Chikungunya virus RNA and antibody testing at a National Reference Laboratory since the emergence of Chikungunya virus in the Americas

Serological and Molecular Epidemiology of Chikungunya Virus Infection in Vietnam, 2017-2019

Chikungunya fever is an acute febrile illness caused by the chikungunya virus (CHIKV), which is transmitted by Aedes mosquitoes. Since 1965, only a few studies with limited scope have been conducted on CHIKV in Vietnam. Thus, this study aimed to determine the seroprevalence and molecular epidemiology of CHIKV infection among febrile patients in Vietnam from 2017 to 2019. A total of 1063 serum samples from 31 provinces were collected and tested for anti-CHIKV IgM and IgG ELISA. The 50% focus reduction neutralization test (FRNT50) was used to confirm CHIKV-neutralizing antibodies. Quantitative real-time RT-PCR (RT-qPCR) was performed to confirm the presence of the CHIKV genome. The results showed that 15.9% (169/1063) of the patients had anti-CHIKV IgM antibodies, 20.1% (214/1063) had anti-CHIKV IgG antibodies, 10.4% (111/1063) had CHIKV-neutralizing antibodies, and 27.7% (130/469) of the samples were positive in RT-qPCR analysis. The E1 CHIKV genome sequences were detected among the positive RT-qPCR samples. Our identified sequences belonged to the East/Central/South/African (ECSA) genotype, which has been prevalent in Vietnam previously, suggesting CHIKV has been maintained and is endemic in Vietnam. This study demonstrates a high prevalence of CHIKV infection in Vietnam and calls for an annual surveillance program to understand its impact.

Understanding the Biology and Immune Pathogenesis of Chikungunya Virus Infection for Diagnostic and Vaccine Development

Chikungunya virus, the causative agent of chikungunya fever, is generally characterized by the sudden onset of symptoms, including fever, rash, myalgia, and headache. In some patients, acute chikungunya virus infection progresses to severe and chronic arthralgia that persists for years. Chikungunya infection is more commonly identified in tropical and subtropical regions. However, recent expansions and epidemics in the temperate regions have raised concerns about the future public health impact of chikungunya diseases. Several underlying factors have likely contributed to the recent re-emergence of chikungunya infection, including urbanization, human travel, viral adaptation to mosquito vectors, lack of effective control measures, and the spread of mosquito vectors to new regions. However, the true burden of chikungunya disease is most likely to be underestimated, particularly in developing countries, due to the lack of standard diagnostic assays and clinical manifestations overlapping with those of other endemic viral infections in the regions. Additionally, there have been no chikungunya vaccines available to prevent the infection. Thus, it is important to update our understanding of the immunopathogenesis of chikungunya infection, its clinical manifestations, the diagnosis, and the development of chikungunya vaccines.

Virological, Serological and Clinical Analysis of Chikungunya Virus Infection in Thai Patients

From 2018 to 2020, the Chikungunya virus (CHIKV) outbreak re-emerged in Thailand with a record of more than 10,000 cases up until the end of 2020. Here, we studied acute CHIKV-infected patients who had presented to the Bangkok Hospital for Tropical Diseases from 2019 to 2020 by assessing the relationship between viral load, clinical features, and serological profile. The results from our study showed that viral load was significantly high in patients with fever, headache, and arthritis. We also determined the neutralizing antibody titer in response to the viral load in patients, and our data support the evidence that an effective neutralizing antibody response against the virus is important for control of the viral load. Moreover, the phylogenetic analysis revealed that the CHIKV strains we studied belonged to the East, Central, and Southern African (ECSA) genotype, of the Indian ocean lineage (IOL), and possessed E1-K211E and E1-I317V mutations. Thus, this study provides insight for a better understanding of CHIKV pathogenesis in acute infection, along with the genomic diversity of the current CHIKV strains circulating in Thailand.

