AsianScientist (Nov. 14, 2017) – In a study published in Infection, Genetics and Evolution, scientists in Japan have discovered that norovirus outbreaks in Indonesia are attributed to individuals who are infected but do not show symptoms of illness.
Norovirus, also referred to as the ‘winter vomiting bug,’ is the most common cause of acute gastroenteritis in humans. In Japan and Europe, the norovirus infection becomes prevalent during the winter season. However, scientists do not understand how it is transmitted in the subtropical climate of Indonesia.
In this study, a Japanese research team demonstrated that the norovirus is present in the stools of healthy volunteers in Indonesia who are asymptomatically infected with the virus. This suggested that asymptomatic infection is a source of norovirus outbreaks.
When the norovirus infects humans, it breeds in the intestine. The researchers thus collected stool samples from healthy volunteers in the city of Surabaya, Indonesia, and performed epidemiological analysis on the norovirus genome in the samples. A total of 512 samples from 18 healthy, asymptomatic volunteers over one year (2015 to 2016) was obtained.
Among these samples, 14 (2.7 percent) tested positive for norovirus. After further analysis, norovirus strains consisting of recombinant variations of the virus were detected, indicating that repeated infections with either the same strain or different strains was prevalent. The researchers concluded that asymptomatic individuals are infected with norovirus at a high rate, and these healthy individuals are an important source of norovirus outbreaks in Indonesia.
The team intends to analyze examples of norovirus infection within the families of the symptomatic carriers, using this data to identify the virus and host factors that are key in converting the norovirus infection from asymptomatic individuals to symptomatic infections. The researchers also plan to analyze the genome families of the epidemic strains and the transmission methods for norovirus infection in sub-tropical Indonesia, which could also help their understanding of norovirus infection in Japan.
The article can be found at: Utsumi et al. (2017) Occurrence of Norovirus Infection in an Asymptomatic Population in Indonesia.
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Source: Kobe University; Photo: Shutterstock.
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