No 10 - 2016

Individually notified diseases 2015
The mycoplasma pneumoniae epidemic is receding

Individually notified diseases 2015

This annual report includes the number of individually notifiable diseases with onset in 2015. The figures may be adjusted later due to late notifications or new information. Totals for 2014 and the annual average for the 5-year period 2010-2014, with the lowest and highest number of annual cases during this period, are given for comparison.

No cases of haemorrhagic fever, plague, polio, rabies or rubella were notified.

See the 2015 Annual Report (PDF)

The mycoplasma pneumoniae epidemic is receding

Since the autumn of 2015, Denmark has witnessed a nation-wide Mycoplasma pneumoniae epidemic, EPI-NEWS 49/15.

The epidemic did not peak until the beginning of January 2016 when more than 15% of all samples tested for M. pneumoniae by PCR were positive and more than 500 weekly cases were detected. Over the course of the past 7 weeks, the number of samples that have tested positive as well as the positive rate have decreased substantially to less than 200 weekly cases and a positive rate just below 6%. The decrease in the number of detected cases and in the positive rate was observed in all five Danish health regions.

The epidemic has thus receded substantially, but it has been prolonged and additional cases should be expected in the weeks to come. Throughout the epidemic, children aged 4-12 years of age have been particularly affected, and the positive rate in this age-group has also been higher than that of any other age-group. Nevertheless, the share of children with positive samples in the patient population has decreased slightly as the epidemic has progressed.

In the beginning of the epidemic (Weeks 40 through 43; 2015) a total of 41% of the positive samples were from children aged 4-12 years, whereas 38% were from those aged 13-45 years. At the end of the epidemic (Weeks 7 through 9; 2016), the percentages for the 2 age groups were 35 and 37, respectively, despite the fact that relatively more children were tested towards the end of the epidemic. The positive rate in the 2 age-groups was different. Thus, a positive rate of 52 and 13 was observed in the beginning of the epidemic, whereas the corresponding rates at the end of the epidemic were 22 and 7.

In December and January, the SSI in collaboration with the Danish departments of clinical microbiology conducted a study into the occurrence of macrolide resistance-associated mutation in M. pneumoniae. Abroad, and in Asia in particular, very high occurrences of macrolide resistance have been detected in M. pneumoniae. The study conducted during the current epidemic comprised samples from more than 300 patients and detected a low macrolide resistance of only 2%. This level is in line with the occurrence that was detected during the double epidemic in 2010 through 2012.
(S.A. Uldum, Microbiology and Infection Control, T.G. Krause, H. Emborg, Department of Infectious Disease Epidemiology)

Link to previous issues of EPI-NEWS

9 March 2016