Prevalence of Rickettsiales (Anaplasma phagocytophilum and Rickettsia spp.) in hard ticks (Ixodes ricinus) in the city of Hamburg, Germany

Abstract

To narrow the gap of missing knowledge on Rickettsia spp. and Anaplasma phagocytophilum infections in ticks in northwestern Germany and, at the same time, to provide first prevalence data on these pathogens in the city of Hamburg, a total of 1,400 questing Ixodes ricinus ticks were collected at ten different public green areas from April until October 2011. Ticks were examined using probe-based quantitative real-time PCR. A percentage of 3.6% (51/1,400) ticks were tested positive for A. phagocytophilum infections divided into 2.1% (3/141) adults [1.7% (1/60) females and 2.5% (2/81) males] and 3.8% (48/1,259) nymphs. The percentage of infected ticks per sampling site varied statistically significantly from 0.7% (1/140) to 12.1% (17/140), whereas between sampling months, no statistically significant differences were observed (2.0-6.5%, 4-13/140). The overall Rickettsia spp. infection rate was 52.5% (735/1,400). In adult ticks, Rickettsia spp. infection rate was 56% (79/141) divided into 61.7% (37/60) infected females and 51.9% (42/81) infected males. Nymphs showed an infection rate of 52.1% (656/1,259). In contrast to A. phagocytophilum infections, no statistically significant differences in Rickettsia spp. infection rates among sampling sites (44.3-63.6%, 62-89/140) were observed, whereas seasonal variations were obvious: the percentage of Rickettsia-positive ticks was significantly lower in April (36.5%, 73/200) and May (29.5%, 59/200) compared to the summer and fall months (55.0-64.5%, 110-129/200). Rickettsia species differentiation via real-time pyrosequencing revealed Rickettsia helvetica as the only occurring species. Co-infections with both Rickettsia spp. and A. phagocytophilum were detected in 2.0% (28/1,400) of the ticks. The present study revealed that in the city of Hamburg, the tick infection rate with A. phagocytophilum is comparable with other German data, whereas the Rickettsia spp. infection rate of 52.5% is by far the highest prevalence detected in Germany so far. As the city of Hamburg has 1.8 million inhabitants and attracts millions of tourists every year, the potential health risk should not be underestimated.

Prevention of transmission of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum by Ixodes spp. ticks to dogs treated with the Seresto® collar (imidacloprid 10% + flumethrin 4.5%)

“…Superiority of the treated group versus the non-treated control group (0.00 vs. 66.67%) was significant (p = 0.009). Ap infection rates in field-collected ticks from Germany used in this study ranged between 2 and 5%, which generally is comparable to other field prevalence data from the country ranging from 2.1 to 6% in adult ticks (May and Strube 2014;Schicht et al 2011;Hildebrandt et al 2010). Thus, the Ap infection rate of 3.1% detected by PCR in the ticks removed from infested dogs during the study can be regarded as representative for field conditions.…”

Borrelia burgdorferi sensu lato and co‐infections with Anaplasma phagocytophilum and Rickettsia spp. in Ixodes ricinus in Hamburg, Germany

“…infections, co‐infections with Rickettsia spp. and Anaplasma phagocytophilum were determined by comparing data from the present study with the findings of a previous study (May & Strube, ).…”

“…infection was significantly lower (13.5% in April and 25.0% in May) than in August (42.5%) and October (48.0%). These spatial and temporal differences in tick infections with pathogenic microorganisms were also described in other northern German studies (Tappe & Strube, ; May & Strube, ; Tappe et al ., ) and may reflect differences in abiotic and biotic conditions, such as in microclimatic factors, the availability of suitable reservoir hosts, tick density, habitat types and vegetation or increased late seasonal tick activity attributable to warmer summers. For example, tick density itself influences the local tick infection rate as I. ricinus plays an important role in maintaining the bacteria (Christova et al ., ).…”

Prevalence of Rickettsia spp. in Ticks and Serological and Clinical Outcomes in Tick-Bitten Individuals in Sweden and on the Åland Islands

“…Ticks may harbour and be simultaneously infested with many microorganisms [14–16]. In a study from Italy, the most frequently observed double infestation in ticks was SFG Rickettsiae and Borrelia burgdorferi sensu lato [17].…”