Are Aedes albopictus or other mosquito species from northern Italy competent to sustain new arboviral outbreaks?

The Asian tiger mosquito Aedes albopictus (Skuse) (Diptera: Culicidae), native to Southeast Asia, has extended its geographical distribution to invade new temperate and tropical regions. This species was introduced in 1990 to Italy and has since become the main pest in urban settings. It was incriminated as a principal vector in the first European outbreak of chikungunya virus (CHIKV) in the province of Ravenna (Italy) in 2007. This outbreak was associated with CHIKV E1-226V, efficiently transmitted by Ae. albopictus. The occurrence of this outbreak in a temperate country led us to estimate the potential of Ae. albopictus to transmit CHIKV and dengue virus (DENV), and to determine the susceptibility to CHIKV of other mosquito species collected in northern Italy. Experimental infections showed that Ae. albopictus exhibited high disseminated infection rates for CHIKV (75.0% in Alessandria; 90.3% in San Lazzaro) and low disseminated infection rates for DENV-2 (14.3% in San Lazzaro; 38.5% in Alessandria). Moreover, Ae. albopictus was able to attain a high level of viral replication, with CHIKV detectable in the salivary glands at day 2 after infection. In addition, the other three mosquito species, Anopheles maculipennis Meigen, Aedes vexans vexans (Meigen) and Culex pipiens L., showed variable susceptibilities to infection with CHIKV, of 0%, 7.7% and 0-33%, respectively. This information on vector competence is crucial in assessing the risk for an outbreak of CHIKV or DENV in Italy.

Tiger mosquito control: new approaches to the issue in local context.

Until recently, the control of mosquitoes has primarily focused on them as a nuisance due to their biting behaviour. This has now evolved into a significant health problem. To deal with this serious issue, a rational approach to vector control should be adopted, with clear, technically sound guidelines enforceable by legislation. The extensive outbreak of Chikungunya in the Indian Ocean during 2005-6 and the subsequent outbreak in the Emilia Romagna region of Italy in August 2007, should prompt a number of actions which must occur without delay in order to prevent any future recurrence of outbreaks. An International Symposium on Chikungunya was held in Alessandria, Italy on February 27th 2008. A number of experts from various disciplines were in attendance, the sole aim to assess the risk of this disease and other mosquito borne diseases occurring in Europe. The meeting culminated in the signing of a declaration called the "Alessandria Resolution" by the experts in attendance and members of several local authorities (see www.zanzare.eu). This act signified joint commitment of an national and international standing, to tackle the spread of the Asian Tiger mosquito and raise awareness among the general public. This paper will share the experiences of the mosquito control programmes in the Italian regions and in Alessandria and Piedmont emphasising key lessons learned.