Proinflammatory Chemokine Levels in Cerebrospinal Fluid of Patients with Neuroinvasive Flavivirus Infections.

Tick-borne encephalitis virus (TBEV) and West Nile virus (WNV) are the most important neuroinvasive arboviruses detected in Europe. In this study, we analyzed cerebrospinal fluid (CSF) concentrations of 12 proinflammatory chemokines (CCL2, CCL3, CCL4, CCL11, CCL17, CCL20, CXCL1, CXCL5, CXCL8, CXCL9, CXCL10, and CXCL11) in 77 patients with neuroinvasive diseases (NIDs). Flavivirus infection was confirmed in 62 patients (TBEV and WNV in 31 patients each), while in 15 patients the etiology of NID was not determined (NDE). Similar patterns of high-level expression of chemokines regulating monocyte/macrophage responses (CCL2), neutrophil recruitment (CXCL1 and CXCL8), and interferon-inducible chemoattractants for leukocytes (CXCL10 and CXCL11) have been observed in WNV and TBEV groups. None of the tested chemokines significantly differed between patients with TBEV or WNV. Concentrations of CCL17, CCL20, CXCL5, CXCL10, and CXCL11 were significantly lower in both WNV and TBEV groups compared to NID NDE patients. The logistic regression model showed that CSF concentrations of CXCL11, CXCL5, and CXCL10 could potentially be used for the classification of patients into the WNV or TBEV group versus groups with other NIDs. This study identified, for the first time, similar patterns of CSF chemokine expression in WNV and TBEV infections, suggesting common immunopathogenic mechanisms in neuroinvasive flavivirus infections that should be further evaluated.

An Overview of Tick-Borne Encephalitis Epidemiology in Endemic Regions of Continental Croatia, 2017-2023.

Tick-borne encephalitis (TBE) represents an important public health problem in Europe. We analyzed the epidemiology of TBE based on data from humans, animals, and Ixodes ricinus ticks in endemic regions of continental Croatia. In the period from 2017 to 2023, cerebrospinal fluid (CSF) and serum samples of 684 patients with neuroinvasive diseases, 2240 horse serum samples, and 300 sheep serum samples were tested for TBEV. In addition, 8751 I. ricinus ticks were collected. CSF samples were tested using RT-PCR. Serological tests (serum, CSF) were performed using commercial ELISA, with confirmation of cross-reactive samples by a virus neutralization test. Eighty-four autochthonous human TBEV cases were confirmed. The majority of patients were in the age group of 40-69 years (58.3%) with a male predominance (70.2%). TBE showed a bimodal seasonality with a large peak in April-August and a small one in October-November. In addition to humans, TBEV IgG antibodies were found in 12.2% of horses and 9.7% of sheep. Seasonal tick abundance corresponds to the reported number of human infections. Continental Croatia is still an active natural focus of TBE. Continuous monitoring of infections in humans, sentinel animals, and ticks is needed for the implementation of preventive measures.

Hantavirus Pulmonary Syndrome Caused by Puumala Orthohantavirus-A Case Report and Literature Review.

In this article, we report on a rare case of acute respiratory distress syndrome (ARDS) caused by the Puumala orthohantavirus (PUUV), which is typically associated with hemorrhagic fever with renal syndrome (HFRS). This is the first documented case of PUUV-associated ARDS in Southeast Europe. The diagnosis was confirmed by serum RT-PCR and serology and corroborated by phylogenetic analysis and chemokine profiling. The patient was a 23-year-old male from Zagreb, Croatia, who had recently traveled throughout Europe. He presented with fever, headache, abdominal pain, and sudden onset of ARDS. Treatment involved high-flow nasal cannula oxygen therapy and glucocorticoids, which resulted in a full recovery. A systematic literature review identified 10 cases of hantavirus pulmonary syndrome (HPS) caused by PUUV in various European countries and Turkey between 2002 and 2023. The median age of patients was 53 years (range 24-73), and six of the patients were male. Most patients were treated in intensive care units, but none received antiviral therapy targeting PUUV. Eight patients survived hospitalization. The presented case highlights the importance of considering HPS in the differential diagnosis of ARDS, even in areas where HFRS is the dominant form of hantavirus infection.

Detection of Bhanja Bandavirus in Patients with Neuroinvasive Disease of Unknown Etiology in Croatia.

