Rotavirus cases among Rotarix vaccinated children below five years during the 2018 outbreak in the Kingdom of Eswatini

Abstract

Background: A large outbreak of diarrhoeal disease in children under 5 years was reported in four surveillance sentinel sites Mbabane Government Hospital, Raleigh Fitkin Memorial Hospital, Hlathikhulu Government Hospital and Good Shepherd Hospital. Rapid increase of number diarrhoeal cases, were reported from week 34 to 41 (August to October 2018). Approximately 1,535 children presented with acute diarrhea, vomiting and dehydration. Methods and materials: Diarrhoeal stool samples were routinely collected for surveillance from children less than 5 years of age to determine the etiology of the diarrhoea. A total of 139 stool samples were tested for rotavirus using enzyme immunoassay kit, Molecular characterization using polyacrylamide gel electrophoresis, semi nested reverse-transcription polymerase chain reaction, sequencing and phylogenetic analysis. Rotavirus negative stool samples were further tested for bacteria and parasites using molecular diagnostic assays. Results: The rotavirus positive samples were positive for group A rotavirus with a prevalence of (117/211) 53% with the age groups mostly affected being;<12 months = (68/117)58.1%, 3-24 months = 23.9% (28/117) and >24 months = 16.2%(19/117). The PAGE patterns observed were long RNA migration pattern. The G3P[8] 59/75(78.6%) rotavirus strain were mainly associated with the outbreak. Phylogenetic analysis of the partial length VP4 P[8] associated G3 clustered together with other P[8] strains detected in Africa and distantly related to vaccine strains (Rotarix™ and RotaTeq™). Pathogens that were observed in Eswatini were Shigella/Enteroinvasive E. coli 18% (11/61) was frequently detected followed by Campylobacter jejuni/coli 13% (8/61) and Giardia lamblia 13% (8/61). Conclusion: Majority of the children affected by the rotavirus received vaccination and the rotavirus genotype G3P[8] was the major cause of these outbreak. It also important to note that the G3P[8] that was circulating was the wild type stains not related to the vaccine strains. As evident from the Maximum likelihood phylogenetic tree generated, G3P[8] study strains clustered in different lineages as compared to the vaccine strains (Rotarix™ and RotaTeq™). Further studies on whole genome sequence analysis are required to determine the evolutionary relationship among the strains and surveillance of rotavirus among the infants should be continued while increasing the rotavirus vaccine coverange and add a booster dose to increase protection.