Clinical features and molecular diagnosis of Chikungunya fever from South India

An epidemic of Chikungunya fever of unprecedented magnitude occurred in many parts of India in early 2006 after an interval of 33 years, and there has been a resurgence in some parts of South India since June 2007. The article highlights clinical manifestations of infection and various molecular tests that were used for diagnoses of Chikungunya virus infection. Of particular interest is the real-time loop-mediated isothermal amplification (RT LAMP) assay, which is rapid and cost-effective and can be adopted at ill-equipped laboratories. Clinical symptoms were characterized by a triad of fever, rash, and severe rheumatic manifestations. RT LAMP identified 20 additional Chikungunya virus-positive cases, compared with reverse-transcriptase polymerase chain reaction. Chikungunya virus was isolated from 20 randomly selected samples. Genotyping of the virus isolates revealed that the East Central South African genotype of Chikungunya virus was the etiologic agent of this epidemic. Molecular diagnosis is an important tool to identify such new vectorborne viral illnesses.

Dual infection by chikungunya virus and other imported infectious agent in a traveller returning from India

Chikungunya virus infection is a vector-borne self-limiting disease. Recent outbreaks in the Indian Ocean islands have drawn attention to the condition. Nevertheless, only a few reports of co-infection with other communicable agents have been reported. The case described now is of a traveller returning from India with concomitant documented chikungunya virus infection associated with systemic amoebiasis. This report highlights the multifaceted pathology that can be encountered with tropical infections.

Mayaro virus: imported cases of human infection in São Paulo State, Brazil

Mayaro virus (MAYV) is an arbovirus (Togaviridae: Alphavirus) enzootic in tropical South America and maintained in a sylvan cycle involving wild vertebrates and Haemagogus mosquitoes. MAYV cases occur sporadically in persons with a history of recent activities inside or around forests. This paper reports three cases of MAYV fever detected in men infected in Camapuã, MS, Brazil. Serum samples collected at four days and two months after the onset of the symptoms and examined by hemagglutination inhibition test, revealed monotypic seroconversion to MAYV. Isolation of the virus was obtained from one of the samples by inoculation of the first blood samples into newborn mice. A suspension of the infected mouse brain was inoculated into C6/36 cells culture and the virus was identified by indirect immunofluorescent assay with alphavirus polyclonal antibodies. RT-PCR, performed with RNA extracted from the supernatant of C6/36 infected cells in the presence of alphavirus generic primers as well as specific MAYV primers, confirmed these results. The reported cases illustrate the importance of laboratory confirmation in establishing a correct diagnosis. Clinical symptoms are not always indicative of a disease caused by an arbovirus. Also MAYV causes febrile illness, which may be mistaken for dengue.

Chikungunya infection in neonates

We describe two neonates in whom chikungunya infection was confirmed by RNA PCR. Important clinical features include apnea, fever, erythematous maculo-papular rash and generalized hyperpigmentation.

The exanthem of dengue fever: Clinical features of two US tourists traveling abroad

BACKGROUND

Dengue fever is the most common identifiable cause of acute febrile illness among travelers returning from South America, South Central Asia, Southeast Asia, and the Caribbean. Although the characteristic exanthem of dengue fever occurs in up to 50% of patients, few descriptions of it are found in the dermatology literature, and discussions of how to distinguish the dengue exanthem from other infectious disease entities are rare. Chikungunya fever is an emerging infectious disease now seen in returning US tourists and should be considered in the differential diagnosis of dengue fever in the appropriate patient.

OBJECTIVE

The purpose of our study was to report two cases of dengue fever among returning US tourists, provide a review of dengue fever, offer an extensive differential diagnosis of dengue fever, and raise awareness among dermatologists of chikungunya fever.

METHODS

This study includes clinical findings of two returning travelers, one who traveled to Mexico and the other to Thailand, complemented by a discussion of both dengue fever and its differential diagnosis.

LIMITATIONS

Limited to 2 case reports.