BACKGROUND: Although the Bhanja bandavirus (BHAV) is widely distributed in some European countries, human infections are rarely reported. This study analyzed the prevalence of BHAV antibodies in patients with neuroinvasive diseases of unsolved etiology. METHODS: A total of 254 Croatian patients who developed neurological symptoms during the four consecutive arbovirus transmission seasons (April 2017-October 2021) were tested. Cerebrospinal fluid (CSF) and urine samples were tested using RT-qPCR. In addition, CSF and serum samples were tested using a virus neutralization test. RESULTS: BHAV RNA was not detected in any samples, while neutralizing (NT) antibodies were detected in serum samples of 53/20.8% of patients (95% CI = 16.0-26.3). In two patients, BHAV NT antibodies were detected in the CSF, indicating a recent infection. Both patients were inhabitants of rural areas in continental Croatia, and one reported a tick bite two weeks before symptoms onset. The seropositivity was high in all age groups (15.2-29.1%). The majority of seropositive patients (94.3%) resided at altitudes less than 200 m above sea level. The prevalence rates correlated positively with population density and negatively with certain climate parameters (temperature, number of hot/warm days). CONCLUSIONS: The presented results indicate that BHAV is distributed in Croatia. Further studies are needed to determine the clinical significance of this neglected arbovirus.

Prediction of unfavorable outcomes in community-acquired bacteremia by SIRS, SOFA and qSOFA scores.

BACKGROUND: Sepsis diagnostic and prognostic scoring systems have changed over time. It remains uncertain which scoring system is the best predictor of unfavorable outcomes. We aimed to evaluate prediction of community-acquired bacteremia (CAB) outcomes using on-admission systemic inflammatory response syndrome (SIRS), sequential organ failure assessment (SOFA) and quick sequential organ failure assessment (qSOFA). METHODS: We present a retrospective observational cohort study of consecutive adult patients hospitalized with CAB over ten years. SIRS, qSOFA and SOFA scores calculated on admission were dichotomized as ≥2 or 0-1. Raw and adjusted incidence of a composite unfavorable outcome (death, septic shock, invasive mechanical ventilation, extra-corporeal membrane oxygenation, renal replacement therapy) over 35 days were compared. RESULTS: Among 1930 patients, 1221 (63.3%) had SIRS, 196 (10.2%) had qSOFA, and 1117 (57.9%) had SOFA≥2. Respective raw and adjusted probabilities of the outcome were similar. Incidence for qSOFA≥2 was high (41.3%) and still considerable for qSOFA 0-1 (5.4%). SOFA≥2 indicated higher risk than SIRS≥2 (14.7% vs. 12.4%), while SOFA 0-1 indicated lower risk than SIRS 0-1 (1.2% vs. 3.1%). This relationship between SOFA and SIRS was also observed in patients with qSOFA 0-1. CONCLUSIONS: qSOFA≥2 was associated with highest probability of unfavorable outcome, but dichotomized SOFA was more precise at high vs. low-risk distinction. Consecutive use of dichotomized qSOFA and SOFA on admission of adults with CAB enables fast and reliable identification of patients at high (qSOFA≥2, risk ~≥35%), moderate (qSOFA 0-1, SOFA≥2, risk ~10%), and low risk (qSOFA 0-1, SOFA 0-1, risk 1-2%) of subsequent unfavorable events.

Extracorporeal membrane oxygenation in COVID-19: Results of the Croatian Extracorporeal Membrane Oxygenation Referral Center.

At the beginning of the COVID-19 pandemic, the role of extracorporeal membrane oxygenation (ECMO) was uncertain and the outcomes of ECMO-treated patients were unfavorable. During the pandemic, medical community realized that carefully selected patients may benefit from ECMO support. The goal of the study was to present the outcomes of ECMO-treated patients with severe COVID-19 ARDS referred to the respiratory ECMO hub in Croatia and to determine variables that influenced the outcome. Our study included all adult patients with confirmed COVID-19 ARDS that required ECMO treatment, in the period between February 2020 and April 2022. All ECMO circuits were veno-venous with femoro-jugular configuration, with drainage at the femoral site. A total of 112 adult patients with COVID-19 induced ARDS were included in the study. All patients had veno-venous ECMO treatment and 34 survived. Surviving patients were discharged home either from the hospital or from a designated rehabilitation facility. The mortality was associated with the incidence of nosocomial bacteremia, occurrence of heparin induced thrombocytopenia and acute renal failure. In order to reduce the mortality in COVID-19 ECMO patients, the treatment should be started as soon as criteria for ECMO are met. Furthermore, complications of the procedure should be detected as soon as possible. However, despite even the optimal approach, the mortality in COVID-19 ECMO patients will surpass that of non-COVID-19 ARDS ECMO patients, mostly due to poor resolving and long lasting ARDS with longer ECMO runs and ensuing infectious complications.

