Browsing by Subject "Rickettsia spp."

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Epidemiologie von Coxiella burnetii, Rickettsia spp., FSME- und Hantaviren in Süddeutschland unter Berücksichtigung klimatischer Veränderungen
(2011) Pluta, Silvia; Mackenstedt, Ute
Zoonoses, which are defined as human infections caused by animal pathogens, are of considerable medical importance. Therefore, it is important to evaluate the distribution of tick- and rodent borne pathogens and the risk of infections for humans. Hence, the epidemiology of specific human pathogens (Coxiella burnetii, Rickettsia spp., TBE-virus and Hantavirus) was studied. As climatic conditions are known to have a significant influence on ticks and rodents, the role of climate change in the epidemiology of the examined pathogens was considered. The role of natural foci in the epidemiology of Coxiella burnetii, the causative agent of Q fever, is widely unknown in Germany. Therefore, ticks of the genus Dermacentor and rodents from Q fever endemic areas in Southern Germany were examined for infections with C. burnetii. Altogether, 1120 ticks and 119 rodents were tested by PCR. However, no infections were detected. Rodent blood samples were additionally tested for antibodies against coxiellae, but likewise, all samples were found to be negative. Hence, no natural foci of Q fever were identified in the examined areas. A role of natural foci in the epidemiology of Q fever in Southern Germany is therefore unlikely. Both Dermacentor marginatus and D. reticulatus act as vectors for Rickettsia spp. To elucidate if human pathogenic rickettsiae are distributed in Southern Germany, Dermacentor ticks were investigated for infections by PCR. Moreover, rodents were screened by molecular and serological methods to identify potential reservoir hosts. The overall prevalence of Rickettsia spp. in 1120 ticks was 33.6%. By sequencing of the rOmpA-gene, R. raoultii was identified in 32.8% and R. slovaca in 0.8% of all examined ticks. Both species are pathogenic for humans; thus, there might be a considerable risk of infection. This was confirmed by the detection of an autochthonous case of R. slovaca-infection in Rhineland-Palatinate. Rickettsia spp. was not detected in any rodents by PCR. However, 48 animals (20.2%), muridae as well as arvicolidae, showed antibodies against rickettsiae. It was, therefore, shown that rodents can actually act as reservoir hosts for Rickettsia spp. To determine the current prevalence of TBE virus in ticks, 7842 Ixodes ricinus from Baden-Württemberg were examined by molecular methods. TBE virus was found in four out of 11 examined areas. Prevalences ranged from 0.13% to 0.66%. No infected ticks were found in other areas. The determined prevalences were lower compared to studies from the 1990ies in the same areas. However, reliable comparisons are difficult due to the low numbers of infected ticks. The viruses of ticks from Gengenbach, Hagnau am Bodensee and Hödinger Tobel were cultured and subsequently characterized by sequencing of the E and NS2a genes. Phylogenetic studies were conducted to identify the TBE virus strains present in Baden-Württemberg. The isolate from Hagnau am Bodensee was identified as strain Salem, whereas the isolates of the other two areas differed substantially from all strains found in the database. Therefore, no identification was possible for these isolates. In 2007, the number of notified hantavirus infections exceeded by far the average case numbers of the preceding years. To determine if the steep rise in human infections is associated with an unusual high virus prevalence in reservoir hosts, red bank voles from the endemic area of the Swabian Albs were examined for infections by molecular and serological methods. The overall prevalence of Puumala hantavirus was 57.9%. In a study in 2001 in the same area, the prevalence was only 10%. Therefore, there was a sixfold rise in virus prevalence which reflects the high number of human cases in the study year. Sequence comparisons showed a close relationship of the hantaviruses from the Swabian Alb to hantaviruses detected in other areas of Baden-Württemberg. The results presented in this study provide the basis for further continuous studies. These are necessary to estimate the actual influence of changes in climate conditions on the examined zoonoses and, thereby, the prospective infection risk for humans.
Rickettsia spp. in ticks of South Luangwa valley, Eastern Province, Zambia
(2023) Phiri, Bruno S. J.; Kattner, Simone; Chitimia-Dobler, Lidia; Woelfel, Silke; Albanus, Celina; Dobler, Gerhard; Küpper, Thomas
Ticks are important vectors for Rickettsia spp. belonging to the Spotted Fever Group responsible for causing Rickettsiosis worldwide. Rickettsioses pose an underestimated health risk to tourists and local inhabitants. There is evidence of the presence of Rickettsia spp. in Zambia, however there is limited data. A total of 1465 ticks were collected in 20 different locations from dogs and cattle including one cat. Ticks were identified by morphological features or by sequencing of the 16S mitochondrial rRNA gene. Individual ticks were further tested for rickettsiae using a pan-Rickettsia real-time-PCR. Rickettsia species in PCR-positive ticks were identified by sequencing the 23S-5S intergenic spacer region or partial ompA gene, respectively. Seven tick species belonging to three different tick genera were found, namely: Amblyomma variegatum, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) microplus, Rhipicephalus simus, Rhipicephalus sanguineus, Rhipicephalus zambesiensis and Haemaphysalis elliptica. Out of the 1465 ticks collected, 67 (4.6%) tested positive in the pan-Rickettsia PCR. This study provides detailed data about the presence of Rickettsia species in South Luangwa Valley, Eastern Province, Zambia for the first time. High prevalence of Rickettsia africae in Amblyomma variegatum was found, which indicates the potential risk of infection in the investigated area. Furthermore, to our best knowledge, this is the first time Rickettsia massiliae, a human pathogen causing spotted fever, has been detected in Zambia.