CONCLUSION

Dengue fever should be considered in the differential diagnosis of fever and rash in the returning traveler. Dermatologists should be aware of the distinctive exanthem of dengue fever. Recognition of the dengue fever rash permits a rapid and early diagnosis, which is critical, as dengue fever can progress to life-threatening dengue hemorrhagic fever or dengue shock syndrome.

Chikungunya virus-induced myopericarditis: toward an increase of dilated cardiomyopathy in countries with epidemics?

The acute stage of infection with chikungunya virus, which is characterized of fever, polyarthritis, and occasional rash, can be complicated by myocarditis, as reported in a 21-year-old woman. Persisting changes on cardiac magnetic resonance imaging one year after disease onset could lead to delayed myocardial damage. An unexpected delayed increase in dilated cardiomyopathy may be observed in countries affected by the outbreak of chikungunya virus disease during 2005-2007.

[First case of chikungunya diagnosed in the Netherlands]

A 52-year-old man was seen in the Diagnostic Centre for Tropical Diseases of the Havenziekenhuis, Rotterdam, presenting with arthralgia, fever and exanthema following a stay in Mauritius. Infection with the Dengue virus infection is a common diagnosis for this combination of complaints, but nowadays chikungunya should also be considered. This is particularly the case when a patient has visited a country in or around the Indian Ocean. Risk areas are La Réunion and Mauritius, where, in February 2005 and April 2005 respectively, epidemics broke out. Chikungunya is a viral infection. The causative virus is an Alpha virus, transmitted by mosquitoes. The symptoms include arthralgia, myalgia, diffuse maculopapular rash, fever and headache. In contrast to dengue, chikungunya is not associated with haemorrhagic diathesis. Treatment takes place in response to the symptoms, since there is no targeted therapy available. The main preventive measure is to prevent mosquito bites. The disease is not deadly and healing is spontaneous. To our knowledge this is the first case of chikungunya diagnosed in the Netherlands during this epidemic. The disease has recently been reported in Italy, where native mosquitoes transmit it.

Chikungunya virus, Cameroon, 2006

We report the isolation of chikungunya virus from a patient during an outbreak of a denguelike syndrome in Cameroon in 2006. The virus was phylogenetically grouped in the Democratic Republic of the Congo cluster, indicating a continuous circulation of a genetically similar chikungunya virus population during 6 years in Central Africa.

Co-infection of dengue virus and chikungunya virus in two patients with acute febrile illness

During an outbreak of chikungunya in a dengue hyperendemic area within the Kinta district of Perak, two patients with acute febrile illness were laboratory confirmed to have co-infection of both dengue and chikungunya viruses in their blood. The concomitant presence of two types of viruses transmitted by the same vector in a susceptible population contributed to the resultant event. A good understanding of virus vector ecology in association with population dynamics and wider application of improved laboratory techniques by using different cell-lines suited for optimal replication of each type of virus and the correct utilization of powerful molecular techniques will enhance accurate diagnosis of these infectious diseases.

Is New Zealand prepared to deal with arboviral diseases?

To now, New Zealand has been spared arboviral diseases, except for the odd imported infection. However, two exotic vector mosquitoes (Ochlerotatus camptorhynchus and Ochlerotatus notoscriptus) have become established in New Zealand and the routine arrival of infected people from overseas may soon lead to local arboviral transmission. Large populations of wild wallabies and Brushtail possums could serve as reservoirs of Ross River virus and other arboviruses. Several other exotic mosquito species, including important disease vectors such as Aedes albopictus and Aedes aegypti, have already been intercepted in New Zealand. It is clear that increased border surveillance is necessary if we are to interdict the establishment of such species. We recommend several measures that should be adopted, including increased training and awareness of public health officials, clinicians and the general public, and taking appropriate steps to make New Zealand self-sustainable in terms of arboviral surveillance, diagnosis, and prevention.

Laboratory capacity for detection of chikungunya virus infections in Europe

In June 2007, the European Network for Diagnostics of Imported Viral Diseases started an external quality assurance analysis of both serological and molecular methods used for Chikungunya virus detection. Here we give preliminary results regarding the laboratory capacity and diagnostic quality for detection of CHIKV infections in Europe.

