Dengue outbreak, but how does this endemic tropical disease arrive in Italy?

There is an outbreak of dengue in Fano, in the Marche, which second Roberto Burioni It’s “out of control.” The virologist from the San Raffaele hospital in Milan took to his social profiles to comment on the situation of the epidemic, and also to clarify what is useful and what is much less so in the kit at a controlled price offered by the Marche region in municipal pharmacies (the repellent is good even if it does not contain any useful active ingredient, the larvicide less so, the disinfectant pen is of no use). Among other things, the kits proposed are just 800 against the 60 thousand residents.

Returning to the central problem, Burioni explained that with 102 official casesa dozen awaiting confirmation and a submerged number of at least double, given that in 80% of cases dengue causes no symptoms, «the situation is out of control, infections are at least double. Let’s hope for the arrival of the cold, think if it had happened in June”, wrote the professor of virology and microbiology at the Vita e Salute San Raffaele University of Milan on Facebook. To diagnose it, a specific test is also needed which naturally not all citizens of Fano and surrounding areas with fever and other osteo-muscular pain will have carried out.

Dengue, what symptoms?

Dengue fever, also nicknamed “bone-breaking fever” due to the virulence of muscle and joint pain it causes in the most severe symptomatic cases, is a tropical infectious disease. We talked about it last year during a bad epidemic in Peru and Argentina. The origin lies in four variants of the same virus (DEN-1, DEN-2, DEN-3, DEN-4) transmitted through the bites of female mosquitoes of the species Aedes aegypti – absent in Italy, replaced by Aedes albopictus that is, by the tiger mosquito – who have in turn bitten an infected person. It is therefore not transmitted from human being to human being, even if man is the main host, but via vector. For this reason the combating mosquitoes is essential.

How an outbreak is created in Italy

As stated in the dedicated ISS card «the virus circulates in the blood of the infected person for 2-7 days, and in this period the mosquito can pick it up and transmit it to others». And it is exactly this the way in which outbreaks are triggered in non-endemic areas of the virus: someone returns to Italy or Europe by plane after a trip to the tropical and subtropical areas of Africa, Southeast Asia and China, India, the Middle East, Latin and Central America, Australia and various areas of the Pacific. At that point he is bitten by tiger mosquitoes present in Italy which they spread the infected blood with other bites generating the so-called indigenous cases of the outbreak, distinct from imported ones. That is, from those who return already infected due to having become infected while travelling. It should also be noted that in recent decades the spread of dengue has increased in many tropical regions but imported cases have also grown, with the increase in movement of goods and people.

How we are intervening in Fano

The Municipality of Fano carried out disinfestation throughout the urban area and started an intervention to eliminate the larvae. This essential work is accompanied by an information campaign dedicated to the reclamation of private areas such as courtyards, gardens and fences: it is necessary to eliminate stagnant water from vases, bowls and containers, wear long, light-coloured clothes, use repellents and install mosquito nets at windows. In short, the same methods that have always been fundamental for all viruses and other pathogens transmitted by insects and mosquitoes. «We have to use repellents, the real ones, not the natural ones – underlines the virologist Burioni interviewed byAdnKronos returning to the matter of repellent kits with lavender and mint essential oils – and ensuring that mosquitoes do not lay eggs and do not proliferate. When an epidemic outbreak is underway it becomes indispensableand kill adult mosquitoes and potentially capable of transmitting the infection.” In one case in twenty dengue has a serious course and in some cases fatal, the Marche outbreak must therefore be taken very seriously.

Vaccine yes or no?

There are no dedicated drugs, but there is one Vaccine however not easy to use: the Qdenga of the Japanese Takeda it is indeed authorized by AIFA from February 2023 and not only does it provide a relatively low antibody response in HIV-negative patients but it should be administered in two doses three months apart. His indication is therefore above all for those who have plans travel of a certain duration to areas where the virus is endemicthat is, between the two tropics, and in particular for those who had already developed the disease in the past, given that if the first infection is asymptomatic or paucisymptomatic in 75-80% of cases a subsequent one can be much stronger. «A second vaccine – recalls the ISS – the Dengvaxia (Sanofi Pasteur), not marketed in Italy, is indicated only for people residing in endemic areas and who have had a previous Dengue infection, confirmed through laboratory tests”. Let’s say that vaccines give the most robust effects in those who have already had an infection.

In conclusion it is necessary to remember the symptoms of the disease: high fever, severe headache, pain behind the eyes, skin rash which can appear on most of the body 3-4 days after the onset of fever, muscle and joint pain but also nausea and vomiting. Typical symptoms are often absent in children.