Regional surveillance for arbovirus in Lazio Region, Italy during the ZIKV epidemic in Latin America

Abstract

Purpose: Due to the presence of a competent vector, mainly Aedes Albopictus, and to the experience of an outbreak of Chikungunya in 2006, Italy has implemented an integrated surveillance system for chikungunya fever, dengue fever and ZIKV fever. We describe temporal trends and geographic origins of vector-borne diseases in the Lazio Region, Italy. Methods & Materials: We analyzed all the notifications for suspected arbovirus infection reported to the Regional Infectious Disease Surveillance System (SERESMI) from December 2014 to April 2016. Routine surveillance data on demographics, clinical features, origin of infection were integrated with data from the Regional Reference Laboratory for Arbovirosis. Confirmed cases are defined as positivity to serological tests and/or molecular detection of the virus in serum samples by PCR, as appropriate. Results: During the reported period, 131 suspected cases of arbovirosis were reported; all suspected cases were returning travelers. Of these, 63 (48.2%) cases were confirmed as arboviral infections: 16 (25.4%) were chikungunya cases, 32 (50.8%) were dengue fever cases and 14 (22.2%) were ZIKV cases. One case of Toscana virus infection was reported. Imported cases of chikungunya fever primarily returned from South America (9/16, 56.3%). Southeast Asia (10/32, 31.3%) contributed the largest proportion of dengue fever cases, followed by Caribbean, Central and South America. Finally, ZIKV infected travelers were returning from South America (9/14, 64.3%), followed by Caribbean (5/14, 35.7%). Main clinical findings were fever, rash, headache and joint pain. Fever was present in the majority of chikungunya and dengue patients, but only in one third of ZIKV patients. Among ZIKV patients, rash was the most frequent clinical finding (12/14, 85.7%). Most of the patients had been already symptomatic during the travel. Starting from January 2016 there was a marked increase in the reporting of suspected cases. Conclusion: The incidence of arboviral infections due to Aedes spp mosquitoes in the Lazio Region, a region densely colonized by Ae. albopictus, should be closely monitored. To date, no secondary autochthonous cases have been identified. The increase in suspected cases in parallel with the media coverage of the ZIKV outbreak in Latin America highlights the importance of risk communication to health care workers.