Chikungunya virus of Central/East African genotype detected in Malaysia

Since its isolation in Tanzania in 1953, chikungunya virus has caused periodic outbreaks in both tropical Africa and Asia. In the last decade, the virus has shown not only increased activity but has expanded its geographical locations, thus classical delineation of various genotypes of chikungunya virus to specific geographic locales no longer holds true. Rapid mass movement of people and the constant presence of the right vectors in this region could have contributed to the change in virus ecology. This paper documents the first detection of chikungunya virus of Central/East genotype in Malaysia from a patient who was most likely infected with the virus during her visit to India. Without good Aedes vector measures, only time will tell whether this genotype rather than the existing endemic genotype will subsequently cause the next chikungunya outbreak in Malaysia.

Ocular manifestations associated with chikungunya

PURPOSE

To report ocular manifestations associated with chikungunya.

DESIGN

Retrospective, nonrandomized, observational case series.

PARTICIPANTS

Nine chikungunya patients with ocular involvement.

METHODS

All patients with chikungunya infection presenting with ocular complaints from September 2006 to October 2006 were included in the study. The infection was confirmed by demonstration of chikungunya immunoglobulin M antibody in sera of all patients. All patients underwent an ophthalmic examination including fundus photography, fundus fluorescein angiography, confocal microscopy of keratic precipitates, and optical coherence tomography. Positive ocular changes were recorded and tabulated.

MAIN OUTCOME MEASURES

Characteristics, frequency, and locations of ocular lesions found in the participants.

RESULTS

There were 9 patients with ocular lesions; 1 had nodular episcleritis, 5 presented with acute iridocyclitis, and 3 had retinitis. Four to 12 weeks before the development of ocular manifestations, all of these patients had fever. Although there were no specific changes of iridocyclitis that were diagnostic of the fever, the retinal changes were consistent with viral retinitis. All patients recovered from the infection with relatively good vision.

CONCLUSION

It appears that iridocyclitis and retinitis are the most common ocular manifestations associated with chikungunya, with a typically benign clinical course. Less frequent ocular lesions include episcleritis. All the patients responded well to the treatment with preservation of good vision. To the best of our knowledge, similar ocular manifestations associated with chikungunya infection have not been reported. In the differential diagnosis of iridocyclitis and retinitis with features suggestive of a viral infection, the entity of chikungunya-associated ocular changes should be considered in the regions affected by the epidemic.

Molecular diagnosis and analysis of Chikungunya virus

BACKGROUND

In March 2005 a Chikungunya fever outbreak began on the islands of the Indian Ocean. The number of cases of this disease dramatically rose amongst these islands before affecting over a million people in India. Travellers to these regions have returned to the UK with the disease leading to a greater than 15-fold increase in the annual number of Chikungunya virus (CHIKV) sero-positive samples in 2006.

OBJECTIVES

A real-time RT-PCR test was developed for CHIKV and designed to detect currently circulating strains of virus as well as other genotypes. Its sensitivity was compared with an existing standard RT-PCR assay and a previously published real-time assay.

STUDY DESIGN

A real-time RT-PCR assay was optimised and evaluated using a panel of 55 clinical serum samples and a synthetic RNA transcript as a positive control. Nucleotide sequencing of part of the E1 gene of CHIKV was used to investigate the relatedness of the samples.

RESULTS

The real-time RT-PCR was 10-fold more sensitive than a conventional block-based RT-PCR and could detect as low as 20 copies of RNA transcript. The assay also had 10-fold improved sensitivity in detecting the outbreak strain of virus when compared to another published TaqMan assay. Analysis of sequences from patients that had travelled to India, Mauritius or the Seychelles showed high similarity with published sequences from the Indian Ocean island of Réunion.

CONCLUSIONS

A sensitive and rapid real-time RT-PCR assay has been developed for CHIKV and tested against current isolates.

[Chikungunya fever, "that which bends". Epidemic in Africa and Asia--several cases imported to Denmark]

Within the last year there has been a re-emergence of chikungunya fever in Africa, Asia and several of the islands in the Indian Ocean. Chikungunya fever is caused by the alfa virus chikungunya, which is transmitted by the Aedes mosquito. Travellers as well as the local population are at risk, and several cases have been imported to Denmark. We review the epidemiology, aetiology, symptoms, diagnosis and treatment. The main symptoms are fever, arthralgia and rash. No vaccination or specific treatment exist and therefore travellers must try to avoid mosquito bites.

