Correlates of disease severity in bluetongue as a model of acute arbovirus infection.

Most viral diseases display a variable clinical outcome due to differences in virus strain virulence and/or individual host susceptibility to infection. Understanding the biological mechanisms differentiating a viral infection displaying severe clinical manifestations from its milder forms can provide the intellectual framework toward therapies and early prognostic markers. This is especially true in arbovirus infections, where most clinical cases are present as mild febrile illness. Here, we used a naturally occurring vector-borne viral disease of ruminants, bluetongue, as an experimental system to uncover the fundamental mechanisms of virus-host interactions resulting in distinct clinical outcomes. As with most viral diseases, clinical symptoms in bluetongue can vary dramatically. We reproduced experimentally distinct clinical forms of bluetongue infection in sheep using three bluetongue virus (BTV) strains (BTV-1IT2006, BTV-1IT2013 and BTV-8FRA2017). Infected animals displayed clinical signs varying from clinically unapparent, to mild and severe disease. We collected and integrated clinical, haematological, virological, and histopathological data resulting in the analyses of 332 individual parameters from each infected and uninfected control animal. We subsequently used machine learning to select the key viral and host processes associated with disease pathogenesis. We identified and experimentally validated five different fundamental processes affecting the severity of bluetongue: (i) virus load and replication in target organs, (ii) modulation of the host type-I IFN response, (iii) pro-inflammatory responses, (iv) vascular damage, and (v) immunosuppression. Overall, we showed that an agnostic machine learning approach can be used to prioritise the different pathogenetic mechanisms affecting the disease outcome of an arbovirus infection.

Arboviral central nervous system infections.

PURPOSE OF REVIEW: This review provides an overview of arthropod-borne virus (arbovirus) infections that are important causes of human neurological infections world-wide. As many of the individual viruses in a specific genus or family cause overlapping clinical syndromes, this review discusses important viruses in groups to highlight some of the similarities and differences in groups of neuroinvasive arbovirus infections. RECENT FINDINGS: Arboviruses that cause neurological infections in humans continue to emerge and distribute to new regions. The geographic range of the vectors, the hosts and subsequent arbovirus infections in humans continues to expand and evolve. As emerging arboviruses move into new geographic regions, it is important to examine the associated epidemiological and clinical impacts of these infections as they enter new populations. SUMMARY: Arboviruses from the Flaviviridae, Togaviridae and Bunyaviridae families continue to emerge and spread into new regions. The arboviruses within these virus families cause characteristic neuroinvasive diseases in human populations. A complete understanding of the epidemiological and clinical features of the neuroinvasive arboviruses is important such that these pathogens can be recognized and diagnosed in humans as they emerge. Ongoing research to develop rapid, accurate diagnostics, therapeutic options and vaccines for these pathogens is needed to address future outbreaks of disease in human populations.

Emerging arboviruses of clinical importance in Central Asia.

Arboviruses are viral pathogens that are transmitted from an animal reservoir to humans via an arthropod vector. These viruses result in a large burden of disease worldwide and show a propensity for establishing new endemic foci in geographically distant regions. The potential impact of arboviruses in Central Asia is unclear due to the scarcity of reports available in English; however, the collation of available data shows that numerous important human viruses are circulating in the region. Pathogens such as Crimean-Congo haemorrhagic fever virus, tick-borne encephalitis virus and Tahyna virus are likely to be responsible for numerous cases of human disease in Central Asia on an annual basis. There is evidence that pathogens such as West Nile virus and sandfly fever virus have resulted in sporadic outbreaks of human disease across the region; these events appear to be triggered by a significant change in the abundance of local arthropod vectors or events altering the contact between humans and local arthropod populations, such as conflict or natural disasters. In addition, there are several under-researched arboviruses that could result in a significant disease, including Karshi virus, Issyk-Kul virus and Syr-Darya Valley fever virus. This review provides the first comprehensive assessment of emerging arboviruses in Central Asia. Further research is required to assess the full impact of arboviruses on human health in the region and to monitor potential spread. Up-to-date information regarding arbovirus endemicity will allow for the development and distribution of rapid diagnostics, the implementation of bite-prevention strategies in at-risk areas and improved travel recommendations.

