Act fast, stop COVID: The successful implementation of the first decentralised Victorian COVID-19 contact tracing and monitoring unit.

OBJECTIVES: To describe the operational model, epidemiology and outcomes of COVID-19 cases managed by the first decentralised Victorian Public Health Unit (PHU) in the Barwon South-West (BSW) region in 2020. METHODS: The Barwon Health team used a clinician-led, locally-based interprofessional model of care, combining clinical care and monitoring, contact tracing and public health measures. RESULTS: From 7th March to 5th October 2020, 575 confirmed COVID-19 cases (82 in Wave 1; 493 in Wave 2) were identified in residents of the BSW region. Overall, 4.7% were admitted to local hospitals (0.7% to intensive care units) and 1.7% died. COVID-19 incidence in the region was 129 cases/100,000. Wave 2 in the region featured community transmission in high-risk settings and among culturally and linguistically diverse and mobile populations. Within 3 months of the initial local case in Wave 2, SARS-COV-2 was eliminated from the community. CONCLUSIONS: A local interprofessional model of care was key to the containment of community transmission and complex outbreaks with the elimination of COVID-19 in the community. IMPLICATIONS FOR PUBLIC HEALTH: Key successes and learnings from the BSW PHU contributed to the improvement of statewide systems and responses and provided an impetus for the implementation of a decentralised public health model for Victoria.

Acute Q fever in patients with an influenza-like illness in regional New South Wales, Australia.

INTRODUCTION: Query (Q) fever is a zoonosis caused by the bacterium Coxiella burnetii typically presenting as an influenza-like illness (ILI) with or without hepatitis. The infection may be missed by clinicians in settings of low endemicity, as the presentation is clinically not specific, and there are many more common differential diagnoses for ILI including SARS-CoV-2 infection. METHODS: Residual serum samples were retrospectively tested for Phase 1 and 2 Q fever-specific IgM, IgG, IgA antibodies by indirect immunofluorescence and C. burnetii DNA by polymerase chain reaction. They had not been previously tested for Q fever, originating from undiagnosed patients with probable ILI, aged 10-70 years and living in regional New South Wales, Australia. The results were compared with contemperaneous data on acute Q fever diagnostic tests which had been performed based on clinicians requests from a geographically similar population. RESULTS: Only one (0.2%) instance of missed acute Q fever was identified after testing samples from 542 eligible patients who had probable ILI between 2016-2023. Laboratory data showed that during the same period, 731 samples were tested for acute Q fever for clinician-initiated requests and of those 70 (9.6%) were positive. Probability of being diagnosed with Q fever after a clinician initiated request was similar regardless of the patients sex, age and the calendar year of sampling. CONCLUSION: In this sample, Q fever was most likely to be diagnosed via clinician requested testing rather than by testing of undiagnosed patients with an influenza like illness.

Characterising Eastern Grey Kangaroos (Macropus giganteus) as Hosts of Coxiella burnetii.

Macropods are often implicated as the main native Australian reservoir hosts of Coxiella burnetii (Q fever); however, the maintenance and transmission capacity of these species are poorly understood. The objective of this cross-sectional study was to describe the epidemiology of C. burnetii in a high-density population of eastern grey kangaroos (Macropus giganteus) in a peri-urban coastal nature reserve in New South Wales, Australia. Blood, faeces and swabs were collected from forty kangaroos as part of a population health assessment. Frozen and formalin-fixed tissues were also collected from 12 kangaroos euthanised on welfare grounds. Specimens were tested for C. burnetii using PCR, serology, histopathology and immunohistochemistry. A total of 33/40 kangaroos were seropositive by immunofluorescence assay (estimated true seroprevalence 84%, 95% confidence interval [CI] 69% to 93%), with evidence of rising titres in two animals that had been tested four years earlier. The PCR prevalence was 65% (95% CI 48% to 79%), with positive detection in most sample types. There was no evidence of pathology consistent with C. burnetii, and immunohistochemistry of PCR-positive tissues was negative. These findings indicate that kangaroos are competent maintenance hosts of C. burnetii, likely forming a significant part of its animal reservoir at the study site.