Development and evaluation of SYBR Green I-based one-step real-time RT-PCR assay for detection and quantification of Chikungunya virus

The development of a one-step SYBR Green I-based real-time RT-PCR assay is reported for detection and quantification of Chikungunya virus (CHIKV) in acute-phase patient serum samples by targeting the E1 structural gene. A linear relationship was obtained between the virus concentration and cycle threshold (C(t)) value over a range of 10(7)-0.1PFU/ml. The reported assay was found to be 10-fold more sensitive compared to conventional RT-PCR with a detection limit of 0.1PFU/ml. The feasibility of this reported assay system for clinical diagnosis was validated with 51 suspected acute-phase serum samples of the recent CHIKV epidemic in southern India, 2006. The comparative evaluation with acute-phase patient serum samples revealed the higher sensitivity of real-time RT-PCR assay by picking up six additional samples with low copy number of template. None of the healthy serum samples analyzed in this study showed amplification. The quantification of the viral load in the acute-phase serum samples was also determined employing the standard curve, which varies from 0.1 to 10(7)PFU/ml. These findings demonstrated that the reported assay has the potential usefulness for clinical diagnosis due to simultaneous detection and quantification of Chikungunya virus in acute-phase patient serum samples.

Chikungunya, an epidemic arbovirosis

Chikungunya is an arboviral disease transmitted by aedes mosquitoes. The virus was first isolated in 1953 in Tanzania. Chikungunya virus is a member of the genus Alphavirus and the family Togaviridae. The disease typically consists of an acute illness characterised by fever, rash, and incapacitating arthralgia. The word chikungunya, used for both the virus and the disease, means "to walk bent over" in some east African languages, and refers to the effect of the joint pains that characterise this dengue-like infection. Chikungunya is a specifically tropical disease, but it is geographically restricted and outbreaks are relatively uncommon. It is only occasionally observed in travellers and military personnel. More than 266 000 people have been infected during the ongoing outbreak in Réunion, in which Aedes albopictus is the presumed vector. In the ongoing Indian outbreak, in which Aedes aegypti is the presumed vector, 1 400 000 cases of chikungunya were reported during 2006. The reasons for the re-emergence of chikungunya on the Indian subcontinent, and for its unprecedented incidence rate in the Indian Ocean region, are unclear. Plausible explanations include increased tourism, chikungunya virus introduction into a naive population, and viral mutation.

[Chikungunya, dream holidays but. . . a painful "souvenir"]

Little is known about chikungunya fever and, until March 2005, this abovirosis was seldom part of the differential diagnosis in the case of a patient with fever after travel return; at this time, a major outbreak of this self-limiting febrile illness was taking place in East Africa heading towards India and now also present in South East Asia. Although the evolution of this arbovirosis is usually favourable, important complications can appear in patients with initial comorbidities and in infants or elderly people. A simple serology can be used to show paraclinical evidence. The use of computer databases and internet surveillance networks is a precious help in establishing the differential diagnosis of patients with fever after travel return.

Chikungunya infection: an emerging rheumatism among travelers returned from Indian Ocean islands. Report of 47 cases

