In this section, we will briefly mention the viruses that cause diarrhoeal diseases. The most prevalent infectious agents in this category are the rotaviruses. The WHO estimates that about 40% of all cases of severe infant diarrhoea worldwide, and at least 500,000 deaths in childhood from diarrhoeal diseases, are due to rotavirus infections – making these viruses the single biggest cause of diarrhoeal deaths. Most cases occur between the ages of three months and two years. Other viruses responsible for diarrhoeal diseases include the noroviruses.
The main manifestations of viral diarrhoeal diseases include acute, very watery diarrhoea, nausea and projectile vomiting, often (but not always) with fever and abdominal pain. Vomiting is called 'projectile' when the person cannot control the rapid emergence of vomit, which is projected forwards from the mouth with great force. Dehydration can occur rapidly in children and is the most common cause of death.
Individuals at highest risk from viral diarrhoeal diseases are malnourished children, weanlings and bottle-fed infants. To help prevent rotavirus infections, encourage exclusive breastfeeding under the age of six months; if the mother cannot breastfeed, or after weaning, encourage feeding with a very clean cup and spoon instead of a bottle. If bottles have to be used, show the parents how to wash the bottles and teats frequently and very thoroughly with clean warm water and soap.