Outbreak Of Acute Febrile Illness Research Articles

A reporter Oropouche virus expressing ZsGreen from the M segment enables pathogenesis studies in mice.

Oropouche fever caused by Oropouche virus (OROV) is a significant zoonosis in Central and South America. Despite its public health significance, we lack high-throughput diagnostics, therapeutics, and a comprehensive knowledge of OROV biology. Reporter viruses are valuable tools to rapidly study virus dynamics and develop neutralization and antiviral screening assays. OROV is a tri-segmented bunyavirus, which makes generating a reporter virus challenging, as introducing foreign elements into the viral genome typically affects fitness. We previously demonstrated that the non-structural gene NSm on the OROV medium (M) segment is non-essential for replication in vitro. Taking advantage of this, we have now generated a recombinant OROV expressing fluorescent protein ZsGreen in place of NSm. This reporter OROV is both stable and pathogenic in IFNAR-/- mice and provides a powerful tool for OROV pathogenesis studies and assay development.IMPORTANCEEmerging and reemerging infectious agents such as zoonotic bunyaviruses are of global health concern. Oropouche virus (OROV) causes recurring outbreaks of acute febrile illness in the Central and South American human populations. Biting midges are the primary transmission vectors, whereas sloths and non-human primates are their reservoir hosts. As global temperatures increase, we will likely see an expansion in arthropod-borne pathogens such as OROV. Therefore, developing reagents to study pathogen biology to aid in identifying druggable targets is essential. Here, we demonstrate the feasibility and use of a fluorescent OROV reporter in mice to study viral dynamics and pathogenesis. We show that this reporter OROV maintains characteristics such as growth and pathogenicity similar to the wild-type virus. Using this reporter virus, we can now develop methods to assist OROV studies and establish various high-throughput assays.

Outbreak investigation of acute febrile illness from the Himalayan foothills: Solving the puzzle of fever.

In September 2022, Panchkula Civil Hospital reported an outbreak of acute febrile illness (AFI) in Pinjore, located in the Himalayan foothills, Haryana, North India. There was an upsurge of fever cases. Blood samples were taken from suspected patients (n = 58) with AFI and subjected to serology of dengue, chikungunya, Japanese encephalitis, leptospira and scrub typhus. The samples were also screened for West Nile & Zika virus RNA using real-time PCR. Viral strains were characterized by sequencing. Of the 58 cases of AFI, Dengue could be identified in 45 (77.58%) followed by JE and Chikungunya in 2 cases each (3.44%), respectively. Among Dengue positive cases, 44 had monoinfection (97.77%) and 1 patient had dengue and JE. None were positive for Zika, West Nile, Scrub typhus, and Leptospira with the testing protocol. Four patients developed dengue with warning signs, such as abdominal pain in one patient and recurrent vomiting in the remaining three. The dengue serotype could be determined in 17 samples and revealed serotype 2. Molecular evolution analysis based on the complete envelope gene revealed that all DENV-2 strains (n = 13) circulated in the outbreak area belonged to the DENV-2 cosmopoliton genotype. In the early stages of infection, relying only on clinical manifestations is ineffective, so both molecular and serological assays along with clinical diagnosis are noteworthy for determining the aetiology of AFI.

Substantial viral and bacterial diversity at the bat-tick interface.

Ticks harbour a high diversity of viruses, bacteria and protozoa. The soft tick Carios vespertilionis (Argasidae) is a common ectoparasite of bats in the Palearctic region and is suspected to be vector and reservoir of viruses and other microbial species in bat populations, some of which may act as zoonotic agents for human disease. The Soprano pipistrelle (Pipistrellus pygmaeus, Vespertilionidae) is widely distributed in Europe, where it can be found inside or close to human habitation. We used meta-transcriptomic sequencing to determine the RNA virome and common microbiota in blood-fed C. vespertilionis ticks collected from a Soprano pipistrelle bat roosting site in south-central Sweden. Our analyses identified 16 viruses from 11 virus families, of which 15 viruses were novel. For the first time in Sweden we identified Issuk-Kul virus, a zoonotic arthropod-borne virus previously associated with outbreaks of acute febrile illness in humans. Probable bat-associated and tick-borne viruses were classified within the families Nairoviridae, Caliciviridae and Hepeviridae, while other invertebrate-associated viruses included members of the Dicistroviridae, Iflaviridae, Nodaviridae, Partitiviridae, Permutotetraviridae, Polycipiviridae and Solemoviridae. Similarly, we found abundant bacteria in C. vespertilionis, including genera with known tick-borne bacteria, such as Coxiella spp. and Rickettsia spp. These findings demonstrate the remarkable diversity of RNA viruses and bacteria present in C. vespertilionis and highlight the importance of bat-associated ectoparasite surveillance as an effective and non-invasive means to track viruses and bacteria circulating in bats and ticks.