Surveillance of Tahyna Orthobunyavirus in Urban Areas in Croatia-The "One Health" Approach.

BACKGROUND: Tahyna orthobunyavirus (TAHV) is a neglected mosquito-borne bunyavirus. Although the virus is widespread in continental Europe, TAHV infections are rarely reported. We analyzed the prevalence of TAHV in humans and different animal species as well as mosquitoes collected in urban areas of Zagreb and its surroundings in the period from 2020 to 2022. METHODS: The study included 32 patients with neuroinvasive disease (NID), 218 asymptomatic individuals, 98 horses, 94 pet animals (dogs and cats), and 4456 Aedes vexans mosquitoes. Cerebrospinal fluid (CSF) and urine samples of patients with NID were tested for the TAHV RNA using a real-time reverse transcription-polymerase chain reaction (RT-qPCR). Human and animal serum samples were tested for TAHV-neutralizing (NT) antibodies using a virus-neutralization test (VNT). Mosquito pools were tested for TAHV RNA using an RT-qPCR. RESULTS: TAHV NT antibodies were detected in 3/9.4% of patients with NID, 8/3.7% of asymptomatic individuals, 29/29.6% of horses, and 11/11.7% of pet animals. There was no difference in the seroprevalence according to age, sex, and area of residence in asymptomatic individuals. In addition, TAHV seropositivity did not differ according to age and sex in pet animals. None of the tested mosquito pools was TAHV RNA-positive. CONCLUSIONS: The presented results highlight the importance of interdisciplinary surveillance ("One Health") of this neglected viral zoonosis.

Detection of Tahyna Orthobunyavirus-Neutralizing Antibodies in Patients with Neuroinvasive Disease in Croatia.

BACKGROUND: Tahyna orthobunyavirus (TAHV) is widely distributed in continental Europe. Very few studies have analyzed TAHV seroprevalence in Croatia. We analyzed the prevalence of TAHV RNA and antibodies in Croatian patients with neuroinvasive disease (NID). METHODS: A total of 218 patients with unsolved NID detected during five consecutive arbovirus transmission seasons (April 2017-October 2021) were tested. Cerebrospinal fluid (CSF) and urine samples were tested for TAHV RNA using RT-PCR. In addition, CSF and serum samples were tested for TAHV antibodies using a virus neutralization test (VNT). RESULTS: Clinical presentations in patients with NID were meningitis (141/64.7%), meningoencephalitis (56/25.7%), myelitis (8/3.7%), and 'febrile headache' (13/5.9%). TAHV RNA was not detected in any of the tested CSF or urine samples; however, TAHV-neutralizing (NT) antibodies were detected in 22/10.1% of patients. Detection of NT antibodies in the CSF of two patients presenting with meningitis suggested recent TAHV infection. TAHV seropositivity increased significantly with age, from 1.8% to 24.4%. There was no difference in seroprevalence between genders or areas of residence (urban, suburban/rural). The majority of seropositive patients (90.9%) resided in floodplains along the rivers in continental Croatia. CONCLUSIONS: The presented results confirm that TAHV is present in Croatia. The prevalence and clinical significance of TAHV infection in the Croatian population have yet to be determined.

Etiology and Outcomes of Healthcare-Associated Meningitis and Ventriculitis-A Single Center Cohort Study.

