Synopses Changing Epidemiology of Q Fever in Germany, 1947-1999 Wiebke Hellenbrand, Thomas Breuer, and Lyle Petersen Robert Koch-Institut, Berlin, Germany The epidemiology of Q fever in Germany was examined by reviewing revelant studies since 1947 and by analyzing available surveillance data since 1962. The average annual Q fever incidence nationwide from 1979 to 1989 was 0.8 per million and from 1990 to 1999, 1.4 per million. The mean annual incidence from 1979 to 1999 ranged from a minimum of 0.1 per million in several north- ern states to 3.1 per million in Baden-Württemberg, in the south. We identified 40 documented outbreaks since 1947; in 24 of these, sheep were implicated as the source of transmission. The seasonality of community outbreaks has shifted from predominantly winter-spring to spring-summer, possibly because of changes in sheep husbandry. The location of recent outbreaks suggests that urbanization of rural areas may be contributing to the increase in Q fever. Pre- vention efforts should focus on reducing sheep-related exposures, particularly near urban areas. Q fever is caused by the pleomorphic, obligate intracel- and investigated (5,29-36). This led us to review the epidemi- lular rickettsial agent Coxiella burnetii, which has an enve- ology of this disease in Germany. lope similar to that of gram-negative bacteria. It is found worldwide except in New Zealand (1). Its most important Methods reservoirs are ticks and ruminant animals such as cows, Clinically manifest Q fever has been statutorily notifi- sheep, and goats (1-4). Although infection rarely causes able since 1962 in the former West Germany and since 1979 major clinical symptoms in animals (5), it has been associ- in the former German Democratic Republic (GDR, East Ger- ated with infertility (6,7) and abortion (8,9), particularly in many). In 1991, the two reporting systems were amalgam- first-bearing newly infected parturient animals (10). Birth ated. The Robert Koch Institute in Berlin receives weekly products from infected animals thus contain high concentra- reports of the number of persons with diagnosed (laboratory- tions of C. burnetii and can be an important source of envi- confirmed or epidemiologically linked) Q fever from local ronmental contamination (11). Transmission to humans and health departments through the state health authorities. other animals by the aerosol route is facilitated by the tenac- Local health departments receive notification of Q fever ity of C. burnetii's survival for months to years in a sporelike infections from hospitals and physicians in private practice. state on wool or fur contaminated with infected tick feces, in The Federal Office of Statistics prepares annual statistical water, and in soil (12). reports of notifiable diseases. We reviewed surveillance data Acute Q fever in humans is characteristically a febrile, on Q fever from humans in Germany since 1962 from these flulike illness associated with pneumonia or hepatitis sources. (2,3,13-18). Rare complications include myocarditis, peri- The mean annual incidence rate was calculated for the carditis, or meningoencephalitis (1,13,19). The death rate periods from 1979 to 1989 and from 1990 to 1999 by taking among persons with Q fever pneumonia is 0.5% to 1.5% (14). the mean number of persons with Q fever reported per year Up to half of patients may suffer protracted fatigue and during each period and dividing by the 1985 and 1995 Ger- weakness after acute disease (20,21). Rarely, more serious man populations, respectively. The mean annual incidence forms of chronic disease (most commonly endocarditis but rate for the period 1979 to 1999 was calculated by taking the also chronic hepatitis and vascular, osteoarticular, or pulmo- mean number of persons with Q fever reported per year and nary infections) may develop months to years after the acute dividing by the 1990 German population. Incidence rates for infection (13,22,23). An increased long-term risk for arterial each of the 16 German states were calculated similarly. disease and death has also been observed (24). We reviewed veterinary surveillance data based on pas- Q fever was first recognized in southern Germany when sive, biannual reports of the number of domestic animal several large outbreaks occurred in rural communities in herds with laboratory-confirmed Q fever (37). To obtain fur- 1947 to 1948 (25-28). Since then, it has been endemic in Ger- ther information on the epidemiology of Q fever in Germany, many. In the 1990s, several large outbreaks were recognized we searched databases (MEDLINE, from 1966; EMBASE, from 1974; AGROKAT, from 1960; CAB ANIMAL, from 1972; and CABVET SCI, from 1972) and reviewed the cited litera- Address for correspondence: Wiebke Hellenbrand, Department of ture in the retrieved relevant articles. In addition, we con- Infectious Diseases Epidemiology, Robert Koch-Institut, Strese- tacted local health departments