Sally Furniss
Well-known member
Chikungunya in Italy: Joint ECDC/WHO European Risk Assessment
Full Report
1. BACKGROUND
On 30 August 2007 the Italian Ministry of Health, through the Early Warning and Response System (EWRS) and under the revised International Health Regulations (IHR)(2005), notified the EU Member States, the European Centre of Diseases Prevention and Control (ECDC)and the IHR contact point of the World Health Organization (WHO) Regional office for Europe, of a laboratory confirmed outbreak of chikungunya fever in the region of Emilia Romagna in north-eastern Italy.
At the time of notification, 131 suspected cases had occurred since the first (then known) case with onset of symptoms on 4 July. The majority of cases were reported from two neighbouring small villages (Castiglione di Ravenna and Castiglione di Cervia) in the province of Ravenna.
Upon recognition of a cluster of 47 cases on 16 august, the initial hypothesis had indicated an arboviral fever as cause of the outbreak, possibly sandfly fever. Considering the suspicion of vector-borne origin of the outbreak, vector control measures (adulticides) were implemented on 18 august in the affected area. The absence of sandflies in the traps ruled out sandfly fever. Chikungunya fever was suspected based on the symptoms presented by the initial cases and on the presence of large numbers of Aedes albopictus mosquitoes in the traps. On 29 august, chikungunya fever was confirmed by laboratory testing.
The outbreak of chikungunya fever in north-eastern Italy is the first documented local vector-borne transmission of Chikungunya virus within the European main land. Considering the presence of the vector Aedes albopictus in other EU countries, and therefore the risk of spread to these areas, the italian health authorities agreed on a joint ECDC/WHO visit, to assess the risk of establishment of local transmission and spread to other EU regions. In order to ensure an optimal outcome of the visit, ECDC invited international experts in epidemiology, virology and entomology, with specific experience in investigating and controlling chikungunya fever outbreaks.
5. CONCLUSIONS
It is rather fortunate that the chikungunya outbreak in Italy occurred relatively late in the mosquito season; while new cases will continue to be reported, it is likely that the current outbreak will fade out in the coming weeks. At the same time, it is now certain that Chikungunya virus can be transmitted in Europe, and public health authorities need to address this new situation and be prepared for the possibility of reappearence of virus transmission in the spring of the next year. This may happen through different scenarios. The persistence of the virus during the winter period, through the survival of infected adult mosquitoes, is a possibility, even though doubtful. Vertical transmission has been shown to occur 'in natura' in a tropical climate. It could possibly cause the re-emergence of Chikungunya virus in the spring of 2008, when vector activity starts again. Finally, the virus could also be reintroduced through international travel, a possibility that applies to all EU countries where Aedes albopictus is present.
Virus transmission in Europe is possible, not only in rural villages, but also in urban settings. Therefore, it is important that the winter period is used to prepare as much as possible for the re-emergence of the virus, in all areas in Europe where the vector is present. Early detections of the first cases is crucial to limit the expansion of new transmission cycles. Key factors in preventing large outbreaks are:
Full Report
1. BACKGROUND
On 30 August 2007 the Italian Ministry of Health, through the Early Warning and Response System (EWRS) and under the revised International Health Regulations (IHR)(2005), notified the EU Member States, the European Centre of Diseases Prevention and Control (ECDC)and the IHR contact point of the World Health Organization (WHO) Regional office for Europe, of a laboratory confirmed outbreak of chikungunya fever in the region of Emilia Romagna in north-eastern Italy.
At the time of notification, 131 suspected cases had occurred since the first (then known) case with onset of symptoms on 4 July. The majority of cases were reported from two neighbouring small villages (Castiglione di Ravenna and Castiglione di Cervia) in the province of Ravenna.
Upon recognition of a cluster of 47 cases on 16 august, the initial hypothesis had indicated an arboviral fever as cause of the outbreak, possibly sandfly fever. Considering the suspicion of vector-borne origin of the outbreak, vector control measures (adulticides) were implemented on 18 august in the affected area. The absence of sandflies in the traps ruled out sandfly fever. Chikungunya fever was suspected based on the symptoms presented by the initial cases and on the presence of large numbers of Aedes albopictus mosquitoes in the traps. On 29 august, chikungunya fever was confirmed by laboratory testing.
The outbreak of chikungunya fever in north-eastern Italy is the first documented local vector-borne transmission of Chikungunya virus within the European main land. Considering the presence of the vector Aedes albopictus in other EU countries, and therefore the risk of spread to these areas, the italian health authorities agreed on a joint ECDC/WHO visit, to assess the risk of establishment of local transmission and spread to other EU regions. In order to ensure an optimal outcome of the visit, ECDC invited international experts in epidemiology, virology and entomology, with specific experience in investigating and controlling chikungunya fever outbreaks.
5. CONCLUSIONS
It is rather fortunate that the chikungunya outbreak in Italy occurred relatively late in the mosquito season; while new cases will continue to be reported, it is likely that the current outbreak will fade out in the coming weeks. At the same time, it is now certain that Chikungunya virus can be transmitted in Europe, and public health authorities need to address this new situation and be prepared for the possibility of reappearence of virus transmission in the spring of the next year. This may happen through different scenarios. The persistence of the virus during the winter period, through the survival of infected adult mosquitoes, is a possibility, even though doubtful. Vertical transmission has been shown to occur 'in natura' in a tropical climate. It could possibly cause the re-emergence of Chikungunya virus in the spring of 2008, when vector activity starts again. Finally, the virus could also be reintroduced through international travel, a possibility that applies to all EU countries where Aedes albopictus is present.
Virus transmission in Europe is possible, not only in rural villages, but also in urban settings. Therefore, it is important that the winter period is used to prepare as much as possible for the re-emergence of the virus, in all areas in Europe where the vector is present. Early detections of the first cases is crucial to limit the expansion of new transmission cycles. Key factors in preventing large outbreaks are:
- awareness of clinicians about the disease and its risk factors;
- strenghtened surveillance systems and rapid notification;
- education and collaboration of the general public in the control of mosquito breeding sites;
- rapid implementation of vector control measures around each case; and
- strenghtened vector monitoring systems.