Establishment and application of an indirect ELISA for Getah virus E2 antibody detection

Getah virus (GETV) is a mosquito-transmitted disease that affects animals, causing fever, aseptic meningitis, and abortion. Its prevalence in China poses risks to both animal health and public well-being. Currently, there is a scarcity of seroepidemiological data on GETV due to the absence of commercial antibody detection kits for pigs. The aim of this study is to develop a rapid, accurate, and sensitive ELISA, providing a reliable tool for GETV seroepidemiology and laying the foundation for future commercial assay development. In this study, we removed specific hydrophobic domains and intracellular structures from E2 proteins and constructed the recombinant plasmid pCold-TF-E2. The recombinant protein was expressed using a prokaryotic expression system, and efficient purification of the rE2 protein was achieved using a nickel affinity column. The purified rE2 protein is suitable for the development of an indirect ELISA (rE2 ELISA). Following the optimization of reaction conditions for the rE2-ELISA, the cut-off value was 0.356. Additionally, the rE2-ELISA method showed a positive rate of 37.1% for IgG antibodies against GETV when testing 986 pig clinical serum samples collected from pigs in Sichuan between May 2022 and September 2022. The rE2-ELISA method displayed a 95.1% overall agreement with VNT, boasting a sensitivity of 98.2% and a specificity of 92.6%. These results indicate that IgG ELISA based on rE2 protein is an efficient and economical method for the detection of GETV antibodies in pigs, facilitating the diagnosis and prevention of GETV.

A micro-PRNT for the detection of Ross River virus antibodies in mosquito blood meals: A useful tool for inferring transmission pathways

Introduction

Many arboviruses of public health significance are maintained in zoonotic cycles with complex transmission pathways. The presence of serum antibody against arboviruses in vertebrates provides evidence of their historical exposure but reveals nothing about the vector-reservoir relationship. Moreover, collecting blood or tissue samples from vertebrate hosts is ethically and logistically challenging. We developed a novel approach for screening the immune status of vertebrates against Ross River virus that allows us to implicate the vectors that form the transmission pathways for this commonly notified Australian arboviral disease.

Methods

A micro-plaque reduction neutralisation test (micro-PRNT) was developed and validated on koala (Phascolarctos cinereus) sera against a standard PRNT. The ability of the micro-PRNT to detect RRV antibodies in mosquito blood meals was then tested using two mosquito models. Laboratory-reared Aedes aegypti were fed, via a membrane, on sheep blood supplemented with RRV seropositive and seronegative human sera. Aedes notoscriptus were fed on RRV seropositive and seronegative human volunteers. Blood-fed mosquitoes were harvested at various time points after feeding and their blood meals analysed for the presence of RRV neutralising antibodies using the micro-PRNT.

Results

There was significant agreement of the plaque neutralisation resulting from the micro-PRNT and standard PRNT techniques (R² = 0.65; P<0.0001) when applied to RRV antibody detection in koala sera. Sensitivity and specificity of the micro-PRNT assay were 88.2% and 96%, respectively, in comparison with the standard PRNT. Blood meals from mosquitoes fed on sheep blood supplemented with RRV antibodies, and on blood from RRV seropositive humans neutralised the virus by ≥50% until 48 hr post feeding. The vertebrate origin of the blood meal was also ascertained for the same samples, in parallel, using established molecular techniques.

Conclusions

The small volumes of blood present in mosquito abdomens can be used to identify RRV antibodies and therefore host exposure to arbovirus infection. In tandem with the accurate identification of the mosquito, and diagnostics for the host origin of the blood meal, this technique has tremendous potential for exploring RRV transmission pathways. It can be adapted for similar studies on other mosquito borne zoonoses.

Ross River Virus Antibody Prevalence, Fiji Islands, 2013-2015

A unique outbreak of Ross River virus (RRV) infection was reported in Fiji in 1979. In 2013, RRV seroprevalence among residents was 46.5% (362/778). Of the residents who were seronegative in 2013 and retested in 2015, 10.9% (21/192) had seroconverted to RRV, suggesting ongoing endemic circulation of RRV in Fiji.