Apoptosis, autophagy and unfolded protein response pathways in Arbovirus replication and pathogenesis.

Arboviruses are pathogens that widely affect the health of people in different communities around the world. Recently, a few successful approaches toward production of effective vaccines against some of these pathogens have been developed, but treatment and prevention of the resulting diseases remain a major health and research concern. The arbovirus infection and replication processes are complex, and many factors are involved in their regulation. Apoptosis, autophagy and the unfolded protein response (UPR) are three mechanisms that are involved in pathogenesis of many viruses. In this review, we focus on the importance of these pathways in the arbovirus replication and infection processes. We provide a brief introduction on how apoptosis, autophagy and the UPR are initiated and regulated, and then discuss the involvement of these pathways in regulation of arbovirus pathogenesis.

Usefulness of minimally invasive autopsy in the diagnosis of arboviruses to increase the sensitivity of the Epidemiological Surveillance System in Ceará, Brazil.

OBJECTIVE: To create a protocol for performing minimally invasive autopsies (MIA) in detecting deaths from arboviruses and report preliminary data from its application in Ceará state, Brazil. METHODS: Training was provided to medical pathologists on MIA. RESULTS: A protocol was established for performing MIA, defining criteria for sample collection, storage methods, and diagnoses to be carried out according to the type of biological sample; 43 MIAs were performed in three months. Of these, 21 (48.8%) arrived at the Death Verification Service (SVO) with arboviruses as a diagnostic hypothesis, and seven (16.3%) were confirmed (six chikungunya cases and one dengue case); cases of COVID-19 (n = 9), tuberculosis (n = 5), meningitis (n = 4), cryptococcosis (n = 1), Creutzfeldt-Jakob disease (n = 1), breast cancer (n = 1), and human rabies (n = 1) were also confirmed. CONCLUSION: The protocol implemented enabled identification of a larger number of suspected arbovirus-related deaths, as well as confirmation of other diseases of interest for surveillance. MAIN RESULTS: A protocol was developed to perform minimally invasive autopsies (MIAs) in Death Verification Services (SVO), capable of expanding the system's capacity to identify a greater number of deaths suspected to be due to arboviruses. IMPLICATIONS FOR SERVICES: The experience suggests that in-service trained health professionals are able to perform MIA, and that use of this technique in SVOs has been shown to be capable of increasing the system's sensitivity in detecting deaths of interest to public health. PERSPECTIVES: Trained professionals will be able to collect biological material in hospitals, through MIA, in cases of interest for health surveillance and when family members do not allow a complete conventional autopsy to be performed.

Arboviruses and Muscle Disorders: From Disease to Cell Biology.

Infections due to arboviruses (arthropod-borne viruses) have dramatically increased worldwide during the last few years. In humans, symptoms associated with acute infection of most arboviruses are often described as "dengue-like syndrome", including fever, rash, conjunctivitis, arthralgia, and muscular symptoms such as myalgia, myositis, or rhabdomyolysis. In some cases, muscular symptoms may persist over months, especially following flavivirus and alphavirus infections. However, in humans the cellular targets of infection in muscle have been rarely identified. Animal models provide insights to elucidate pathological mechanisms through studying viral tropism, viral-induced inflammation, or potential viral persistence in the muscle compartment. The tropism of arboviruses for muscle cells as well as the viral-induced cytopathic effect and cellular alterations can be confirmed in vitro using cellular models. This review describes the link between muscle alterations and arbovirus infection, and the underlying mechanisms.

Severity Index for Suspected Arbovirus (SISA): Machine learning for accurate prediction of hospitalization in subjects suspected of arboviral infection.

