Gastroenteritis viruses

Asymptomatic shedding and High infectious dose

Asymptomatic shedding refers to the excretion of viral particles in feces even after the individual has recovered from symptoms of the infection. This can pose a significant risk for the transmission of the virus, as infected individuals may unknowingly spread the virus to others through contaminated surfaces or food. The term 'high infectious dose' refers to the small number of viral particles required to cause an infection, particularly highlighted in noroviruses, where as few as 18 viral particles can trigger illness. These characteristics contribute to the rapid spread of viral gastroenteritis in communal settings, emphasizing the importance of hygiene and sanitation practices.

Rotavirus

A non-enveloped virus responsible for severe gastroenteritis in children, featuring a triple-layer capsid and requiring the VP4 protein's cleavage by host proteases for infectivity.

Norovirus

A highly transmissible, non-enveloped virus that mainly affects adults and is known for outbreaks in closed environments, characterized by its high infectious dose and potential for asymptomatic shedding.

Pathogenesis and Transmission

The process by which a virus causes disease in the host involves disrupting normal host functions. Gastrointestinal viruses primarily use the oral-fecal route for transmission, often through contaminated food or water.

Epidemiology

The study of how frequently diseases occur in different groups of people and their causes. Key concerns in viral gastroenteritis include dehydration and the impact on young children and the elderly.

VP4 protein and Triple-layer capsid

The VP4 protein of rotavirus is crucial for infectivity, and the virus features a triple-layer capsid that protects its RNA genome. Noroviruses produce sub-genomic RNA for efficient protein synthesis.

Immunity

The state of being resistant to a specific infection, which is often not long-lasting for RNA viruses like rotavirus and norovirus. Immunity to infections such as astroviruses may lead to lasting resistance.

Asymptomatic shedding and High infectious dose

Asymptomatic shedding refers to the excretion of the virus in feces after symptoms have resolved, contributing to transmission risks. High infectious dose indicates the low number of viral particles needed to initiate an infection, particularly noted in noroviruses.