Phylogeography of Human and Animal Coxiella burnetii Strains: Genetic Fingerprinting of Q Fever in Belgium

Abstract

Q fever is a zoonotic disease caused by the bacteria Coxiella burnetii. Domestic ruminants are the primary source for human infection, and the identification of likely contamination routes from the reservoir animals the critical point to implement control programs. This study shows that Q fever is detected in Belgium in abortion of cattle, goat and sheep at a different degree of apparent prevalence (1.93%, 9.19%, and 5.50%, respectively). In addition, and for the first time, it is detected in abortion of alpaca (Vicugna pacos), raising questions on the role of these animals as reservoirs. To determine the relationship between animal and human strains, Multiple Locus Variable-number Tandem Repeat Analysis (MLVA) (n=146), Single-Nucleotide Polymorphism (SNP) (n=92) and Whole Genome Sequencing (WGS) (n=4) methods were used to characterize samples/strains during 2009-2019. Three MLVA clusters (A, B, C) subdivided in 23 subclusters (A1-A12, B1-B8, C1-C3) and 3 SNP types (SNP1, SNP2, SNP6) were identified. The SNP2 type/MLVA cluster A was the most abundant and dispersed genotype over the entire territory, but it seemed not responsible for human cases, as it was only present in animal samples. The SNP1/MLVA B and SNP6/MLVA C clusters were mostly found in small ruminant and human samples, with the rare possibility of spillovers in cattle. SNP1/MLVA B cluster was present in all Belgian areas, while the SNP6/MLVA C cluster appeared more concentrated in the Western provinces. A broad analysis of European MLVA profiles confirmed the host-species distribution described for Belgian samples. In silico genotyping (WGS) further identified the spacer types and the genomic groups of C. burnetii Belgian strains: cattle and goat SNP2/MLVA A isolates belonged to ST61 and genomic group III, while the goat SNP1/MLVA B strain was classified as ST33 and genomic group II. In conclusion, Q fever is widespread in all Belgian domestic ruminants and in alpaca. We determined that the public health risk in Belgium is likely linked to specific genomic groups (SNP1/MLVA B and SNP6/MLVA C) mostly found in small ruminant strains. Considering the concordance between Belgian and European results, these considerations could be extended to other European countries.

Belgian bulk tank milk surveillance program reveals the impact of a continuous vaccination protocol for small ruminants against Coxiella burnetii

“…Despite the correspondences to the Netherlands regarding the geography, genetically similar circulating strains, breeding conditions as well as raised awareness of general practitioners towards the diagnostics of Q fever, not more than 20 domestic human cases were reported annually in Belgium. The animal and human cases could not be allied although the majority of human cases was observed in the region of clustered animal cases and the public health risk in Belgium is likely linked to specific genomic groups (SNP1/MLVA B and SNP6/MLVA C) mostly found in small ruminant strains (Tomaiuolo et al., 2021). Q fever transmission is multifactorial, and a higher incidence of human Q fever may have been related to other underlying aspects, including environmental and socioeconomic factors (Tissot‐Dupont et al., 2004).…”

A zoonotic cause of blood culture-negative infective endocarditis in Belgium: Case report and review of the literature on Q fever

“…The C. burnetii infection in animals, named coxiellosis, is widespread in all Belgian domestic ruminants. The human contamination in Belgium is mostly linked to specific genomic groups such as SNP1 (as in our patient) and SNP6, which are mostly found in small ruminants [8] .…”

Heterogeneity of Tick Abundance and Infection with Zoonotic Pathogenic Bacteria in a Belgian Peri-Urban Forest

“…The prevalence of these pathogenic agents in ticks are currently not well known in Belgium. The C. burnetii Nine Mile strain (RSA 493), originally isolated in 1935 from the tick Dermacentor andersoni, was recently isolated in Belgium [40]. Public health signi cance of such low pathogen presence is di cult to assess with the number of pools tested in this study.…”

“…In humans, it can cause acute or chronic illness, but the diagnosis is challenging because most human infections are subclinical or give u-like symptoms [37][38][39]. In Belgium, Q fever is widespread in Belgian domestic ruminants [40] and 25 cases of Q fever are con rmed yearly [41]. Infections generally occur through inhalation of C. burnetii contaminated aerosols in milk, faeces, urine and birth products or abortions from infected ruminants [37,39,42].…”