The immune response to a Coxiella burnetii vaccine in sheep varies according to their natural pre-exposure.

Q fever in humans is caused by Coxiella (C.) burnetii. In 2008 and 2012, cases of Q fever in humans were linked to an infected flock of approximately 650 ewes. Since 2013 gimmers (G'13, G'14, G'15 etc.) were primary vaccinated (two doses) with an inactivated C.burnetii vaccine without any revaccination. In 2013, 30 ewes were primary vaccinated (A'13). Shedding was annually monitored by qPCR-testing of vaginal and nasal swabs collected at lambing. Animals were tested for Phase I- (PhI) and PhII-antibodies (Ab) and for PhII-specific-interferon-γ (IFN-γ) before and after vaccination. The effect of a revaccination was determined in 2018 and 2023. Groups of randomly selected gimmers primary vaccinated in 2015, 2016 and 2017 and a mixed group of older animals (A'13, G'13 and G'14) were revaccinated once in 2018. The trial was repeated in 2023 on groups primary vaccinated in 2019-2023. Major shedding after the outbreak in 2012 ceased in 2014. Thereafter C.burnetii was only sporadically detected at low-level in 2018, 2021 and 2023. Sheep naturally exposed to C.burnetii during the outbreak in 2012 (A'13, G'13) mounted a strong and complete (PhI, PhII, IFN-γ) recall immune response after vaccination. A serological PhI+/PhII+ pattern dominated after vaccination. In contrast, since 2014 a weaker immune response (PhII-titre, IFN-γ) and a dominance of the PhI-/PhII+ pattern was observed in vaccinated gimmers. The number of serologically non-responding gimmers to vaccination increased to 25.0 % in G'16/G'17 and 40.4 % in G'19/G'20. But revaccination even three (G'15 in 2018) and four (G'19 in 2023) years after primary vaccination resulted in a strong and complete immune response. No difference of the immune response nor to more recently primary vaccinated animals (G'23 in 2023) nor to those animals that were present during the outbreak (A'13/G'13/G'14 in 2018) was observed.

Long-term control of Coxiellosis in sheep by annual primary vaccination of gimmers.

Coxiella (C.) burnetii, a Gram-negative intracellular bacterium, causes Q fever in humans and Coxiellosis in animals. Ruminants are a primary source of human infection with C.burnetii. In 2013, vaccination was implemented in a sheep flock with 650 ewes associated with two outbreaks of Q fever in humans in 2008 and 2012. Only gimmers (yearlings) received two doses of a commercial C.burnetii phase I whole cell vaccine three weeks apart (primary vaccination) without any revaccination. Vaginal and nasal swabs collected shortly after lambing were tested by qPCR. Additionally, a group of non-vaccinated sentinels was serologically monitored for phase I (PhI), II (PhII) antibodies and for Interferon γ (IFN-γ) after stimulation of whole blood cells with PhII-antigen with and without an IL-10-neutralizing monoclonal antibody. In 2021, 679 sera collected in 2014-2021 were retested retrospectively with three commercial ELISA kits and one batch of an in-house PhI/PhII-ELISA. A low-level shedding of C.burnetii (<103 mean C.burnetii/swab) was observed until 2014. In 2021 C.burnetii was detected in two animals (<103.1C.burnetii/swab), but vaginal swabs collected at two subsequent lambing seasons remained negative. Seroconversion of sentinels was detected until 2017. However, the retrospective analysis of sentinels in 2021 revealed additional single seropositive animals from 2018 to 2021. IFN-γ reactivity was observed during the whole study period; it peaked in 2014 and in 2018 and decreased thereafter. The sporadic detection of C.burnetii and the immune responses of sentinels suggested that a subliminal infection persisted despite vaccination. Nevertheless, vaccination of gimmers prevented the development of a major outbreak, it controlled the infection and reduced the risk of human infection.

[Surveillance of wild birds for avian influenza A virus (AIV) in Bavaria in the years 2007 and 2008]. / Wildvogelmonitoring zum Vorkommen von aviärem Influenza A Virus (AIV) in Bayern in den Jahren 2007 und 2008.

