No 1/2 - 2019

Infections in 2018

Infections in 2018

Danish disease outbreaks

2018 witnessed various Danish disease outbreaks. The winter period was characterised by a prolonged influenza epidemic dominated by influenza B which lead to a considerable number of admissions and excess mortality among the elderly, EPI-NEWS 23-24/18. Considerable pressure was reported from overcrowded hospitals. Influenza B is rarely the dominant strain, and this influenza type is normally not associated with a serious disease burden in elderly people.

Furthermore, the influenza B virus included in the trivalent vaccine and the influenza B virus in circulation were different, causing a low influenza B vaccine effectiveness. Even so, the majority of patients admitted with influenza had not been vaccinated even though they belonged to a risk group, and the influenza vaccine provided good protection against influenza A.

The season demonstrated that influenza B can cause a considerable and serious disease burden, that there is a need for more effective influenza vaccines, and that attention is still needed to increase the vaccination coverage among the risk groups. In the 2017/18 season, the vaccine coverage was only 50% among the elderly, which is far below the WHO’s 75% target , and the coverage was characterised by relatively large geographical variation.  

For the second year running, the season brought a large number of enteroviral infections. Positive samples from more than 500 patients were submitted to Statens Serum Institut (SSI) for enhanced analysis. A large share of these samples were due to a meningitis outbreak caused by echo virus 30 that started already in the summer of 2017 and receded in the course of the autumn. This type of virus also caused outbreaks in several other European countries. Additionally, cases were identified of enterovirus infection caused by virus types that may cause serious neurological disease with pareses, enterovirus D68 and enterovirus A71, EPI-NEWS 41/18.

The year also brought several large foodborne outbreaks. In January, an outbreak of hepatitis A was detected, EPI-NEWS 11/18. The outbreak counted a total of 30 patients. Within a single week, epidemiological studies had identified a specific brand of Iranian dates as the source of infection, after which the dates were withdrawn from the market and the outbreak ceased. 

In June, nine persons became infected by botulism after having supper at a private party, EPI-NEWS 25/18. The affected persons developed symptoms to varying degrees in the days following the meal, several experienced paralysis of the respiratory muscles and needed artificial respiratory support. The patients were given an antidote, partly from the SSI’s own preparedness stock, partly procured from Sweden, Norway and Germany. A home-made jelly ring with jarred lumpfish roe was later identified as the source of infection. This is the largest botulism outbreak reported since monitoring was initiated in 1980.  

The end of the year was characterised by a large outbreak of a special type of monophasic Salmonella Typhimurium, so far recording a total of 36 cases. By December, epidemiological studies identified pork sausage as the source of infection. Even so, not all patients had ingested pork sausage, and it is therefore assumed that other pork products may also have caused some disease cases with the salmonella type in question, which was identified by whole-genome sequencing. 

All three foodborne outbreaks were solved and handled in close collaboration between the SSI, the departments of clinical microbiology, the Danish Veterinary and Food Administration and DTU Food. The Danish Patient Safety Authority and the treating healthcare staff at several hospitals, particularly Sønderborg Hospital, were also heavily involved in the investigation of the botulism outbreak. The three outbreaks underline how important it is that the SSI provides a specialised diagnostic preparedness programme and typing capacity facilitating rapid identification of outbreaks caused by the same micro-organism. Furthermore, the SSI holds expertise in conducting epidemiological studies to identify sources of infection. The botulism outbreak also underlines the importance of maintaining a preparedness stock of antitoxins and demonstrates that the SSI is capable of activating its international network rapidly when needed to ensure preparedness supplies. 


On 1 April 2018, free measles vaccination was introduced for non-immune adults, EPI-NEWS 13-14/2018. Even though Denmark has had in place a two-dose MMR vaccination programme for 30 years, there is still a group of younger adults aged up to 45 years who have not been vaccinated and have not had the measles. The SSI has calculated that a total of 3,614 persons born in 1999 or earlier received the vaccination offer in 2018.

Measles have been eliminated  in Denmark, EPI-NEWS 37/17, but measles virus is still being introduced by non-immune travellers from other countries where measles remain in circulation and cause outbreaks. In 2018, a total of eight measles cases were notified in Denmark. Three persons had become infected in Denmark by an unknown shared source of infection, whereas the remaining five cases were individual travel-related cases.

