No abstract

The diagnosis of Q fever (Coxiella burnetii infection) relies primarily on the serological detection of specific antibodies. Recently, PCR-based methods have been introduced in diagnostic laboratories. Unfortunately, the fastest and most reliable 'real-time' detection method, which employs the 'online' detection of target nucleotide sequences while the amplification process is still in progress, requires expensive devices and consumables. In this study, we present a simple method that combines the simplicity of conventional PCR with new technical and methodical enhancements, resulting in a fast, specific and easy method for the molecular detection of C. burnetii. A collection of C. burnetii reference strains was tested with the modified conventional gel-based PCR approach applying a particluar PCR buffer (QIAGEN(®) Fast Cycling PCR kit) and using a closed ready-to-use gel-cassette-system (FlashGel(®)) for the visualization of specific PCR products. The modified conventional PCR method reached nearly the speed of the LightCycler(®) HybProbe real-time PCR assay (120 vs. 90 min) and showed equal sensitivity and specificity. The general cost per PCR run was 25% less than that for the LightCycler method. These improvements make this method suitable for small laboratories with limited resources and for deployable PCR diagnostics in field laboratories.

Coxiella burnetii is the causative agent of Q fever. It can infect animals, humans, and birds, as well as ticks, and it has a worldwide geographical distribution. To better understand the epidemiology of C. burnetii in Somalia, ticks infesting camels were collected from five different regions, including Bari, Nugaal, Mudug, Sool, and Sanaag, between January and March 2018. Collected ticks were tested for C. burnetii and Coxiella-like endosymbiont DNA by using IS1111, icd, and Com1-target PCR assays. Moreover, sequencing of the 16S-rRNA was conducted. Molecular characterization and typing were done by adaA-gene analysis and plasmid-type identification. Further typing was carried out by 14-marker Multi-Locus Variable-Number Tandem Repeats (MLVA/VNTR) analysis. The investigated ticks (n = 237) were identified as Hyalomma spp. (n = 227, 95.8%), Amblyomma spp. (n = 8, 3.4%), and Ripicephalus spp. (n = 2, 0.8%), and 59.1% (140/237) of them were positive for Coxiella spp. While Sanger sequencing and plasmid-type identification revealed a C. burnetii that harbours the QpRS-plasmid, MLVA/VNTR genotyping showed a new genotype which was initially named D21. In conclusion, this is the first report of C. burnetii in ticks in Somalia. The findings denote the possibility that C. burnetii is endemic in Somalia. Further epidemiological studies investigating samples from humans, animals, and ticks within the context of “One Health” are warranted.