Divergent Barmah Forest Virus from Papua New Guinea

We report a case of Barmah Forest virus infection in a child from Central Province, Papua New Guinea, who had no previous travel history. Genomic characterization of the virus showed divergent origin compared with viruses previously detected, supporting the hypothesis that the range of Barmah Forest virus extends beyond Australia.

GloPID-R report on chikungunya, o'nyong-nyong and Mayaro virus, part 2: Epidemiological distribution of o'nyong-nyong virus

The GloPID-R (Global Research Collaboration for Infectious Disease Preparedness) chikungunya (CHIKV), o'nyong-nyong (ONNV) and Mayaro virus (MAYV) Working Group has been established to identify gaps of knowledge about the natural history, epidemiology and medical management of infection by these viruses, and to provide adapted recommendations for future investigations. Here, we present a report dedicated to ONNV epidemiological distribution. Two large-scale ONNV outbreaks have been identified in Africa in the last 60 years, interspersed with sporadic serosurveys and case reports of returning travelers. The assessment of the real scale of ONNV circulation in Africa remains a difficult task and surveillance studies are necessary to fill this gap. The identification of ONNV etiology is made complicated by the absence of multiplex tools in co-circulation areas and that of reference standards, as well as the high cross-reactivity with related pathogens observed in serological tests, in particular with CHIKV. This is a specific obstacle for seroprevalence studies, that necessitate an improvement of serological tools to provide robust results. The scarcity of existent genetic data currently limits molecular epidemiology studies. ONNV epidemiology would also benefit from reinforced entomological and environmental surveillance. Finally, the natural history of the disease deserves to be further investigated, with a specific attention paid to long-term complications. Considering our incomplete knowledge on ONNV distribution, GloPID-R CHIKV, ONNV and MAYV experts recommend that a major effort should be done to fill existing gaps.

Prediction of MAYV peptide antigens for immunodiagnostic tests by immunoinformatics and molecular dynamics simulations

The Mayaro virus is endemic to South America, and the possible involvement of Aedes spp. mosquitoes in its transmission is a risk factor for outbreaks of greater proportions. The virus causes a potentially disabling illness known as Mayaro fever, which is similar to that caused by the chikungunya virus. The cocirculation of both viruses, with their clinical and structural similarities, and the absence of prophylactic and therapeutic measures highlight the need for studies that seek to understand the Mayaro virus. Using approaches in silico, we identified an antigenic and specific epitope (p_MAYV4) in domain A of the E2 glycoprotein of the Mayaro virus. This epitope was theoretically predicted to be stable and exposed on the surface of the protein, where it showed key properties that enable its interaction with neutralizing antibodies. These characteristics make it an interesting target for the development of immunodiagnostic platforms. Molecular dynamics simulation-based structural analysis showed that the PHE95 residue in the E1 fusion loop region is conserved among Alphavirus family members. PHE95 interacts with the hydrophobic residues of the E2 glycoprotein to form a cage-shaped structure that is critical to assemble and stabilize the E1/E2 heterodimer. These results provide important insights useful for the advancement of diagnostic platforms and the study of therapeutic alternatives.

Establishment of an Alphavirus-Specific Neutralization Assay to Distinguish Infections with Different Members of the Semliki Forest complex

Background: Alphaviruses are transmitted by arthropod vectors and can be found worldwide. Alphaviruses of the Semliki Forest complex such as chikungunya virus (CHIKV), Mayaro virus (MAYV) or Ross River virus (RRV) cause acute febrile illness and long-lasting arthralgia in humans, which cannot be clinically discriminated from a dengue virus or Zika virus infection. Alphaviruses utilize a diverse array of mosquito vectors for transmission and spread. For instance, adaptation of CHIKV to transmission by Aedes albopictus has increased its spread and resulted in large outbreaks in the Indian Ocean islands. For many alphaviruses commercial diagnostic tests are not available or show cross-reactivity among alphaviruses. Climate change and globalization will increase the spread of alphaviruses and monitoring of infections is necessary and requires virus-specific methods. Method: We established an alphavirus neutralization assay in a 384-well format by using pseudotyped lentiviral vectors. Results: MAYV-specific reactivity could be discriminated from CHIKV reactivity. Human plasma from blood donors infected with RRV could be clearly identified and did not cross-react with other alphaviruses. Conclusion: This safe and easy to use multiplex assay allows the discrimination of alphavirus-specific reactivity within a single assay and has potential for epidemiological surveillance. It might also be useful for the development of a pan-alphavirus vaccine.