for unpublished details on mann Str. 90-102, 10963 Berlin, Germany; fax: 30-4547-3533; e- recent outbreaks. mail: [email protected] Vol. 7, No. 5, September-October 2001 789 Emerging Infectious Diseases Synopses Figure 1. Number of reported cases of Q fever in Germany, 1962-1999. *In 1993, 184 persons with Q fever were officially reported; 101 of these persons were part of the outbreak in Oberscheid, Hesse, and were only reported to the Robert Koch Institute and not to the federal Office of Statistics (36). However, a total of 97 symptomatic persons with serologically confirmed Q fever were described in a report of the outbreak in Dortmund, Northrhine-Westphalia, and 43 serologically con- firmed symptomatic cases were reported in an outbreak among military recruits in Sontra, Hesse (Table 1). Thus a minimum of 94 persons with Q fever were not officially reported in 1993. (In Northrhine-Westphalia, 34 cases were reported; thus a minimum of 97 - 34 = 63 cases were not reported. In Hesse, 117 cases were reported, including 105 in conjunction with the Oberscheid outbreak [Table 1]; thus, a minimum of 43 - [117-105] = 31 cases were not reported from Hesse). Sources: (36), Robert Koch-Institute, and Federal Office of Statistics, Wiesbaden. Results Outbreak We documented 40 outbreaks of Q fever in humans from Surveillance 1947 to 1999 (Table 1). In all but three outbreaks, the dis- Human Q fever surveillance data since 1962 indicate an ease was confirmed in at least some of the persons affected, irregular cyclic incidence pattern (Figure 1). Very few cases either serologically or by transmission from human serum or were reported from states constituting the former GDR sputum to mice or guinea pigs. (approximately one fourth of the German population), with Sheep were implicated in the transmission of Q fever to the exception of the years 1982 and 1983, when an outbreak humans in at least 24 of the documented outbreaks (in six occurred in Thuringia (38). To consider the long-term inci- rural community outbreaks the source was uncertain). Expo- dence pattern between 1962 and 1999, data from West Ger- sure to products of conception was explicitly considered the man states must be considered separately. Except for 1979 to potential source of infection in 11 of the sheep-associated 1991, when there is little cyclicity, the interval between the outbreaks. In the outbreak in Dortmund, Northrhine-West- peaks is approximately 4 to 6 years. The peak in 1993 with phalia, a case-control study revealed that exposure to 181 (278, if unreported cases from two outbreaks [30,35] are manure contaminated with the products of conception from taken into account) and the peak in 1999 with 268 cases infected sheep was associated with Q fever (35). Infectious (West German states) were the highest since 1964, when 437 dust produced by shearing of sheep whose wool was presum- cases were reported. ably contaminated with infected tick feces was suspected as The average annual incidence of Q fever in Germany another possible source of transmission, since shearing and from 1979 to 1999 was 1.1 per million population. From 1979 disease occurrence were temporally associated in 3 of these to 1989, the incidence was 0.8 per million population, and 11 outbreaks and as the main source in one other outbreak. from 1990 to 1999, 1.4 per million population. The mean In 12 outbreaks, sheep located near or migrating through annual incidence rates calculated from 1979 to 1999 were inhabited areas were implicated without specification of the generally higher in the southern German states–highest in presumed mechanism of transmission. Dry weather or wind Baden-Württemberg (4.1 per million), followed by Hesse (2.8 blowing from areas where sheep were located to inhabited per million), Rhineland-Palatinate (0.9 per million), and areas was thought to play a contributory role in at least 14 Bavaria (0.8 per million) (Figure 2). The high average inci- outbreaks. dence observed in West Berlin (1.4 per million) is explained Cattle were suspected as the source of infection in six by an outbreak in 1992 (5,39). Had the outbreak not outbreaks; four were community outbreaks (40-43). In the occurred, an incidence rate of 0.2 per million would have Niederrhein outbreak in 1958 (42,43), exposure to products been observed in Berlin in this period. of conception aborted by a seropositive cow and to other seropositive cows sold at an animal fair was considered to be the source of infection (42,43). Exposure to infected cows, Emerging Infectious Diseases 790 Vol. 7, No. 5, September-October 2001 Synopses an increase in disease activity during this interval: The annual number of reported human Q fever cases was 0.6 cases per year between 1962 and 1977 but averaged 5.3 cases per year from 1978 to 1986. In a seroprevalence study among German federal armed forces personnel from 1985 to 1987 (51), 22% of 1,651 blood donors had antibodies to C.