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Q fever is a worldwide zoonotic infection caused by Coxiella burnetii. In Belgium, the disease must be notified, and the incidence is low. Human contamination is mostly due to sheep and goats. Herein, we report a case of chronic Q fever presenting as a prolonged fever in a patient with a history of valve prosthesis. Blood culture-negative endocarditis was diagnosed through an assessment including echocardiography and systematic serological testing. Despite the absence of travel abroad or obvious contact with domestic or wildlife animals, C. burnetii phase I and phase II IgG antibody titers were > 1:8192, and polymerase chain reaction performed on blood was positive for C. burnetii. Genotypic single nucleotide polymorphism (SNP) analysis of the pathogen strain identified a SNP-type 1 genomic group, which is associated with small ruminants in Belgium. The epidemiological investigation did not confirm the presence of positive C. burnetii cattle or sheep herds in the vicinity of the patient’s workplace and home, nor in the pest animals surrounding the workplace. Patients with risk factors for chronic Q fever should be tested for C. burnetii infection in case of prolonged fever of unknown origin, osteomyelitis, abscess or blood culture-negative endocarditis, even in the absence of direct exposure to animals.

Coxevac® is the EMA-approved veterinary vaccine for the protection of cattle and goats against Q fever, a zoonotic bacterial disease due to Coxiella burnetii. Since Coxevac® reduces bacterial shedding and clinical symptoms but does not prevent infection, novel, ready-to-use vaccine formulations are needed to increase its immunogenicity. Here, a goat vaccination-challenge model was used to evaluate the impact of the commercially available saponin-based QuilA® adjuvant on Coxevac® immunity. Upon challenge, the QuilA®-Coxevac® group showed a stronger immune response reflected in a higher magnitude of total IgG and an increase in circulating and splenic CD8+ T-cells compared to the Coxevac® and challenged-control groups. The QuilA®-Coxevac® group was characterized by a targeted Th1-type response (IFNγ, IP10) associated with increased transcripts of CD8+ and NK cells in spleens and γδ T cells in bronchial lymph nodes. Coxevac® vaccinated animals presented an intermediate expression of Th1-related genes, while the challenged-control group showed an immune response characterized by pro-inflammatory (IL1β, TNFα, IL12), Th2 (IL4 and IL13), Th17 (IL17A) and other immunoregulatory cytokines (IL6, IL10). An intriguing role was observed for γδ T cells, which were of TBX21- and SOX4-types in the QuilA®-Coxevac® and challenged control group, respectively. Overall, the addition of QuilA® resulted in a sustained Th1-type activation associated with an increased vaccine-induced bacterial clearance of 33.3% as compared to Coxevac® only. QuilA® could be proposed as a readily-applied veterinary solution to improve Coxevac® efficacy against C. burnetii infection in field settings. [ABSTRACT FROM AUTHOR]

Endemic Q fever in small ruminants remains an ongoing challenge for veterinary and human public health agencies. Though surveillance programs are implemented in Belgium, infection patterns and vaccination profiles, driving variables, as well as geographical clustering were not presented until now. Based on data from a decade of bulk tank milk analysis between 2009 and 2019, shedding in dairy goat herds declined from 16% (8/50) to 6% (10/162), whereas seroprevalence remained between 32% and 40%. Merely up to two shedding dairy sheep flocks were detected until 2019; seroprevalence peaked in 2017 (43%, 12/28) and declined thereafter. The number of animals in the holding influenced significantly (p =.048) the likelihood of shedding, whereas other established risk factors such as uncovered manure, high abortion rates and diversified farm structure could not be confirmed to significantly affect infection on Belgian herd level. Intermittent, incomplete and unsynchronized vaccinated herds shed Coxiella burnetii significantly more often and longer (p <.001) than continuously, complete and synchronized vaccinated herds. Spatial analyses revealed restricted but matching, homogenous clusters with ≤35 km diameter, concentrated in the coastal region close to the border to the Netherlands from 2009 to 2012, and broadened, heterogeneous clusters with ≥45 km diameter between 2014 and 2016 spreading south‐west. Though the majority of human cases was notified in this region, the animal clusters could not be allied with Q fever cases. The impact of environmental factors as well as the role of wildlife, rodents and ticks on the transmission between flocks and to humans remains to be elucidated to harness additional epidemiological drivers of Q fever in Belgium. In conclusion, attempts to reduce the burden of Q fever in Belgium should particularly focus on the timely, complete and synchronized vaccination of flocks, including the breeding sire, and particularity in high‐risk areas. [ABSTRACT FROM AUTHOR]

