The study, published in ‘Eurosurveillance’, has analyzed 2,443 positive samples of EV between January 2019 and December 2024, of which five have tested positive for EV-C105. Specifically, one of the positives occurred in 2019; two in 2023; and two in 2024.
This is the first time this genotype has been detected in Spain since the surveillance of non-polio enteroviruses was established at CNM-ISCIII in 2006 through molecular methods. However, the results coincide with an increase in detections in other European countries, such as the United Kingdom, Slovenia, Italy, the Netherlands, and Belgium, which have also seen a rise since 2023.
Enteroviruses are a group of viruses that can cause a wide variety of diseases, from mild respiratory infections to severe neurological conditions, but until this study, only two cases worldwide had been documented where EV-C105 was associated with neurological conditions.
Thus, this research, in addition to identifying the presence of EV-C105 in respiratory cases, as reflected in most of the sporadic cases reported in the scientific literature, has also detected two neurological cases, related to two hospitalizations for meningitis and acute flaccid paralysis.
Furthermore, phylogenetic analyses of the EV-C105 strains detected in Spain have revealed that four of them belong to a new emerging lineage, called C1. This lineage is characterized by four mutations in key regions of the virus, which could be related to its ability to evade the immune system or to transmit more rapidly.
In this context, the research emphasizes the need to strengthen genomic surveillance to expand the databases of EV-C105 sequences, which will improve the understanding of its evolution and spread, and facilitate surveillance in case there are more strains in C1 that could be causing more neurological infections in children across Europe.
DIFFICULTY IN DETECTION
The detection of EV-C105 in multiplex PCR panels used in laboratories is challenging because, unlike other enteroviruses, it has a divergent genomic region called 5′-UTR.
In this regard, the CNM research has used various respiratory panels in participating hospitals to successfully identify it. The article points out that some commercial detection methods may not be able to detect it, potentially leading to underreporting of cases.
Another key aspect highlighted in this study is the appropriate choice of clinical samples. Traditionally, fecal and respiratory samples are the most commonly used for detecting enteroviruses in cases of neurological diseases, such as encephalitis or paralysis. However, it has been observed that some respiratory enteroviruses, like EV-D68, which can also cause neurological diseases, are rarely detected in feces.
In this line, EV-C105 also presents challenges for detection only in fecal samples in patients with neurological diseases, so for this study, the diagnoses of these patients were made through respiratory samples, as fecal samples were negative.
A similar finding seems to occur with EV-C105, as the two patients with neurological diseases in this study were diagnosed through respiratory samples, while fecal samples were negative. This highlights the importance of including respiratory samples in enterovirus surveillance, even in cases with neurological symptoms.
Overall, given that EV-C105 is an enterovirus with little presence in the scientific literature, the study’s conclusions emphasize the need to intensify genomic surveillance of these viruses and expand databases with complete genomes to better understand their evolution and transmission, given their potential to cause severe diseases and their rapid spread in Europe.
Furthermore, they recommend that clinicians be vigilant for possible neurological infections caused by this virus, especially in children, and suggest ensuring the collection of respiratory and fecal samples, as EV-C105 could pose a «new challenge» for public health in Spain and Europe.
FUENTE