Selective precipitation reaction: a novel diagnostic test for tissue pathology in Atlantic salmon, Salmo salar, infected with salmonid alphavirus (SAV3)

While investigating biomarkers for infection with salmonid alphavirus (SAV), the cause of pancreas disease (PD), a selective precipitation reaction (SPR) has been discovered in serum which could be an on-farm qualitative test and an in-laboratory quantitative assay for health assessments in aquaculture. Mixing serum from Atlantic salmon, Salmo salar, with SAV infection with a sodium acetate buffer caused a visible precipitation which does not occur with serum from healthy salmon. Proteomic examination of the precipitate has revealed that the components are a mix of muscle proteins, for example enolase and aldolase, along with serum protein such as serotransferrin and complement C9. The assay has been optimized for molarity, pH, temperature and wavelength so that the precipitation can be measured as the change in optical density at 340 nm (Δ₃₄₀ ). Application of the SPR assay to serum samples from a cohabitation trial of SAV infection in salmon showed that the Δ₃₄₀ in infected fish rose from undetectable to a maximum at 6 weeks post-infection correlating with histopathological score of pancreas, heart and muscle damage. This test may have a valuable role to play in the diagnostic evaluation of stock health in salmon.

Mosquito-transmitted viruses - the great Brazilian challenge

Arboviruses pose a serious threat to public health worldwide, overloading the healthcare system and causing economic losses. These viruses form a very diverse group, and in Brazil, arboviruses belonging to the families Flaviviridae and Togaviridae are predominant. Unfortunately, the number of arboviruses increases in proportion with factors such as deforestation, poor sanitation, climate changes, and introduction of new viruses like Chikungunya virus and Zika virus. In Brazil, dengue is endemic, along with the presence of other arboviruses. The situation is complicated by the scarcity of diagnostic infrastructure and the absence of approved vaccines for these diseases. Disease control, thus, relies solely on vector control. Therefore, enhanced clinical knowledge and improved general awareness about these arboviruses are indispensable to tackle diagnostic inadequacies.

Arboviral diseases and malaria in Australia, 2013-14: Annual report of the National Arbovirus and Malaria Advisory Committee

This report describes the epidemiology of mosquito-borne diseases of public health importance in Australia during the 2013-14 season (1 July 2013 to 30 June 2014) and includes data from human notifications, sentinel chicken, vector and virus surveillance programs. The National Notifiable Diseases Surveillance System received notifications for 8,898 cases of disease transmitted by mosquitoes during the 2013-14 season. The Australasian alphaviruses Barmah Forest virus and Ross River virus accounted for 6,372 (72%) total notifications. However, over-diagnosis and possible false positive diagnostic test results for these 2 infections mean that the true burden of infection is likely overestimated, and as a consequence, the case definitions have been amended. There were 94 notifications of imported chikungunya virus infection and 13 cases of imported Zika virus infection. There were 212 notifications of dengue virus infection acquired in Australia and 1,795 cases acquired overseas, with an additional 14 cases for which the place of acquisition was unknown. Imported cases of dengue were most frequently acquired in Indonesia (51%). No cases of locally-acquired malaria were notified during the 2013-14 season, though there were 373 notifications of overseas-acquired malaria. In 2013-14, arbovirus and mosquito surveillance programs were conducted in most jurisdictions. Surveillance for exotic mosquitoes at international ports of entry continues to be a vital part of preventing the spread of vectors of mosquito-borne diseases such as dengue to new areas of Australia, with 13 detections of exotic mosquitoes at the ports of entry in 2013-14.