Detection of Various Rickettsial Species in Ticks Collected from Small Ruminants in Western Iran.

Background: Most of the rickettsioses are transmitted by ticks, and often overlooked by the medical profession, but are clinically important as they cause major human diseases. Recent studies have shown the existence of some rickettsial species in Iran, but very little information is available about the status of rickettsial epidemiology and ecology. This study investigated the presence of Rickettsia spp. in ticks and ruminants in western of Iran by molecular methods. Materials and Methods: 250 blood samples were collected from sheep and goats, as well as 244 ticks were collected opportunistically from ruminants in the Kurdistan province. The collected samples were tested using a real-time quantitative PCR (qPCR) assay targeting the Rickettsia 16SrRNA gene. Rickettsia spp. positive by the qPCR were further amplified by conventional PCR of the gltA and OmpA genes. These ampliqons were further analyzed by sequencing. Results: The ticks species collected in this study included Rhipicephalus sanguineus, Rh. turanicus, Haemaphysalis concinna, and Dermacentor marginatus. In total, DNA of Rickettsia spp. was detected in 131 collected ticks (53.7%). Of the positives, Rickettsia slovaca (59.2%) and Ri. hoogstraalii (16.3%) were the most common species identified followed by Ri. raoultii, Ri. massiliae, Ri. sibirica, and Ri. conorii subsp. israelensis. In contrast, there were no positives observed in the blood samples collected from ruminants. Conclusion: The results indicate the presence of rickettsial species in ticks. The detection of these pathogens is significant because they cause clinical disease in humans. The results support the notion that the Iranian public health system needs to be more aware of these diseases.

Tissue distribution of Coxiella burnetii and antibody responses in macropods co-grazing with livestock in Queensland, Australia.

Coxiella burnetii, the causative agent of Q fever, is a zoonotic bacteria of global public health significance. The organism has a complex, diverse, and relatively poorly understood animal reservoir but there is increasing evidence that macropods play some part in the epidemiology of Q fever in Australia. The aim of this cross-sectional survey was to estimate the animal- and tissue-level prevalence of coxiellosis amongst eastern grey (Macropus giganteus) and red (Osphranter rufus) kangaroos co-grazing with domestic cattle in a Q fever endemic area in Queensland. Serum, faeces and tissue samples from a range of organs were collected from 50 kangaroos. A total of 537 tissue samples were tested by real-time PCR, of which 99 specimens from 42 kangaroos (84% of animals, 95% confidence interval [CI], 71% to 93%) were positive for the C. burnetii IS1111 gene when tested in duplicate. Twenty of these specimens from 16 kangaroos (32%, 95% CI 20% to 47%) were also positive for the com1 or htpAB genes. Serum antibodies were present in 24 (57%, 95% CI 41% to 72%) of the PCR positive animals. There was no statistically significant difference in PCR positivity between organs and no single sample type consistently identified C. burnetii positive kangaroos. The results from this study identify a high apparent prevalence of C. burnetii amongst macropods in the study area, albeit seemingly with an inconsistent distribution within tissues and in relatively small quantities, often verging on the limits of detection. We recommend Q fever surveillance in macropods should involve a combination of serosurveys and molecular testing to increase chances of detection in a population, noting that a range of tissues would likely need to be sampled to confirm the diagnosis in a suspect positive animal.

Gaps and inconsistencies in the current knowledge and implementation of biosafety and biosecurity practices for rickettsial pathogens.