Investigations of seasonal outbreaks of acute encephalitis syndrome due to Orientia tsutsugamushi in Gorakhpur region, India: A One Health case study.

Gorakhpur division consisting of Gorakhpur and neighboring districts Deoria, Kushinagar and Maharajganj in Uttar Pradesh, India, have been witnessing seasonal outbreaks of acute encephalitis syndrome (AES) among children for the last three decades. Investigations conducted during 2005 identified Japanese encephalitis (JE) virus as an aetiology of AES. With the introduction of JE vaccination and other control strategies, the incidence of JE in the region declined, however, outbreaks of acute febrile illness with neurological manifestations continued to occur. Subsequent investigations identified Orientia tsutsugamushi, as the major aetiology of AES outbreaks in the region. This review details clinical, epidemiological, animal and entomological investigations conducted for AES due to O. tsutsugamushi during 2015 and 2017 in Gorakhpur region. Surveillance of acute febrile illness among children attending peripheral health facilities identified scrub typhus as an important aetiology of febrile illness during monsoon and post-monsoon months. Population-based serosurveys indicated high endemicity of scrub typhus. Entomological studies demonstrated natural infection of O. tsutsugamushi in small animal hosts and vector mites. Children acquired this infection through recent exposure to outdoor environment, while playing, or visiting fields or defecating in open fields. A few of the children with scrub typhus progress to develop CNS manifestations. Hence, early administration of appropriate antibiotics is crucial in preventing progression of AFI due to scrub typhus to AES. The investigations conducted by the multi-disciplinary team helped understand the transmission dynamics of scrub typhus in Gorakhpur division and recommend strategies for its control.

In-depth characterization of a novel live-attenuated Mayaro virus vaccine candidate using an immunocompetent mouse model of Mayaro disease

Mayaro virus (MAYV) is endemic in South American countries where it is responsible for sporadic outbreaks of acute febrile illness. The hallmark of MAYV infection is a highly debilitating and chronic arthralgia. Although MAYV emergence is a potential threat, there are no specific therapies or licensed vaccine. In this study, we developed a murine model of MAYV infection that emulates many of the most relevant clinical features of the infection in humans and tested a live-attenuated MAYV vaccine candidate (MAYV/IRES). Intraplantar inoculation of a WT strain of MAYV into immunocompetent mice induced persistent hypernociception, transient viral replication in target organs, systemic production of inflammatory cytokines, chemokines and specific humoral IgM and IgG responses. Inoculation of MAYV/IRES in BALB/c mice induced strong specific cellular and humoral responses. Moreover, MAYV/IRES vaccination of immunocompetent and interferon receptor-defective mice resulted in protection from disease induced by the virulent wt MAYV strain. Thus, this study describes a novel model of MAYV infection in immunocompetent mice and highlights the potential role of a live-attenuated MAYV vaccine candidate in host’s protection from disease induced by a virulent MAYV strain.

Enzyme-linked immunosorbent assay using recombinant envelope protein 2 antigen for diagnosis of Chikungunya virus

BackgroundChikungunya (CHIKV) virus is an important mosquito-borne virus causing outbreaks of acute febrile illness with arthropathy. The detection of specific antibodies against CHIKV is used for diagnosis after the acute viremic phase of the disease. However, a major challenge for serologic diagnosis of CHIKV and other alphaviruses is the cross-reactivity of antibodies to common antigens among these viruses. In the present study, we have developed an enzyme-linked immunosorbend assay using a recombinant envelope protein 2 of CHIKV produced in Escherichia coli system, as a capture antigen.ResultsHigh titers (1600 to 12,800) of anti-CHIKV antibodies were detected in human sera analyzed by the CHIKV assay, suggesting it may detect low levels of the antibodies presence. On the other side, cross-reactivity was not observed in mouse hyperimmune sera to Mayaro virus and other alphaviruses analyzed by the CHIKV immunosorbend assay, suggesting it is a CHIKV-specific test. Fifty-nine human serum samples of CHIKV infection suspected cases were tested for immunoglobulin G (IgG) and M (IgM) antibodies detection using the CHIKV immunosorbend assay. A total of 44% (26/59) of samples were positive for IgG to CHIKV, determining 89.66% sensitivity and 100% specificity when the assay is compared to a CHIKV-specific neutralization assay. In addition, 40.6% (24/59) of samples were positive for IgM, determining 92.48% sensitivity and 79.04% specificity by a Bayesian method in the absence of a gold standard. Moreover, CHIKV immunosorbend assay showed similar sensibilities to a commercial immunochromatography assay (Lumiquick, USA) for CHIKV IgG and IgM detection.ConclusionIn short, we have developed a rapid, simple, specific and sensitive CHIKV immunosorbend assay for IgG and IgM detection and our results showed potential applicability on the diagnosis of infections by this virus.