BACKGROUND: Dengue, chikungunya, and Zika are arboviruses of major global health concern. Decisions regarding the clinical management of suspected arboviral infection are challenging in resource-limited settings, particularly when deciding on patient hospitalization. The objective of this study was to determine if hospitalization of individuals with suspected arboviral infections could be predicted using subject intake data. METHODOLOGY/PRINCIPAL FINDINGS: Two prediction models were developed using data from a surveillance study in Machala, a city in southern coastal Ecuador with a high burden of arboviral infections. Data were obtained from subjects who presented at sentinel medical centers with suspected arboviral infection (November 2013 to September 2017). The first prediction model-called the Severity Index for Suspected Arbovirus (SISA)-used only demographic and symptom data. The second prediction model-called the Severity Index for Suspected Arbovirus with Laboratory (SISAL)-incorporated laboratory data. These models were selected by comparing the prediction ability of seven machine learning algorithms; the area under the receiver operating characteristic curve from the prediction of a test dataset was used to select the final algorithm for each model. After eliminating those with missing data, the SISA dataset had 534 subjects, and the SISAL dataset had 98 subjects. For SISA, the best prediction algorithm was the generalized boosting model, with an AUC of 0.91. For SISAL, the best prediction algorithm was the elastic net with an AUC of 0.94. A sensitivity analysis revealed that SISA and SISAL are not directly comparable to one another. CONCLUSIONS/SIGNIFICANCE: Both SISA and SISAL were able to predict arbovirus hospitalization with a high degree of accuracy in our dataset. These algorithms will need to be tested and validated on new data from future patients. Machine learning is a powerful prediction tool and provides an excellent option for new management tools and clinical assessment of arboviral infection.

Apoptosis induced by Ibaraki virus does not affect virus replication and cell death in hamster lung HmLu-1 cells.

Ibaraki virus (IBAV) is an arbovirus that is transmitted by biting midges and causes Ibaraki disease in cattle. IBAV induces apoptosis in several mammalian cell lines, and apoptosis in turn facilitates IBAV replication. In addition, virus-induced apoptosis may contribute to mammalian-specific pathogenicity considering that some arboviruses induce apoptosis in mammalian cells but not in insect cells. In this study, we found that when hamster lung cells (HmLu-1) are used as a virus host, IBAV causes severe cytopathic effects with little induction of apoptosis. Furthermore, pharmacological inhibition of apoptosis did not affect IBAV-induced cytotoxicity. These results indicate the existence of an apoptosis-independent pathway in which IBAV replicates and exerts cytotoxicity in mammalian cells.

Neurological manifestations of pediatric arboviral infections in the Americas.

Dengue, Zika, Chikungunya and yellow fever viruses are arboviruses transmitted by the mosquito Aedes aegypti. These viruses exhibit marked neurotropism but have rarely been studied. Here, we conduct an integrative review of the neurological manifestations caused by these arboviruses in the pediatric population. Data on patients under 18 years of age were extracted from literature databases. The most frequently reported neurological manifestations were encephalitis, meningitis, seizures, hypotonia, paresis, and behavioral changes. This review highlights the importance of accurately diagnosing these arboviral infections in children and adolescents with neurological manifestations.

Diagnostic Value of Platelet and Leukocyte Counts in the Differential Diagnosis of Fever in the Returning Traveler.