[DETECTION OF VENEZUELAN EQUINE ENCEPHALOMYELITIS VIRUS RNA IN BIOLOGICAL SAMPLES BY REVERSE-TRANSCRIPTION POLYMERASE CHAIN REACTION]

AIM

Detection-and identification of Venezuelan equine encephalomyelitis (VEE) virus RNA in biological samples by reverse-transcription polymerase chain reaction (RT-PCR) and RT-PCR in real time (rRT-PCR).

MATERIALS AND METHODS

VEE, Sindbis, West Nile, Japanese and tick-borne encephalitis viruses were studied. Cell culture of chicken fibroblasts, outbred mice and rats, Javanese macaques were used in the experiments. Biological activity determination of the running culture of causative agents used in the experiments was carried out by negative colony method in monolayer cell culture under agar coating. and using intra-cerebral infection of mice. Reagent kits developed in the 48th Central Research Institute and Institute of Analytical Instrument Engineering were used during execution of experiments of VEE virus RNA detection by RT-PCR and rRT-PCR.

RESULTS

VEE virus was detected in biological samples by various methods. Data from RT-PCR and rRT-PCR are in accordance with the results of virus detection in samples using sensitive animals.

CONCLUSION

Use of molecular-diagnostics methods for detection in biological samples of a causative agent of a dangerous infectious disease is important for procuring biological safety of Russian Federation.

Ross River virus infection surveillance in the Greater Perth Metropolitan area--has there been an increase in cases in the winter months?

An increase in off-season (June to September) Ross River virus (RRV) notifications from the greater Perth metropolitan area was observed from 2006 to 2009. We investigated the increase to determine whether it is likely to have reflected a true increase in off-season cases. A single positive RRV IgM test result is sufficient for RRV notification but where follow-up testing was performed, the positive predictive value of an IgM test where IgG was negative was very low in the off-season and also in the season when using the only commercially available test kit. The increase in off-season notifications was not associated with an increase in off-season testing. Some Perth laboratories use more stringent notification criteria than the nationally agreed RRV case definition, and the geographical distribution of samples tested varies between laboratories. Our findings make a strong case to change the nationally agreed case definition for RRV to not accept a single IgM positive test result as laboratory definitive evidence where the IgG is negative. Our study also identified a range of challenges in interpreting changes in seasonal patterns and geographical distribution of RRV. Any such observed changes should be investigated through further data analysis and/or mosquito trapping and testing in order to assess validity.

[Isolation of the Chikungunya virus in Moscow from the Indonesian visitor (September, 2013)]

The results of the virological identification of the Chikungunya fever case in Moscow (September, 2013) in an Indonesian visitor are presented. The clinic, electron microscopy, and molecular genetic data are discussed. The Ghikungunya virus (CHIKV) strain CHIKVILEIV-Moscow/1/2013 belonging to the Asian genotype (ID GenBank KF872195) was deposited into the Russian State Collection of viruses (GKV 1239; 18.11.2013).

Serological correlates of immune protection conferred by Chikungunya virus infection

Chikungunya virus (CHIKV), an Alphavirus of the family Togaviridae is a positive strand RNA virus that is transmitted commonly by the Aedes mosquitoes. The characteristic clinical symptom of the virus infection is incapacitating arthralgia that could persist for few weeks to several months in the affected individuals (1, 2). High morbidity with severe polyarthralgia, rashes and ocular, hemorrhagic and sensorineural complications are reported in the re-emerging infection (3-5). The acquisition of an A226V mutation in the envelope protein E1 has increased the transmissibility of the virus in the widely prevalent Ae. Albopictus mosquitoes (6). CHIKV infection has become more widespread in the recent years as the mosquito vectors have expanded into new areas. Imported cases of CHIKV have been reported in nearly 40 countries until now (7).