Healthcare associated meningitis and ventriculitis (HCAMV) are serious complications of neurosurgical procedures. We conducted a retrospective cohort study of patients with HCAMV treated at the University Hospital for Infectious Diseases Zagreb during the 2013-2019 period. A total of 144 patients with 151 episodes of HCAMV were included. The most common indications for neurosurgical procedures were brain tumor, hemorrhage and hydrocephalus. Etiology was identified in 90 (59.6%) episodes (either positive CSF culture or positive PCR), and in other 61 (40.39%) the diagnosis of HCAMV was made based on clinical and CSF parameters, without microbiologic confirmation. Carbapenem-resistant Acinetobacter baumannii was the most common pathogen (15.89%), followed by Staphylococcus aureus (13.91%), Pseudomonas aeruginosa (13.25%) and Coagulase negative staphylococci (7.95%). Overall, 24 (16.3%) patients died, and the majority had adverse outcomes, persistent vegetative state (8, 5.56%) and severe disability (31, 21.53%). The worst clinical outcomes were observed in A. baumannii infections. High rate of complications, the need for external ventricular drainage (re)placement often complicated with nosocomial infections and prolonged stay in intensive care units were observed. Clinicians should be aware of local microbial epidemiology on guiding proper empirical antimicrobial treatment in patients with HCAMV.

Extracorporeal membrane oxygenation for the treatment of ARDS in Covid-19 and influenza patients: Does etiology matter?

At the beginning of the COVID 19 pandemic, the outcome of patients treated with ECMO was discouraging. Subsequently, it became clear that a certain group of patients may benefit from ECMO treatment. The primary objective of this study was to compare the outcome of ECMO treatment in COVID-19 and influenza patients referred to a tertiary care center. A total of 119 adult patients required ECMO treatment following ARDS secondary to H1N1 (49) and SARS-CoV-2 (70) in the referral ECMO Center based in Zagreb between October 2009 and October 2021. Our study revealed a significantly higher mortality in COVID-19 patients compared to H1N1 influenza when the onset of ARDS was severe enough to require ECMO support. Based on these results and current knowledge, we argue that ECMO treatment for ARDS in COVID-19 patients is more challenging compared to H1N1 influenza patients. Therefore, referral to the most experienced ECMO centers should be considered. Additionally, patient selection and timing for ECMO treatment play a key role in relation to outcome. Mortality rate in COVID-19 patients requiring ECMO treatment may be used as a reference frame for ECMO centers to ensure best possible care and outcome.

Severe West Nile Virus Neuroinvasive Disease: Clinical Characteristics, Short- and Long-Term Outcomes.

West Nile Virus Neuroinvasive Disease (WNV NID) requires prolonged intensive care treatment, resulting in high mortality and early disability. Long-term results are lacking. We have conducted an observational retrospective study with a prospective follow-up of WNV NID patients treated at the Intensive Care Unit (ICU), University Hospital for Infectious Diseases, Zagreb, Croatia, 2013-2018. Short-term outcomes were vital status, length of stay (LOS), modified Rankin Scale (mRS), and disposition at discharge. Long-term outcomes were vital status and mRS at follow-up. Twenty-three patients were identified, 78.3% males, median age 72 (range 33-84) years. Two patients (8.7%) died in the ICU, with no lethal outcomes after ICU discharge. The median ICU LOS was 19 days (range 5-73), and the median hospital LOS was 34 days (range 7-97). At discharge, 15 (65.2%) patients had moderate to severe/mRS 3-5, 6 (26.0%) had slight disability/mRS 2-1, no patients were symptom-free/mRS 0. Ten (47.6%) survivors were discharged to rehabilitation facilities. The median time to follow-up was nine months (range 6-69). At follow-up, seven patients died (30.5%), five (21.7%) had moderate to severe/mRS 3-5, one (4.3%) had slight disability/mRS 2-1, six (26.1%) had no symptoms/mRS 0, and four (17.4%) were lost to follow-up. Briefly, ten (43.5%) survivors improved their functional status, one (4.3%) was unaltered, and one (4.3%) aggravated. In patients with severe WNV NID, intensive treatment in the acute phase followed by inpatient rehabilitation resulted in significant recovery of functional status after several months.

Emerging Trends in the West Nile Virus Epidemiology in Croatia in the 'One Health' Context, 2011-2020.