Malaria, arbovirus infection and travelers' diarrhea are among the most common etiologies of fever after a stay in the tropics. Because the initial symptoms of these diseases often overlap, the differential diagnostic remains a challenge. The aim of this study was to establish the effectiveness of platelet and leukocyte counts in the differential diagnosis of fever in the returning traveler. Between 2013 and 2016, patients with a clinical suspicion of malaria, who had thick blood smears performed were retrospectively included. The microbiological etiology of each episode was established based on molecular detection in the case of arbovirus infection, the detection of pathogens in stool samples for diarrhea and other gastrointestinal symptoms and the thick and thin blood smear results for malaria. A total of 1,218 episodes were included. Malaria, arbovirus infection, and diarrhea and other gastrointestinal symptoms caused 102 (8.4%), 68 (5.6%), and 72 (5.9%) episodes, respectively. The median platelet counts in malaria episodes were 89 × 109/L and thrombocytopenia (< 150,000 × 109 platelets/L) yielded a 98% negative predictive value to predict malaria. The median leukocyte counts in arbovirus infection episodes were 3.19 × 109/L and leucopenia (< 4 × 109 leukocytes/L) yielded a 97.9% negative predictive value to predict arbovirus infections. Platelet and leukocyte counts were not significantly altered in episodes caused by diarrhea and other gastrointestinal symptoms. Initial platelet and leukocyte counts might be useful for the clinical differential diagnosis of fever in the returning traveler. Although these results are insufficient to establish a diagnosis, they should be considered in the initial clinical assessment.

Emerging souvenirs-clinical presentation of the returning traveller with imported arbovirus infections in Europe.

BACKGROUND: Arboviruses are an emerging group of viruses that are causing increasing health concerns globally, including in Europe. Clinical presentation usually consists of a nonspecific febrile illness that may be accompanied by rash, arthralgia and arthritis, with or without neurological or haemorrhagic syndromes. The range of differential diagnoses of other infectious and noninfectious aetiologies is broad, presenting a challenge for physicians. While knowledge of the geographical distribution of pathogens and the current epidemiological situation, incubation periods, exposure risk factors and vaccination history can help guide the diagnostic approach, the nonspecific and variable clinical presentation can delay final diagnosis. AIMS AND SOURCES: This narrative review aims to summarize the main clinical and laboratory-based findings of the three most common imported arboviruses in Europe. Evidence is extracted from published literature and clinical expertise of European arbovirus experts. CONTENT: We present three cases that highlight similarities and differences between some of the most common travel-related arboviruses imported to Europe. These include a patient with chikungunya virus infection presenting in Greece, a case of dengue fever in Turkey and a travel-related case of Zika virus infection in Romania. IMPLICATIONS: Early diagnosis of travel-imported cases is important to reduce the risk of localized outbreaks of tropical arboviruses such as dengue and chikungunya and the risk of local transmission from body fluids or vertical transmission. Given the global relevance of arboviruses and the continuous risk of (re)emerging arbovirus events, clinicians should be aware of the clinical syndromes of arbovirus fevers and the potential pitfalls in diagnosis.

Preparing clinicians for (re-)emerging arbovirus infectious diseases in Europe.

BACKGROUND: Arthropod-borne virus (Arbovirus) infections are considered an emerging threat for Europe, with an increase in cases in recent decades. The increase in global travel and trade has contributed to the introduction of vectors and viruses into new geographical areas. Tropical arboviruses such as dengue and chikungunya have re-emerged causing local, sporadic outbreaks ignited by travel-imported cases. The recent Zika virus outbreak in the Americas highlighted a need to strengthen preparedness for (re-)emerging arbovirus infections globally. AIMS: To strengthen preparedness for the early identification of (re-)emerging arbovirus outbreaks in Europe and highlight areas for research. SOURCES: An evidence review of published and grey literature together with consultations with European arbovirus experts. CONTENT: This paper presents an overview of endemic and travel-imported arboviruses of clinical significance in Europe. The overview includes syndromic presentation, risk factors for infection and risk of transmission as well as an update on treatments and vaccinations and surveillance notifications and reporting. The paper also presents predictive modelled risks of further geographical expansion of vectors and viruses. IMPLICATIONS: There are a range of arboviruses of clinical significance to Europe. There has been an increase in notifications of endemic and travel-imported arbovirus cases in recent years and an increased geographical range of vectors and viruses. The heterogeneity in surveillance reporting indicates a risk for the early identification of (re-)emerging outbreaks. The data presented show a need to strengthen preparedness for (re-)emerging arbovirus infections and a need for research into neglected arboviruses, risks of non-vector transmission and effective therapeutics and vaccinations.

