West Nile virus: Fourth victim in Lazio. Italy leads Europe in number of infections.

A 93-year-old woman died at the Spallanzani Hospital in Rome from West Nile virus . The patient, originally from Cisterna di Latina, had been admitted to the San Paolo Hospital in Velletri, from where she was later transferred to the National Institute of Infectious Diseases in Rome. This is the fourth confirmed West Nile virus death in Lazio.

This rapid increase places Italy first in Europe in terms of infections. This is confirmed by the report from the European Centers for Disease Prevention and Control, which published its weekly bulletin updated to July 30. The document specifies that the data is being updated and includes both confirmed and probable cases.

The agency has updated its weekly bulletin, which states that "from the beginning of 2025 to July 30, five countries in Europe have reported human cases of West Nile virus infection: Bulgaria, France, Greece, Italy, and Romania." The report includes confirmed and probable cases, specifying that the counts "are preliminary and should be interpreted with caution, as they may be revised by countries as more information becomes available. Therefore, totals are not provided." Looking at the table, however, Italy has recorded the highest number of infections, followed at a distant second by Greece, Romania, Bulgaria, and France. And the ECDC specifies that "the highest number of cases has been reported in the province of Latina," in the Lazio region.

In week 31 (July 24-30), indigenous human West Nile virus infections were reported for the first time in the 2025 season by Bulgaria (in one region) and France (in one region). Greece reported infections in three new regions, Italy in seven new regions, and Romania in one new region, compared to the previous week.

It is an infectious disease transmitted by mosquitoes , particularly those of the Culex pipiens genus , which primarily affects wild birds. Mosquitoes become infected by biting birds and sometimes transmit the virus to accidental hosts such as horses and humans. The mosquito that transmits West Nile virus is not the tiger mosquito, but rather our nocturnal common mosquito, which bites from dusk to dawn. Other possible transmission routes include blood transfusions and organ transplants from infected donors, and even more rarely, congenital infections transmitted from mother to fetus through human milk have been reported.

Most infected people show no symptoms . Of those who do show symptoms, about 20% experience mild symptoms such as fever, headache, nausea, vomiting, swollen lymph nodes, and skin rashes. These symptoms can last a few days, or in rare cases, a few weeks, and can vary greatly depending on the person's age.

A mild fever is more common in children, while symptoms in young people include moderately high fever, red eyes, headache, and muscle aches. In the elderly and debilitated, however, symptoms can be more severe. The most severe symptoms occur in an average of less than 1% of infected people (1 in 150) and include high fever, severe headache, muscle weakness, disorientation, tremors, vision changes, numbness, convulsions, and even paralysis and coma. Some neurological effects may be permanent.

West Nile fever, like dengue, "is a disease caused by a virus" carried by mosquitoes, although "the dynamics of spread are different. While for dengue the cycle is human-tiger mosquito-human, for West Nile the reservoirs are birds and the vector is the common mosquito that infects humans by biting them. In this context, crows and seagulls in cities could influence the epidemiology of some infectious diseases, including West Nile . Fortunately, for now, no problems have been reported in cities and it is not certain that they will ever happen." This is explained by Gianni Rezza, former director of Prevention at the Ministry of Health and now associate professor of Hygiene at the Vita-Salute San Raffaele University. But how will West Nile evolve this summer in our country? "National data," Rezza emphasized on social media, "do not show an excess of cases compared to previous years, but there is evidence of an expansion of the outbreaks, which this year, at least for now, are more active in some areas of central and southern Italy (provinces of Latina, Anzio/Nettuno, province of Caserta) than in the Po Valley. Historical data from recent years show an increase in cases in August and then a decreasing trend starting in September. This isn't a rule, but it's what we've consistently observed, and it's not certain that it will be observed (for better or worse) this summer too, given climate change and the anticipated heatwaves."