West Nile virus (WNV) is one of the most widely distributed (re-)emerging arboviruses. In Croatia, acute WNV infections as well as seropositivity were detected in humans, horses, birds and poultry. Although serologic evidence of WNV human infections dates back to the 1970s, no clinical cases were reported until 2012. WNV outbreaks, as well as sporadic infections, were continuously recorded in continental Croatian counties from 2012 to 2018. In addition, acute asymptomatic infections (IgM antibodies) in horses have been regularly notified in continental regions since 2012, while seropositive horses (seroprevalence rates 3.7-21.4%) were detected in both continental and coastal regions. Moreover, WNV seropositivity in poultry (1.8-22.9%) was reported from 2013 to 2020. During the largest WNV outbreak in 2018, WNV RNA was detected for the first time in two dead goshawks (Accipiter gentilis) from the same aviary in North-West Croatia, while WNV antibodies were found in one buzzard (Butteo butteo) from the same region. In addition, WNV RNA was detected in a dead blackbird (Turdus merula) at the Croatian littoral. The phylogenetic analysis of 11 strains detected in urine samples of patients with neuroinvasive disease and 1 strain detected in a goshawk showed circulation of WNV lineage 2. Thus far, WNV has not been detected in mosquitoes in Croatia.

Meningitis caused by Campylobacter jejuni: a case presentation and literature review.

Objectives: Campylobacter jejuni is one of the most common causative agents of gastroenteritis; however C. jejuni meningitis is rarely described. Therefore, little is known about its epidemiology, clinical presentation, diagnostic methods, treatment, and outcomes.Methods: In this paper, we report a case of an adult patient with C. jejuni meningitis. In addition, we reviewed 16 cases of C. jejuni published since 1980.Results: We described a 62-year-old immunocompromised patient with meningitis and gastroenteritis in whom C. jejuni was rapidly detected in cerebrospinal fluid (CSF) using 16S rDNA, while blood culture yielded the same pathogen with 48 h delay. Following 21 day-long treatment with meropenem, our patient fully recovered. Literature review revealed that C. jejuni meningitis is mainly described in newborns and adults with central nervous system comorbidities and it is most frequently detected by bacterial cultures.Conclusion: There are no clear recommendations for antimicrobial treatment of C. jejuni meningitis, but meropenem seems to be a safe and effective choice. High hopes are placed in new, broad-range culture-independent molecular methods that enable rapid pathogen detection, even in case of negative cultures.

DOES THE TYPE OF SURGERY IN BRAIN ABSCESS PATIENTS INFLUENCE THE OUTCOME? ANALYSIS BASED ON THE PROPENSITY SCORE METHOD.

There are different options for surgical treatment of brain abscess, mainly standard craniotomy and stereotactic aspiration. It has not yet been established which of these options is associated with a more favorable outcome under similar baseline conditions of patients. Demographic characteristics, microbiology, clinical presentation, and treatment outcome were analyzed for surgically treated adult patients with brain abscess over a 14-year period. A propensity score model was applied to account for baseline conditions that may determine the choice of neurosurgical method. The propensity score was included in the prediction of a favorable outcome, defined as a Glasgow Outcome Scale (GOS) score 4 or 5. We analyzed 91 adult surgically treated patients, of which 53 had standard craniotomy and 38 stereotactic aspiration of brain abscess. Focal neurological deficit was the most common symptom present in 60 (65.9%) patients on admission. Sixty-seven (73.6%) patients had GOS 4 or 5, and seven (7.7%) patients died. The choice of surgery did not influence the outcome (OR 1.181, 95% CI 0.349-3.995), neither did the time elapsed from diagnosis to surgery (OR 0.998, 95% CI 0.981-1.015). Propensity towards standard craniotomy procedure did not influence outcome in brain abscess patients (OR 1.181, 95% CI 0.349-3.995). Worse outcome (GOS below 4) was independently associated with Glasgow Coma Score (GCS) on admission (OR 0.787, CI 0.656-0.944). The choice of neurosurgical procedure did not influence the outcome in patients with brain abscess. Patients with brain abscess who had lower GCS on admission also had worse outcome.

A retrospective comparison between influenza and COVID-19-associated ARDS in a Croatian tertiary care center.