Prevalence and characteristics of dengue and chikungunya infections among acute febrile patients in Nong Khai Province, Thailand

We conducted a cross sectional study at three hospitals of Nong Khai Province, Thailand to determine the prevalence and characteristics of dengue and chikungunya infection among patients who sought care. The study population was acute febrile patients who visited these hospitals during 1 August -31 October, 2010 who were aged 2-60 years and had clinical symptoms compatible with the case definition. Dengue and chikungunya cases were confirmed by an ELISA IgM titer or RT-PCR. We also reviewed surveillance data of dengue and chikungunya infections from 2003-2009. Of the 200 participants recruited into the study, 103 patients (51.5%) were confirmed to have acute dengue infection; dengue serotype 2 was the most prevalence serotype. The ages of confirmed dengue cases ranged from 2-37 years old. The distribution of cases showed that dengue morbidity tended to be clustered in adjacent areas, particularly in Mueang District. Only a small proportion of the patients uses mosquito repellant and had screens on their windows. One patient (0.5%) had laboratory confirmed chikungunya infection. She was from Rattanawapi District, an area where no chikungunya had been reported before. Since the disease varies by age and geographic location, increased awareness of health care workers and public health officers about the diseases in the area is needed for early detection of cases and to promote early prevention and control measures.

Dried-blood spots: a cost-effective field method for the detection of Chikungunya virus circulation in remote areas

BACKGROUND

In 2005, there were outbreaks of febrile polyarthritis due to Chikungunya virus (CHIKV) in the Comoros Islands. CHIKV then spread to other islands in the Indian Ocean: La Réunion, Mauritius, Seychelles and Madagascar. These outbreaks revealed the lack of surveillance and preparedness of Madagascar and other countries. Thus, it was decided in 2007 to establish a syndrome-based surveillance network to monitor dengue-like illness.

OBJECTIVE

This study aims to evaluate the use of capillary blood samples blotted on filter papers for molecular diagnosis of CHIKV infection. Venous blood samples can be difficult to obtain and the shipment of serum in appropriate temperature conditions is too costly for most developing countries.

METHODOLOGY AND PRINCIPAL FINDINGS

Venous blood and dried-blood blotted on filter paper (DBFP) were collected during the last CHIKV outbreak in Madagascar (2010) and as part of our routine surveillance of dengue-like illness. All samples were tested by real-time RT-PCR and results with serum and DBFP samples were compared for each patient. The sensitivity and specificity of tests performed with DBFP, relative to those with venous samples (defined as 100%) were 93.1% (95% CI:[84.7-97.7]) and 94.4% (95% CI:[88.3-97.7]), respectively. The Kappa coefficient 0.87 (95% CI:[0.80-0.94]) was excellent.

CONCLUSION

This study shows that DBFP specimens can be used as a cost-effective alternative sampling method for the surveillance and monitoring of CHIKV circulation and emergence in developing countries, and probably also for other arboviruses. The loss of sensitivity is insignificant and involved a very small number of patients, all with low viral loads. Whether viruses can be isolated from dried blood spots remains to be determined.

Diagnosis of Barmah Forest virus infection by a nested real-time SYBR green RT-PCR assay

Barmah Forest virus (BFV) is a mosquito borne (+) ssRNA alphavirus found only in Australia. It causes rash, myalgia and arthralgia in humans and is usually diagnosed serologically. We developed a real-time PCR assay to detect BFV in an effort to improve diagnosis early in the course of infection. The limit of detection was 16 genome equivalents with a specificity of 100%. Fifty five serum samples from BFV-infected patients were tested by the PCR. 52 of 53 antibody-positive samples were PCR negative. Two culture-positive (neutralizing antibody negative) samples were positive on first round PCR, while one sample (IgM and neutralizing antibody strongly positive, IgG negative) was positive on second round PCR, suggesting that viral RNA is detectable and transiently present in early infection. PCR can provide results faster than culture, is capable of high throughput and by sequencing the PCR product strain variants can be characterized.

