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Infectious Disease Epidemiology Annual Report - 2019

Executive Summary

full report in German

The Infectious Disease Epidemiology Annual Report provides a summary and assessment of notifications of infectious diseases reported to the Robert Koch Institute.

As in the previous year, influenza and chickenpox, the gastrointestinal diseases norovirus gastroenteritis, Campylobacter enteritis and rotavirus gastroenteritis were the five most commonly reported notifiable diseases. After the unusually severe flu season in the previous year, the number of notified influenza cases as well as data from the Working Group Influenza (AGI) sentinel surveillance from 2018/2019 indicate a moderate season. Additionally, the number of notified cases of Campylobacter enteritis, the most commonly mandatory notifiable bacterial gastrointestinal disease, was markedly less in 2019 than in previous years. Possible causes for this decrease have not been determined and are currently being investigated.

In 2019, increases in reported Hepatitis E and leptospirosis cases were observed. For both diseases, increases are likely attributable to increased awareness of these diseases by physicians as well as increased laboratory testing. The increasing trend of notified Legionnaire’s disease cases that has been observed over the past several years continued for 2019. For Hantavirus infections, marked fluctuations in notified cases from year to year are typical. Due to the intense beech mast in 2018, the incidence of Hantavirus infections in 2019 was very high. In comparison to the previous year, the number of notified tick-borne encephalitis cases decreased markedly. Large fluctuations occur with regard to travel-related infections, which are dependent on the epidemiological situation in countries where infection took place as well as travel patterns. In 2019, the number of notified cases of chikungunya and denguefever increased steeply. The main reported country of infection for both was Thailand. In Germany, there are suitable regional conditions for support of the vector responsible for transmission of chikungunya and dengue.

The first cases of mosquito-borne West Nile virus (WNV) infection transmitted in Germany were documented in 2019. All confirmed cases were from areas where WNV circulation in horses and birds has been recorded. The virus has the capability to overwinter in Germany and is primarily transmitted by Culex mosquitoes. Physicians are recommended to test for WNV in patients with encephalitis or fever of unknown aetiology (with or without rash), particularly in summer and for patients that were in areas with known WNV circulation in animals or humans. The recommendation also applies to patients with no travel-related history.

The continued decrease in pathogen typing of diseases such as EHEC, HUS and listeriosis over the past several years has posed a significant challenge regarding identification of outbreaks. Additionally, capsule typing is not carried out frequently for Haemophilus influenzae infections, which prevents the determination of whether a change in the pathogen spectrum is accompanying the increase in reported cases. The monitoring of serotype distribution, for example for invasive menigococcal infections, as well as recording of individual vaccination status and vaccination coverage in the population is crucial for evaluation of vaccination recommendations and decision making regarding vaccination against additional serogroups.

Despite the availability of effective vaccinations, the majority of vaccine preventable diseases, for example, Hepatitis A, chickenpox and whooping cough occurred in unvaccinated individuals. The large number of mumps cases in vaccinated individuals in 2019 is a cause for concern and must be further investigated to determine possible factors for inadequate protection despite timely vaccination.

A clear effect of the increased use of HIV pre-exposure prophylaxis (HIV PrEP) on the number of newly diagnosed HIV infections was not able to be determined from the notification data from 2019. After a continued decrease in notified, newly diagnosed HIV infections over the past 3 years, the number of notified, newly diagnosed infections increased in 2019. It can not be ruled out that already existing HIV infections were diagnosed during testing carried out in conjunction with HIV PrEP, which is a desirable effect of PrEP. The decrease in reported, newly diagnosed HIV infections associated with the increase in the number of individuals undergoing PrEP reported in other countries has not been, as of the end of 2019, observed in Germany.

Date: 15.12.2020