The trust in and coverage of the HPV vaccination increased once more in 2018. So far, a total of 72% of the girls who turned 13 in 2018 (birth year 2005) have received the first HPV vaccination. Two years back (birth year 2003), the corresponding number was 47%.  

Towards the end of 2018, the Danish government launched an initiative aiming to enhance the vaccination effort The initiative comprises, among others, a free HPV vaccination offer for 12-year-old boys from mid-2019 and an offer of more effective influenza vaccines for risk groups as from 2019. Additionally, as from mid-2019, the SSI can send out reminders to parents before the expected time of vaccination and further reminders of any lacking vaccinations. We hope that this will contribute to a higher number of vaccines being given at the recommended time and to increase the vaccination coverage further.

Antimicrobial resistance

Antimicrobial resistance (AMR) is one of the primary threats against public health. Recent studies have estimated that 33,000 people die in Europe annually due to AMR. 
Monitoring of the consumption of antimicrobials and the occurrence of multi-resistant bacteria provides essential information about when and where extra efforts and control measures may be needed. 

In recent years, Denmark has seen an increase in the occurrence of infections with carbapenemase-producing organisms (CPO), and outbreaks have been reported in and between hospitals. These bacteria often cause infections that are very hard to treat as the number of effective antibiotics is limited. They may therefore mark the first small steps towards the post-antimicrobial era, and therefore CPO infections are taken very seriously.

The number of CPO cases increased from 115 cases in 99 patients in 2016 to 123 cases in 115 patients in 2017, corresponding to a 6% increase, EPI-NEWS 46/18.  To enhance the efforts made to counter CPO, 2018 saw the introduction of mandatory CPO notification, and the Danish Health Authority published Guideline on the prevention of CPO spreading, EPI-NEWS 37/18. The guideline is an important step in the prevention of further spreading of CPO and works in conjunction with the existing National infection hygiene guidelines (NIHG) that provide general precautions and NIHG giving supplemental precautions for infections and carrier state in Danish healthcare.

The 2018 DANMAP report demonstrated that the share of MRSA in bacteraemias with Staphyloccocus aureus stagnated (2.2% in 2017 and 2.1% in 2016) , and the total number of new MRSA cases observed in 2017 (3,579) was also in line with the level observed in 2016 (3,550). Correspondingly, the number of vancomycin-resistant enterococci (VRE) recorded in 2017 (508 cases) is on a par with the number recorded in 2016 (515 cases), EPI-NEWS 46/18. 

For many years, Denmark has seen approx. two annual cases of multidrug-resistant (MDR) tuberculosis (TB), even though the number of cases has followed a slightly increasing trend in recent years. In 2018, a total of five MDR-TB cases were detected. Four of the five cases belong to the same chain of infection, i.e. patients who have infected each other. So far, MDR-TB has been observed only sporadically in Denmark, and no spreading of MDR-TB has been observed, apart from individual cases among family members. The four connected MDR-TB cases in 2018, of which one is connected to a case from 2010, is the first example of more than sporadic spreading of MDR-TB in Denmark. Treating MDR-TB is extremely difficult and costly. It is therefore important to initiate contact tracing as early as possible. Fortunately, the SSI can now detect MDR-TB within few days thanks to novel diagnostic methods.  

In many ways, Denmark has been at the forefront of reducing the use of antibiotics and fighting AMR. Many developing countries are experiencing far greater difficulties in doing so. Fighting AMR is therefore very much an international issue requiring strong cross-sectorial collaboration counting the healthcare, veterinary and agricultural sectors. It is therefore encouraging that an initiative, funded in part by the Danish government, was launched to establish an independent international One-Health research and knowledge centre focusing on antimicrobial resistance with a view to identifying solutions that may benefit low and middle income countries.

Climate change

Climate change may have a considerable impact on society, including the healthcare sector. The year 2018 was characterised by a long, sunny, hot and dry summer that broke several records. Two periods, in particular, brought nationwide heat waves; one in the beginning of May and another towards the end of July and the beginning of August. Throughout the summer, an excess mortality was observed that is estimated to have caused 265 fatalities (95% confidence interval 229-303), mainly affecting the elderly. This mortality was associated with the high temperatures. 