Chikungunya virus infection: an overview

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus belonging to the Togaviridae family, first isolated in Tanzania in 1952. The main vectors are mosquitoes from the Aedes species. Recently, the establishment of an envelope mutation increased infectivity for A. albopictus. CHIKV has recently re-emerged causing millions of infections in countries around the Indian Ocean characterized by climate conditions favourable to high vector density. Importation of human cases to European regions with high density of suitable arthropod vectors (such as A. albopictus) may trigger autochthonous outbreaks. The clinical signs of CHIKV infection include non-specific flu-like symptoms, and a characteristic rash accompanied by joint pain that may last for a long time after the resolution of the infection. The death rate is not particularly high, but excess mortality has been observed in concomitance with large CHIKV outbreaks. Deregulation of innate defense mechanisms, such as cytokine inflammatory response, may participate in the main clinical signs of CHIKV infection, and the establishment of persistent (chronic) disease. There is no specific therapy, and prevention is the main countermeasure. Prevention is based on insect control and in avoiding mosquito bites in endemic countries. Diagnosis is based on the detection of virus by molecular methods or by virus culture on the first days of infection, and by detection of an immune response in later stages. CHIKV infection must be suspected in patients with compatible clinical symptoms returning from epidemic/endemic areas. Differential diagnosis should take into account the cross-reactivity with other viruses from the same antigenic complex (i.e. O'nyong-nyong virus).

[The tropical disease Chikungunya fever has come to Europe]

Chikungunya fever is an acute febrile illness associated with severe, often debilitating polyarthralgias. The disease is caused by the Chikungunya virus (CHIKV), an arthropod-borne virus that is transmitted to humans primarily via the bite of an infected mosquito. Since a re-emergence of CHIKV in 2004 in the Indian Ocean islands, the virus has spread into novel locations such as Europe. In Italy, an outbreak occurred in 2007. A mutation in CHIKV (E1-A226V) appears to improve virus survival in Ae. albopictus and also increase its virulence. Further attention should be given the disease since it is emerging in Europe.

Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya

This review article discusses important infectious illnesses, namely malaria, dengue, and chikungunya, in travelers returning from endemic areas. Malaria and dengue are two of the most common systemic illnesses reported in returning travelers. Because chikungunya is gaining importance, it is also briefly discussed. The clinical significance of these diseases is mainly due to the possibility of sudden deterioration with high mortality in clinically healthy looking patients. The key clinical features, their diagnosis, and treatment algorithms are discussed in detail to help in early diagnosis and appropriate clinical management of such travelers presenting in emergency departments.

Coinfection with dengue and chikungunya--a case report

Dengue fever outbreaks are reported from India since last 10 years. Since 2005, chikungunya is also causing massive outbreaks in India and other parts of Asia. Both viruses are transmitted by aedes genus and both viruses can re-emerge in many regions due to climatic changes. The clinical presentation of both arthropod borne diseases are similar. Here a concomitant infection of chikungunya and dengue is reported in an 8-year-old child.

Centers for Disease Control and Prevention (CDC). Chikungunya outbreak--Cambodia, February-March 2012

Chikungunya virus (CHIKV) is an alphavirus transmitted to humans through the bite of infected Aedes mosquitoes. CHIKV causes fever and usually is not fatal, but can cause debilitating joint pains or, in rare instances, severe illness. The East/Central/South African strain of chikungunya has been emerging in Asia since 2006, first in the Indian subcontinent, then Thailand. This report describes the characteristics of a local outbreak linked with chikungunya reemergence in a rural Asian setting. Sporadic cases of chikungunya were identified in Cambodia in 2011. Antibodies to CHIKV have been detected in serum collected in Cambodia in 2007, but the strain could not be identified for those cases (U.S. Naval Medical Research Unit 2, unpublished data, 2012). On March 7, 2012, several cases of rash with fever were reported among village residents of Trapeang Roka in Kampong Speu Province, Cambodia. Subsequent field investigation revealed that four of six blood samples from affected persons were positive for CHIKV by polymerase chain reaction (PCR) at U.S. Naval Medical Research Unit 2 in Phnom Penh. Investigators from the Cambodian Communicable Disease Control Department, National Malaria Center, Institut Pasteur du Cambodge (IPC), local health centers, and village authorities conducted a seroprevalence study of village residents on March 26 to gather information for response planning and control efforts. The outbreak affected families throughout the village, and 44.7% of the population tested had evidence of infection by CHIKV, which affected all age groups. Public health agencies and policymakers in affected and nearby unaffected areas of Asia and elsewhere should be alert to the potential spread and reemergence of CHIKV.