Use of TaqMan Array Cards to Screen Outbreak Specimens for Causes of Febrile Illness in Tanzania

We describe the deployment of a custom-designed molecular diagnostic TaqMan Array Card (TAC) to screen for 31 bacterial, protozoal, and viral etiologies in blood from outbreaks of acute febrile illness in Tanzania during 2015-2017. On outbreaks notified to the Tanzanian Ministry of Health, epidemiologists were dispatched and specimens were collected, transported to a central national laboratory, and tested by TAC within 2 days. This algorithm streamlined investigation, diagnosed a typhoid outbreak, and excluded dozens of other etiologies. This method is usable in-country and may be incorporated into algorithms for diagnosing outbreaks.

Concurrent Outbreaks of St. Louis Encephalitis Virus and West Nile Virus Disease - Arizona, 2015.

St. Louis encephalitis virus (SLEV) and West Nile virus (WNV) are closely related mosquito-borne flaviviruses that can cause outbreaks of acute febrile illness and neurologic disease. Both viruses are endemic throughout much of the United States and have the same Culex species mosquito vectors and avian hosts (1); however, since WNV was first identified in the United States in 1999, SLEV disease incidence has been substantially lower than WNV disease incidence, and no outbreaks involving the two viruses circulating in the same location at the same time have been identified. Currently, there is a commercially available laboratory test for diagnosis of acute WNV infection, but there is no commercially available SLEV test, and all SLEV testing must be performed at public health laboratories. In addition, because antibodies against SLEV and WNV can cross-react on standard diagnostic tests, confirmatory neutralizing antibody testing at public health laboratories is usually required to determine the flavivirus species (2). This report describes the first known concurrent outbreaks of SLEV and WNV disease in the United States.

Respiratory Syncytial Virus Outbreak in the Basic Military Training Camp of the Republic of Korea Air Force

Objectives:An outbreak of acute febrile illness occurred in the Republic of Korea Air Force boot camp from May to July 2011. An epidemiological investigation of the causative agent, which was of a highly infective nature, was conducted.Methods:Throat swabs were carried out and a multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) assay was performed to identify possible causative factors.Results:The mean age of patients who had febrile illness during the study period was 20.24 years. The multiplex RT-PCR assay identified respiratory syncytial virus (RSV) as the causative agent. The main symptoms were sore throat (76.0%), sputum (72.8%), cough (72.1%), tonsillar hypertrophy (67.9%), and rhinorrhea (55.9%). The mean temperature was 38.75°C and the attack rate among the recruits was 15.7% (588 out of 3750 recruits), while the mean duration of fever was 2.3 days. The prognosis was generally favorable with supportive care but recurrent fever occurred in 10.1% of the patients within a month.Conclusions:This is the first epidemiological study of an RSV outbreak that developed in a healthy young adult group. In the event of an outbreak of an acute febrile illness of a highly infective nature in facilities used by a young adult group, RSV should be considered among the possible causative agents.

Emerging alphaviruses in the Americas: Chikungunya and Mayaro.

Chikungunya virus (CHIKV) and Mayaro virus (MAYV) are emergent arthropod-borne viruses that produce outbreaks of acute febrile illness with arthropathy. Despite their different continental origins, CHIKV and MAYV are closely related and are components of the Semliki Forest Complex of the Alphavirus (Togaviridae). MAYV and, more recently, CHIKV, which are both transmitted by Aedes mosquitoes, have resulted in severe public health problems in the Americas, including Brazil. In this review, we present aspects of the pathogenesis, clinical presentation and treatment of febrile illnesses produced by CHIKV and MAYV. We also discuss the epidemiological aspects and effects related to the prophylaxis of infections by both viruses.

An outbreak of acute febrile illness caused by Sandfly Fever Sicilian Virus in the Afar region of Ethiopia, 2011.