A large chikungunya virus (CHIKV) outbreak emerged in 2005-2006 in the Indian Ocean islands, including Comoros, Mayotte, Mauritius, the Seychelles, and particularly in Reunion Island where 35% of 770,000 inhabitants were infected in 6 months. More recently, circulation of the virus has been documented in Madagascar and in India where CHIKV is spreading rapidly. CHIKV-infected visitors have returned home to nonendemic regions from these islands. We conducted a 14-month prospective observational study on the clinical aspects of CHIKV infection imported to Marseilles, France, in travelers returning from the Indian Ocean islands. A total of 47 patients have been diagnosed with imported CHIKV infection confirmed by serology, reverse transcription-polymerase chain reaction, and/or viral culture. At the early stage of the disease (within 10 days of the disease onset), fever was present in 45 of 47 patients. A rash was present in the first week in 25 cases. All patients suffered with arthritis. The most frequently affected joints were fingers, wrists, toes, and ankles. Eight patients were hospitalized during the acute stage, including 2 severe life-threatening cases. A total of 38 patients remained symptomatic after the tenth day with chronic peripheral rheumatism, characterized by severe joint pain and multiple tenosynovitis, with a dramatically limited ability to ambulate and carry out activities in daily life. Three patients were hospitalized at this stage for severe persistent handicap. Follow-up demonstrated slow improvement in joint pain and stiffness despite symptomatic treatment, mainly antiinflammatory and analgesic drugs. In the current series we describe 2 stages of the disease, an initial severe febrile and eruptive polyarthritis, followed by disabling peripheral rheumatism that can persist for months. We point out the possibility of transitory peripheral vascular disorders during the second stage and the occasional benefit of short-term corticosteroids. As CHIKV could spread throughout the world, all physicians should be prepared to encounter this arboviral infection.

Outbreak of chikungunya on Reunion Island: early clinical and laboratory features in 157 adult patients

BACKGROUND

Chikungunya is a reemerging disease. In 2005-2006, a severe outbreak occurred on Reunion Island in the southwestern part of the Indian Ocean. Other islands in this area were affected during the same period.

METHODS

Adult patients with acute chikungunya (defined as onset of fever and/or polyarthralgia in the 5 days preceding consultation) and laboratory-confirmed chikungunya who were referred to Groupe Hospitalier Sud Reunion during the period from March 2005 through April 2006 were included in this retrospective study. Their clinical and laboratory features are reported.

RESULTS

Laboratory-confirmed acute chikungunya was documented in 157 patients. The mean age of patients was 57.9 years, and the ratio of male to female patients was 1.24 : 1. Sixty percent of patients had at least 1 comorbidity. Ninety-seven patients (61.8%) were hospitalized, and 60 (38.2%) were treated as outpatients. Five fatalities were reported. One hundred fifty-one patients (96.1%) experienced polyarthralgia, and 129 (89%) experienced fever. Gastrointestinal symptoms were reported by 74 patients (47.1%), and skin rash was reported by 63 (40.1%). Hemorrhagic signs were rare. Lymphopenia and hypocalcemia were the prominent laboratory findings. Severe thrombocytopenia was rarely observed.

CONCLUSIONS

Chikungunya virus can be responsible for explosive outbreaks of disease. Polyarthralgia and fever are the 2 main clinical features. In this era of travel and globalization, chikungunya should be considered in the differential diagnosis of febrile polyarthralgia with an abrupt onset.

[Marseilles, the Indian Ocean and Chikungunya virus]

In recent decades Marseilles, through immigration, has become the largest Comorian city outside the archipelago. It is also home to a faculty of medicine that has made infectious diseases one of its fields of excellence. During the last two years, Marseilles has spearheaded the metropolitan French response to the Chikungunya crisis in the Indian Ocean region, and especially in the Reunion Island and Mayotte. Laveran military teaching hospital (Hôpital d'instruction des armées, HIA) has managed one of the largest metropolitan cohorts. Its teams have also reported the broad clinical spectrum of the disease in its later stages, and especially the high incidence of incapacitating tenosynovitis and distal arthritis, as well as the occurrence of a transient acrosyndrome during the second and third months in nearly one-quarter of patients. Importantly, they have also identified a mixed cryoglobulin in more than 90% of patients, the level of which matches clinical symptoms and is sensitive to systemic steroid therapy. This discovery opens the way to a better understanding of the pathophysiology of this viral disease. The Tropical Virology laboratory of the Tropical Medicine Institute of the Army health service (IMTSSA), which has close links with the national references center (CNRS) arbovirus laboratory, has developed new diagnostic tools, notably based on RT-PCR. Together with national reference center (CNRS), the laboratory produces and supplies antigens for Chikungunya serological tests in metropolitan France and overseas. It has taken into account the presence of cryoglobulins, which can lead to false-negative results in infected patients, and has considerably increased the diagnostic yield of serological techniques. The laboratory's fundamental research focuses on genomic characterization of viral variants isolated from humans and from the vector, and also on viral protease expression, for functional studies and antiviral candidate drug selection. The laboratory also collaborates with clinical teams in Reunion and metropolitan France working on humoral and cellular immune responses and on the different clinical forms of the disease. The Epidemiology and Public Health Department of IMTSSA conducted an epidemiological study of all gendarmes working in Reunion at the end of the epidemic (June 2006). This study, done in partnership with the tropical virology laboratory and CNRS, is helping to complete the clinical description of the epidemic, in an unbiased population. In 2007, it will form the basis for a prospective cohort study in which these patients will be monitored for several years to better document the chronic phase of the disease in a population with excellent healthcare access. Finally, the department has provided the civil authorities with advice and support in disease-control operations in Reunion. Communication played an important role in the management of this crisis, showing how crucial it now is for healthcare professionals to develop relevant skills. The Army Health Service in Maarseilles was never isolated from its university partners, as witnessed by clinical collaboration between Laveran HIA and CHU Nord (a Marseilles teaching hospital) and by virological cooperation between the IMTSSA and Etablissement français du sang (EFS) laboratories. This experience is highly encouraging with respect to the creation in Marseilles of a healthcare research network (RTRS) devoted to tropical and emerging infectious diseases.