Abstract Background Malaria rapid diagnostic tests (RDTs) are kits that generally include 20 to 25 test strips or cassettes, but only a single buffer vial. In field settings, laboratory staff occasionally uses saline, distilled water (liquids for parenteral drugs dilution) or tap water as substitutes for the RDT kit's buffer to compensate for the loss of a diluent bottle. The present study assessed the effect of buffer substitution on the RDT results. Methods Twenty-seven RDT brands were run with EDTA-blood samples of five malaria-free subjects, who were negative for rheumatoid factor and antinuclear antibodies. Saline, distilled water and tap water were used as substitute liquids. RDTs were also run with distilled water, without adding blood. Results were compared to those obtained with the RDT kit's buffer and Plasmodium positive samples. Results Only eight cassettes (in four RDT brands) showed no control line and were considered invalid. Visible test lines occurred for at least one malaria-free sample and one of the substitutes in 20/27 (74%) RDT brands (saline: n = 16; distilled water: n = 17; and tap water: n = 20), and in 15 RDTs which were run with distilled water only. They occurred for all Plasmodium antigens and RDT formats (two-, three- and four-band RDTs). Clearance of the background of the strip was excellent except for saline. The aspects (colour, intensity and crispness) of the control and the false-positive test lines were similar to those obtained with the RDT kits' buffer and Plasmodium positive samples. Conclusion Replacement of the RDT kit's dedicated buffer by saline, distilled water and tap water can cause false-positive test results.

Abstract Background The prozone effect (or high doses-hook phenomenon) consists of false-negative or false-low results in immunological tests, due to an excess of either antigens or antibodies. Although frequently cited as a cause of false-negative results in malaria rapid diagnostic tests (RDTs), especially at high parasite densities of Plasmodium falciparum, it has been poorly documented. In this study, a panel of malaria RDTs was challenged with clinical samples with P. falciparum hyperparasitaemia (> 5% infected red blood cells). Methods Twenty-two RDT brands were tested with seven samples, both undiluted and upon 10 ×, 50 × and 100 × dilutions in NaCl 0.9%. The P. falciparum targets included histidine-rich protein-2 (HRP-2, n = 17) and P. falciparum-specific parasite lactate dehydrogenase (Pf-pLDH, n = 5). Test lines intensities were recorded in the following categories: negative, faint, weak, medium or strong. The prozone effect was defined as an increase in test line intensity of at least one category after dilution, if observed upon duplicate testing and by two readers. Results Sixteen of the 17 HRP-2 based RDTs were affected by prozone: the prozone effect was observed in at least one RDT sample/brand combination for 16/17 HRP-2 based RDTs in 6/7 samples, but not for any of the Pf-pLDH tests. The HRP-2 line intensities of the undiluted sample/brand combinations with prozone effect (n = 51) included a single negative (1.9%) and 29 faint and weak readings (56.9%). The other target lens (P. vivax-pLDH, pan-specific pLDH and aldolase) did not show a prozone effect. Conclusion This study confirms the prozone effect as a cause of false-negative HRP-2 RDTs in samples with hyperparasitaemia.

To the Editor: Belgium was declared free of bovine brucellosis by the European Union in 2003 (http:// eur-lex.europa.eu/LexUriServ/ LexUriServ.do?uri=OJ:L:2003:156 :0074:0078:EN:PDF). To maintain this status, the Federal Agency for the Safety [...]

Coxiella burnetii is a globally distributed zoonotic γ-proteobacterium with an obligatory intracellular lifestyle. It is the causative agent of Q fever in humans and of coxiellosis among ruminants, although the agent is also detected in ticks, birds, and various other mammalian species. Requirements for intracellular multiplication together with the necessity for biosafety level 3 facilities restrict the cultivation of C. burnetii to specialized laboratories. Development of a novel medium formulation enabling axenic growth of C. burnetii has facilitated fundamental genetic studies. This review provides critical insights into direct diagnostic methods currently available for C. burnetii. It encompasses molecular detection methods, isolation, and propagation of the bacteria and its genetic characterization. Differentiation of C. burnetii from Coxiella-like organisms is an essential diagnostic prerequisite, particularly when handling and analyzing ticks. [ABSTRACT FROM AUTHOR]