BACKGROUND: Since the beginning of the Corona virus disease 2019 (COVID-19) pandemic the new Severe acute respiratory syndrome coronoavirus 2 (SARS-CoV­2) virus has been repeatedly compared to the influenza virus; however, the comparison of invasively mechanically ventilated patients with acute respiratory distress syndrome (ARDS) caused by these viruses is very scarce. The purpose of this study was to compare clinical course and laboratory parameters between the most severely ill flu and COVID 19 patients treated with invasive mechanical ventilation (IMV). METHODS: The study was conducted at the intensive care unit (ICU) of the tertiary care hospital in Zagreb, Croatia in the period between November 2018 and July 2020. Investigation included 72 adult patients requiring IMV due to influenza or SARS-CoV­2 virus infection and 42 patients had influenza and 30 had SARS-CoV­2 virus infection and the comparison between two etiological groups was conducted. RESULTS: Invasively mechanically ventilated patients with COVID 19 and influenza differ in certain aspects. COVID 19 patients are older, male, have lower C-reactive protein (CRP) levels and have less need for extracorporeal membrane oxygenation (ECMO) support. In other measured variables, including mortality, the difference between influenza or SARS-CoV­2 etiology was not significant. CONCLUSION: High mortality of IMV patients with influenza and COVID 19 with 55% and 63%, respectively, challenges and urges medical and especially ICU community to expand our quest for further treatments, especially since ECMO use that is scarcely required in COVID 19 patients probably has limited impact in reducing mortality in COVID 19 patients.

Cauda equina arachnoiditis - a rare manifestation of West Nile virus neuroinvasive disease: A case report.

BACKGROUND: Data regarding the neuroradiology features of the West Nile virus neuroinvasive disease (WNV NID) is rather scarce. To contribute to the knowledge of the WNV NID, we present a patient with a combination of encephalitis and acute flaccid paresis, with cauda equina arachnoiditis as the main magnetic resonance (MR) finding. CASE SUMMARY: A 72-year-old female patient was admitted due to fever, headache and gait instability. During the first several days she developed somnolence, aphasia, urinary incontinence, constipation, and asymmetric lower extremities weakness. Cerebrospinal fluid analysis indicated encephalitis. Native brain computed tomography and MR were unremarkable, while spinal MR demonstrated cauda equina enhancement without cord lesions. Virology testing revealed WNV IgM and IgG antibodies in serum and cerebrospinal fluid, which confirmed acute WNV NID. The treatment was supportive. After two months only a slight improvement was noticed but cognitive impairment, loss of sphincter control and asymmetric inferior extremities weakness remained. The patient died after a month on chronic rehabilitation. CONCLUSION: Cauda equina arachnoiditis is a rare, but possible neuroradiological feature in acute flaccid paresis form of WNV NID.

Epidemiology of Usutu Virus: The European Scenario.

Usutu virus (USUV) is an emerging arbovirus isolated in 1959 (Usutu River, Swaziland). Previously restricted to sub-Saharan Africa, the virus was introduced in Europe in 1996. While the USUV has received little attention in Africa, the virus emergence has prompted numerous studies with robust epidemiological surveillance programs in Europe. The natural transmission cycle of USUV involves mosquitoes (vectors) and birds (amplifying hosts) with humans and other mammals considered incidental ("dead-end") hosts. In Africa, the virus was isolated in mosquitoes, rodents and birds and serologically detected in horses and dogs. In Europe, USUV was detected in bats, whereas antibodies were found in different animal species (horses, dogs, squirrels, wild boar, deer and lizards). While bird mortalities were not reported in Africa, in Europe USUV was shown to be highly pathogenic for several bird species, especially blackbirds (Turdus merula) and great gray owls (Strix nebulosa). Furthermore, neurotropism of USUV for humans was reported for the first time in both immunocompromised and immunocompetent patients. Epizootics and genetic diversity of USUV in different bird species as well as detection of the virus in mosquitoes suggest repeated USUV introductions into Europe with endemization in some countries. The zoonotic potential of USUV has been reported in a growing number of human cases. Clinical cases of neuroinvasive disease and USUV fever, as well as seroconversion in blood donors were reported in Europe since 2009. While most USUV strains detected in humans, birds and mosquitoes belong to European USUV lineages, several reports indicate the presence of African lineages as well. Since spreading trends of USUV are likely to continue, continuous multidisciplinary interventions ("One Health" concept) should be conducted for monitoring and prevention of this emerging arboviral infection.

West Nile Virus: An Emerging Threat in Transplant Population.

West Nile virus (WNV) has become one of the new challenges for transplant programs. In addition to transmission by mosquito bite, interhuman transmission is possible through blood products or organ transplantation. Majority of WNV infections present as asymptomatic or mild febrile illness, with less than 1% of infected developing neuroinvasive disease. Many studies report naturally acquired or donor-derived WNV infections in solid-organ transplant recipients, mainly kidney, but also liver, heart, lungs and pancreas. Given the much higher risk of neuroinvasive disease (40% and even higher) based on serologic and clinical studies and increased mortality in transplant population, WNV infection should be considered in all patients presented with fever and neurological symptoms after transplantation, especially during the arbovirus transmission season.

