| Abstrakt: |
Tick-associated Rickettsiales are important pathogens with relevance for public and animal health; therefore, knowledge regarding their distribution is essential for risk assessment and disease prevention. To investigate the prevalence of Anaplasma phagocytophilumand Rickettsiaspp. in northern Germany, Ixodesticks were flagged monthly from April to October in 2018 and 2019 at three collection sites each in the regions of Bremen, Emsland, Hanover, Kassel and Uelzen. A total of 3150 ticks (1052 females, 1048 males and 1050 nymphs) were individually examined for rickettsial infections using probe-based quantitative real-time PCR. Overall prevalence of A. phagocytophilumwas 6.4% (202/3150; 6.7% [71/1052] in females, 7.5% [79/1048] in males and 5.0% [52/1050] in nymphs). For Rickettsiaspp., the overall prevalence was 29.6% (931/3150; 33.4% [351/1052] in females, 28.3% [297/1048] in males and 27.0% [283/1050] in nymphs). Rickettsiaspecies identification by real-time pyrosequencing on a subset of 409 positive samples was successful in 407 cases (99.5%). Rickettsia helveticawas the predominant species with a detection rate of 99.8% (406/407). Additionally, Rickettsia monacensiswas detected in one tick (0.2%). Generalized linear mixed models showed significant regional as well as monthly differences regarding the prevalence of both pathogens. In addition, the prevalence of both pathogens was significantly higher in 2018 (A. phagocytophilum: 8.0% [126/1575], Rickettsiaspp.: 35.4% [558/1575]) than in 2019 (A. phagocytophilum: 4.8% [76/1575], Rickettsiaspp.: 23.9% [373/1575]). In contrast, no effect of landscape type on pathogen prevalence was found. As Rickettsiaspp.-detection was based on the single-copy gene gltA, it was possible to calculate the individual pathogen load per tick, which was significantly higher in female ticks than in nymphs (mean values: 8.19 × 104vs. 9.58 × 103). Regional, seasonal and biennial prevalence differences of tick-transmitted Rickettsiales show the necessity to investigate ticks from multiple locations, over several months and in more than one year to reliably assess the infection risk on a larger geographical scale. |
Full Text from ScienceDirect