Lack of Evidence of Chikungunya Virus Infection among Blood Donors during the Chikungunya Outbreak in Lazio Region, Italy, 2017

Background: The latest European Chikungunya virus (CHIKV) outbreak occurred in Italy in 2017, in the municipalities of Anzio and Rome (Lazio Region), with a secondary outbreak in the Calabrian Region. Most CHIKV infections are symptomatic but about 15% of people who acquire the infection may be asymptomatic. A retrospective study was conducted with the aim of assessing the prevalence of recent/ongoing CHIKV infections on the blood donor population in the Lazio Region, during the 2017 outbreak (including in the period before it was detected). Methods: The study was conducted on 4595 plasma samples from donors who donated in 14 different Blood Establishments in the Lazio Region, in the period June–November 2017. A total of 389 of these samples were collected in provinces not affected by the outbreak and were used as negative controls. All samples were tested for IgM detection by the use of an ELISA test, and positive samples were tested for confirmation through the use of a PRNT. Molecular tests were performed on sera that were found to be IgM-positive or borderline. Results: A total of 41 (0.89%) blood donors tested positive for IgM. None of these positive IgM ELISA results was confirmed either by PRNT or by molecular tests. Conclusions: Our study has shown no evidence of recent/ongoing CHIKV infection in blood donors of the affected area.

Chikungunya infection in pregnancy - reassuring maternal and perinatal outcomes: a retrospective observational study

OBJECTIVE

To evaluate pregnancy and neonatal outcomes, disease severity, and mother-to-child transmission of pregnant women with Chikungunya infection (CHIKV).

DESIGN

Retrospective observational study.

SETTING

Grenada.

POPULATION

Women who gave birth during a Chikungunya outbreak between January 2014 and September 2015 were eligible.

METHODS

This descriptive study investigated 731 mother-infant pairs who gave birth during a CHIKV outbreak. Women and infants underwent serological testing for CHIKV by ELISA.

MAIN OUTCOME MEASURES

Primary outcomes: composite pregnancy complication (abruption, vaginal bleeding, preterm labour/cervical incompetence, cesarean delivery for fetal distress/abruption/placental abnormality or delivery for fetal distress) and composite neonatal morbidity.

RESULTS

Of 416 mother-infant pairs, 150 (36%) had CHIKV during pregnancy, 135 (33%) had never had CHIKV, and 131 (31%) had CHIKV outside of pregnancy. Mean duration of joint pain was shorter among women infected during pregnancy (μ = 898 days, σ = 277 days) compared with infections outside of pregnancy (μ = 1064 days, σ = 244 days) (P < 0.0001). Rates of pregnancy complications (RR = 0.76, P = 0.599), intrapartum complications (RR = 1.50, P = 0.633), and neonatal outcomes were otherwise similar. Possible mother-to-child transmission occurred in two (1.3%) mother-infant pairs and two of eight intrapartum infections (25%).

CONCLUSION

CHIKV infection during pregnancy may be protective against long-term joint pain sequelae that are often associated with acute CHIKV infection. Infection during pregnancy did not appear to pose a risk for pregnancy complications or neonatal health, but maternal infection just prior to delivery might have increased risk of mother-to-child transmission of CHIKV.

TWEETABLE ABSTRACT

Chikungunya infection did not increase risk of pregnancy complications or adverse neonatal outcomes, unless infection was just prior to delivery.

Long-Term Persistence of Chikungunya Virus-Associated Manifestations and Anti-Chikungunya Virus Antibody in Southern Thailand: 5 Years After an Outbreak in 2008-2009

