Gymnast María Herranz, 17, died in the early hours of April 17-18, 2024 in Guadalajara hospital due to a fulminant case of meningitis B. The news caused great consternation in the world of sport and led to the start of an investigation which has now revealed that a new variant of meningococcus B caused a virulent epidemic in which another person died and two others were hospitalized in hospital. They were all between 17 and 31 years old.
The conclusions of the work have now been published in Eurosurveillancejournal of the European Center for Disease Control (ECDC). The investigation does not mention the gymnast – these studies use anonymous data – but four health sources confirmed this to EL PAÍS.
Raquel Abad, senior scientist at the National Center for Microbiology (CNM) and lead author, highlights the uniqueness of the epidemic: “It is more common for meningitis B to occur in isolated cases than in clusters of several patients with an epidemiological link. Genetic testing also revealed that the cause was a new variant of the bacterium. Neisseria meningitidis not described until then. “It also drew attention to the fact that it caused an epidemic of this virulence when it was first identified, which reinforces the need to monitor these new variants.”
Meningococcus B is the most common serogroup (there are also A, C, W, Y…) of bacteria Neisseria meningitidis. The serious infections it causes are called invasive meningococcal disease (IMD) and cause meningitis – infection of the membranes covering the brain – or sepsis, when it invades the bloodstream.
“In both cases it is a low incidence but devastating disease. It is not uncommon for those affected to go from being perfectly well to developing fatal symptoms or suffering significant consequences in 24 hours,” explains María Teresa Ledo, of the Spanish Society of Preventive Medicine, Public Health and Health Management (SEMPSPGS).
The origin of the epidemic: a meeting in March 2024
The article places the origin of the epidemic in a meeting held in March 2024 with 13 participants with an average age of 30 years. Three days later, one of them began to experience fever, pain when swallowing and diarrhea. After 48 hours he was admitted to hospital and “that same day he died with a diagnosis of meningococcal sepsis”.
Two days later, a second person who lived with the first developed similar symptoms. “He was admitted to hospital with a diagnosis of septic meningitis,” the study continues. He spent 14 days hospitalized, but managed to recover and was discharged.
Two weeks after the first meeting, eight of his assistants went to a small town in Guadalajara for three days with other people. One of them – who had not been at the first meeting, but was at the second – started having headaches, fever and vomiting after five days. “He was hospitalized for meningococcal meningitis.” He recovered and was discharged a week later.
The latest link in the epidemic is that of María Herranz. The gymnast lived in Cabanillas del Campo, a nearby town where the second group had gone. She began experiencing fever and abdominal pain on April 17, and although she was immediately admitted to hospital, she died within a few hours. Although the epidemiological link to the epidemic appears weak, genetic tests concluded that he was infected with the same variant as others affected.
The characteristics of the epidemic show that the new form of the pathogen was circulating in those weeks among some people of the two groups and in the area they visited in Guadalajara. Some infections were asymptomatic – otherwise the disease would not have reached María Herranz – and others developed severe symptoms. This is common with meningococcus, according to experts.
“Many people are infected without suffering any harm, while others develop very serious symptoms. One in 10 infected people will even be asymptomatic carriers of the bacterium without suffering any health problems,” says Ledo.
The need for close contact for transmission
THE Neisseria meningitidis It requires close contact to be transmitted and does so through saliva and respiratory secretions. It initially colonizes the upper respiratory tract and, in most cases, the immune system manages to keep it at bay. But in some circumstances, the meningococcus crosses the nasal mucosa and progresses to meningitis, sepsis, or both.
A weakened immune system can favor this poor evolution. Another moment of risk is when the first infection occurs, which is more common in children, adolescents and young adults due to their way of relating. “This is why rapid intervention by public health services when a case is detected to identify contacts is very important. The way to prevent new cases is to administer antibiotic prophylaxis,” explains Ledo. The study states that in this epidemic “200 close contacts were identified”, who were offered prophylaxis.
The authors underline that “the high lethality of the epidemic (two out of four cases) is also surprising and constitutes another relevant aspect to take into account in the surveillance of these variants”. Mortality among people who develop invasive meningococcal disease due to serogroup B is usually around 10%.
Raquel Abad says that, after the epidemic, the “National Microbiology Center detected two more cases caused by the new variant.” One of these occurred in December 2024 and the other last January, although the clinical evolution of both patients was not revealed.
One explanation for the months that have passed without new diagnoses could be that the variant has died out, although it could also continue to live asymptomatically in some people or have caused another case without being detected. The Center, which depends on the Carlos III Health Institute, receives the majority of samples from meningitis cases in Spain, between 70% and 80%, but not all.
336 cases and 31 deaths in 2024
Diego García Martínez de Artola, spokesperson for the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), explains that the emergence of new variants of Neisseria meningitidis It is not a strange thing, even if the virulence of this epidemic is: “It is something that happens very often with this bacterium and with another of the same genus that causes gonorrhea, Neisseria gonorrhoeae. The reason is that they have great genetic diversity and the ability to capture the DNA of other bacteria. Neisseria. The result is that recombinations occur that give rise to new variants.”
According to the 2024 report of the Carlos III Institute of Health, 336 cases and 31 deaths were reported in Spain last year due to invasive meningococcal disease – which is obligatory –, with a mortality rate of 9.23%. Two out of three patients were caused by serogroup B. The vast majority of deaths occur among the elderly, while among children these have been reduced in the last decade thanks to vaccines. According to the report, the now published epidemic caused two of the four deaths recorded from the disease in Spain in 2024 among people aged 15 to 44.
Pere Godoy, of the surveillance group of the Spanish Society of Epidemiology (SEE), explains that “in three years there has been a resurgence of cases caused by meningococcus B, the incidence of which decreased significantly in 2020 with the pandemic and is now recovering its predominance among the rest of the serogroups”. According to this expert, it remains to be seen whether the vaccine used against him, called Bexsero, will be able to mitigate its impact at the population level, something that another vaccine has achieved, the so-called “conjugate” which protects against other serogroups such as A, C, W and Y.