Additionally, the high seawater temperatures created good conditions for the growth of Vibrio and Shewanella bacteria in inner Danish waters. Marine bacteria infections are currently not notifiable, but the SSI knows that the departments of clinical microbiology have detected a considerably higher number of infections with these marine bacteria than was the case in previous years. 

Europe also recorded several outbreaks due to mosquito-transmitted conditions. Among others, an unusually high occurrence of West Nile Fever was recorded in South and East Europe. A total of approx. 1,500 cases were reported, which is seven times more than in the previous season. The majority of cases were reported from Italy (576), Greece (311), Romania (277) and Hungary (215), whereas a limited number of cases were reported from Croatia, France, Austria, Bulgaria, the Czech Republic and Cyprus. West Nile Fever is caused by a virus that may affect animals as well as humans (i.e., a zoonosis).

Transmission occurs mainly through Culex mosquito bites, the common biting mosquito. The year also reported several locally acquired dengue cases in limited areas of both Spain and France, and several Greek cases of vivax malaria introduced by immigrants and transmitted locally by mosquitos were reported. Climate change affects the prevalence of various species of mosquito in Europe, and concurrently globalization increases the risk that new viruses are introduced into Europe. In future, we must prepare for infections that we previously considered “exotic”, as these infections will increasingly also be acquired during travel within Europe. 

Other international outbreaks

Considerable attention has been given to the current Ebola outbreak located in the northeastern corner of the Democratic Republic of the Congo (the North Kivu and Ituri provinces) bordering on the neighbouring countries of Uganda and Rwanda. The outbreak was announced on 1 August 2018, and by 27 December it comprised 591 cases including 357 deaths. Thus, this is the second-largest Ebola outbreak only surpassed by the West African Ebola outbreak in 2014-16 that caused 28,600 cases including 11,325 deaths. Despite the lessons learned by the WHO and aid organisations during the West African outbreak and the fact that a vaccine is now available, the outbreak has continued.

The WHO and the aid organisations have been present since the beginning of the outbreak but are challenged by considerable geographic spreading of cases within the affected provinces. The outbreak is being countered by the usual methods, e.g., disease monitoring, testing, isolation of suspected patients, infection tracing, hygiene precautions, information efforts targeting the local population, aid to facilitate safe burials, etc. Furthermore, contacts and healthcare staff have been vaccinated (so-called ring vaccination), currently including approx. 54,000 vacinees.

The containment of the outbreak  is challenged by troubles and armed conflicts in the area and widespread opposition from locals, which, among others, have resulted in healthcare staff and international aid workers being attacked. Spreading to neighbouring areas has been feared, but despite active monitoring, no cases have yet been observed in the neighbouring countries. The latest risk assessment from the European Centre for Disease Prevention and Control (the ECDC) published on 21 December 2018 assesses that the risk of spreading to Europe is very low.

In situations where infrastructure and healthcare systems collapse due to war or other catastrophes, infections spread easily. Yemen, in particular, has been heavily affected by a very large cholera outbreak. In the days leading up to 11 November 2018, there were reports of 300,000 cases and 2,600 deaths in Yemen, but other African countries have also been affected by cholera, particularly the Democratic Republic of the Congo recording nearly 90,000 cases. 

News from the SSI

In the course of 2018, a new transport solution was introduced that ensures that samples are collected in the night from four of the Danish regions and transported to the SSI. This typically allows the SSI to initiate the analysis of the received samples on the day they arrive to the SSI. 

The opening hours of the Department of Tuberculosis and Mycobacteria have been expanded. Thus, the Department can now be reached on working days from 8 am to 8 pm and on some bank holidays from 9 am to 2 pm. Due to the Congolese Ebola outbreak, a 24-hour on-call service  has been established to provide Ebola diagnostics. 

For the first time ever, the SSI participated in the People’s Political Festival (Folkemødet) on the island of Bornholm. The SSI will also participate in 2019. Additionally, a new and more user-friendly website has been launched, EPI-NEWS 48/18.

The SSI is also preparing the take-over of the veterinary disease preparedness measures in collaboration with the University of Copenhagen. Even though the hand-over was scheduled to take place in 2020, some analyses, e.g. for avian influenza, will pass to the SSI as from March 2019. Analyses for important livestock diseases such as swine fever and foot-and-mouth disease are expected to pass to the SSI as from the summer of 2019.  In this context, major efforts are being made to enhance the laboratory facilities at the SSI.

With this summary of important events from 2018, 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)