A rapid molecular detection protocol for Chikungunya virus directly performed on Aedes albopictus (tiger mosquito)

Abstract

INTRODUCTIONChikungunya is an emerging Arbovirus of immense public health concern in Southeast Asian and African countries (6). Chikungunya virus (ChikV) is a single stranded positive sense enveloped RNA virus. It is a member of Alphavirus genus of the Togaviridae family and is transmitted to humans by Aedes aegypti (4). ChikV has two Open Reading Frames (ORFs), codifying for non structural proteins (nsP1, nsP2, nsP3 e nsP4) and for structural proteins (C, E2, E3, E1). ChikV produces an illness in humans that is often characterized by sudden onset of fever, headache, fatigue, nausea, vomiting, rashes, myalgia and severe arthralgic pain (3, 5). Arthralgia may persist in a small proportion of cases even for months and has a great economic impact in many tropical countries. Currently, the diagnosis of ChikV-infection is accomplished through either virus isolation or detection of virus-specific antibodies by ELISA or genomic detection by retro transcriptase polymerase chain reaction (RT-PCR). In the last few years tiger mosquito, Aedes albopictus (Diptera: Culicidae), spread quickly and widely in the whole Italian territory. These insects are ideal vectors for different Arboviruses, particularly Dengue virus (DenV), and ChikV, causing millions of patients in the world per year. From ECDC data (European Centre for Diseases Control), several Member States have reported ChikV fever cases in travellers returning from affected areas, above all in South-East Asia. ChikV appeared for the first time in Italy in 2007 and spread in the Provinces of Ravenna, Rimini, Forlì and Bologna, causing more than 300 clinical cases (2). The great alarm in the Italian population drove health authorities to improve the surveillance of Arboviruses. This situation prompted regional public health authorities and the Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche to begin a Surveillance Plan for this virus and a Vector Monitoring Program in the Marche Region, which is close to the area where the virus first appeared. The aim of this plan was the reduction of vector density and the very early individualization of illness cases to prevent viral spread. Monitoring was carried out by ovitraps, while