A monitoring programme has been initiated in Bavaria to continuously control wild birds for the presence of avian Influenza A virus (AIV) and to monitor the possible occurrence and accumulation of notifiable AIV subtypes as an early-warning system. In addition information about the regional, seasonal and species-specific distribution of AIV could be obtained. Between July 2007 and December 2008 samples from 5864 wild birds of twelve different zoological orders had been collected (cloacal- and tracheal swab samples, droppings, and organs) and analysed. AIV genomes were detected in 3.7% of the 5864 wild birds by RT real time PCR. The subtype component H5 was identified in 52 samples (0.9%) and the N1 subtype component in 13 samples (0.2%), but never in combination with each other. The hemagglutinine subtype component H7 could not be detected. Most of the positive AIV genome results originated from samples in the district Swabia, which is situated in the central area of the south-west bird migration route across southern Germany and harbours favourable resting areas for migrating birds. Mallards (Anas platyrhynchos) were the most frequently sampled bird species and had the highest AIV infection rate of 6.4%, followed by Tufted ducks (Aythya fuligula) (AIV prevalence of 5.4%), Mute Swans (Cygnus olor) (1.6%), Coots (Fulica atra) (0.3%) and Greylag Goose (Anser anser) (0.1%). The detection rate of AIV in Bavarian wild birds showed a seasonal peak in autumn/winter. Ten virus isolates could be obtained after sample inoculation in embryonated hen's eggs.

Highly pathogenic avian influenza virus (H5N1) in frozen duck carcasses, Germany, 2007.

We conducted phylogenetic and epidemiologic analyses to determine sources of outbreaks of highly pathogenic avian influenza virus (HPAIV), subtype H5N1, in poultry holdings in 2007 in Germany, and a suspected incursion of HPAIV into the food chain through contaminated deep-frozen duck carcasses. In summer 2007, HPAIV (H5N1) outbreaks in 3 poultry holdings in Germany were temporally, spatially, and phylogenetically linked to outbreaks in wild aquatic birds. Detection of HPAIV (H5N1) in frozen duck carcass samples of retained slaughter batches of 1 farm indicated that silent infection had occurred for some time before the incidental detection. Phylogenetic analysis established a direct epidemiologic link between HPAIV isolated from duck meat and strains isolated from 3 further outbreaks in December 2007 in backyard chickens that had access to uncooked offal from commercial deep-frozen duck carcasses. Measures that will prevent such undetected introduction of HPAIV (H5N1) into the food chain are urgently required.

Severe course of rat bite-associated Weil's disease in a patient diagnosed with a new Leptospira-specific real-time quantitative LUX-PCR.

Leptospirosis is a zoonotic disease with global distribution, caused by spirochaetes of the genus Leptospira. Transmission of Leptospira interrogans serovar Icterohaemorrhagiae, the causative agent of Weil's disease, to humans usually results from exposure to the urine of infected, but mostly asymptomatic, rodents, either by direct contact or indirectly through contaminated soil or water. Although regarded as a re-emerging infectious disease, human leptospirosis is probably underdiagnosed due to its often unspecific clinical appearance and difficulties in culturing leptospires. Therefore, more rapid and specific diagnostic procedures are needed. Here we describe a novel real-time quantitative PCR system developed for the accurate and fast diagnosis of pathogenic Leptospira spp. Its usefulness in the management of a patient with rat bite-associated multiorgan failure is demonstrated.

Genetic evidence for multi-event imports of avian influenza virus A (H5N1) into Bavaria, Germany.

The almost simultaneous initial detections of avian influenza A H5N1 viruses in central Europe in February 2006, at a time devoid of migratory bird activity, raised the question of the origin of these viruses. This report presents molecular data from Europe providing evidence for multiple and spatially overlapping H5N1 introductions into Bavaria, Germany.

[BHV-1 eradication program in Bavaria: a marker-independent strategy]. / BHV-1-Bekämpfung in Bayern: Eine markerunabhängige Strategie.

In Bavaria a BHV-1 eradication program was initiated in 1986 and was changed to a compulsory program in 1998. The eradication success increased progressively from < 50% in 1986 to 87% of the farms in 2002. BHV 1-free farms are controlled by bulk milk serology twice a year along with blood serology in animals that are negative but from herds where positive field virus infected animals are present. All serological tests are performed with an indirect ELISA test, all positive results are confirmed by a gB ELISA. Currently about 100.000 virus infected cattle are in Bavarian herds, approximately 80% of these animals are in heavily infected herds (> 10 infected animals). These herds comprise about 5% of all Bavarian herds. The eradication of the virus in these heavily infected herds is the most diifficult, whereas the prevention of new infections appears controllable. In this review current problems in BHV1 eradication are named and possible improvements are discussed.

[Requirements for the use of ELISA systems in eradication programs]. / Anforderungen an den Umgang mit ELISA-Systemen bei Bekämpfungsverfahren.

Users of ELISA test systems applied in eradication schemes must be aware of their potential and their limitations. Means to improve laboratory quality as well as strict performance of the test procedure are essential. Sensitivity and specificity of test systems are limited. Therefore the establishment of a cascade of methods to verify questionable and positive results is important. Thus false positive results, which may threat the general acceptance of an eradication scheme, can be avoided.