INTRODUCTION: Rickettsia spp. and Orientia spp. are the causes of neglected infections that can lead to severe febrile and systemic illnesses in humans. Implementing proper biosafety practices when handling these pathogens is crucial to ensure a safe and sustainable work environment. It is essential to assess the current knowledge and identify any potential gaps to develop effective measures that minimise the risk of exposure to these pathogens. By doing so, we can establish a comprehensive framework that promotes safety, mitigates hazards, and safeguards the well-being of personnel and the surrounding community. METHODS AND RESULTS: This review aimed to synthesise and determine the evidence base for biosafety precautions for Rickettsia spp. and Orientia spp. pathogens. Enhancing our understanding of the relative infectious risk associated with different strains of Rickettsia and Orientia spp. requires identifying the infectious dose of these pathogens that can cause human disease. The application of risk groups for Rickettsia and Orientia spp. is inconsistent across jurisdictions. There is also incomplete evidence regarding decontamination methods for these pathogens. With regards to Orientia spp. most of the available information is derived from experiments conducted with Rickettsia spp. CONCLUSIONS: Rickettsia and Orientia spp. are neglected diseases, as demonstrated by the lack of evidence-based and specific biosafety information about these pathogens. In the case of Orientia spp., most of the available information is derived from Rickettsia spp., which may not be appropriate and overstate the risks of working with this pathogen. The advent of effective antibiotic therapy and a better understanding of the true hazards and risks associated with pathogen manipulation should inform decisions, allowing a sustainable and safe work environment.

Synthetic Particulate Subunit Vaccines for the Prevention of Q Fever.

Coxiella burnetti is an intracellular bacterium that causes Q fever, a disease of worldwide importance. Q-VAX® , the approved human Q fever vaccine, is a whole cell vaccine associated with safety concerns. Here a safe particulate subunit vaccine candidate is developed that is ambient-temperature stable and can be cost-effectively manufactured. Endotoxin-free Escherichia coli is bioengineered to efficiently self-assemble biopolymer particles (BPs) that are densely coated with either strings of 18 T-cell epitopes (COX-BP) or two full-length immunodominant antigens (YbgF-BP-Com1) all derived from C. burnetii. BP vaccine candidates are ambient-temperature stable. Safety and immunogenicity are confirmed in mice and guinea pig (GP) models. YbgF-BP-Com1 elicits specific and strong humoral immune responses in GPs with IgG titers that are at least 1 000 times higher than those induced by Q-VAX® . BP vaccine candidates are not reactogenic. After challenge with C. burnetii, YbgF-BP-Com1 vaccine leads to reduced fever responses and pathogen burden in the liver and the induction of proinflammatory cytokines IL-12 and IFN-γ inducible protein (IP-10) when compared to negative control groups. These data suggest that YbgF-BP-Com1 induces functional immune responses reducing infection by C. burnetii. Collectively, these findings illustrate the potential of BPs as effective antigen carrier for Q fever vaccine development.

A serological assay using Tropheryma whipplei antigens for the presumptive exclusion of Whipple disease.

Whipple disease (WD) is a rare infection in genetically susceptible people caused by the bacterium Tropheryma whipplei. An indirect immunofluorescence serological assay (IFA), detecting patient antibodies to the bacterium, was developed using T. whipplei as antigen. We hypothesised that this assay could be used to rule out WD in patients in whom the diagnosis was being considered, based on high immunoglobulin (Ig) G titres to T. whipplei. In this study, 16 confirmed WD patients and 156 age-matched controls from across Australia were compared serologically. WD patients mostly underproduced IgG antibody to T. whipplei, with titres of ≤1:32 being common. While at an antibody titre of <1:64 the assay sensitivity for WD was only 69% [95% confidence interval (CI) 41-89%], its specificity for excluding WD was 91% (95% CI 85-95%). This specificity increased to 95% (95% CI 90-98%) at an antibody titre of <1:16. Patients with antibody titres of >1:64 were unlikely to have WD. At this titre, the seroprevalence of T. whipplei IgG antibody was 92% (223/242) in Australian blood donors. Unlike other serological assays, which are used to confirm a specific infection, this novel assay is designed to rule out WD infection with a specificity in Australia of 91%. Further validation of this assay, by trialling in other countries, should now be undertaken, as its usefulness is dependent on there being a high background seropositivity to T. whipplei in the general population at the location in which the assay is being used.

Q fever - immune responses and novel vaccine strategies.