Chikungunya fever, a disease caused by chikungunya virus (CHIKV), reemerged and affected over 52,000 people in southern Thailand in 2008 and 2009. The CHIKV strain involved in this outbreak was the East Central South African (ECSA) strain with the E1-A226V mutation. The prevalence of CHIKV-associated chronic discomfort varied by virus lineage. This retrospective cohort study aims to describe the CHIKV-related symptoms persisting in CHIKV-affected patients, related factors, and the presence of anti-CHIKV immunoglobulin G (IgG) antibodies 5 years after the onset of disease. From 5,344 of the study population screened, a total of 89 affected patients reported persistent arthralgia 5 years after the disease onset (nonrecovery rate = 1.7%). Of the 141 affected patients enrolled, 122 cases (86.5%; 77 cases with persistent arthralgia and 45 cases of fully recovered) still had detectable levels of anti-CHIKV IgG antibodies. Long-term persistence of chronic joint symptoms is associated with the severity of the disease during the initial phase of the infection, but not gender, age, or comorbidities. The common manifestations were arthralgia (75.3%), morning joint stiffness (39.0%), muscle pain (19.5%), and occasional joint swelling (16.9%). Chronic joint symptoms could occur in either a fluctuating or a persistent manner and usually caused moderate pain. The joints affected were mainly fingers (71.4%), wrists (51.9%), and knees (50.6%). Most patients had polyarthralgia with symmetrical joint involvement. In some cases with persistent arthralgia, atypical manifestations, including severe depression with suicide attempts, severe weight loss, and severe hair loss, were found, and some patients still experienced severe joint pain.

Proinflammatory Cytokines and Chemokines as Biomarkers of Persistent Arthralgia and Severe Disease After Chikungunya Virus Infection: A 5-Year Follow-Up Study in Southern Thailand

Chikungunya fever is a re-emerging viral disease caused by chikungunya virus (CHIKV). The disease is generally self-limiting, but chronic arthralgia/arthritis may persist for months or years. We evaluated the expression of 12 cytokines/chemokines and matrix metalloproteinases (MMP)-1 and MMP-3 using enzyme-linked immunosorbent assays (ELISAs) and compared among patients who still had arthralgia (persistent arthralgia), patients who had fully recovered, and healthy controls. There was a significant increase in interleukin (IL)-1β, IL-6, IL-8, monocyte chemotactic protein-1 (MCP-1), MMP-1, and MMP-3 levels in patients with persistent arthralgia in comparison to healthy controls (p < 0.05) and a significant increase in tumor necrosis factor-alpha (TNF-α), MMP-1, and MMP-3 levels in patients with persistent arthralgia in comparison to patients who had fully recovered (p < 0.05). Interferon (IFN)-γ, IL-6, and transforming growth factor beta (TGF-β) levels tended to be increased in patients with chronic CHIKV-induced arthritis compared with fully recovered. TNF-α, IL-12, and MCP-1 levels were elevated (p < 0.05), whereas regulated on activation, normal T cell expressed and secreted (RANTES) levels were decreased in patients with severe pain compared with patients with nonsevere pain (p < 0.05). IFN-γ, IL-1β, IL-6, and IL-8 levels tended to be elevated in patients with severe pain compared with patients with nonsevere pain. We proposed a role played by TNF-α, IL-6, IL-8, and MCP-1 in persistent arthralgia or chronic disease through the activation of MMP-1 and MMP-3. The increase in TNF-α, IL-12, and MCP-1 levels (and the tendency toward an increase in IFN-γ, IL-1β, IL-6, and IL-8 levels) in patients with severe pain compared with patients with nonsevere pain suggests the role of these inflammatory markers in chronic disease and severity of the disease.

GloPID-R report on Chikungunya, O'nyong-nyong and Mayaro virus, part I: Biological diagnostics

The GloPID-R (Global Research Collaboration for Infectious Disease Preparedness) Chikungunya (CHIKV), O'nyong-nyong (ONNV) and Mayaro virus (MAYV) Working Group is investigating the natural history, epidemiology and medical management of infection by these viruses, to identify knowledge gaps and to propose recommendations for direct future investigations and rectification measures. Here, we present the first report dedicated to diagnostic aspects of CHIKV, ONNV and MAYV. Regarding diagnosis of the disease at the acute phase, molecular assays previously described for the three viruses require further evaluation, standardized protocols and the availability of international standards representing the genetic diversity of the viruses. Detection of specific IgM would benefit from further investigations to clarify the extent of cross-reactivity among the three viruses, the sensitivity of the assays, and the possible interfering role of cryoglobulinaemia. Implementation of reference panels and external quality assessments for both molecular and serological assays is necessary. Regarding sero-epidemiological studies, there is no reported high-throughput assay that can distinguish among these different viruses in areas of potential co-circulation. New specific tools and/or improved standardized protocols are needed to enable large-scale epidemiological studies of public health relevance to be performed. Considering the high risk of future CHIKV, MAYV and ONNV outbreaks, the Working Group recommends that a major investigation should be initiated to fill the existing diagnostic gaps.

