This was a cross-sectional study. The data were collected from 01 February 2020 to 28 February 2021, focused on the assessment of rotavirus infection in children presenting with acute diarrhoea at the Albert Schweitzer Hospital (HAS). All children with diarrhoea who come to the hospital are seen in the paediatric ward. A full-year recruitment period was chosen to cover all seasons (dry and rainy) in the region. Lambaréné is a small town in Gabon,¹¹ it is located 240 km (by road) southeast of Libreville (the capital of Gabon). Lambaréné’s climate is equatorial: hot and humid. The year begins with a dry season between January and February, followed by a rainy season between March and May, a dry season from June to September and finally a rainy season from October to December.

All children under 5 years with acute diarrhoea (characterised by loose, watery stools that typically last for a short duration, up to 2 weeks¹² consulting in the paediatric ward were eligible. Neonates and children whose parents refused to provide informed consent to participate were excluded.

After explaining the study to parents and/or legal guardians, informed consent was signed, and all children meeting the inclusion criteria were included in the study. The medical investigator collected socio-demographic information (age, sex, number of persons living in the same room, education level of mother or guardian) and vaccination status using a data collection form. Clinical examination was performed to evaluate hydration and neurological status and the presence of fever (which was defined as an axillary temperature exceeding 37.5 °C on admission). Stool specimens were collected on the day of enrolment using a sterile container and sent to the microbiology laboratory for analysis on the same day. Stool samples were processed using an immunochromatographic assay detection kit, SD BIOLINE Rota and Adeno (Standard Diagnostic, Inc.), Suwon city, Korea, according to the manufacturer’s instructions. The Standard Diagnostic (SD) BIOLINE Rota and Adeno test has a sensitivity of 94% and specificity of 98.3%.¹³

The estimated sample size of the study was 152 children under 5 years, calculated based on the minimum proportion of rotavirus expected of 11%^3,14 among children under 5 years with acute diarrhoea in the region: confidence interval (CI) of 95% (type value 1.96) and random error of 5% (type value of 0.05). The sample size was determined using EPI Info software.¹⁵

The data entered in the ‘Redcap’ database was exported with R Studio software version 3.6.1 (Foundation for Statistical Computing, Vienna, Austria) for clearance and statistical analysis. The normality of the quantitative variables was assessed using the Shapiro–Wilk test and visual inspection of the histogram. To identify the factors associated with rotavirus infection, we categorised them into two groups: socio-demographic and clinical factors. Firstly, a bivariate analysis of the variable ‘rotavirus’ with demographic and clinical characteristics was made. Secondly, we performed the multivariate analysis (logistic regression). The socio-demographic and clinical variables with a p-value less than 0.2 during the bivariate analysis were included in the multivariable model. We added to this the variables (children’s age, gender, source of drinking water and fever), which did not meet the 20% p-value rate at the bivariate level but were described in the literature as associated with rotavirus infection. Crude odds ratio (COR) and adjusted odds ratios (aOR) were generated, as well as their 95% CI. We checked the adequacy of the model using the Hosmer and Lemeshow test (goodness-of-fit test). The model adequacy test concluded that there was a good adequacy with a p-value = 0.888.

Ethical clearance to conduct this study was obtained from the Lambaréné Medical Research Center Institutional Research Ethics Committee (No. 003/2017). Parents or guardians were requested to sign a consent form for their willingness to participate in the study.

A total of 201 parents or guardians’ children were approached for the study, and 178 agreed to have their children included. The median age of the children was 12 months, with an interquartile range (IQR) of 7–18 months. None of the children received the rotavirus vaccine. The mothers or guardians of the children who had diarrhoea during the study period were aged 18–48 years. The majority (56%, n = 100/178) of these mothers were young adults between 18 years and 25 years of age. The peak of rotavirus proportion was observed during the dry season.

The proportion of rotavirus infection in children who provided stool samples was 22% (n = 39/178; 95% CI: 16% – 29%). In a bivariate analysis, children from mothers between the ages of 26 years and 30 years, compared to those between the ages of 31 years and 48 years, were more likely to have rotavirus in their stools (OR = 2.38; 95% CI: 1.87–7.13), as shown in Table 1. Children whose mother had at least secondary education were less likely to have rotaviruses in their stool (OR = 2.51, 95% CI: 1.16–5.83). The associated clinical factors were: lethargy (OR = 2.85; 95% CI: 1.34–6.04), dehydration (OR = 2.32; 95% CI: 1.11–5.14) and hospitalisation (OR = 2.54; 95% CI: 1.23–5.35) (Table 2).

Independent clinical presentations associated with rotavirus infection were using water-closet toilets (aOR = 0.38; 95% CI: 0.15–0.94), dehydration aOR = 2.65; 95% CI: 1.09–6.86), vomiting (aOR = 3.15; 95% CI: 1.29–8.25), lethargy (aOR = 3.12; 95% CI: 1.16–8.71) and hospitalisation (aOR = 4.63 (95% CI: 1.7–13.65), as shown in Table 3.

Our study best describes the hospital-based proportion of rotavirus diarrhoea in Lambaréné. Our study is of public health interest; it determines the proportion of rotavirus diarrhoea before the possible introduction of the rotavirus vaccine in the EPI in Gabon. This study is the first, to our knowledge, to describe the factors associated with rotavirus in children under five in Lambaréné. However, some limitations are to be noted. The cross-sectional design of our study did not allow the collection of additional follow-up data. It would have been interesting to follow up with children to assess the outcome of treatment and mortality related to rotaviruses in Lambaréné. In addition, the causal relationship between diarrhoea and the presence of rotaviruses cannot be established in our study, and we cannot exclusively associate clinical signs with rotaviruses alone because the other pathogens responsible for gastroenteritis in children were not assessed. No genotyping analysis was performed to determine the serotype and genotype of rotavirus. This was also a hospital-based study, so we may have missed a lot of non-hospitalised cases. Despite these limitations, our study greatly contributes to enriching the epidemiology of rotavirus infection in SSA, especially in central Africa, where data on the proportion of rotavirus infection are scarce. Our study also opens up research perspectives on the morbidity and cost-effectiveness of the introduction of the rotavirus vaccine could have among children in Gabon