Emerging viral infections

Unique disorders appear episodically in human populations and cause life-threatening systemic or neurological disease. Historical examples of such disorders include von Economo encephalitis, a disorder of presumed viral etiology; acquired immune deficiency syndrome, caused by the human immunodeficiency virus; and severe acute respiratory syndrome, caused by a member of the coronavirus family. This article describes the factors that contribute to the emergence of infectious diseases and focuses on selected recent examples of emerging viral infections that can affect the nervous system of infants, children, and adolescents.

Morbidity and impaired quality of life 30 months after chikungunya infection: comparative cohort of infected and uninfected French military policemen in Reunion Island

We compared the morbidity and quality of life of military policemen ("gendarmes") infected with chikungunya virus (CHIKV+) 30 months after contamination. We categorized the subjects in 3 groups: healed patients (n = 48), non-healed patients (n = 37, 44% of CHIKV+), and uninfected subjects (CHIKV-, n = 297). Data were self-recorded in this retrospective cohort study; they included sociodemographic information, clinical symptoms, and the Medical Outcome Study 36-item short-form health survey (MOS-SF36) quality of life questionnaire. The study population was mostly men (92%), with a median age of 42.8 years, regardless of CHIKV status. The main complaints were rheumatic symptoms (pain, stiffness, and swelling), reported 5 times more often by non-healed CHIKV+ subjects and 2-3 times more often by healed CHIKV+ subjects than by CHIKV- subjects, and fatigue. The CHIKV+ patients reported more use of health care services. Thirty months after infection, all rheumatic symptoms were more frequent and intense among CHIKV+ than among CHIKV- subjects, with a gradient of severity between healed and non-healed CHIKV+ subjects. Non-healed CHIKV+ subjects reported subsequent limitation in their activities. All dimensions of MOS-SF36 as well as physical and mental component summaries were impaired in CHIKV+ compared to CHIKV- subjects, with a decreasing gradient of impairment from non-healed to healed CHIKV+ subjects, then to CHIKV- subjects. These observations confirm the long-term impact of CHIKV infection on both physical and mental health. Questions persist regarding the duration of this impairment and the possibility of a return to "before CHIKV" health status for infected patients.

Chikungunya fever

Chikungunya fever (CF) is an acute illness caused by Chikungunya virus (CHIKV) belonging to the alphavirus genus of the Alphaviruses (Togaviridae) family. The virus is transmitted by Aedes mosquitoes. CF is primarily tropical disease occurring in Africa, Asia and Indian Ocean islands but in the last decade an outbreak of CHIKV autochthonous infections were reported in Italy and France. It is associated with viral genome mutations facilitating transmission of the disease by Aedes albopictus, a mosquito occurring in several European countries. The CF is highly symptomatic, characterized by fever, cutaneuos rash and severe athralgia and arthritis. In some patients severe neurological or hemorrhagic manifestations occur. The disease is self-limiting but a part of the patients suffers from a long-lasting arthritis akin to rheumatoid arthritis. Treatment is only symptomatic. Prevention includes reduction of mosquito bite (mosquito net, repellent) or application of measures against mosquito larvae. Vaccination is not currently available but investigations are in progress. CF presents a significant worldwide health problem affecting in the last decade millions of person, and currently dangerous also for European countries.

First detection of chikungunya infection and transmission in Brunei Darussalam

This report describes the chikungunya cases and local transmission detected in Brunei Darussalam for the first time, despite the country being situated in a region that has experienced a multitude of outbreaks over the years. A combined strategy of active case detection, patient isolation and vector control measures was deployed in an attempt to avert further transmission. The findings have important public health implications for international surveillance and control strategies for this re-emerging disease.

Chikungunya virus infection, a threat to public health

Many countries in the world have reported human infections by chikungunya virus (CHIKV) a mosquito-borne togavirus belonging to the genus alpha virus. After half a century of focal out breaks of acute febrile poly arthralgia, the disease had spread unexpectedly in the past decade with large outbreaks in Africa around the Indian Ocean and in Bangladesh. In Asia, CHIKV is thought to be transmitted by the same mosquito as dengue, Aedes aegypti and Aedes albopictus. Due to similarities in clinical presentation with dengue, limited awareness and a lack of laboratory diagnostic facilities, CHIKV is probably often under diagnosed or misdiagnosed as dengue. Treatment is supportive. The prognosis is generally good although some patients experience chronic arthritis. There is no vaccine or antiviral therapy against CHIKV. Early identification of disease and control of vector will prevent the spread of disease.

