“IT IS NECESSARY TO MONITOR THE DYNAMICS OF OTHER VIRUSES THAT CAUSE DIARRHEA EVEN WITH THE INTRODUCTION OF THE VACCINE AGAINST ROTAVIRUS”

Diarrhea surveillance results in children under 5 years of age highlight the need to continue monitoring enteric viruses even after nearly 10 years of rotavirus vaccine introduction in Mozambique. This finding is part of the scientific article entitled "Detection of enteric viruses in children under five years of age before and after the introduction of the rotavirus vaccine in Manhiça district, southern Mozambique, 2008-2019," recently published in the journal Viruses and authored by Percina Chirinda, a laboratory technician and junior researcher at the Manhiça Health Research Center (CISM).

Diarrhea is a leading cause of death, ranking third among children globally. The main causes of infectious diarrhea are enteric viruses, which account for approximately 75% of cases, particularly rotavirus and others such as norovirus, enteric adenovirus, sapovirus, and astrovirus. The Global Enteric Multicenter Study (GEMS) was conducted between 2007 and 2012 to estimate the burden and identify the main etiologies of childhood diarrhea in sub-Saharan Africa (Kenya, Mali, Gambia, and Mozambique) and Asia (Bangladesh, India, and Pakistan).

The study identified rotavirus as the main cause of diarrhea, and based on these results, the rotavirus vaccine was introduced in Mozambique in 2015. After the vaccine's introduction in Mozambique, CISM established a Diarrhea Surveillance Platform in the Manhiça district, which demonstrated a significant reduction in rotavirus diarrhea. However, there was still no data demonstrating the behavior of other enteric viruses that cause diarrhea, explains Percina, lead author of the article. "Reports from other countries have shown that as rotavirus diarrhea decreased, diarrhea from other viruses increased. With this study, we wanted to know what happened after the vaccine was introduced. So, we compared positivity in children hospitalized with moderate to severe diarrhea, with mild diarrhea, and in community controls to determine the changes resulting from the vaccine introduction."

This study analyzed approximately 4,634 stool samples, of which 1,779 were from diarrhea cases and 2,855 were from controls. It showed an increased frequency of detection of some enteric viruses after the introduction of the vaccine. For example, an increase in norovirus GII, enteric adenovirus, astrovirus, and sapovirus was observed in children with moderate to severe diarrhea and mild diarrhea. The researcher emphasizes that the results of this study show that with the introduction of the rotavirus vaccine, other viruses are becoming increasingly important. "We need to continue to monitor, monitor, and monitor the transmission dynamics of these viruses. In some countries, for example, the main cause of diarrhea after the introduction of the vaccine is norovirus, so attention has shifted. Therefore, it is necessary to conduct continuous molecular surveillance to generate data for the implementation of appropriate control and prevention measures, such as the development of new vaccines," she concluded.

The researcher also reported that the process of writing the article was challenging, but a unique experience. "However, we had positive experiences throughout the study and writing the article, which was led by Dr. Inácio Mandomando, the study's principal investigator. "When I looked at the first version of the manuscript and now look at the final article, the difference is stark. As the study coordinator for the laboratory area, it was a challenge to write for an audience with varying levels of knowledge, so they could read the article and understand its content. Normally, I only write for the scientific community I'm part of. Therefore, this was a major learning experience, as it was my first article as first co-author," said the researcher.