Lack of serological and molecular evidence of arbovirus infections in bats from Brazil.

Viruses are important agents of emerging zoonoses and are a substantial public health issue. Among emerging viruses, an important group are arboviruses, which are characterized by being maintained in nature in cycles involving hematophagous arthropod vectors and a wide range of vertebrate hosts. Recently, bats have received increasing attention as an important source for the emergence of zoonoses and as possible viral reservoirs. Among the arboviruses, there are many representatives of the genera Flavivirus and Alphavirus, which are responsible for important epidemics such as Dengue virus, Zika virus and Chikungunya virus. Due to the importance of analyzing potential viral reservoirs for zoonosis control and expanding our knowledge of bat viruses, this study aimed to investigate the presence of viruses of the Alphavirus and Flavivirus genera in bats. We analyzed serum, liver, lungs and intestine from 103 bats sampled in northeast and southern Brazil via Nested-PCR and the hemagglutination inhibition test. All samples tested in this study were negative for arboviruses, suggesting that no active or past infection was present in the captured bats. These data indicate that the bats examined herein probably do not constitute a reservoir for these viruses in the studied areas. Further studies are needed to clarify the role of bats as reservoirs and sources of infection of these viral zoonoses.

Necropsy findings and arbovirus surveillance in mourning doves from the southeastern United States.

Mourning doves (Zenaida macroura) are the most abundant and widespread native member of the columbid family, as well as a major migratory game species, in the United States. However, there is little information on mortality factors in mourning doves. Records of necropsy accessions at the Southeastern Cooperative Wildlife Disease Study (SCWDS) from 15 southeastern states, from 1971 through 2005, were reviewed. One hundred thirty-five mourning doves were submitted from nine states during the 35-yr period. Trichomonosis constituted 40% (n = 54) of all diagnoses and was the most frequent diagnosis. Toxicoses and avian pox constituted 18.5% (n = 25) and 14.8% (n = 20) of all diagnoses, respectively. Remaining diagnoses included trauma, suspected toxicosis, Ascaridia columbae infection, suspected tick paralysis, and undetermined. Adults were observed more frequently with trichomonosis (94.1%) and toxicoses (68%) as compared to juveniles, but a gender predisposition was not apparent for either disease. Age and gender predilections were not apparent for cases of avian pox. The majority of the trichomonosis and avian pox cases were observed in the spring-summer, whereas the majority of the toxicosis cases were observed in the winter-spring. Additionally, the Georgia Department of Human Resources-Division of Public Health and West Virginia Department of Health and Human Resources submitted 809 mourning doves to SCWDS from 2001 through 2005 for West Nile virus surveillance efforts. West Nile virus was isolated from 2.1% (n = 17) and eastern equine encephalitis virus (EEEV) was isolated from 0.2% (n = 2) of the submitted birds.

Clinical, laboratory and virological data from suspected ZIKV patients in an endemic arbovirus area.