Cellular and Molecular Immune Response to Chikungunya Virus Infection

Chikungunya virus (CHIKV) is a re-emergent arthropod-borne virus (arbovirus) that causes a disease characterized primarily by fever, rash and severe persistent polyarthralgia. In the last decade, CHIKV has become a serious public health problem causing several outbreaks around the world. Despite the fact that CHIKV has been around since 1952, our knowledge about immunopathology, innate and adaptive immune response involved in this infectious disease is incomplete. In this review, we provide an updated summary of the current knowledge about immune response to CHIKV and about soluble immunological markers associated with the morbidity, prognosis and chronicity of this arbovirus disease. In addition, we discuss the progress in the research of new vaccines for preventing CHIKV infection and the use of monoclonal antibodies as a promising therapeutic strategy.

Chikungunya Infection: A Re-emerging Epidemic

Chikungunya (CHIK) is an arboviral infection caused by the chikungunya virus. An unusual feature of CHIK is its long periods of quiescence followed by an epidemic of devastating severity that can involve millions of people. Manifestations of CHIK range from a mild self-limiting febrile illness with arthralgia and rash to crippling acute and lingering debilitating arthritis. In about 10–60% of patients, musculoskeletal symptoms may persist for up to 3–5 years. Management is mainly symptomatic, with analgesics, antipyretics and non-steroidal anti-inflammatory agents. Ecological changes together with alterations in the viral genome facilitate the development of newer variants with greater pathogenicity, a matter of great concern. The social and economic burdens to a society as a result of CHIK epidemics have generated a considerable interest in the scientific community to decipher the reasons underlying myriad manifestations and to develop management strategies for tackling the menace of CHIK across the globe.

Chikungunya virus infection in Aruba: Diagnosis, clinical features and predictors of post-chikungunya chronic polyarthralgia

BACKGROUND

Chikungunya virus (CHIKV) emerged in Aruba for the first time in 2014. We studied the clinical presentation of acute CHIKV infection and the contribution of serologic and molecular assays to its diagnosis. In a cohort of confirmed CHIKV cases, we analysed the frequency, duration and predictors of post-chikungunya chronic polyarthralgia (pCHIK-CPA), defined as joint pains lasting longer than 6 weeks or longer than 1 year.

METHODOLOGY

Patient sera obtained within 10 days of symptom onset were tested for CHIKV, using an indirect immunofluorescence test for the detection of CHIKV-specific Immunoglobulin M (IgM) and post-hoc, by reverse-transcription polymerase chain reaction (RT-PCR). CHIKV was isolated from selected samples and genotyped. For confirmed CHIKV cases, clinical data from chart review were complemented by a Telephone survey, conducted 18-24 months after diagnosis. When joint pain was reported, the duration, presence of inflammatory signs, type and number of joints affected, were recorded. Joint involvement was scored according to the 2010 'American College of Rheumatology/ European League Against Rheumatism' criteria for seronegative rheumatoid arthritis (ACR-score). Risk factors for pCHIK-CPA were identified by logistic regression.

