Rotavirus causes a third of hospitalizations for diarrhea in children under 5 in poor countries

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Human rotavirus infection is responsible for 1 in 3 (33.5%) hospitalizations for childhood diarrhea in children under five years of age in low- and middle-income countries.

When separated by age group, rotavirus continued to be the main agent causing hospitalization for diarrhea in all age groups, from 0 to 59 months, although infection by Shigella (bacteria) was proportionally higher in older children (reaching 17.9% in children aged 2 to 5 years versus 14.3% when considering all age groups).

In more severe cases, diarrhea resulting from the infection can lead to death. According to the WHO (World Health Organization), about half a million children worldwide die annually from complications of acute diarrhea.

The data are from a global study published in the scientific journal BMJ Global Health. The research, which was funded by the Bill and Melinda Gates Foundation, analyzed cases of childhood hospitalizations at 33 infectious disease surveillance centers (sentinel hospitals, with a record of at least 100 hospitalizations for diarrhea in children under five years of age) in 28 low- and middle-income countries in 2017 and 2018.

Among the countries are Bolivia, Ecuador, Paraguay and Peru in South America. Brazil was not included, but it has reference centers for sentinels of the so-called gastroenteric viruses, including Fiocruz (Fundação Oswaldo Cruz), in Rio de Janeiro.

To carry out the study, the researchers analyzed stool samples from nearly 26,000 patients hospitalized for diarrhea under the age of five and randomly tested one-fifth of them. The analyzes consisted of a PCR-type exam, which looks for the genetic material of the pathogen causing the infection — which can be viral, bacterial or other.

Rotavirus was present in 33.5% of the samples, while the other agents found were adenovirus (19.2%), norovirus (18%), the bacterium Shigella (14.3%) and sapovirus (10%). Another 12 different types of microorganisms, including bacteria Escherichia coli and the parasite Cryptosporidiumwere found in up to 1% of the materials.

THE Shigella was also the main responsible for childhood hospitalization in Central American countries (19.2%), while in South America (the study did not include Brazil) it was the norovirus type viruses (22.2%).

According to the researchers, the fact that rotavirus is not the main agent causing diarrhea in Latin American countries is due to the introduction of a national immunization program since 2010. Also according to the study, the introduction of vaccination has reduced by more than 50% the number of children hospitalized in these places (hospitalization rate from 42.1%, where there is no immunization, to 20.8%).

For José Paulo Gagliardi Leite, a researcher at the Laboratory of Comparative and Environmental Virology at the Oswaldo Cruz Institute (IOC/Fiocruz) and one of the authors of the study, the introduction of vaccination changes the behavior of this and other pathogens, which become more prevalent.

“The child will only have immunological maturity at 3 to 4 years, so what we see after immunization is a later hospitalization, and this is important because after acute respiratory infections diarrhea is the main cause of morbidity and mortality. [agravamento da saúde com risco de morte] in children under 5 years old”, he says.

According to other surveys, the introduction of the vaccine against human rotavirus was effective in reducing by 40% infections by the virus in children, which coincides with the result pointed out in the study.

Rotavirus vaccination coverage in Brazil, however, has been falling since 2018, according to data from the National Immunization Program Information System (SI-PNI, taken from DataSUS). After falling from 2016 to 2017, the application grew in 2018, reaching 91.33%. Afterwards, the rate dropped to 85.40% in 2019, 77.29% in 2020 and 70.53% in 2021

Data for 2022, still partial, show that less than half of children so far have received the vaccine in the states, with 45.33%.

According to the researchers, even with the presence of vaccination, some regions of the world continued with a high circulation of rotavirus, which can be explained by insufficient vaccine coverage, the high cost that rotavirus infections continue to present in the population and the low circulation of other pathogens in these countries.

The scientists conclude with a message of the importance of increasing vaccine coverage in countries where the prevalence of rotavirus is still the main cause of hospitalization for diarrhea in children and of also seeking more effective vaccines – currently, the vaccine available has an efficacy of 50% to 60%.

“The data confirm the importance of continuing and extending the coverage and introduction of rotavirus vaccination, as advocated by the WHO, which expects all children under 5 years of age to be immunized with at least one dose, but just under half of children born in 2018 globally were immunized,” the scientists say.

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