[Skin and mucosal manifestations of chikungunya virus infection in adults in Reunion Island]

Numerous skin and mucosal manifestations were observed during the 2005-2006 chikungunya epidemic in Reunion Island. A prospective study was carried out in a consecutive series of 212 patients treated for chikungunya at the emergency unit of the Saint-Pierre Hospital in Reunion Island from March 8 to April 27, 2006. Diagnosis of chikungunya was suspected in patients with fever and joint pain and confirmed by RT-PCR and/or serology (IgM). Skin involvement was observed in 50% of patients. It consisted of exanthema with patches of healthy skin mainly on the trunk and limbs that sometimes displayed diffuse, congestive and even edematous features. Itching was reported in some cases (19.3%) and was sometimes isolated. Peeling of the skin was observed in a few cases but remained uncommon in adults. Outcome was rapidly favorable in most cases sometimes with scaling or persistence of dyschromic patches. These findings suggest that chikungunya should be suspected in subjects presenting a febrile rash while in an endemic areas or after returning from a tropical zone.

Centers for Disease Control and Prevention (CDC). Update: chikungunya fever diagnosed among international travelers--United States, 2006

Chikungunya virus (CHIKV) is a mosquitoborne alphavirus indigenous to tropical Africa and Asia, where it causes endemic and epidemic chikungunya (CHIK) fever, an acute illness characterized by fever, arthralgias, and sometimes arthritis, commonly accompanied by conjunctivitis and rash. Although symptoms of CHIKV infection usually last days to weeks, joint symptoms and signs usually last for months and occasionally for 1 year or longer; deaths from CHIKV infection are rare. No specific antiviral treatment exists for CHIKV infection; treatment consists of supportive care, including analgesics and anti-inflammatory medication for joint symptoms. During 2005-2006, an epidemic of CHIK fever occurred on islands in the Indian Ocean and in India, resulting in millions of clinically suspected cases, mainly in southern India. In the United States, CHIK fever has been diagnosed in travelers from abroad. CDC previously reported 12 imported cases of CHIK fever diagnosed in the United States from 2005 through late September 2006, including 11 with illness onset in 2006. This report of 26 additional imported cases with onset in 2006 underscores the importance of recognizing such cases among travelers. Health-care providers are encouraged to suspect CHIKV infection in travelers with fever and arthralgias who have recently returned from areas with CHIKV transmission. Acute- and convalescent-phase serum specimens can be submitted to CDC for testing through state health departments. Public health officials and health-care providers are encouraged to be vigilant for the possibility of indigenous CHIKV transmission in areas of the United States where CHIKV mosquito vectors are prevalent.

