Prevention and the planning of effective responses to various infectious diseases are key public health topics for EU countries. Different vaccination policies, epidemiological study activities, and the analysis of antimicrobial resistance can be introduced as a precautionary measure; the occurrence of cancers and dietary dysfunction can increase the incidence of these infectious diseases.
The governments of EU countries are supported in this activity by two agencies:
- ECDC (European Centre for Disease Prevention and Control), which aims to keep an eye on what is "new" that may endanger the continent's health, particularly emerging diseases and changes for our climates.
- EMA (European Medicines Agency), with a broad overview of drugs, their management and analysis, always with a focus on what's new from the scientific world, serves as a support in combating known and "new" infectious diseases. The EMA conducts extensive safety testing in relation to the claimed qualities and side effects of individual drugs.
The latest Epidemiological Report prepared by ECDC showed the following data in Europe:
- Respiratory tract infections: H1N1 virus (pandemic A virus) dominant in our continent for influenza and obviously in the last 2 years pandemic from Covid-19;
- Tuberculosis: over 70,000 new cases per year;
- HIV, HBV (hepatitis B) and HCV (hepatitis C): about 28 thousand new cases per year;
- Chlamydia: with 340 thousand reported cases per year, it is the most common sexually transmitted infection in Europe;
- Water- and food-borne diseases: gastrointestinal infections by Campylobacter are the most frequent followed by those by Salmonella. Among protozoa, the most prevalent on the continent is Giardia Lamblia, Legionnaires' disease, which has seen a 17% increase;
- Vector-borne diseases: malaria, dengue and chikungunya are the "classics" of diseases imported by travelers from countries where these diseases are endemic, but with Malaria Cases have been detected in Spain, Belgium and Greece; Dengue and Chikungunya have been detected in France. West Nile Fever has been classified as endemic in some Southeastern European nations;
- Antibiotic resistance: this is an increasing phenomenon in EU countries and particularly for bacteria such as E. coli and Klebsiella pneumoniae;
- Vaccine-preventable diseasesEurope's commitment to fight measles and rubella is always at the forefront. Health policies aimed at increasing vaccine coverage on diseases of this type have resulted in declining cases of Meningococcal C and Mumps.
Rising global temperatures and more specifically the tropicalization of Europe is increasing the risk of local development of infectious and tropical diseases. Among the countries noting increasing increases in tropical diseases in recent years we have Italy, Greece, Serbia, Romania, and Hungary. There are also increasing cases of hospitalizations for West Nile Virus: about 500 cases with 22 deaths.
Doctors are blindsided by "new" infectious cases they do not know about, except theoretically from books, with little clinical experience. Hospitals increasingly face overt or suspected cases of forms of Malaria, Dengue, Chikungunya and West Nile Fever. Dermatologists also see cases of Leishmaniasis Infantum with visceral and not just cutaneous extensions increasing in the Mediterranean basin.
In the past two years, Covid-19 has shown how the world can be taken by surprise, still all hypotheses about the origin of a viral infectious disease (species jump from bat or pangolin, point of origin local market or Wuhan scientific laboratory) are still open, yet previous experiences on SARS or MERS and related spillover should have taught something.
Changing local climatic conditions, the discovery of new vectors in insects and ticks, and warming seas lead one to think of tropical diseases being "transferred." Scholars say that over time another deadly virus will spread, again making a species jump from animal to human, there are in fact more than 1.7 million viruses in mammals and birds.
In the last period, 900 new viruses were discovered, including:
- 160 coronaviruses;
- 1 new strain of Ebola;
- 18 zoonotic viruses, kept under control such as Lassa and Marburg (which causes hemorrhagic fever).
Is Europe fertile territory for Yellow Fever mosquitoes?
We have long sensed a deep furrow drawn by tropical diseases: their globalization.
Yellow Fever, like Dengue, Zika, Chikungunya thanks to their "Carrier" the Aedes aegypti mosquito have a high probability of becoming common on our continent. Warmer weather and increased rainfall increase the number of areas where Aedes can proliferate, plus this vector has the ability to adapt to new conditions with ease.
Several scientific studies using computer simulations have created a geographic plot of the coming years for countries at risk: China, North America and Europe; for the latter, the countries at risk are Greece, Turkey, Portugal and Spain.
Another relevant factor in combating mosquitoes are pest control activities during their breeding periods; unfortunately, the last two years of pandemic has limited these operations by increasing the proliferation of these insects.
Prof. Jan Semenza of ECDC also pointed out that continuous alternations of very hot days alternating with torrential-type rains are the first signs of tropicalization of the European climate.
Aedes aegypti, along with ticks, being cold-blooded are affected in the faster reproduction of climatic "lurching," with wild birds as viral reservoir in the migration period.
The invasion of this mosquito in Europe is therefore possible and is now underway.
Historical data speak of a three-fold increase in these insects to new areas other than the usual ones.
The return from tropical travel
No cases of local infectious contagion have been reported in Italy in recent years; the cases detected have been related to returns from travel to endemic areas. For example, in 2017 Belgium reported 1 case of yellow fever returning from Suriname and 4 returning from South America. The geographical area of interest is in the tropical areas of Africa and South America.
The cycles of spread and symptoms
The disease has two main cycles of spread:
- Urban: infected individuals > mosquito > susceptible individuals;
- Silvestre: virus from monkeys > mosquitoes > humans.
The onset of symptoms as is known presents with fever, muscle pain, headache and nausea.
Possible developments are:
- Mild form - to follow after about 4 days, there is remission with limitation of fever and symptoms, the abortive form of the disease resolves at this point;
- Severe form - about 20-25% of patients enter this stage instead, with the development of a new fever, systemic and skin bleeding, "black" vomiting and jaundice. Of the most severe cases, the mortality rate is 20% as there is no contrasting targeted therapy.
The name of this infection "Yellow Fever" comes from two reasons:
- One of the symptoms it causes in severe cases, jaundice vomiting related to liver damage;
- The cultural origin: yellow from Latin flavus, as the virus with an RNA genome is part of the Flaviviridae family.
How to protect ourselves?
The main prevention measures remain mosquito pest control and behavioral measures to protect against mosquito bites.
The vaccine is mandatory in many countries and is recommended for travelers to endemic areas. It is a single administration subcutaneous vaccine with live/attenuated viral strain, at least 10 days before travel. Protection is not total and is around 75%; antibodies last about 10 years.
Historical background in Italy.
The virus first arrived in Europe from 1635 with Jesuit Raymond Breton and 1649 in Gibraltar with ships from the West Indies.
It first appeared in Italy in 1804 in Livorno when it traveled with sailors and landed causing 636 deaths. It later showed up in port cities due to commercial traffic, which brought the mosquito:
- 1889 in Naples, Pisa, Livorno, and La Spezia;
- 1928 in Catania, Taranto, Brindisi;
- 1907, 1916 and in 1944 to Genoa.
In Europe, the year to remember as the number of cases is 2018: 13 cases among France, Germany, Romania, the Netherlands, the Czech Republic, and the United Kingdom).
Conclusions
The only hope is the climate, the real weapon against this mosquito: Aedes Aegypti cannot overcome the harsh winter climate of Europe.
Since the 1990s, however, the Aedes species with Albopictus (the so-called "tiger") has been present in Italy. The absence of Aedes Aegypti has not eliminated the possibility of introduction of the disease because the native tiger, according to many authors, has the characteristics for some viral strains of Yellow Jack.
The effectiveness of transmission is more limited than Aegypti but common sense indicates that we should not rule out anything from the point of view of health surveillance, while also evaluating the climate, rising temperatures and consequently tropicalization.
