Epidemiology of rotatirus diarrhoea in children under five years years of age from selected healthcare facilities in Swaziland

Abstract

Background: It has been established that rotaviruses are the main cause of acute gastroenteritis in children worldwide, resulting in more than 453 000 deaths, with a high mortality still occurring in African countries and Asia. In Swaziland, diarrheal diseases are a common cause of morbidity and mortality among children <5 years of age. Approximately 10% of hospitalised Swazi children die due to diarrhoea every year. Through financial assistance from the World Health Organization (WHO), many African countries have conducted a lot of rotavirus disease studies. In Swaziland, the epidemiology of rotavirus infection is unknown due to lack of data. Thus, the study’s aim was to examine the epidemiology and characterize rotavirus strains in children <5 years of age, hospitalised and attending the outpatient departments of public and private healthcare facilities in Swaziland.

Materials and methods: A total of 745 diarrheal stool specimens were collected from children <5 years of age from April 2009 to December 2010. Group A rotavirus antigen was detected using a commercially available enzyme immunoassay (EIA) kit (ProSpectTM, Oxoid Ltd, UK). Polyacrylamide gel electrophoresis (PAGE) was used to determine the electrophoretic pattern of rotavirus strains. The P and G genotypes were established by reverse transcription polymerase chain reaction (RT-PCR) and multiplex hemi-nested PCR amplification of the VP4 and VP7 genes respectively, using type-specific primers. Sequencing was performed on 35 specimens to confirm the circulating genotypes. The phylogenetic tree and similarity distances between genotypes were constructed using the neighbour joining method and the Kimura two-parameter model package in the MEGA version 5.05 software program.

Results: Group A rotavirus was detected at 13.3% in 2009 (based on samples collected from April to December) and 23.4% in 2010 (based on one year collection) from children <5 years of age hospitalized and attending outpatient departments. The rotavirus infection was more frequently detected in the age group 0-11 months (22.2%). Gender did not play a major role in rotavirus infection, because both male (20.8%) and female (18.8%) children were equally affected. Of the children that were admitted in the hospital, 33.3% were affected by rotavirus infection compared to those attending the outpatient departments (13.5%). The rotavirus infection was observed during the cooler, drier months of the year. The three most predominant G and P genotypes detected were G2P[4] (30.4%), followed by G1P[8] (15.5%) and G9P[8] (8.8%). A significant number of uncommon rotavirus strains (32.4%), mixed infections (8.8%) and nontypeables (4.1%) were also detected. The circulating genotypes detected were classified into lineages and sub-lineages defined by phylogenetic analysis of nucleotide sequences. The Swaziland strains were found clustering with known African and global strains from the GenBank.

Conclusion: The findings of this study reveal that group A rotaviruses are the etiological agents of severe diarrhoea in children under 5 years in Swaziland. The diversity of rotavirus strains that were detected highlights the importance of introducing the rotavirus vaccine in the country. The currently licensed vaccines may confer protection against the circulating strains detected in this study. Data on the burden of rotavirus disease in Swaziland will be used to convince the Ministry of Health and policy makers in the country to advocate for the introduction of the rotavirus vaccine. This is the first data on the epidemiology and characterization of rotavirus strains in Swaziland; therefore there is a need for continuing with the surveillance of rotavirus in the existing sentinel sites to determine the impact of rotavirus infection over time. It is also essential to continuously monitor the rotavirus strains circulating among Swazi children.