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. It is an occupational risk for employees of animal industries and is associated with contact with wildlife and domestic animals. Although Q fever infection may be asymptomatic, chronic sequelae such as endocarditis occur in 5% of symptomatic individuals. Disease outcomes may be predicted through measurement of immune correlates. Vaccination is the most efficient method to prevent Q fever. Currently, Q-VAX is the only licenced human vaccine. Q-VAX is highly effective; however, individuals previously exposed to C. burnetii are at risk of adverse reactions. This review examines the immunological responses of acute and chronic Q fever and the efforts to provide a safer and cost-effective Q fever vaccine.

Q fever is a disease that is spread by some animals, such as sheep and cattle, to humans. Although most people will recover if they get Q fever, some become very ill. There is a vaccine for Q fever (Q-VAX), but it can cause a reaction when given to some people. Research is ongoing into how the human immune system reacts to the bacteria that causes Q fever. A small number of people who get Q fever will develop a prolonged disease that can be serious and affect the heart, which is why there is also research into developing new vaccines for this disease. This research will look at those parts of the germ that causes Q fever that can be used for a new vaccine.

The presence of Rickettsia felis in communities in the central highlands of Vietnam.

Rickettsia felis is an emerging flea-borne spotted fever pathogen that causes febrile illness in humans. In Vietnam, R. felis was detected in hospitalized patients, but there is no information on its presence in the Vietnamese community. This cross-sectional study aimed to determine the presence of R. felis in humans of the Central Highlands of Vietnam. A total of 158 blood and 213 serum samples were subjected to PCR and IFAT, respectively, to detect the presence of R. felis DNA and antibodies against R. felis. PCR assays detected R. felis DNA in four out of 158 blood samples, accounting for a prevalence of 2.53 % (95 % CI: 0.81 %-6.76 %). Phylogenetic analysis indicated the presence of R. felis and R. felis genotype RF2125 in the communities in the Central Highlands of Vietnam. The result of IFAT identified seven out of 213 serum samples (3.29 %, 95 % CI: 1.45 %-6.93 %) positive for antibodies against R. felis. This study was the first to demonstrate the presence of active R. felis infections in the communities in the Central Highlands of Vietnam utilizing both molecular and serological methods.

Q fever immunology: the quest for a safe and effective vaccine.

Q fever is an infectious zoonotic disease, caused by the Gram-negative bacterium Coxiella burnetii. Transmission occurs from livestock to humans through inhalation of a survival form of the bacterium, the Small Cell Variant, often via handling of animal parturition products. Q fever manifests as an acute self-limiting febrile illness or as a chronic disease with complications such as vasculitis and endocarditis. The current preventative human Q fever vaccine Q-VAX poses limitations on its worldwide implementation due to reactogenic responses in pre-sensitized individuals. Many strategies have been undertaken to develop a universal Q fever vaccine but with little success to date. The mechanisms of the underlying reactogenic responses remain only partially understood and are important factors in the development of a safe Q fever vaccine. This review provides an overview of previous and current experimental vaccines developed for use against Q fever and proposes approaches to develop a vaccine that establishes immunological memory while eliminating harmful reactogenic responses.

Molecular detection of Rickettsia sp. genotype RF2125 from household dogs in the central highlands of Vietnam.

Rickettsia felis, a zoonotic vector-borne bacteria, is reported globally in humans, animals, and its invertebrate hosts. This study was designed to detect antibodies against R. felis and the DNA of R. felis in blood of domestic dogs in the Central Highlands of Vietnam using immunofluorescence antibody test (IFAT), and ompB- and gltA-PCRs, respectively. Using IFAT, 23 out of 338 plasma samples collected from household dogs were seropositive for R. felis, accounting for 6.80% (CI 95%: 4.45-10.1%). Of 171 buffy coat samples from household dogs, 50 were positive for spotted fever group rickettsioses using ompB-PCR assay, accounting for 29.2% (CI 95%: 22.6-36.7%). The gltA-PCR assay detected R. felis in 30% (15/50) of ompB-positive samples. DNA sequencing of ompB-PCR and gltA-PCR products confirmed the presence of R. felis and Rickettsia sp. genotype RF2125 / R. asembonensis. Our findings suggest a potential risk of R. felis infection in the communities in the Central Highlands of Vietnam, and the reservoir role of dogs to Rickettsia sp. genotype RF2125.