PRINCIPAL FINDINGS

Acute CHIKV infection was diagnosed in 269 of 498 sera, by detection of IgM (n = 105), by RT-PCR (n = 59), or by both methods (n = 105). Asian genotype was confirmed in 7 samples. Clinical data were complete for 171 of 248 (69.0%) patients, aged 15 years or older (median 49.4 [35.0-59.6]). The female-to-male ratio was 2.2. The main acute symptoms were arthralgia (94%), fever (85%), myalgia (85%), headache (73%) and rash (63%). In patients with arthralgia (n = 160), pCHIK-CPA longer than 6 weeks was reported by 44% and longer than 1 year by 26% of cases. Inflammatory signs, stiffness, edema and redness were frequent (71%, 39% and 21%, respectively). Joints involved were knees (66%), ankles (50%), fingers (52%), feet (46%), shoulders (36%), elbows (34%), wrists (35%), hips (31%), toes (28.1%) and spine (28.1%). Independent predictors of pCHIK-CPA longer than 1 year were female gender (OR 5.9, 95%-CI [2.1-19.6]); high ACR-score (7.4, [2.7-23.3]), and detection of CHIKV-RNA in serum beyond 7 days of symptom onset (6.4, [1.4-34.1].

CONCLUSIONS

We identified 269 CHIKV patients after the first outbreak of Asian genotype CHIKV in Aruba in 2014-2015. RT-PCR yielded 59 (28%) additional CHIKV diagnoses compared to IgM antibody detection alone. Arthralgia, fever and skin rash were the dominant acute phase symptoms. pCHIK-CPA longer than 1 year affected 26% of cases and was predicted by female gender, high ACR-score and CHIKV-RNA detection beyond 7 days of symptom onset.

Chikungunya: Report from the task force on tropical diseases by the World Federation of Societies of intensive and critical care medicine

Chikungunya is an arbovirus that is transmitted by the Aedes mosquito causing a febrile illness with periodic outbreaks in large parts of the world. In the last decade it has become a public health concern in a host of countries and has affected international tourists. In the vast majority of cases Chikungunya presents as an acute febrile illness, associated with rash, headache, myalgia and debilitating arthralgia or even polyarthritis. A small proportion of patients present atypically with nervous, ocular, renal, myocardial, respiratory and renal system involvement and may require ICU management. Over the years the epidemic potential of the virus has become apparent with spread related to an increase in global travel and the successful adaptation of the Aedes mosquito to the urban and sylvan environments in numerous countries. These epidemics have affected millions of people across the globe. Treatment is usually symptomatic and supportive.

Chikungunya Virus Infections Among Infants-Who Classification Not Applicable

Chikungunya virus caused an epidemic on Curaçao in 2014-2015. Infants are highly at risk for clinical syndromes as sepsis-like illness and central nervous system disease. Clinical recognition is important if laboratory test, polymerase chain reaction and enzyme-linked immunosorbent assay are not available. The World Health Organization created criteria for identification of probable Chikungunya virus. None of the studied infants met these criteria. We believe the criteria suggested by World Health Organization should be modified for infants.

Recent progress on chikungunya virus research

Chikungunya virus (CHIKV) is an arbovirus transmitted by Aedes mosquitos in tropical and subtropical regions across the world. After decades of sporadic outbreaks, it re-emerged in Africa, Asia, India Ocean and America suddenly, causing major regional epidemics recently and becoming a notable global health problem. Infection by CHIKV results in a spectrum of clinical diseases including an acute self-limiting febrile illness in most individuals, a chronic phase of recurrent join pain in a proportion of patients, and long-term arthralgia for months to years for the unfortunate few. No specific anti-viral drugs or licensed vaccines for CHIKV are available so far. A better understanding of virus-host interactions is essential for the development of therapeutics and vaccines. To this end, we reviewed the existing knowledge on CHIKV’s epidemiology, clinical presentation, molecular virology, diagnostic approaches, host immune response, vaccine development, and available animal models. Such a comprehensive overview, we believe, will shed lights on the promises and challenges in CHIKV vaccine development.

