Prevalence of human bocavirus in children with acute gastroenteritis

Abstract

Background: Acute gastroenteritis (AGE) is a major cause of morbidity and mortality in children globally. Several reports have indicated that diarrheal diseases caused by viruses, bacteria and parasites are associated with unsafe drinking water, poor sanitation and hygiene practices which leads to infection in vulnerable individuals. Human Bocavirus (HBoV) have been reported globally in numerous studies as an emerging viral pathogen involved in AGE. However factors contributing to the infection, the genetic diversity and the transmission of the virus are poorly understood globally. There is currently limited data for HBoV prevalence, genetic diversity and possible transmission routes of the virus in South Africa, especially in rural communities where there is still challenges of poor water and sanitation infrastructure. Even though HBoV have been extensively reported globally, to date most of the reports have been reported in developed countries. Therefore, given the excessive burden of diarrheal diseases in developing countries, it is important to investigate the role of HBoV in diarrhea in a developing country such as South Africa. Objective: To determine the prevalence of HBoV in children with acute gastroenteritis and investigate the genetic diversity of strains circulating in the rural Vhembe district, Limpopo province, SA. Methods: In order to support the rationale of this research study, a systematic literature review which assessed the role of HBoV in diarrheal diseases in Africa, other developing countries and worldwide was carried out. Studies were selected which met the inclusion criteria: (i) Studies performed in Africa/other developing countries/worldwide between year 2005 and 2016. (ii) Studies for the detection of HBoV in patients with/without diarrhea and respiratory tract symptoms. (iii) Studies using standardized laboratory techniques for detection of HBoV including PCR, realtime-PCR, and Multiplex PCR (m-PCR). To determine the prevalence of HBoV genotypes in children (≤5 years) from rural communities in SA suffering from AGE, a study which investigated the prevalence of HBoV in children with AGE was done between 2017 and 2018 in rural communities in the Vhembe district municipality of the Limpopo province. A total of 141 stool samples were collected from children ≤5 years with AGE and the prevalence of HBoV was determined using a real-time multiplex PCR. Genetic characterization of HBoV was achieved through Sanger DNA sequencing, where the NS1 gene was used to confirm circulating HBoV genotypes. The genotypes were compared with those of reference strains available in NCBI GenBank circulating globally and phylogenetic trees were constructed using the Molecular Evolutionary Genetics Analysis (MEGA) 7 program. Results and Discussion: The literature search on HBoV prevalence yielded a total of 756 studies of which 70 met the inclusion criteria which included 11 studies from African countries and 59 studies from other developing countries and worldwide. The review showed that the prevalence rate of HBoV in Africa was 13%. Furthermore, revealed that HBoV infections are most likely to be underreported in Africa. HBoV was detected in 8 (5.7%) stools from the 141 children with AGE and mostly in children between 1-24 months of age. HBoV1 and HBoV3 genotypes were each detected in 3 (37.5%) stool samples and HBoV2 in 2 (25%) stool samples. Phylogenetic analyses were performed to compare identified HBoV genotypes to global circulating strains. Co-infection with other enteric viruses were also seen with Rotavirus (3/8; 37.5%); Adenovirus (3/8; 37.5%); Norovirus (2/8; 25%) and Astrovirus (1/8; 12.5%) in this study. Conclusion: The findings highlighted the prevalence and genetic diversity of HBV strains circulating in a rural area with little or no water and sanitation infrastructure. To our knowledge this is the first study in SA showing circulating HBoV genotypes in rural communities. More surveillance of individuals suffering from infections in South Africa is required to monitor the prevalence of HBoV and help understand the role of HBoV in individuals suffering from gastroenteritis with/without respiratory tract infection.