Gianni Messeri

Transmission Potential of Chikungunya Virus and Control Measures: The Case of Italy

During summer 2007 Italy has experienced an epidemic caused by Chikungunya virus – the first large outbreak documented in a temperate climate country – with approximately 161 laboratory confirmed cases concentrated in two bordering villages in North–Eastern Italy comprising 3,968 inhabitants. The seroprevalence was recently estimated to be 10.2%. In this work we provide estimates of the transmission potential of the virus and we assess the efficacy of the measures undertaken by public health authorities to control the epidemic spread. To such aim, we developed a model describing the temporal dynamics of the competent vector, known as Aedes albopictus, explicitly depending on climatic factors, coupled to an epidemic transmission model describing the spread of the epidemic in both humans and mosquitoes. The cumulative number of notified cases predicted by the model was 185 on average (95% CI 117–278), in good agreement with observed data. The probability of observing a major outbreak after the introduction of an infective human case was estimated to be in the range of 32%–76%. We found that the basic reproduction number was in the range of 1.8–6 but it could have been even larger, depending on the density of mosquitoes, which in turn depends on seasonal meteorological effects, besides other local abiotic factors. These results confirm the increasing risk of tropical vector–borne diseases in temperate climate countries, as a consequence of globalization. However, our results show that an epidemic can be controlled by performing a timely intervention, even if the transmission potential of Chikungunya virus is sensibly high.

Assessment of the risk of malaria re-introduction in the Maremma plain (Central Italy) using a multi-factorial approach

AbstractKeywords: Mosquito-borne diseases, Residual anophelism, Anopheles labranchiae, Vectorial capacity, Climatechange, Plasmodium falciparum, Experimental infectionBackgroundIn recent years, the increase in globalization [1], the risein the average temperature of the earth together with anincreasing frequency and intensity of extreme weatherevents, as storms, floods and droughts [2,3], and theenvironmental changes induced by human activities [4],have raised the concern about the possible introductionor reintroduction of Vector Borne Diseases in Countrieswhere these were absent or eradicated [5]. These con-siderations, coupled with the recent spread of somemosquito vector borne diseases in Europe [6,7] and theincreasing number of imported malaria cases recordedin the Continent [8] have renewed interest in the possi-ble reintroduction of malaria in Southern Europe [7-9],particularly in the countries facing the Western Medi-terranean Basin, where potential Anopheline vectors arestill present [10-13]. Moreover, in recent years auto-chthonous malaria cases have been sporadically reportedin Italy, France, Spain and Greece [14-20].In 2005, a five-year study was implemented in Italy, aswell as in other South European countries, with the aim toassess the status of the local potential malaria vectors andthe possible re-introduction of malaria transmission[21-25]. In Italy, the selected study area was the Maremmaplain, a region that was hyperendemic for malaria until60 years ago [26-28] and that more recently was recog-nized as the major “at risk” area for the malaria reintro-duction into Italy [14,29,30].In Maremma, after the malaria eradication campaign(1947-1951), Anopheles labranchiae, the main endophilicvector of the Anopheles maculipennis complex was dra-matically reduced in abundance. However, in subsequentyears, the species has progressively re-colonized most ofthe area coming back to substantial densities [31-33].This was mainly due to the introduction of intensive ricecultivation in the early 1970s. Since then, Maremma hasbeen subjected to continuous entomological surveillancethat was intensified after1997, when an autochthonousPlasmodium vivax malaria case, transmitted byAn. lab-ranchiae, occurred in the Province of Grosseto [14]. Thestudies carried out in the area since eradication, providesa database that allowed a follow-up the history of malariaand its vectors in Maremma over the past 60 years. Start-ing from the findings of the most recent entomologicaland environmental studies [23,34], the present study waschosen to evaluate the malariogenic potential of the areausing a multifactorial approach.Methods

Weather-Related Flood and Landslide Damage: A Risk Index for Italian Regions

The frequency of natural hazards has been increasing in the last decades in Europe and specifically in Mediterranean regions due to climate change. For example heavy precipitation events can lead to disasters through the interaction with exposed and vulnerable people and natural systems. It is therefore necessary a prevention planning to preserve human health and to reduce economic losses. Prevention should mainly be carried out with more adequate land management, also supported by the development of an appropriate risk prediction tool based on weather forecasts. The main aim of this study is to investigate the relationship between weather types (WTs) and the frequency of floods and landslides that have caused damage to properties, personal injuries, or deaths in the Italian regions over recent decades. In particular, a specific risk index (WT-FLARI) for each WT was developed at national and regional scale. This study has identified a specific risk index associated with each weather type, calibrated for each Italian region and applicable to both annual and seasonal levels. The risk index represents the seasonal and annual vulnerability of each Italian region and indicates that additional preventive actions are necessary for some regions. The results of this study represent a good starting point towards the development of a tool to support policy-makers, local authorities and health agencies in planning actions, mainly in the medium to long term, aimed at the weather damage reduction that represents an important issue of the World Meteorological Organization mission.

Development and application of a forecasting system to avoid spring frost damage in chiana valley

Late frost is one of the more serious adversity for Italian agriculture. Several methods have been developed to protect cultivations, but their application results particularly effective (also from an economic point of view) only if supported by forecasting systems during the more susceptible period of the year. On these basis a forecasting system of late frost in Val di Chiana (an area in central Italy mainly cultivated with cereals and high quality fruits) was developed. The system consists in an empirical model, based on a preventive agroclimatic analysis of the area to identify night cooling dynamics (for several meteorological conditions) in the spring. A network of 10 thermohygrometric stations was installed in the area integrating the information obtained by a local agrometeorological station network. The final product was a forecasting bulletin emitted every three hours beginning from the 13:00 p.m. A validation of the system was performed for 2006 to verify the forecast skill.