Original article
Trends in surveillance data of human Lyme borreliosis from six federal states in eastern Germany, 2009–2012

https://doi.org/10.1016/j.ttbdis.2013.10.010Get rights and content

Abstract

Lyme borreliosis (LB) is the most frequent vector-borne disease in Germany. For more than 10 years, data from mandatory notifications have been available from 6 federal states in the eastern part of Germany. A common case definition was applied. Clinical manifestations of erythema migrans, neuroborreliosis (radiculoneuritis, cranial neuritis, meningitis), and Lyme arthritis were notifiable. From 2009 to 2012, altogether 18,894 cases were notified. The overall incidence varied between 34.9 cases/100,000 inhabitants in 2009 and 19.54 cases/100,000 persons in 2012. LB in eastern Germany showed a pronounced seasonality with a peak in August. Decreasing as well as increasing trends were observed in different federal states. Females predominated among all cases (55.3%). The age distribution was bimodal with incidence peaks in children 5–9 years old (32.4 cases/100,000 persons in 2011) and in adults aged 60–69 years (56.7 cases/100,000 persons in 2011). Erythema migrans affected 95.4% of the patients and acute neuroborreliosis 3.3%. Among the latter, the most common manifestation was radiculoneuritis (n = 316). Neuritis cranialis was more common in children than in adults (p < 0.01). The same was true for meningitis (p < 0.01). Altogether 2.0% of the LB cases developed Lyme arthritis. LB has a significant disease burden in the study area. Different levels of under-ascertainment in the surveillance system could explain parts of the differences in the incidence. Furthermore, there may be discrepancies in disease awareness among patients and physicians. Changes in time and differences among geographical regions could result from variations in risk factors related to human behaviour (e.g., outdoor activity). Additionally, vector-related risk factors may have varied (e.g., landscape, climate). Public health strategies with a particular focus on the high-incidence age groups should promote daily checks for ticks and prompt removal of ticks after exposure to avoid infection. Physicians should be able to recognize LB patients with early manifestations and promptly treat those appropriately.

Introduction

Lyme borreliosis (LB, Lyme disease) caused by the spirochaete Borrelia (B.) burgdorferi senso lato is the most frequent vector-borne disease in the northern hemisphere. It is transmitted by bites of hard ticks of the Ixodes ricinus complex. Germany is considered an area with a high disease prevalence (Lindgren and Jaenson, 2006).

LB is a potentially serious infection and can affect the skin, the joints, the nervous system, and less frequently the heart and the eyes (Stanek et al., 2012, Strle and Stanek, 2009). The most common disease manifestation is erythema migrans (EM), a characteristic expanding skin lesion with or without central clearing. Additionally, LB can present in more severe manifestations as neuroborreliosis (NB) and Lyme arthritis (LA). NB affects the central or peripheral nervous system, solely or in combination. Clinical manifestations include radiculopathy, lymphocytic meningitis, and cranial neuropathy (most often a facial neuropathy). LA presents as mono- or oligoarthritis, persisting or with recurrent attacks.

Surveillance data from mandatory disease notification systems are only available from a few European countries and are collected on the basis of different case definitions and different technical implementations (voluntary reporting, laboratory reporting vs. physician reporting, or hospital diagnoses) (Rizzoli et al., 2011). In Europe, annual incidences of notified cases of 80.0/100,000 inhabitants or higher are reported from Slovenia, Austria, and southern Sweden. Incidence is also high in the Netherlands and Switzerland while Poland and France report incidences below 20.0/100,000 (Lindgren and Jaenson, 2006).

This report provides an analysis of the frequency and distribution of notified cases of LB in eastern Germany. Associations between demographic characteristics and clinical manifestations were assessed, and geographical patterns and time trends were analyzed.

Section snippets

Materials and methods

LB is not a nationwide notifiable disease in Germany. However, in the 6 neighbouring federal states Berlin, Brandenburg, Mecklenburg-Western Pomerania, Saxony, Saxony-Anhalt, and Thuringia (hereafter referred to as eastern Germany) systems of mandatory disease notification were established by special legal ordinance between 1991 and 1997. In 5 out of 6 states, the physicians, and in 4 out of 6 states the laboratories, have to report cases of LB to the local health authority of their place of

Demographic characteristics

From 2009 to 2012, 18,894 cases of LB were reported in the study area. The highest incidence was observed in 2009 (34.9 cases per 100,000 inhabitants) and the lowest incidence in 2012 (19.54 cases per 100,000 inhabitants). There was a bimodal distribution of age-specific incidence of LB (Fig. 1). The first maximum occurred in children aged 5–9 years. Incidence rose again in adults from the 25–29-year-old to the second and more prominent peak in the 50–69-year-old. Across all age groups, LB

Demographics

This is the first epidemiological analysis of the German surveillance data after the introduction of the revised case definition in January 2009, which also includes LA as a newly notifiable disease manifestation. Furthermore, the revised case definition differentiates between the laboratory evidence for radiculoneuritis, meningitis, and cranial neuritis. The definition for the most common manifestation EM has remained unmodified. Therefore, we think this change had only minor influence on

Limitations

There are two groups of limitations in this study which are inherent to the dataset. Firstly, it can be assumed that especially patients with an EM, which is usually easily treatable by general practitioners, are often not reported to the local health office. Furthermore, there may be cases reported as LB with disease due to another cause. Difficulties in diagnosing severe disease manifestations can lead to insufficient case ascertainment in LB surveillance (ECDC, 2012, Müller et al., 2012,

Conclusions

Population-based seroprevalence studies and surveys for pathogens in vectors should be used to complement the data from notification systems. Altogether, this should provide a better understanding of the key epidemiological features and may allow better estimation of the burden of this disease in the future.

The risk of acquiring LB is significant in Germany. Thus, personal protection, e.g. wearing appropriate clothing as well as regularly searching the body for ticks and prompt removal of ticks

Acknowledgements

We thank physicians and laboratories reporting the patients and district health authorities and the federal state authorities of Berlin, Brandenburg, Mecklenburg-Western Pomerania, Saxony, Saxony-Anhalt, and Thuringia for the establishment of the surveillance system.

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