Rapid, specific detection of alphaviruses from tissue cultures using a replicon-defective reporter gene assay

We established a rapid, specific technique for detecting alphaviruses using a replicon-defective reporter gene assay derived from the Sindbis virus XJ-160. The pVaXJ expression vector containing the XJ-160 genome was engineered to form the expression vectors pVaXJ-EGFP expressing enhanced green fluorescence protein (EGFP) or pVaXJ-GLuc expressing Gaussia luciferase (GLuc). The replicon-defective reporter plasmids pVaXJ-EGFPΔnsp4 and pVaXJ-GLucΔnsp4 were constructed by deleting 1139 bp in the non-structural protein 4 (nsP4) gene. The deletion in the nsP4 gene prevented the defective replicons from replicating and expressing reporter genes in transfected BHK-21 cells. However, when these transfected cells were infected with an alphavirus, the non-structural proteins expressed by the alphavirus could act on the defective replicons in trans and induce the expression of the reporter genes. The replicon-defective plasmids were used to visualize the presence of alphavirus qualitatively or detect it quantitatively. Specificity tests showed that this assay could detect a variety of alphaviruses from tissue cultures, while other RNA viruses, such as Japanese encephalitis virus and Tahyna virus, gave negative results with this system. Sensitivity tests showed that the limit of detection (LOD) of this replicon-defective assay is between 1 and 10 PFU for Sindbis viruses. These results indicate that, with the help of the replicon-defective alphavirus detection technique, we can specifically, sensitively, and rapidly detect alphaviruses in tissue cultures. The detection technique constructed here may be well suited for use in clinical examination and epidemiological surveillance, as well as for rapid screening of potential viral biological warfare agents.

[Chikungunya epidemic in 2005-2006: questions from occupational health professionals]

The exceptionally large-scale chikungunya outbreak that struck Reunion Island in 2005-2006 raised numerous yet-unresolved issues for occupational medicine professionals such as massive use of insecticides and recognition of occupational diseases.

[Five-year outcome of mother-to-child transmission of chikungunya virus]

Chikungunya virus is an arbovirus (alphavirus) transmitted by Aedes albopictus in Reunion Island. A huge chikungunya outbreak swept Reunion Island in 2005- 2006. We report the first case of chikungunya neonatal infection and the 5-years outcome of the 18 neonates hospitalized in neonatal intensive care unit between June 2005 and March 2006.

[Chikungunya on Reunion Island. Experience, opinion, and proposals of general practitioners: poorly understood symptoms, lack of treatment protocol, exaggerated sequels, neglected players]

In 2005-2006 the Chikungunya caused a major sanitary crisis in Reunion for which neither the authorities, nor the healthcare professionals were prepared, as the symptoms were poorly defined, the treatment not validated and the sequels underestimated. General practioners described "in vivo" clinical and therapeutic facts and help conducted three ground studies. They were indeed the doctors of first recourse for painful and feverish patients. Have we drawn all lessons of this sanitary crisis that struck nearly the third of the population? Are we better prepared to face the acute and the chronic forms of a forthcoming epidemic? Efforts and indisputable institutional progress were made, but "Everything" still remains to be made combining all health professional efforts with a better consideration of the professionals of ground.

[Judicial or administrative settlement of medical malpractice claims. Update on medical liability]

Settlement of medical malpractice claims was radically changed by the Kouchner Law that set up a rapid, effective system of indemnification. Victims can choose between conventional court proceedings and a non-judicial conciliation procedure. Choice between the two processes depends on the circumstances of the case.

[The messenger syndrome]

Since mid 2005 pediatricians of the Groupe hospitalier Sud Reunion de Saint-Pierre have observed a self-imposed requirement to test for mother-to-child transmission of chikungunya. Sanitary authorities refuse to consider such testing as necessary. The risk of mother-to-child transmission was not mentioned in literature of the time.