Elevated plasma RANTES in fibrodysplasia ossificans progressiva - A novel therapeutic target?

Fibrodysplasia ossificans progressiva (FOP) is a rare hereditary disease caused by a mutation in the intracellular domain of the activin A receptor type I and is characterized by episodes (flare-ups) of progressive heterotopic endochondral ossification (HO) in the soft tissues. The mutation alone is not sufficient for the occurrence of HO since flare-ups are triggered by inflammation and activation of the innate immune system. A number of cellular and humoral mediators have been implicated in animal and in vitro models. Observations in humans support the inflammatory nature of the condition, but data on the involved mediators are variable. We hypothesize that for induction of flare-ups in patients with FOP increase in at least one of the pro-inflammatory cytokines is both essential and sufficient to trigger the entire process of the inflammatory cells influx resulting in the novel ectopic bone formation and we suggest that C-C motif ligand 5 (CCL5), a pro-inflammatory chemokine also known as Regulated on activation, normal T-cell expressed and secreted (RANTES), might be the key candidate. CCL5 is a chemoattractant for all cellular types implicated in HO and is produced by the cells of the tissue microenvironment at the sites of HO as well as by the pro-inflammatory cellular mediators. CCL5 induces ossification in cultured human pluripotent mesenchymal cells (hMSCs) and in the primary culture of monocytes from FOP patients (but not from their healthy relatives), stimulation with lipopolysaccharide induces CCL5 expression. Finally, in a pilot study we used a panel of 23 cytokines and chemokines to screen the plasma samples of three subjects: a female patient with FOP during a flare-up; a female patient with hyperostosis corticalis generalisata (van Buchem disease), another rare disease characterized by excessive bone formation at the sites where it regularly occurs that does not include inflammatory events; and a healthy woman without bone disorders. There appeared a rather clear-cut signal of a 2-fold higher level of CCL5 in the FOP patient vs. the healthy subject and the van Buchem patient. Evaluation of the hypothesis would require an international prospective study, with main motivation being the lack of a conclusive treatment as the major unmet need in FOP. A treatment targeting CCL5 receptor already exists and is used in HIV-infected patients.

Prevalence and molecular epidemiology of West Nile and Usutu virus infections in Croatia in the 'One health' context, 2018.

In 2018, Croatia reported the largest outbreak of West Nile virus (WNV) infections as well as the re-occurrence of human Usutu virus (USUV) infections. For the first time, fatal WNV and USUV infections were detected in wild birds. We analysed epidemiological characteristics and molecular epidemiology of WNV and USUV infections detected during 2018 transmission season. From April to November, 178 patients with neuroinvasive disease and 68 patients with febrile disease were tested for WNV and USUV. Viral RNA was detected in cerebrospinal fluid (CSF) and urine samples using a real-time RT-PCR. Positive samples were tested by nested RT-PCR and nucleotide sequencing. IgM/IgG antibodies were detected in serum/CSF samples using ELISA with confirmation of cross-reactive samples by virus neutralization test (VNT). WNV neuroinvasive disease was confirmed in 54 and WNV fever in seven patients from 10 continental Croatian counties. Areas affected in 2018 were those in which cases occurred in previous seasons, while in three areas human cases were reported for the first time. Phylogenetic analysis of six strains from patients residing in different geographic areas showed circulation of WNV lineage 2. In three patients, neuroinvasive USUV infection was confirmed by RT-PCR or VNT. Sequence analysis of one detected strain revealed USUV Europe 2 lineage. During the same period, a total of 2,574 horse and 1,069 poultry serum samples were tested for WNV antibodies using ELISA. Acute asymptomatic WNV infection (IgM antibodies) was documented in 20/0.7% horses. WNV IgG antibodies were found in 307/11.9% horses and in 125/12.7% poultry. WNV RNA was detected in two goshawks and USUV RNA was detected in one blackbird from north-western Croatia. In the Zagreb area, 3,670 female mosquitoes were collected. One Culex pipiens pool collected in July tested positive for USUV RNA. Our results highlight the importance of continuous multidisciplinary 'One health' surveillance of these emerging arboviruses.