The impact of paediatric rotavirus gastroenteritis remains high in Gipuzkoa

The rotavirus is the main cause of severe, acute paediatric gastroenteritis across the world. According to estimates by the WHO, in 2013 there were over 200,000 deaths of children associated with acute rotavirus gastroenteritis across the world with nearly all the cases in developing countries. In developed countries, mortality from the rotavirus is very low, but it places a considerable burden on healthcare systems. Despite that, "it is an illness that has been little studied in terms of its epidemiological characteristics, in other words, seasonality, distribution by age and incidence, and genotypes (virus subtypes) in circulation. That is why this work is providing fresh data that may be important for the health authorities when it comes to making decisions in the matter of healthcare, such as the deployment or otherwise of the vaccination against the rotavirus", said Ainara Arana, author of the research conducted at the UPV/EHU and at Biodonostia.

The study concludes that even though the impact of rotavirus infections has lessened throughout the monitoring period, it remains significant: the rotavirus has been the first cause of hospitalisation due to acute gastroenteritis in children under the age of five. During the twenty years covered by the research a reduction has been seen not only in outpatient samples but also in the number of cases admitted to hospital as a result of rotavirus gastroenteritis. "This fact could be linked to the better management of infant diarrhoeas in the family environment, improvements in healthcare, and increased use of oral rehydration solutions that provide fluids and salts to reduce the risk of dehydration, above all in very small children. So many of the cases are treated at home by parents and are not referred to hospital".

On the other hand, during the last five years of the study a delay in the onset of epidemics has been noticed. "In countries in the south of Europe (Spain, Italy, etc.) the epidemics usually start around November and in countries located further north, such as the United Kingdom, they start later on, around January. Yet we have seen that in our area from 2011 onwards the onset of the epidemic has been delayed until January or even February, and tends to be on a par with those of countries in Northern Europe," added Arana. With respect to the causes of this shift, "it could be due to climate change or to the fact that some of the nearby European countries have greater vaccination coverage, although these are mere hypotheses". With respect to the genotypes circulating in Gipuzkoa, "their distribution is fairly similar to that observed in Europe: G1 is the most frequent genotype, followed by the emerging G9 and G12 genotypes that are playing an increasingly significant role. During the last five years studied, G12 is even more prevalent than G1". However, the study highlighted the occurrence of infections by rare genotypes of animal origin (e.g. sheep) and the frequent circulation of viruses of various, distant geographical origins (Asia, Australia, etc.) and even of recombined (hybrid) viruses.  The author of the study stresses the importance of "monitoring the strains circulating in our area to find out whether the vaccinations existing on the market continue to be effective since new genotypes could emerge and would make the modification of the composition of the current vaccines advisable".

Reinfections

Rotavirus reinfections account for just over 1% of the cases requiring medical assistance. "That does not mean that there have hardly been any reinfections, but that they did not need to go to the doctor". The study shows that most of the reinfections are caused by genotypes that are different from the one that caused the first infection, in other words, "if a child is infected by one type of virus, it is more probable that he/she will be reinfected by another type of virus that is different from the one that caused the first infection," added Ainara Arana.

Additional information

This study is part of the PhD thesis of Ainara Arana-Salaverría (Irun, 1986) ‘Epidemiología de la infección por rotavirus en Gipuzkoa (1995-2015). Carga de la enfermedad y genotipos circulantes' [Epidemiology of rotavirus infection in Gipuzkoa (1995-2015). Burden of the illness and circulating genotypes]. The thesis was supervised by Dr Emilio Pérez-Trallero, Professor of Preventive Medicine and Public Health of the UPV/EHU and Head of the Microbiology Service at University Hospital Donostia, and co-supervised by Dr Gustavo Cilla-Eguiluz, head of the Virology and Serology Section of the Microbiology Service at University Hospital Donostia. The researcher obtained a pre-doctoral grant from the Basque Government to do her thesis. In addition to that, she did an internship at the Institute of Infection and Global Health in Liverpool.