Recommendations of the Brazilian Society of Rheumatology for diagnosis and treatment of Chikungunya fever. Part 1 - Diagnosis and special situations

Chikungunya fever has become a relevant public health problem in countries where epidemics occur. Until 2013, only imported cases occurred in the Americas, but in October of that year, the first cases were reported in Saint Marin island in the Caribbean. The first autochthonous cases were confirmed in Brazil in September 2014; until epidemiological week 37 of 2016, 236,287 probable cases of infection with Chikungunya virus had been registered, 116,523 of which had serological confirmation. Environmental changes caused by humans, disorderly urban growth and an ever-increasing number of international travelers were described as the factors responsible for the emergence of large-scale epidemics. Clinically characterized by fever and joint pain in the acute stage, approximately half of patients progress to the chronic stage (beyond 3 months), which is accompanied by persistent and disabling pain. The aim of the present study was to formulate recommendations for the diagnosis and treatment of Chikungunya fever in Brazil. A literature review was performed in the MEDLINE, SciELO and PubMed databases to ground the decisions for recommendations. The degree of concordance among experts was established through the Delphi method, involving 2 in-person meetings and several online voting rounds. In total, 25 recommendations were formulated and divided into 3 thematic groups: (1) clinical, laboratory and imaging diagnosis; (2) special situations; and (3) treatment. The first 2 themes are presented in part 1, and treatment is presented in part 2.

Chikungunya Infection: a Global Public Health Menace

Chikungunya virus (CHIKV) has been involved in epidemics in African and Asian subcontinents and, of late, has transcended to affect the Americas. Aedes aegypti and Aedes albopictus are the major vectors for CHIKV infection, which results in dissemination of virus to various vital organs. Entry of virus into these tissues causes infiltration of innate immune cells, monocytes, macrophages, neutrophils, natural killer cells, and adaptive immune cells. Macrophages bearing the replicating virus, in turn, secrete pro-inflammatory cytokines IL-1β, TNF-α, and IL-17. Together, this pro-inflammatory milieu induces osteoclastogenesis, bone loss, and erosion. CHIKV is characterized by fever, headache, myalgia, rash, and symmetric polyarthritis, which is generally self-limiting. In a subset of cases, however, musculoskeletal symptoms may persist for up to 3-5 years. Viral culture and isolation from blood cells of infected patients are the gold standards for diagnosis of CHIKV. In routine practice, however, assays for anti-CHIKV IgM antibodies are used for diagnosis, as elevated levels in blood of infected patients are noted from 10 days following infection for up to 3-6 months. Early diagnosis of CHIKV is possible by nucleic acid detection techniques. Treatment of acute CHIKV is mainly symptomatic, with analgesics, non-steroidal anti-inflammatory agents (NSAIDs), and low-dose steroids. No vaccines or anti-viral medicines have been approved for clinical therapy in CHIKV as yet. Hydroxychloroquine and methotrexate have been used in chronic CHIKV infection with variable success.

Chikungunya: important lessons from the Jamaican experience

Objectives.

To describe the clinical presentation of chikungunya virus (CHIKV) illness in adults during the 2014 outbreak in Jamaica and to determine the predictive value of the case definition.

Methods.

A cross-sectional study was conducted using clinical data from suspected cases of CHIKV that were reported to the Ministry of Health in April – December 2014. In addition, charts were reviewed of all individuals over 15 years of age with suspected CHIKV based on a diagnosis of CHIKV or “acute viral illness” that presented to four major health centers in Jamaica during the week prior to and the peak week of the epidemic. Data abstracted from these charts using a modified CHIKV Case Investigation Form included demographics, clinical findings, and laboratory tests.

Results.

In 2014, the Ministry of Health of Jamaica received 4 447 notifications of CHIKV infection. PCR testing was conducted on 137 suspected CHIKV cases (56 men and 81 women; median age 28 years) and was positive for 89 (65%) persons. In all, 205 health charts were identified that met the selection criteria (51 men and 154 women, median age 43 years). The most commonly reported symptoms were arthralgia (86%) and fever (76%). Of those who met the epidemiologic case definition for CHIKV as defined by the Pan American Health Organization, only 34% had this diagnosis recorded. Acute viral illness was the most frequently recorded diagnosis (n = 79; 58%).

Conclusions.

Broader case definitions for acute CHIKV illness may be needed to identify suspected cases during an outbreak. Standardized data collection forms and validation of case definitions may be useful for future outbreaks.

