Viruses and bacteria in Catalonia: What are we getting sick from most?

BarcelonaThe laboratory at Hospital Clínic de Barcelona was the first in Spain to detect a new coronavirus that ultimately caused the worst health crisis in modern times. It was February 25, 2020, as the head of the center's Microbiology Service, Climent Casals, recalls, and the date is etched in memory. The outbreak of COVID-19 paralyzed the world with serious health, economic, and social consequences, but it also had a major impact on the other pathogens that had been circulating in our country until then; it displaced them and practically achieved a monopoly on infections. Five years later, pre-pandemic normality has returned, and the map of bacteria and viruses has also changed. Therefore, professionals insist on the importance of having a surveillance system capable of detecting and anticipating any emergency. so that what happened in 2020 does not happen again.

The microbiological notification system has existed in Catalonia for three decades, where professionals report all viruses and bacteria that cause infectious diseases. Over the years, it has been strengthened and improved, especially after the pandemic, and more and more tests are being carried out with the aim of having the maximum amount of information on the pathogens circulating in our country, detecting possible sources of contagion, and anticipating dangers. Last year, for example, Catalan laboratories reported more than 100,000 cases of diseases caused by microorganisms. The most frequent were the bacteria that causes chlamydia, the influenza virus, the bacteria behind gonorrhea, whooping cough, and the bacterium Campylobacter, One of the microorganisms that causes diarrhea, according to the latest report from the Department of Health, to which ARA has had access. These five microorganisms account for more than 60% of all infectious diseases reported by laboratories.

"We're working to ensure we don't miss any source of infection, especially if they're highly infectious, highly deadly, or vaccine-preventable diseases," explains Casals, who details that the map of viruses and bacteria has changed significantly in recent years due to COVID-19. As many microorganisms barely caused infections during the pandemic, herd immunity declined, and once normality returned thanks to vaccines, these pathogens returned with a vengeance and had room to roam, as many people's defenses weren't prepared, especially children. This has led, for example, to a spike in whooping cough, a highly infectious disease with outbreaks every three to five years. Specifically, it went from 359 cases in 2023 to 10,783 last year, an increase of almost 3,000%.

Now, since the surveillance system is working, the threat has been detected and a solution has been found to stop the spread of the disease. In this case, there is an effective vaccine against the disease and Health has included it this year in the injection calendar for adolescents from 11 and 12 years old, as recommended by the Advisory Council on Immunization, so Casals is convinced that there will be a drop in cases thanks to prevention.

Another example is the respiratory syncytial virus (RSV), which causes one of the most common respiratory infections and is one of the main causes of hospitalization in children. Before the pandemic, it was one of the most common infectious diseases in our country, but in 2023, vaccination began for children under 6 months of age and a significant reduction in cases of bronchiolitis, emergency room visits, and hospitalizations has been achieved. "We no longer see it in the top 10; it was a brave gamble and it has turned out very well," the expert celebrates.

Prevention of sexually transmitted infections fails

One of the major outstanding tasks that experts have long pointed out is prevention of sexually transmitted infections, which are increasingly common throughout Europe. In Catalonia, since 2010, increase by an average of 32.4% each year, and in 2024, 38,544 cases were reported, of which more than 16,000 were chlamydia and more than 13,000 were gonorrhea. In fact, the number of positive cases in our country exceeds the European and Spanish average for all sexually transmitted infections. Behind thisincrease in casesHowever, there are many factors. On the one hand, there are many diagnostic tests and large-scale screenings that detect people who don't show symptoms of the disease. On the other hand, there is an increase in risky sexual behaviors, a decline in condom use, and an increase in the number of sexual partners a person has. All of this has created a breeding ground for these infections to rise relentlessly in recent years.

The head of the Microbiology Department at Vall d'Hebron Hospital in Barcelona, ​​Nieves Larrosa, is clear that this increase is not only due to the efforts made to detect them, but also to the fact that social behaviors have changed. "Fear has been lost, especially among the younger population," maintains the expert, since the age group where most cases are concentrated is between 20 and 30 years old. Larrosa warns that this volume of cases will have a long-term impact, as chlamydia can cause infertility if left untreated, and gonorrhea is increasingly resistant to the antibiotics used to mitigate it. In fact, in another report accessed by ARA, the Department of Health warns that it is necessary to develop new treatments to "combat this growing threat to Catalan public health," as resistance is expected to increase in the coming years.

Another sexually transmitted disease that emerged significantly was MPOX, formerly known as monkeypox. Larrosa notes that there were thousands of infections in 2022 (more than 7,500 cases across Spain), and, furthermore, a new, more contagious and virulent variant was detected last year in African countries. The cases reached Europe, and in Catalonia, efforts were made to detect it quickly and prevent its spread, but no cases of the new variant have been found. Even so, the effort to detect the disease explains why between 2023 and 2024, reported cases grew by 153%, reaching 266 positive diagnoses. Both Larrosa and Casals agree that this is proof that the system works and that constant surveillance is key to detecting any threat. "We are prepared for whatever comes, even if it is unknown, like COVID. We have tests to know which family any pathogen comes from, even if we have never seen it before, and from there we can make decisions," the expert concludes.