BACKGROUND: The emergence of Zika virus (ZIKV) presents new challenges to both clinicians and public health authorities. Overlapping clinical features between the diseases caused by ZIKV, dengue (DENV) and chikungunya (CHIKV) and the lack of validated serological assays for ZIKV make accurate diagnosis difficult. Brazilian authorities largely rely on clinical and epidemiological data for the epidemiological and clinical classifications of most ZIKV cases. OBJECTIVE: To report the laboratory and clinical profiles of patients diagnosed with Zika fever based only on clinical and epidemiological data. STUDY DESIGN: We analyzed 433 suspected cases of ZIKV identified by the attending physician based on proposed clinical criteria. The samples were also screened for ZIKV, DENV and CHIKV using PCR. RESULTS: Of the 433 patients analyzed, 168 (38.8%) were laboratory-confirmed for arboviruses: 96 were positive for ZIKV, 67 were positive for DENV (56 for DENV-2, 9 for DENV-1, and 2 for DENV-4), four were positive for co-infection with ZIKV/DENV-2, and one was positive for CHIKV. The most common signs or symptoms in the patients with laboratory-confirmed ZIKV were rash (100%), arthralgia (77.1%), fever (74.0%), myalgia (74.0%) and non-purulent conjunctivitis (69.8%). In patients with laboratory-confirmed DENV infections, the most frequently observed symptoms were rash (100%), fever (79.1%), myalgia (74.6%), headache (73.1%) and arthralgia (70.1%). The measure of association between clinical manifestations and laboratory manifestations among patients with ZIKV and DENV detected a statistically significant difference only in abdominal pain (p=0.04), leukopenia (p=0.003), and thrombocytopenia (p=0.01). CONCLUSION: Our data suggests that clinical and epidemiological criteria alone are not a good tool for ZIKV and DENV differentiation, and that laboratory diagnosis should be mandatory.

Syndromic Approach to Arboviral Diagnostics for Global Travelers as a Basis for Infectious Disease Surveillance.

BACKGROUND: Arboviruses have overlapping geographical distributions and can cause symptoms that coincide with more common infections. Therefore, arbovirus infections are often neglected by travel diagnostics. Here, we assessed the potential of syndrome-based approaches for diagnosis and surveillance of neglected arboviral diseases in returning travelers. METHOD: To map the patients high at risk of missed clinical arboviral infections we compared the quantity of all arboviral diagnostic requests by physicians in the Netherlands, from 2009 through 2013, with a literature-based assessment of the travelers' likely exposure to an arbovirus. RESULTS: 2153 patients, with travel and clinical history were evaluated. The diagnostic assay for dengue virus (DENV) was the most commonly requested (86%). Of travelers returning from Southeast Asia with symptoms compatible with chikungunya virus (CHIKV), only 55% were tested. For travelers in Europe, arbovirus diagnostics were rarely requested. Over all, diagnostics for most arboviruses were requested only on severe clinical presentation. CONCLUSION: Travel destination and syndrome were used inconsistently for triage of diagnostics, likely resulting in vast under-diagnosis of arboviral infections of public health significance. This study shows the need for more awareness among physicians and standardization of syndromic diagnostic algorithms.

An immunopathologic component in experimental togavirus encephalitis.

The effects of immune manipulation upon survival and histopathology in two experimental group B togavirus encephalitides were studied in inbred mice. The median survival time 8 days after intracerebral injection of Langat virus increased to 10 days with an immunosuppressive course of cyclophosphamide, with concomitant reduction in the inflammatory response. Adoptive immunization with immune lymphoid cells or serum also tended to prolong Langat virus survival while increasing inflammation. Survival following intracerebral West Nile virus (7 days) was unaffected by immunosuppression or adoptive transfer, although suppression was associated with less severe CNS lesions, and immune serum with less necrosis. These findings indicate that the immune response may be both protective and pathology-inducing in some togarvirus encephalitides. The differences in host response to these two related agents suggest caution in generalizing about the role of the immune response in viral infections.

Experimental viral polymyositis: age dependency and immune responses to Ross River virus infection in mice.

Ross River virus (RRV) causes an age-dependent myositis in mice. Infected 4-week-old mice develop no clinical signs, but 1-week-old mice develop weakness and myositis. Humoral and cell-mediated immune responses to RRV in the two age groups are comparable, and immunosuppression does not alter age-dependent resistance to clinical disease. Immunosuppression of 1-week-old mice protracts clinical signs and reduces muscle inflammation but does not alter muscle necrosis or regeneration. These studies suggest that immune responses do not determine age dependency of RRV myositis and that muscle necrosis results from direct viral lysis of muscle fibers.