In malaria-endemic regions, many medical facilities have limited capacity to diagnose non-malarial etiologies of acute febrile illness (AFI). As a result, the etiology of AFI is seldom determined, although AFI remains a major cause of morbidity in developing countries. An outbreak of AFI was reported in the Afar region of Ethiopia in August of 2011. Retrospectively, 12,816 suspected AFI cases were identified by review of medical records. Symptoms were mild and self-limiting within 3 days after the date of onset; no fatalities were identified. All initial test results of AFI patient specimens were negative for selected pathogens using standard microbiological and molecular techniques. High-throughput sequencing of nucleic acid extracts of serum specimens from 29 AFI cases identified 17 (59%) of 29 samples as positive for Sandfly Fever Sicilian Virus (SFSV). These results were further confirmed by specific reverse transcription polymerase chain reaction. This is the first study implicating SFSV as an etiological agent for AFI in Ethiopia.

A Study of Etiological Pattern in an Epidemic of Acute Febrile Illness during Monsoon in a Tertiary Health Care Institute of Uttarakhand, India.

Many parts of India are endemic for the dengue, malaria, typhoid and scrub typhus infections. The relative contribution of these illnesses in an outbreak of acute febrile illness is not known in this region. The present study was conducted to find out the etiological pattern in an epidemic of acute febrile illness in Uttarakhand during the monsoon period. The study also focuses on concurrent infections and tries to find out the mortality outcomes. A retrospective study of four months was conducted on 1141 patients who presented with fever, and were suspected to have dengue, malaria, typhoid or scrub typhus. Patients of 12-years of age or above were included in the study. Serological tests for dengue, malaria, typhoid and scrub typhus were performed. Slides for malaria parasite were examined. In case of enteric fever only culture positive cases were included in the study. Among the 1141 febrile patients dengue was detected in 812(71.2 %), malaria in 146(12.8%), typhoid in 92(8.1%) and scrub typhus in 69(6.0%) cases. Mixed infection was noted in 22(1.9%). Maximum (71.2 %) cases of fever were caused by dengue but significant number (32.3%) of patients suffered from malaria typhoid and scrub typhus. Many (1.9%) suffered from concurrent and multiple infections.

Reverse Genetics Recovery of Lujo Virus and Role of Virus RNA Secondary Structures in Efficient Virus Growth

Arenaviruses are rodent-borne viruses with a bisegmented RNA genome. A genetically unique arenavirus, Lujo virus, was recently discovered as the causal agent of a nosocomial outbreak of acute febrile illness with hemorrhagic manifestations in Zambia and South Africa. The outbreak had a case fatality rate of 80%. A reverse genetics system to rescue infectious Lujo virus from cDNA was established to investigate the biological properties of this virus. Sequencing the genomic termini showed unique nucleotides at the 3' terminus of the S segment promoter element. While developing this system, we discovered that reconstructing infectious Lujo virus using the previously reported L segment intergenic region (IGR), comprising the arenaviral transcription termination signal, yielded an attenuated Lujo virus. Resequencing revealed that the correct L segment IGR was 36 nucleotides longer, and incorporating it into the reconstructed Lujo virus restored the growth rate to that of the authentic clinical virus isolate. These additional nucleotides were predicted to more than double the free energy of the IGR main stem-loop structure. In addition, incorporating the newly determined L-IGR into a replicon reporter system enhanced the expression of a luciferase reporter L segment. Overall, these results imply that an extremely stable secondary structure within the L-IGR is critical for Lujo virus propagation and viral protein production. The technology for producing recombinant Lujo virus now provides a method to precisely investigate the molecular determinants of virulence of this newly identified pathogen.

Identification of Oropouche Orthobunyavirus in the Cerebrospinal Fluid of Three Patients in the Amazonas, Brazil

Oropouche fever is the second most frequent arboviral infection in Brazil, surpassed only by dengue. Oropouche virus (OROV) causes large and explosive outbreaks of acute febrile illness in cities and villages in the Amazon and Central-Plateau regions. Cerebrospinal fluid (CSF) samples from 110 meningoencephalitis patients were analyzed. The RNA extracted from fluid was submitted to reverse transcription-polymerase chain reaction and sequencing to identify OROV. Three CSF samples showed the presence of OROV causing infection in the central nervous system (CNS). These patients are adults. Two of the patients had other diseases affecting CNS and immune systems: neurocysticercosis and acquired immunodeficiency syndrome, respectively. Nucleotide sequence analysis showed that the OROV from the CSF of these patients belonged to genotype I. We show here that severe Oropouche disease is occurring during outbreaks of this virus in Brazil.