Viral exanthems in the tropics

Viral exanthems are a common problem in tropical regions, particularly affecting children. Most exanthems are transient and harmless, but some are potentially very dangerous. Pregnant women and malnourished or immunocompromised infants carry the greatest risk of adverse outcome. In this article, parvovirus B19; dengue and yellow fever; West Nile, Barmah Forest, Marburg, and Ebola viruses, and human herpesviruses; asymmetric periflexural exanthema of childhood; measles; rubella; enteroviruses; Lassa fever; and South American hemorrhagic fevers will be discussed.

[The first case of imported infection of Chikungunya virus in the Czech Republic]

The authors describe the first confirmed case of tropical fever caused by Chikungunya virus imported into the Czech Republic. As the virus belonging to the Alphavirus genus of the Togaviridae family is transmitted by mosquitoes of the genus Aedes it is classified as an arbovirus. A 43-year-old woman became ill following her arrival from the island of Mauritius where she had stayed during an epidemic. The patient presenting with typical symptoms of the disease recovered completely. Chikungunya virus as the etiological agent was confirmed serologically by the complement fixation reaction in the Czech National Reference Laboratory for Arboviruses.

[Cases of Chikungunya fever in Italy in travellers returning from the Indian Ocean and risk of introduction of the disease to Italy]

Chikungunya fever is a viral disease characterized by fever, arthralgia and rash. A large outbreak of Chikungunya fever began in 2005 in La Reunion, and it is still ongoing on many islands and countries of the Indian Ocean. Several cases have been detected in Europe in travellers returning from the affected areas. The disease is transmitted by the bite of Aedes mosquitoes, which are also widespread in Italy. We describe 7 cases of Chikungunya fever imported into Italy by travellers returning from affected countries. The current outbreak is described, and the risk of establishment of a chain of transmission in Italy is discussed.

Rapid and real-time detection of Chikungunya virus by reverse transcription loop-mediated isothermal amplification assay

The standardization and validation of a one-step, single-tube, accelerated, quantitative reverse transcription (RT) loop-mediated isothermal amplification (RT-LAMP) assay targeting the E1 gene for the rapid and real-time detection of Chikungunya virus (CHIKV) are reported. A linear relationship between the amount of template and time of positivity value over a range of 2 x 10(8) to 2 x 10(2) copies was obtained. The feasibility of CHIKV RT-LAMP for clinical diagnosis was validated with patient serum samples from an ongoing epidemic in Southern India. Optimal assay conditions with zero background were established for the detection of low levels of CHIKV in acute-phase patient serum samples. The comparative evaluation of the RT-LAMP assay with acute-phase patient serum samples demonstrated exceptionally higher sensitivity by correctly identifying 21 additional positive borderline cases that were missed by conventional RT-PCR (P < 0.0001) with a detection limit of 20 copies. The quantification of virus load in patient serum samples was also determined from the standard curve based on their time of positivity and was found to be in the range of 2 x 10(8) to 2 x 10(1) copies. In addition, the field applicability of the RT-LAMP assay was also demonstrated by standardizing SYBR Green I-based RT-LAMP wherein the amplification was carried out in a water bath at 63 degrees C for 60 min, which was followed by monitoring gene amplification with the naked eye through color changes. These findings demonstrated that the RT-LAMP assay is a valuable tool for rapid, real-time detection as well as quantification of CHIKV in acute-phase serum samples without requiring any sophisticated equipment and has potential usefulness for clinical diagnosis and surveillance of CHIKV in developing countries.

Chikungunya epidemic: an Indian perspective

Chikungunya, caused by the chikungunya virus, recently emerged as an important public health problem in the Indian Ocean Islands and India. In 2006, an estimated 1.38 million people across southern and central India developed symptomatic disease. The incidence of the disease may have been higher but may have been underreported due to lack of accurate reporting. First isolated in Tanzania in 1953, the chikungunya virus belongs to the family Togaviridae (single-stranded RNA alphaviruses) and has 3 distinct genotypes: East African, West African and Asian. Previous outbreaks in India (1963 and 1973) were caused by the Asian genotypes, but the 2005 epidemic in the Indian Ocean islands and the 2006 epidemic in India have been attributed to the East African genotype. The virus is transmitted to humans by the bites of mosquitoes of the species Aedes aegypti and A. albopictus. Researchers speculate that mutation of the virus, absence of herd immunity, lack of vector control, and globalization of trade and travel might have contributed to the resurgence of the infection. Chikungunya is characterized by high fever, severe arthralgia and rash. Although viral diagnostics (culture, serological tests and polymerase chain reaction tests) can be used to confirm the infection, these tests are not accessible during outbreaks to the majority of the population. The disease is a self-limiting febrile illness and treatment is symptomatic. As no effective vaccine or antiviral drugs are available, mosquito control by evidence-based interventions is the most appropriate strategy to contain the epidemic and pre-empt future outbreaks.