A Novel Marine Mammal Coxiella burnetii-Genome Sequencing Identifies a New Genotype with Potential Virulence.

The obligate intracellular bacterial pathogen Coxiella burnetii has been identified in a few species of marine mammals, some of which are showing population declines. It has been hypothesized that C. burnetii in marine mammals is a distinct genotype that varies significantly from the typical terrestrial genotypes. It appears to lack an IS1111. Isolates originating from Australian marine animals have a distinctly non-Australian profile of multiple-locus variable-number tandem-repeat analysis (MLVA). Extracted Coxiella DNA of Australian fur seal placental origin was sequenced using the Novaseq platform. Illumina 150 bp paired-end reads were filtered and trimmed with Trimgalore. The microbial community present in the sequenced genome was evaluated with Kraken and Bracken software using the NCBI database. A phylogenetic analysis was performed using 1131 core genes. Core genes were identified using Panaroo and inputted into Iqtree to determine the maximum-likelihood tree. A second phylogenetic tree was created using Rickettsiella grylii and using seven housekeeping genes. Results were compared with the C. burnetii Nine Mile RSA439 virulent genome. This new Australian marine mammal isolate of Coxiella (PG457) appears to be a novel genotype that lacks IS1111 and has a distinct MLVA signature (ms26, ms27, ms28, ms30, and ms31). The presence of genes for multiple virulence factors appears to give this genotype sufficient pathogenicity for it to be considered a possible causative agent of abortion in Australian fur seals as well as a potential zoonotic risk.

Unravelling the Diversity of Microorganisms in Ticks from Australian Wildlife.

Ticks and tick-borne pathogens pose a significant threat to the health and welfare of humans and animals. Our knowledge about pathogens carried by ticks of Australian wildlife is limited. This study aimed to characterise ticks and tick-borne microorganisms from a range of wildlife species across six sites in Victoria, Australia. Following morphological and molecular characterisation (targeting 16S rRNA and cytochrome c oxidase I), tick DNA extracts (n = 140) were subjected to microfluidic real-time PCR-based screening for the detection of microorganisms and Rickettsia-specific real-time qPCRs. Five species of ixodid ticks were identified, including Aponomma auruginans, Ixodes (I.) antechini, I. kohlsi, I. tasmani and I. trichosuri. Phylogenetic analyses of 16S rRNA sequences of I. tasmani revealed two subclades, indicating a potential cryptic species. The microfluidic real-time PCR detected seven different microorganisms as a single (in 13/45 ticks) or multiple infections (27/45). The most common microorganisms detected were Apicomplexa (84.4%, 38/45) followed by Rickettsia sp. (55.6%, 25/45), Theileria sp. (22.2% 10/45), Bartonella sp. (17.8%, 8/45), Coxiella-like sp. (6.7%, 3/45), Hepatozoon sp. (2.2%, 1/45), and Ehrlichia sp. (2.2%, 1/45). Phylogenetic analyses of four Rickettsia loci showed that the Rickettsia isolates detected herein potentially belonged to a novel species of Rickettsia. This study demonstrated that ticks of Australian wildlife carry a diverse array of microorganisms. Given the direct and indirect human-wildlife-livestock interactions, there is a need to adopt a One Health approach for continuous surveillance of tick-associated pathogens/microorganisms to minimise the associated threats to animal and human health.

Pacific Gulls (Larus pacificus) as Potential Vectors of Coxiella burnetii in an Australian Fur Seal Breeding Colony.