Analytical and clinical performance of a Chikungunya qRT-PCR for Central and South America

Chikungunya was introduced into the Americas in 2015 causing a pandemic across the continent. Testing during the acute phase of infection relies on qRT-PCR, but available assays have a number of limitations. A qRT-PCR assay specific to the chikungunya E1 gene was designed using sequence data from contemporary strains. A probit analysis established the 95% limit of detection as 19.6 copies per reaction. We compared the assay with a US Centers for Disease Control (CDC) chikungunya qRT-PCR as the reference standard. The assay had a sensitivity and specificity of 98.4% and 100% in 90 samples retrospectively collected in Guatemala. In a further 74 febrile samples prospectively collected in Ecuador and Guatemala the test had a sensitivity and specificity of 100% and 98.4%, respectively. Sequencing the nsp4 gene of the discordant positive sample indicated the presence of chikungunya RNA, and mismatches to the primer binding sites of the CDC assay.

Evaluation of Two Enzyme-Linked Immunosorbent Assay Kits for Chikungunya Virus IgM Using Samples from Deceased Organ and Tissue Donors

The identification of nearly 3,500 cases of chikungunya virus (CHIKV) infection in U.S. residents returning in 2014 and 2015 from areas in which it is endemic has raised concerns within the transplant community that, should recently infected individuals become organ and/or tissue donors, CHIKV would be transmitted to transplant recipients. Thus, tests designed to detect recent CHIKV infection among U.S. organ and tissue donors may become necessary in the future. Accordingly, we evaluated 2 enzyme-linked immunosorbent assays (ELISAs) for CHIKV IgM readily available in the United States using 1,000 deidentified serum or plasma specimens collected from donors between November 2014 and March 2015. The Euroimmun indirect ELISA identified 38 reactive specimens; however, all 38 were negative for CHIKV IgG and IgM in immunofluorescence assays (IFAs) conducted at a reference laboratory and, thus, were falsely reactive in the Euroimmun CHIKV IgM assay. The InBios IgM-capture ELISA identified 26 reactive samples, and one was still reactive (index ≥ 1.00) when retested using the InBios kit with a background subtraction modification to identify false reactivity. This reactive specimen was CHIKV IgM negative but IgG positive by IFAs at two reference laboratories; plaque reduction neutralization testing (PRNT) demonstrated CHIKV-specific reactivity. The IgG and PRNT findings strongly suggest that the InBios CHIKV IgM-reactive result represents true reactivity, even though the IgM IFA result was negative. If testing organ/tissue donors for CHIKV IgM becomes necessary, the limitations of the currently available CHIKV IgM ELISAs and options for their optimization must be understood to avoid organ/tissue wastage due to falsely reactive results.

Arbovirus Infections

PURPOSE OF REVIEW

Arbovirus (arthropod-borne virus) infections are increasingly important causes of neurologic disease in the United States through both endemic transmission and travel-associated infections. This article reviews the major arbovirus infections that can cause neurologic disease likely to be encountered in the United States.

RECENT FINDINGS

West Nile virus continues to be an important cause of epidemic encephalitis, while emerging arbovirus infections such as dengue and chikungunya have rapidly expanded their geographic distribution. As emerging arboviruses expand in new geographic regions, neurologic abnormalities are reported in new patient populations.

SUMMARY

Emerging arbovirus infections are increasingly important causes of neurologic disease throughout the world and in the United States. While no US Food and Drug Administration (FDA)-approved therapy is yet available for these infections, prompt recognition and diagnosis from the consulting neurologist will ensure appropriate supportive care for the patient.

Simultaneous detection of Zika, Chikungunya and Dengue viruses by a multiplex real-time RT-PCR assay

BACKGROUND

In the recent past, arboviruses such as Chikungunya (CHIKV) and Zika (ZIKV) have increased their area of endemicity and presented as an emerging global public health threat.

OBJECTIVES

To design an assay for the simultaneous detection of ZIKV, CHIKV and Dengue (DENV) 1-4 from patients with symptoms of arboviral infection. This would be advantageous because of the similar clinical presentation typically encountered with these viruses and their co-circulation in endemic areas.

