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

Abstract

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.

A Novel Poxvirus-Based Vaccine, MVA-CHIKV, Is Highly Immunogenic and Protects Mice against Chikungunya Infection

“…In 2005, CHIKV reemerged as an outbreak on La Réunion Island (15) and has spread to different places in Africa, islands in the Indian Ocean, India, Southeast Asia, and southern Europe, affecting millions of people (3,(16)(17)(18)(19)(20)(21)(22)(23), revealing that the virus is a public threat that could cause a worldwide epidemic (4,6,24,25). Thus, the development of a prophylactic CHIKV vaccine is a high priority that has been moving forward to control CHIKV infection (26).…”

Defining the risk of Zika and chikungunya virus transmission in human population centers of the eastern United States

“…Depending on human movement, daily activities, and vector exposure (which will depend upon socioeconomic factors, among other things), our model may under-or over-estimate risk, as has been illustrated by data and in individual-based models for mosquito-borne disease that incorporate more heterogeneity [63][64][65][66]. However, models that assume even mixing have performed relatively well and been useful in understanding risk of urban mosquitoborne disease transmission [67][68][69].…”

“…A number of epidemiological models have considered arboviral transmissions (particularly dengue and chikungunya) focusing on different aspects of disease transmission [67,70,[72][73][74][75][76] and characteristics such as seasonality, temperature dependence, cross-immunity with multiple strains, and control measures [77][78][79][80][81][82][83][84][85]. Several recently published modeling studies for Zika transmission have focused on fitting models to current transmission in the South Pacific and South and Central America [68,[86][87][88] with Ae.…”

Chikungunya fever in Canada: fever and polyarthritis in a returned traveller

“…There have also been confirmed reports of Chikungunya fever in travellers returning to Canada, 6 the United States 2 and Europe. 7 In geographic locations with favourable environmental conditions and competent vectors, chikungunya virus can spread locally. Increasing temperatures and rainfall in parts of North America are expected to favour the propagation of a number of vector-borne diseases, including chikun gunya virus.…”

“…8 There has been a recently described outbreak of hundreds of cases in Italy initiated by a traveller returning from India. 7 There is ongoing disease activity in Indonesia, Papua New Guinea, the Philippines and India; more than 100 cases, most believed to have originated in Indonesia, have been reported in Australia. As of December 2013, autochthonous chikungunya virus has emerged in the western hemisphere, with a large ongoing outbreak in the Caribbean.…”