Recently, Coxiella burnetii has been described as a novel pathogen potentially contributing to decreased pup production in Australian fur seals (AusFS, Arctocephalus pusillus doriferus). Pacific gulls (PGs, Larus pacificus) are known to scavenge AusFS placental material during the fur seal breeding season. It is hypothesized that PGs may act as vectors for this pathogen. In the present study, cloacal swabs, oral swabs and serum were collected from PGs on Kanowna Island (KI, an AusFS breeding colony) and a nearby island, Seal Island (SI), not occupied by pinnipeds. All sample sets were evaluated with qPCR for the com1, htpAB and IS1111 markers. Most oral and cloacal swabs from KI tested positive on both the com1 (94.1%; 88.2%) and htpAB targets (76.5%; 76.5%). Amplification was very low from the SI oral swabs and cloacal swabs. Only the KI serum samples had amplification (17.7% for both com1 and htpAB). There was no IS1111 amplification in either colony. The results demonstrate that PGs can potentially act as vectors for the spread of C. burnetii. In some birds, C. burnetii was detectable in the serum, indicating that gulls can experience bacteraemia. It appears that different feeding strategies in the same species within the same ecosystem can have profound effects on the prevalence of pathogens. Further studies are required to better understand the epidemiology and potential risks of this organism.

The Troublesome Ticks Research Protocol: Developing a Comprehensive, Multidiscipline Research Plan for Investigating Human Tick-Associated Disease in Australia.

In Australia, there is a paucity of data about the extent and impact of zoonotic tick-related illnesses. Even less is understood about a multifaceted illness referred to as Debilitating Symptom Complexes Attributed to Ticks (DSCATT). Here, we describe a research plan for investigating the aetiology, pathophysiology, and clinical outcomes of human tick-associated disease in Australia. Our approach focuses on the transmission of potential pathogens and the immunological responses of the patient after a tick bite. The protocol is strengthened by prospective data collection, the recruitment of two external matched control groups, and sophisticated integrative data analysis which, collectively, will allow the robust demonstration of associations between a tick bite and the development of clinical and pathological abnormalities. Various laboratory analyses are performed including metagenomics to investigate the potential transmission of bacteria, protozoa and/or viruses during tick bite. In addition, multi-omics technology is applied to investigate links between host immune responses and potential infectious and non-infectious disease causations. Psychometric profiling is also used to investigate whether psychological attributes influence symptom development. This research will fill important knowledge gaps about tick-borne diseases. Ultimately, we hope the results will promote improved diagnostic outcomes, and inform the safe management and treatment of patients bitten by ticks in Australia.

Genetic Diversity of Coxiella burnetii in Iran by Multi-Spacer Sequence Typing.

Coxiella burnetii, the zoonotic agent of Q fever, has a worldwide distribution including Iran. However, no information regarding the circulating genotype of this infection has been reported in Iran. This study aimed to evaluate the genetic diversity of C. burnetii in Iran using the multi-spacer sequence typing (MST) method. First, 14 positive C. burnetii samples (collected from four sheep, three goats, and seven cattle) were confirmed using quantitative polymerase chain reaction (qPCR) targeting the IS1111 gene. Then, ten spacers (Cox 2, 5, 18, 20, 22, 37, 51, 56, 57, and 61) were amplified using PCR for future MST analysis. The in-silico MST genotyping analysis of domestic ruminant samples revealed two new alleles (Cox5.11 and Cox56.15) in Cox5 and Cox56 loci that led to the emergence of four novel MST genotypes (MST62, 63, 64, and 65) and one MST genotype that has been previously described (MST61). This study showed the circulation of five MST C. burnetii genotypes among Iranian domestic ruminants. Understanding the C. burnetii genotypic profiles is critical in determining and preventing Q fever outbreaks.

Investigation of Rickettsia conorii in Patients Suspected of Having Crimean-Congo Hemorrhagic Fever.

Rickettsia conorii is the causative agent of Mediterranean spotted fever (MSF). Misdiagnosis of MSF may occur with febrile syndromes associated with rash and thrombocytopenia, such as Crimean-Congo hemorrhagic fever (CCHF). This study aimed to determine the prevalence of R. conorii among serum samples obtained from 260 suspected CCHF patients with features of MSF in Iran (2018-2020). The quantitative polymerase chain reaction (qPCR) method detected three (1.15%) positive 16S rDNA Rickettsia spp. samples that were classified as R. conorii subsp. conorii, R. conorii subsp. Israelensis, and R. helvetica using the sequencing of gltA, ompA, and 17kDa genes. Furthermore, R. conorii IgM antibodies presented in 38 (14.62%) patients by the enzyme-linked immunosorbent assay (ELISA) method. Out of 97 MSF patients with available paired serum samples, IgM seroconversion and a four-fold increase were observed in 14 (14.43%) and 12 (12.37%) patients, respectively. We concluded that rickettsial agents are present in Iran and may be misdiagnosed with other febrile syndromes.

