Genetic and epidemiological analysis of norovirus from children with gastroenteritis in Botswana, 2013-2015.
BACKGROUND
Norovirus is a leading cause of viral gastroenteritis worldwide with a peak of disease seen in children. The epidemiological analysis regarding the virus strains in Africa is limited. The first report of norovirus in Botswana was in 2010 and currently, the prevalence and circulating genotypes of norovirus are unknown, as the country has no systems to report the norovirus cases. This study investigated the prevalence, patterns and molecular characteristics of norovirus infections among children ≤5 years of age admitted with acute gastroenteritis at four hospitals in Botswana.


METHODS
A total of 484 faecal samples were collected from children who were admitted with acute gastroenteritis during the rotavirus vaccine impact survey between July 2013 and December 2015. Norovirus was detected using real-time RT-PCR. Positive samples were genotyped using conventional RT-PCR followed by partial sequencing of the capsid and RdRp genes. Norovirus strains were determined by nucleotide sequence analysis using the online Norovirus Genotyping Tool Version 1.0, and confirmed using maximum likelihood tree construction as implemented in MEGA 6.0.


RESULTS
The prevalence of norovirus was 9.3% (95% CI 6.7-11.9). The genotype diversity was dominated by the GII.4 strain at 69.7%. This was followed by GII.2, GII.12 each at 9.1%, GI.9 at 6.6% and GII.6, GII.10 each at 3.0%. The most common combined RdRp/Capsid genotype was the GII.Pe/GII.4 Sydney 2012. Norovirus was detected during most part of the year; however, there was a preponderance of cases in the wet season (December to March).


CONCLUSION
The study showed a possible decline of norovirus infections in the last 10 years since the first report. An upward trend seen between 2013 and 2015 may be attributable to the success of rotavirus vaccine introductions in 2012. Knowledge of circulating genotypes, seasonal trends and overall prevalence is critical for prevention programming and possible future vaccine design implications.
['Makhaola|Kgomotso|K|', 'Moyo|Sikhulile|S|', 'Lechiile|Kwana|K|', 'Goldfarb|David M|DM|', 'Kebaabetswe|Lemme P|LP|']
D000293:Adolescent D001902:Botswana D017250:Caliciviridae Infections D002648:Child D002675:Child, Preschool D005243:Feces D005260:Female D005759:Gastroenteritis D005838:Genotype D006801:Humans D007223:Infant D007231:Infant, Newborn D008297:Male D058889:Molecular Typing D029322:Norovirus D010802:Phylogeny D015995:Prevalence D012367:RNA, Viral D017423:Sequence Analysis, RNA D055815:Young Adult
Norovirus Botswana Genotyping GII.4 variants GII.Pe-GII.4