06 September 2007
An outbreak of chikungunya fever in the province of Ravenna, Italy
R Angelini1 AC Finarelli2, P Angelini2, C Po2, K Petropulacos3, P Macini2, C Fiorentini4, C Fortuna4, G Venturi4, R Romi4, G Majori4, L Nicoletti4, G Rezza4, A Cassone (firstname.lastname@example.org)4
1. Dipartimento Sanità Pubblica, Azienda Unità Sanitaria Locale (Department of Public Health, Local Health Unit), Ravenna, Italy
2. Servizio di Sanità Pubblica, Regione Emilia-Romagna, Bologna, Italy
3. Servizio Presidi ospedalieri, Regione Emilia-Romagna, Bologna, Italy
4. Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy
Chikungunya fever is a viral disease transmitted by Aedes spp mosquitoes. The infection is endemic in parts of Africa, South-east Asia and on the Indian sub-continent. Since 2005, large outbreaks have been reported in several islands in the Indian Ocean and in India . Travellers from areas affected by chikungunya have been diagnosed with chikungunya fever in several European countries, including Italy , but local transmission involving mosquitoes has not occurred so far.
During the month of August, local health authorities of the province of Ravenna, Region Emilia-Romagna, Italy, detected an unusually high number of cases of febrile illness in Castiglione di Cervia and Castiglione di Ravenna, two small villages divided by a river. At the end of the month, clinical and epidemiological investigations carried out by the local Health Units in collaboration with the Region and the Reference Laboratory of the Istituto Superiore di Sanità in Rome, suggested an arbovirus as the possible cause of the outbreak. Serological testing and PCR confirmed the diagnosis of chikungunya fever. In addition, the chikungunya virus was detected by PCR in Aedes albopictus, which is considered to be the most likely vector for this outbreak.
The case definition used includes high fever and joint pain and/or rash and/or asthenia, and, for cases with no apparent link with the two initially affected villages, or with areas affected by secondary clusters, laboratory confirmation.
Number of cases
To date (4 September 2007), a total of 197 cases have been reported. Of these, 166 fulfil the case-definition criteria: 147 are from the initial outbreak area of Castiglione di Cervia or Castiglione di Ravenna, whereas 19 are from secondary clusters in neighbouring suburbs of the towns of Cesena (13 cases) and Cervia (six cases). The remaining 31 suspected cases need further epidemiological investigation (i.e. affected areas visited in the last 14 days) and/or laboratory confirmation. These cases, with no apparent link with the main affected areas, are scattered throughout the Region; their blood samples have not been tested yet.
The index case is believed to be a foreigner coming from an affected area in the Indian subcontinent and not resident in Castiglione. He arrived in Italy on June 21 and developed symptoms two days later when he was in Castiglione di Cervia. The peak of the epidemic curve occurred during the third week of August. Other sporadic cases have been recently detected in neighbouring areas, but the epidemic curve shows a decreasing trend in Castiglione di Cervia and Castiglione di Ravenna.
In the large majority of the patients, the disease was mild and self-limiting. Preliminary data from Castiglione show that fever lasted for a few days in most patients and a macular rash appeared in more than 50% of cases; however, arthralgia was intense and often persistent even after the abatement of fever. Only one death occurred, in an 83-year-old man with severe underlying conditions.
An active surveillance system based on general practitioners and hospital emergency units was set up in the whole Region on 29 August. Implemented control measures include the use of insecticides (pyrethroids and antilarval products) in public as well as private sites within 100 metres around the residence of all confirmed and suspected cases, and communication to the public to inspire active involvement in vector control measures and general health education. A protocol on how to measure the efficacy of the control measures is being implemented.
A surveillance system for monitoring Aedes albopictus distribution has been active in the whole of the Emilia-Romagna Region since 2006. A surveillance for chikungunya infection in A. albopictus is being considered. Blood, organ and tissue donation has been suspended in the affected area, i.e. Ravenna municipality, Cervia, Cesena, Cesenatico.
- ECDC. Chikungunya fact sheet. Available from: http://www.ecdc.europa.eu/Health_topics/Chikungunya_Fever/Disease_facts.html
- Beltrame A, Angheben A, Bisoffi Z, Monteiro G, Marocco S, Calleri G et al. Imported chikungunya infection, Italy [letter]. Emerg Infect Dis [serial on the Internet]. 2007 Aug. Available from: http://www.cdc.gov/EID/content/13/8/1264.htm
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