An O-Specific Polysaccharide/Tetanus Toxoid Conjugate Vaccine Induces Protection in Guinea Pigs against Virulent Challenge with Coxiella burnetii.

Q fever is caused by the bacterium Coxiella burnetii and is spread to humans from infected animals especially goats, sheep and cattle, predominantly when giving birth. There is an effective human vaccine (Q-VAX) against Q fever, and although Q fever is a worldwide problem, the vaccine is only used in Australia due to difficulties associated with its use and the risk of adverse reactions. The desire to protect humans, particularly farmers and abattoir workers, from Q fever prompted the development of a new safe and effective human vaccine without all the difficulties associated with the current vaccine. Candidate vaccines were prepared using purified O-specific polysaccharide (OSP) extracted from the lipopolysaccharide of virulent (phase 1) C. burnetii, strain Nine Mile, which was then conjugated to a tetanus toxoid (TT) carrier protein. Two vaccines were prepared using OSP from C. burnetii grown in embryonated eggs (vaccine A) and axenic media (vaccine B). Vaccines with or without alum adjuvant were used to vaccinate guinea pigs, which were later challenged by intranasal inoculation with virulent C. burnetii. Both vaccines protected guinea pigs from fever and loss of weight post challenge. Post-mortem samples of the spleen, liver and kidney of vaccinated guinea pigs contained substantially less C. burnetii DNA as measured by PCR than those of the unvaccinated control animals. This study demonstrated that a C. burnetii OSP-TT conjugate vaccine is capable of inducing protection against virulent C. burnetii in guinea pigs. Additionally, OSP derived from C. burnetii grown in axenic media compared to OSP from embryonated eggs is equivalent in terms of providing a protective immune response.

Comparison of the Serion IgM ELISA and Microscopic Agglutination Test for diagnosis of Leptospira spp. infections in sera from different geographical origins and estimation of Leptospira seroprevalence in the Wiwa indigenous population from Colombia.

Leptospirosis is among the most important zoonotic diseases in (sub-)tropical countries. The research objective was to evaluate the accuracy of the Serion IgM ELISA EST125M against the Microscopic Agglutination Test (MAT = imperfect reference test); to assess its ability to diagnose acute leptospirosis infections and to detect previous exposure to leptospires in an endemic setting. In addition, to estimate the overall Leptospira spp. seroprevalence in the Wiwa indigenous population in North-East Colombia. We analysed serum samples from confirmed leptospirosis patients from the Netherlands (N = 14), blood donor sera from Switzerland (N = 20), and sera from a cross-sectional study in Colombia (N = 321). All leptospirosis ELISA-positive, and a random of negative samples from Colombia were tested by the MAT for confirmation. The ELISA performed with a sensitivity of 100% (95% CI 77% - 100%) and a specificity of 100% (95% CI 83% - 100%) based on MAT confirmed Leptospira spp. positive and negative samples. In the cross-sectional study in Colombia, the ELISA performed with a sensitivity of 100% (95% CI 2-100%) and a specificity of 21% (95% CI 15-28%). Assuming a 5% Leptospira spp. seroprevalence in this population, the positive predictive value was 6% and the negative predictive value 100%. The Leptospira spp. seroprevalence in the Wiwas tested by the ELISA was 39%; however, by MAT only 0.3%. The ELISA is suitable to diagnose leptospirosis in acutely ill patients in Europe several days after onset of disease. For cross-sectional studies it is not recommended due to its low specificity. Despite the evidence of a high leptospirosis prevalence in other study areas and populations in Colombia, the Wiwa do not seem to be highly exposed to Leptospira spp.. Nevertheless, leptospirosis should be considered and tested in patients presenting with febrile illness.