STUDY DESIGN

In this study we have developed and validated a triplex real time reverse transcription PCR assay using hydrolysis probes targeting the non-structural 5 (NS5) region of ZIKV, non-structural protein 4 (nsP4) from CHIKV and 3' untranslated region (3'UTR) of DENV 1-4.

RESULTS AND CONCLUSIONS

The 95% LOD by the triplex assay was 15 copies/reaction for DENV-1 and less than 10 copies/reaction for all other viruses. The triplex assay was 100% specific and did not amplify any of the other viruses tested. The assay was reproducible and adaptable to testing different specimen types including serum, plasma, urine, placental tissue, brain tissue and amniotic fluid. This assay can be easily implemented for diagnostic testing of patient samples, even in a high throughput laboratory.

High Incidence of Chikungunya Virus and Frequency of Viremic Blood Donations during Epidemic, Puerto Rico, USA, 2014

Deaths were rarely observed, but newborns and other vulnerable populations are at risk for severe complications.

Chikungunya virus (CHIKV) caused large epidemics throughout the Caribbean in 2014. We conducted nucleic acid amplification testing (NAAT) for CHIKV RNA (n = 29,695) and serologic testing for IgG against CHIKV (n = 1,232) in archived blood donor samples collected during and after an epidemic in Puerto Rico in 2014. NAAT yields peaked in October with 2.1% of donations positive for CHIKV RNA. A total of 14% of NAAT-reactive donations posed a high risk for virus transmission by transfusion because of high virus RNA copy numbers (10⁴–10⁹ RNA copies/mL) and a lack of specific IgM and IgG responses. Testing of minipools of 16 donations would not have detected 62.5% of RNA-positive donations detectable by individual donor testing, including individual donations without IgM and IgG. Serosurveys before and after the epidemic demonstrated that nearly 25% of blood donors in Puerto Rico acquired CHIKV infections and seroconverted during the epidemic.

Diagnostic potential of monoclonal antibodies against the capsid protein of chikungunya virus for detection of recent infection

Chikungunya fever is self-limiting. However, neurological and hemorrhagic complications have been seen in recent outbreaks. The clinical manifestations of this disease are similar to those of dengue virus infection, indicating the need for differential diagnosis in areas such as India, which are endemic for both viruses. The aim of the present study was to develop monoclonal antibodies (MAbs) against Chikungunya virus (CHIKV) and assess their use in MAb-based IgM capture ELISA (MAC ELISA). The ELISA detects CHIKV-specific IgM antibodies, a marker of recent infection, in a patient's serum. One IgG1 and two IgM isotype hybrids were obtained. All of the subclones derived from the IgG1 hybrid recognized the C protein of CHIKV. The anti-C MAb ClVE4/D9 was the most promising as a detector antibody in MAC ELISA (C-MAb ELISA) yielding higher positive-to-negative (P/N) ratios. When compared with the CHIKV MAC ELISA kit developed by the National Institute of Virology (NIV), Pune (NIV MAC ELISA), the sensitivity of the test was 87.01 % with 100 % specificity. The positive and negative predictive values (PPV and NPV) were 100 % and 94.47 %, respectively. In precision testing, standard deviation (SD) and coefficient of variation (% CV) values of the C-MAb ELISA were within acceptable limits. The C-MAb ELISA detected anti-CHIKV IgM in serum of patients up to five months after the onset of infection, indicating that anti-C MAbs have strong potential for use in MAC ELISA to detect recent CHIKV infection.

A Case of Diabetic Ketoacidosis Following Chikungunya Virus Infection

Chikungunya is a mosquito-borne viral disease that has recently become endemic in the Caribbean, including the island of Puerto Rico. We present the case of a 50-year-old Puerto Rican man who traveled to St. Louis for business and was diagnosed with acute chikungunya virus infection with atypical features causing diabetic ketoacidosis. This case highlights the need to keep tropical infectious diseases on the differential diagnosis in appropriate individuals and the ways in which tropical infectious diseases can masquerade as part of common presentations.