Infections in Denmark in 2018

In 2018, Denmark was affected by several nationwide disease outbreaks. That is evident from this year’s first issue of EPI-NEWS from Statens Serum Institut. In this issue, the SSI provides the traditional status on infections and outbreaks recorded in the year that passed.

Among the disease outbreaks were the prolonged influenza epidemic that affected Denmark in the winter period. The epidemic was, among others, dominated by an influenza B type that was not included in the vaccine offered free of charge to the risk groups.

During the season, many people were admitted to hospital, and an excess mortality was observed among the elderly. The majority of those who were admitted and/or died had, however, not been vaccinated, even though they belonged to a risk group.

"Therefore, an increase in the vaccination coverage is warranted, not least among the elderly. During the influenza season, coverage was only 50%, which is far below the WHO’s 75% coverage target", notes Tyra Grove Krause, head of the SSI’s Department of Infectious Disease Epidemiology and Prevention.

Several large foodborne outbreaks

Last year also brought several large foodborne outbreaks. In particular, three outbreaks stand out:

It started out already in January with a large hepatitis A outbreak that affected 30 persons. After one week, the SSI had identified the source of the outbreak. The source was Iranian dates, which were therefore withdrawn from the market.

In June, Denmark witnessed this year’s most serious outbreak. A total of nine persons became infected with botulism (also known as sausage poisoning) after having had supper at a private party. All cases were admitted and several experienced paralyses and breathing difficulties and required artificial respiratory support even though they had been given an antidote. This is the largest botulism outbreak since monitoring was initiated in 1980. Thorough studies established that the source of infection was a home-made jelly ring with jarred lumpfish roe.

Finally, the year concluded with a large salmonella outbreak (Salmonella Typhimurium). So far, the outbreak counts 36 cases. Epidemiological studies in December indicated that pork sausage was the cause of the majority of the cases, whereas the remaining cases are assumed to have ingested other pork products.

All three outbreaks were handled and solved in close collaboration between the SSI, the departments of clinical microbiology at Danish hospitals, the Danish Veterinary and Food Administration and DTU Food.

A good vaccination year

In the context of vaccination, 2018 was characterised by the introduction on 1 April of free measles vaccination for all non-immune adults. So far, 3,614 people have accepted the offer.

“Even though measles have been eliminated  in Denmark, eight measles cases were notified last year. Three of the cases had become infected in Denmark by an unknown common source of infection, whereas the remainder were individual cases who had become infected while travelling,” explains Tyra Grove Krause.

She also finds it encouraging that the confidence in and coverage of HPV vaccination continued to rise in 2018.

"So far, a total of 71% of the girls who turned 13 in 2005 have received their first HPV vaccination. That indicates that we’re back on the right path with respect to coverage".

And now the boys are also joining the scheme. At the end of 2018, the Danish government launched an initiative aiming to enhance vaccine efforts. The initiative encourages adding to current measures by offering free HPV vaccination to 12-year-old boys.

Resistant bacteria are a serious threat

The SSI’s report also mentions some of the other major infection issues that Denmark and the rest of the world are facing. Among those, the increased number of infections due to antimicrobial-resistant bacteria.

"Antimicrobial resistance (AMR) is one of the primary threats against public health. Recent studies estimate that 33,000 persons die annually in Europe alone due to AMR", notes Tyra Grove Krause.

Even though Denmark has been at the forefront of lowering antimicrobial consumption and curbing AMR in many ways, Denmark is also affected by the problem.

Among others, the occurrence of infections with carbapenemase-producing organisms (CPO) has risen in Denmark in recent years. CPOs are bacteria that often cause infections to which there are no good alternative treatment options.

In 2018, we also witnessed five cases of multi-resistant tuberculosis. Four of these cases belong to a single chain of infection.

Antimicrobial resistance is an international issue. It is therefore encouraging that an initiative supported by the Danish government has been taken to establish an international and independent research and knowledge centre in Denmark that will focus on solutions to prevent antimicrobial resistance.

Hot weather caused more deaths

The climate and climate change constitutes another considerable challenge to public health. The long and very hot summer thus caused more deaths than is normally the case.

"In the course of the summer, we observed an excess mortality of 265 deaths, mainly among the elderly. This excess mortality is associated with the hot weather", notes Tyra Grove Krause. 

The increased temperatures also produced an increased number of marine bacteria in inner Danish waters - and therefore also more infections were recorded due to these bacteria.

Finally, Europe experienced more outbreaks of mosquito-borne conditions than is normally the case. Among others, an unusually high number of West Nile Fever cases was seen in South and East Europe in the course of the summer. A total of approx. 1,500 cases were reported. That is seven times more than in 2017.