Challenges of Establishing the Correct Diagnosis of Outbreaks of Acute Febrile Illnesses in Africa: The Case of a Likely Brucella Outbreak among Nomadic Pastoralists, Northeast Kenya, March–July 2005

An outbreak of acute febrile illness was reported among Somali pastoralists in remote, arid Northeast Kenya, where drinking raw milk is common. Blood specimens from 12 patients, collected mostly in the late convalescent phase, were tested for viral, bacterial, and parasitic pathogens. All were negative for viral and typhoid serology. Nine patients had Brucella antibodies present by at least one of the tests, four of whom had evidence suggestive of acute infection by the reference serologic microscopic agglutination test. Three patients were positive for leptospiral antibody by immunoglobulin M enzyme-linked immunosorbent assay, and two were positive for malaria. Although sensitive and specific point-of-care testing methods will improve diagnosis of acute febrile illness in developing countries, challenges of interpretation still remain when the outbreaks are remote, specimens collected too late, and positive results for multiple diseases are obtained. Better diagnostics and tools that can decipher overlapping signs and symptoms in such settings are needed.

Mayaro Fever in the City of Manaus, Brazil, 2007–2008

Mayaro Alphavirus is an arbovirus that causes outbreaks of acute febrile illness in the Amazon region of South America. We show here the cases of Mayaro fever that occurred in 2007-2008, in Manaus, a large city and capital of the Amazonas State, in Western Brazilian Amazon. IgM antibodies to Mayaro virus (MAYV) were detected by an enzyme immunoassay using infected cell cultures as antigen in the sera of 33 patients from both genera and 6-65 years old. MAYV genome was also detected by RT-PCR in the blood of 1/33 of these patients. The patients presented mainly with headache, arthralgia, myalgia, ocular pain, and rash. These cases of Mayaro fever are likely to represent the tip of an iceberg, and probably a much greater number of cases occurred in Manaus in the study period.

Investigation into an outbreak of acute febrile illness in Sangli district of Maharashtra State, India

Investigation into an outbreak of acute febrile illness in Sangli district of Maharashtra State, India

Oropouche Fever Outbreak, Manaus, Brazil, 2007–2008

Oropouche Fever Outbreak, Manaus, Brazil, 2007–2008

T7 RNA polymerase-dependent and -independent systems for cDNA-based rescue of Rift Valley fever virus

Rift Valley fever virus (RVFV) is responsible for large and recurrent outbreaks of acute febrile illness among humans and domesticated animals in Africa. It belongs to the family Bunyaviridae, genus Phlebovirus, and its negative-stranded RNA genome consists of three segments. Here, we report the establishment and characterization of two different systems to rescue the RVFV wild-type strain ZH548. The first system is based on the BHK-21 cell clone BSR-T7/5, which stably expresses T7 RNA polymerase (T7 pol). Rescue of wild-type RVFV was achieved with three T7 pol-driven cDNA plasmids representing the viral RNA segments in the antigenomic sense. The second system involves 293T cells transfected with three RNA pol I-driven plasmids for the viral segments and two RNA pol II-driven support plasmids to express the viral polymerase components L and N. It is known that the 5' triphosphate group of T7 pol transcripts strongly activates the antiviral interferon system via the intracellular RNA receptor RIG-I. Nonetheless, both the T7 pol and the pol I/II system were of similar efficiency. This was even true for the rescue of a RVFV mutant lacking the interferon antagonist nonstructural proteins. Further experiments demonstrated that the unresponsiveness of BHK-21 and BSR-T7/5 cells to T7 pol transcripts is most probably due to a deficiency in the RIG-I pathway. Our reverse genetics systems now enable us to manipulate the genome of RVFV and study its virulence mechanisms. Moreover, the finding that BHK-derived cell lines have a compromised RIG-I pathway may explain their suitability for propagating and rescuing a wide variety of viruses.

Update: Outbreak of acute febrile illness among athletes participating in Eco-Challenge-Sabah 2000—Borneo, Malaysia, 2000

Editors’ note: This article is part of a regular series on emerging infections from the Centers for Disease Control and Prevention (CDC) and the EMERGEncy ID NET, an emergency department–based and CDC-collaborative surveillance network. Important infectious disease public health information with relevance to emergency physicians is reported. The goal of this series is to advance knowledge about communicable diseases in emergency medicine and foster cooperation between the front line of clinical medicine and public health agencies. [Centers for Disease Control and Prevention. Update: outbreak of acute febrile illness among athletes participating in Eco-Challenge-Sabah 2000—Borneo, Malaysia, 2000. MMWR Morb Mortal Wkly Rep. 2001;50:21-24.]