West Nile: A group of physicists led by Professor Andrea Maria Chiariello develops a mathematical model

In recent weeks, the West Nile virus (WNV) has once again become a focus of attention in Campania, where a death and several serious cases have recently been reported in the provinces of Naples and Caserta. This is neither a new phenomenon nor a situation that should cause alarm: the virus has been circulating steadily in our country for several years now (a), and its spread is closely linked to the presence of mosquitoes, which in turn depends on environmental and meteorological conditions, such as rising temperatures. Understanding how these factors can influence the course of infections is therefore becoming increasingly important.

To better understand how this virus spreads across Italian regions, a group of Neapolitan physicists led by Andrea Maria Chiariello, a professor in the “E. Pancini’ Department of Physics at the University of Naples Federico II and an expert in theoretical physics applied to biological systems, has developed a new physical-mathematical model capable of interpreting epidemiological data and indicating possible scenarios for the progression of infection waves (source: https://arxiv.org/abs/2606.20489).

Andrea Fontana and Simone Tambascia, co-authors of the study, explain that the model is based on two simple main components: the human population and viral vectors— namely, common mosquitoes—which, as they move through the system, interact with individuals and can cause new infections (b). The population evolves based on a quantum version of the so-called Game of Life, a mathematical “game” developed in the early 1970s to study how complex collective behaviors can emerge from simple local interactions and which, in this approach, is used to simulate the dynamics and mobility of the human population.

In summary: when environmental conditions favor a greater presence of mosquitoes, the opportunities for the virus to reach humans also increase. It is precisely this process that the model seeks to translate into quantitative terms.

The Study

By comparing the model’s results with data provided by the Istituto Superiore di Sanità (ISS), the research team demonstrated that the method is capable of reconstructing with great accuracy the outbreaks observed in Italy in previous years, such as in 2025, when a particularly high number of cases was recorded in Lazio, Campania, and Veneto.

One of the most interesting findings concerns the relationship with weather conditions. In fact, by comparing the major epidemic waves of 2018, 2022, and 2025 with climate data, the researchers observed that, in the model, the growth of the mosquito population follows a trend consistent with rising summer temperatures and changes in relative humidity. The number of outbreaks considered does not yet allow for the establishment of a definitive statistical correlation, but the result points to a possible link between weather conditions, mosquito proliferation, and the spread of infections.

Once calibrated using real-world data, the model allows for the testing of various scenarios. For example, it is possible to simulate what happens if the mosquito population increases—as might occur due to particularly favorable environmental conditions—or decreases as a result of control and pest management measures. The simulations show how variations in mosquito presence can significantly alter the course of an epidemic outbreak. The approach is also highly flexible and can be extended to the study of other vector-borne infections, such as dengue and Zika, which are prevalent primarily in Latin America and are also being studied by Chiariello’s group using this method.

Currently, the group is using 2026 data provided by the ISS to evaluate possible scenarios for the current season. Based on the available data, the model reconstructs the initial phase of West Nile virus spread and simulates different outcomes depending on the dynamics of the mosquito population, which in turn can be influenced by meteorological parameters such as temperature and humidity. The goal, explains Professor Chiariello, is to offer not only a quantitative description of the phenomenon, but above all a tool for interpreting the data, comparing different scenarios, and contributing to the evaluation of prevention strategies (c).

The message is simple: no need for alarm. Limiting, whenever possible, the conditions that favor mosquito proliferation can help prevent the spread of the virus—for example, by avoiding standing water in plant saucers and containers left outdoors. This is also because, as the simulations suggest, addressing the presence of mosquitoes means directly acting on one of the factors that significantly influence the potential for the virus to spread.