Centers for Disease Control and Prevention (CDC). Chikungunya fever diagnosed among international travelers--United States, 2005-2006

Chikungunya virus (CHIKV) is an alphavirus indigenous to tropical Africa and Asia, where it is transmitted to humans by the bite of infected mosquitoes, usually of the genus Aedes. Chikungunya (CHIK) fever, the disease caused by CHIKV, was first recognized in epidemic form in East Africa during 1952-1953. The word "chikungunya" is thought to derive from description in local dialect of the contorted posture of patients afflicted with the severe joint pain associated with this disease. Because CHIK fever epidemics are sustained by human-mosquito-human transmission, the epidemic cycle is similar to those of dengue and urban yellow fever. Large outbreaks of CHIK fever have been reported recently on several islands in the Indian Ocean and in India. In 2006, CHIK fever cases also have been reported in travelers returning from known outbreak areas to Europe, Canada, the Caribbean (Martinique), and South America (French Guyana). During 2005-2006, 12 cases of CHIK fever were diagnosed serologically and virologically at CDC in travelers who arrived in the United States from areas known to be epidemic or endemic for CHIK fever. This report describes four of these cases and provides guidance to health-care providers. Clinicians should be alert for additional cases among travelers, and public health officials should be alert to evidence of local transmission of chikungunya virus (CHIKV), introduced through infection of local mosquitoes by a person with viremia.

Reverse transcription-PCR-enzyme-linked immunosorbent assay for rapid detection and differentiation of alphavirus infections

Due to the lack of a rapid, simple, and inexpensive assay for detecting alphavirus infections, we combined a reverse transcription-PCR with an enzyme-linked immunosorbent assay (RT-PCR-ELISA) to identify human pathogenic alphaviruses that are endemic in the New World. By combining the sensitivity of PCR, the detection simplicity of ELISA, and the specificities of DNA probes, this method rapidly detected and differentiated closely related species and subtypes of several medically important alphaviruses. After an amplification using RT-PCR with primers targeting conserved sequences in the nonstructural protein 1 gene, sequence-specific, biotin-labeled probes targeted against Venezuelan, eastern, and western equine encephalitis or Mayaro virus genes were used for the detection of amplicons using ELISA. The assay is simple, fast, and easy to perform in an ordinary diagnostic laboratory or clinical setting. Nucleic acid derived from cell cultures infected with several alphaviruses, clinical specimens, and mosquito pools as well as frozen and paraffin-embedded animal tissues were detected and identified within 6 to 7 h in a sensitive and specific manner.

Epitope-blocking enzyme-linked immunosorbent assay for detection of antibodies to Ross River virus in vertebrate sera

We describe the development of an epitope-blocking enzyme-linked immunosorbent assay (ELISA) for the sensitive and rapid detection of antibodies to Ross River virus (RRV) in human sera and known vertebrate host species. This ELISA provides an alternative method for the serodiagnosis of RRV infections.

Reemergence of an unusual disease: the chikungunya epidemic

Since the beginning of 2006, a crippling mosquito-borne disease has shown an explosive emergence in nations in the Indian Ocean area. By March 7, 2006, 157,000 people had been infected in the French island La Réunion, and the disease had spread to the islands of Seychelles, Mauritius, and Mayotte (French). Subsequently, the disease appeared in India, China, and European countries. The World Health Organization is taking measures to assist in fighting the epidemic. This article describes the disease, its recent emergence, and the current epidemic.