitals in order to curb this worrying development. The CPO guideline is based on National infection-hygienic recommendations on supplementary preventive measures regarding infections and carrier status in the health care sector, Section 5.

The number of new MRSA cases increased in 2016, EPI-NEW 23/17. The rise was due to a continued increase in the number of imported and community-acquired cases. As previously, a very low incidence of hospital-acquired MRSA cases was recorded, indicating that the national Danish MRSA guidelines are working well. Whereas the number of MRSA findings in persons with contact to livestock remained stable in 2016, a slight increase was observed in the number of livestock MRSA CC398 cases among persons who have no contact with pigs. In 2017, in collaboration with the Danish Veterinary and Food Administration the SSI launched a hygiene course for people who handle live pigs in an occupational capacity. The aim of the course is to reduce the risk that resistant bacteria from, e.g., pig barns end up in the community.

An important prerequisite to initiating and evaluating preventive measures targeting AMR is having in place a flexible and continuous surveillance . Towards the end of 2017, a new version of The Danish Microbiology Database (MiBa) was implemented as part of the e-RES project. In future, it will therefore be possible to collect data on all resistance tests performed at local clinical microbiology laboratories. This will considerably improve our opportunity to monitor both newly emerged and known types of resistance and to follow the development in AMR via the MiBa.

Disease outbreaks

As in previous years, in 2017 several disease outbreaks were identified and resolved by use of whole-genome sequencing (WGS), where the “DNA fingerprint” of the pathogenic bateria is mapped as part of routine disease surveillance. In August, a listeria outbreak was identified and the source of infection was established as being cold-smoked salmon from a Polish manufacturer, as the exact same listeria bacterium was detected in the product and in the affected patients. In line herewith, interviews revealed that the patients had ingested cold-smoked salmon. The product was rapidly withdrawn from the Danish market. In September 2017, the same type of listeria was found in France in salmon from the same Polish manufacturer. No human listeria cases in France could be associated with this product, but the same type was found in a patient in June 2016.

Modern microbiology methods cannot replace the traditional epidemiological methods, but considerable synergies may be reaped by combining the different approaches for disease investigation. One limitation of the microbiology approach is that microbiological samples are not collected from all foods, and therefore bacterial isolates from foods are not always available for comparison with isolated from patients.

In October 2017, a salmonella outbreak was identified. The outbreak counted 13 persons who all had a specific salmonella type. An electronic questionnaire was made in which both patients and healthy controls were shown a range of salami product photos. In the questionnaire, cold cut Fuet Coins from Spain, sold in the Netto Supermarket chain, was singled out far more often by patients, and the product was withdrawn from the market. It was subsequently established that a concurrent Swedish outbreak with another type of salmonella was caused by a fuet salami product from the same Spanish manufacturer. This seemingly indicated a general hygiene problem at the manufacturer.

An ongoing European hepatitis A outbreak, mainly among men who have sex with men (MSM), was also identified using virus sequencing. The outbreak now counts nearly 4,000 cases that have been detected since 1 June 2016, including 10 Danish cases. In order to prevent further cases, MSM are encouraged to receive hepatitis A vaccination, EPI-NEWS 10/17.

The 2016-17 influenza season was dominated by influenza A (H3N2) virus and caused an elevated number of admitted patients and excess mortality among the elderly, EPI-NEWS 24/17. By using whole-genome sequencing, it was possible to detect several changes in the influenza A (H3N2) virus, which could be divided into four main groups, and the influenza vaccine effectiveness varied between these groups. Overall, the season’s influenza vaccine provided only limited protection against influenza infection among the elderly.

All of these outbreaks underpin the strength of using WGS, but also the need to continuously use standard descriptive and analytic epidemiological methods for outbreak investigation. In addition, the outbreaks illustrate the importance of international cooperation in the investigation and prevention of disease outbreaks.

Vector-borne diseases

Internationally, vector-borne infectious diseases remain a significant cause of morbidity as well as mortality. In Europe, the tiger mosquito (Aedes albopictus), which can transmit infections such as dengue, Chikungunya, West Nile fever and Zika, is common around the Mediterranean. 2017 saw a major Chikungunya outbreak in the Lazio Region of Italy, including Rome. The outbreak counted more than 240 cases. Additionally, minor Chikungunya outbreaks were recorded in France. Europe also recorded several sporadic cases of malaria, which is transmitted by the Anopheles mosquito, in Greece, Italy, France and on Cyprus, EPI-NEWS 39/17. In addition, recurring outbreaks of West Nile fever were seen in southern Europe. Climate change may affect the occurrence of mosquitoes or other disease vectors, and increased travelling activity may increase the risk of introducing exotic viruses. We may therefore expect to see more outbreaks of “tropical diseases” in Europe in the future, and these diseases may also gain a more or less permanent foothold in some areas.

The future of Statens Serum Institut secured

For the SSI, 2017 was also an eventful year. In January, the vaccine production was finally divested, EPI-NEWS 3/17. Subsequently, the framework determining the SSI’s future was established in a government decision stipulating that a strong national infectious disease preparedness programme will be maintained at the SSI, among others to counter new infection threats and the risk of outbreaks with infectious diseases. The decision was underpinned by the finance agreement between the Danish state and the Regions, establishing that the SSI will continue to perform diagnostic analyses critical to the infectious disease preparedness programme, and handle the digital surveillance, among others based on MiBa data. Additionally, a consortium consisting of the University of Copenhagen (UC) and the SSI won a public tender for the veterinary preparedness programme which is handled by the National Veterinary Institute, Technical University of Denmark, until 2020. The tender includes policy advisory services for the Danish Veterinary and Food Administration. As from January 2020, this task will be handled by the UC-SSI consortium. The new agreement boosts the “One Health” perspective of the Danish infectious disease preparedness programme by introducing joint monitoring of human and animal infections with a view to improving our understanding of zoonotic infections that are transmitted from animals to humans and vice versa.

With this summary of important events in 2017, the SSI takes the opportunity to extend our wishes for a happy New Year to all readers of EPI-NEWS.

(T.G. Krause, Department of Infectious Disease Epidemiology and Prevention)