More than dengue or zika we should worry about measles

Dengue, zika, chikungunya: strange, exotic, mysterious, disturbing names. They are those of emerging infectious diseases which in epidemic form are affecting various areas of the world in recent years. A “corollary” apparently less serious, but in reality no less relevant, than the recent Covid-19 pandemic which has upset our lives. They raise alarm because they represent a new threat to global health and are growing. Even if the numbers are still limited, they are starting to appear in Italy too. Don’t worry though: you need to know them to be prepared to face them.

They are viral diseases transmitted by such mosquitoes Aedes carriers of the pathogenic virus and manifest themselves with high fever, headache, muscle and joint pain, often accompanied by erythema or skin rashes. Although in some cases the symptoms are more subtle, sometimes even absent, to the point that the pathology goes unnoticed.

Dengue is a term that derives from an African expression (dinga) used to describe an illness caused by an evil spirit, an expression which in turn probably derives from the Spanish dengue (annoying), a word intended to indicate the particular and painful gait characteristic of those suffering from this “bone-breaking fever”. It is a disease that has been known for some time, but which is now exploding due to climate change which causes mosquito larvae to proliferate uncontrollably in nations particularly sensitive to the effects of the climate. This is the case of Brazil, where dengue now has its unstoppable epidemic epicentre, with a rate of twenty thousand infections per day and almost two million sick people since 2000.

A quarter of those infected have serious manifestations and of these approximately 5 percent present serious complications. Without adequate treatment, the virus, especially in elderly people, has a lethality of 15 percent. Even if there is an effective vaccine, according to the Pan American Health Organization, it will not be able to control the ongoing epidemic. Both because the population is reluctant to get vaccinated, and because the tetravalent vaccine now in use is not produced in sufficient quantities compared to demand. With this scenario, the fear of reaching five million cases by the end of the year is real. In a world as interconnected as ours, the epidemic can quickly spread to other countries in Latin America and the southern part of North America. The risk that it could also spread to the countries of the Mediterranean basin in the summer is not so remote.

Zika virus infection, also transmitted by mosquitoes, presents a more contained clinical picture because only in a few cases does it cause fever, joint pain and skin rashes. Most people who contract this infection show no symptoms, and many do not know they are infected. However, this subtle picture represents a serious risk for pregnant women, who, if they contract the disease, can then give birth to newborns affected by microcephaly. That is, children who have an abnormally small head size because the brain does not develop typically and remains small.

Chikungunya is an African word which with this term (which literally means “that which curves” or “situation which contorts”) describes the typical condition of these sick people who, due to fever and intense muscle and joint pain, tend to remain absolutely immobile and to assume pain-relieving positions. In most cases patients recover completely, however in some cases joint pain can persist for months or even years. Serious complications rarely occur, however in the elderly the disease can be a contributing cause of death.

There are no specific antiviral treatments and treatments focus on alleviating symptoms. A targeted vaccine was recently approved in the United States.

Alongside these, other well-known infections are making a comeback. Like the re-emerging measles, with a surge in cases affecting children from birth to 4 years in Central Asia but recently also in Europe. An increase linked to the lack of adequate attention from health services in many countries, but above all to the drastic drop in vaccinated subjects. According to the European Center for Disease Prevention and Control (ECDC), in the EU alone, between March 2023 and February 2024, 5,770 cases of measles and at least 5 deaths due to the infectious disease were recorded. This is accompanied by a 10-fold increase in cases of whooping cough compared to the previous two years.

Even in Italy, the data from the Istituto Superiore di Sanità on measles cases are not very comforting: over 200 sick people in the first three months of this year and over 80 percent are unvaccinated subjects. There are also many people over 30 years old. These first data seem to confirm that an epidemic is starting. Measles, despite what is commonly thought, is not a trivial disease: if caught in adulthood it can be a serious pathology and cause complications. In Italy vaccination coverage is not optimal, despite the obligation reintroduced a few years ago, and this explains the current situation. It is essential to promote campaigns aimed at restoring vaccination protection for at-risk groups.

Another cause for concern is the avian influenza virus which continues to spread, including in Europe, causing outbreaks in poultry farms, high mortality among wild birds and species jumps (spillover) now also infecting wild and domestic mammals. These viruses continue to evolve globally and, as wild birds migrate, strains carrying mutations may increasingly be selected for adaptation to mammals. Indeed, it is already known that several mammals can become infected, even if they are not the preferential hosts of avian viruses. However, wild mammals could act as “bridge guests” between wild birds and domestic mammals (think of cats for example, who live in homes but also have access to the outside in open-air environments with the possibility of interacting with others potentially infected wild mammals) and humans. These infections in humans are now absolutely isolated cases.

However, if avian influenza viruses acquired the ability to spread efficiently between humans, large-scale transmission could rapidly occur due to the lack of specific immune defenses against these viruses in humans. It would be a risky scenario for a new pandemic. For this reason, it is necessary to intervene to mitigate the risk of adaptation of these viruses to mammals and humans, limiting exposure to possible sources of infection and preventing the spread of infected animals by isolating them and killing them if necessary. In perspective OneHealth (there is only one health for humans, animals and the environment which are closely related to each other) it is necessary to strengthen supervision of animals and people, promote collaboration between the veterinary and medical fields, have the guarantee of being able to have rapid diagnoses and implement preventive vaccination measures.

While the growing cases of infections around the world, some new and some re-emerging, are making headlines and causing alarm, we should not, however, be afraid or worry more than necessary. We need to be careful and be prepared to avoid (if possible) or deal with (if necessary) these pathologies. We will have to try to coexist with the germs (bacteria and viruses) that appeared on the face of the Earth three billion years ago (therefore long before us sapiens, who have only existed for a few hundred thousand years), but also to defend ourselves from the dangerous ones because cause of disease. With simple systems capable of creating mechanical barriers against them: from the most common hygiene rules to the use of masks where necessary. But also with more sophisticated systems capable of creating effective defenses: immunological, such as vaccinations, and therapeutic, such as antiviral drugs.