TY - JOUR

T1 - Rickettsiosis in Denmark

T2 - A nation-wide survey

AU - Jensen, Bo Bødker

AU - Andersen, Nanna Skaarup

AU - Wölfel, Silke

AU - Chen, Ming

AU - Paarup, Helene M.

AU - Olesen, Carsten Riis

AU - Fournier, Pierre Edouard

AU - Jensen, Per Moestrup

AU - Skarphedinsson, Sigurdur

N1 - Publisher Copyright: © 2023

PY - 2023

Y1 - 2023

N2 - Rickettsia helvetica has been reported at varying prevalences in Danish and other European Ixodes ricinus populations. Though apparently widespread and with reported cases of human infection, the significance of the bacteria as a threat to public health remains unclear. We present a nation-wide survey of rickettsia in ticks, roe deer and humans in Denmark. Ticks were collected by flagging and screened for presence of rickettsial DNA by polymerase chain reaction. Sera from roe deer, hunters, neuroborreliosis patients and blood donors were analyzed for presence of anti-R. helvetica and Rickettsia felis antibodies by immunofluorescence microscopy. The Rickettsia minimum infection rate in ticks was 4.9 % (367/973 pools positive, 7510 ticks in total), with 3.9 % in nymphs and 9.3 % in adults. Rickettsia helvetica accounted for 4.17 % and Rickettsia monacensis for 0.03 %, 0.6 % comprised non-differentiable rickettsial DNA. The prevalence of antibodies against R. helvetica was 2.8 % (9/319) in roe deer, while no hunters (n = 536) or blood donors (n = 181) were positive. The prevalence of anti-R. helvetica antibodies among Lyme neuroborreliosis patients was 6 % (3/47), where it co-occurred with Anaplasma phagocytophilum. Based on our study autochthonous rickettsiosis is of limited concern to the public health in Denmark, but our finding of R. monacensis for the first time in Denmark illustrates the dynamic nature of tick-borne pathogens, emphasizing that continuous surveillance is necessary.

AB - Rickettsia helvetica has been reported at varying prevalences in Danish and other European Ixodes ricinus populations. Though apparently widespread and with reported cases of human infection, the significance of the bacteria as a threat to public health remains unclear. We present a nation-wide survey of rickettsia in ticks, roe deer and humans in Denmark. Ticks were collected by flagging and screened for presence of rickettsial DNA by polymerase chain reaction. Sera from roe deer, hunters, neuroborreliosis patients and blood donors were analyzed for presence of anti-R. helvetica and Rickettsia felis antibodies by immunofluorescence microscopy. The Rickettsia minimum infection rate in ticks was 4.9 % (367/973 pools positive, 7510 ticks in total), with 3.9 % in nymphs and 9.3 % in adults. Rickettsia helvetica accounted for 4.17 % and Rickettsia monacensis for 0.03 %, 0.6 % comprised non-differentiable rickettsial DNA. The prevalence of antibodies against R. helvetica was 2.8 % (9/319) in roe deer, while no hunters (n = 536) or blood donors (n = 181) were positive. The prevalence of anti-R. helvetica antibodies among Lyme neuroborreliosis patients was 6 % (3/47), where it co-occurred with Anaplasma phagocytophilum. Based on our study autochthonous rickettsiosis is of limited concern to the public health in Denmark, but our finding of R. monacensis for the first time in Denmark illustrates the dynamic nature of tick-borne pathogens, emphasizing that continuous surveillance is necessary.

KW - Co-infection

KW - Lyme Borreliosis

KW - Rickettsia helvetica

KW - Rickettsia monacensis

KW - Rickettsiosis

KW - Tick-borne infection

U2 - 10.1016/j.ttbdis.2023.102236

DO - 10.1016/j.ttbdis.2023.102236

M3 - Letter

C2 - 37708802

AN - SCOPUS:85170660301

VL - 14

JO - Ticks and Tick-borne Diseases

JF - Ticks and Tick-borne Diseases

SN - 1877-959X

IS - 6

M1 - 102236

ER -