The rapid spread of the deadly coronavirus may be due to "faecal-oral transmission", according to Chinese researchers, who have discovered the live virus in stool specimens for the first time.
The discovery announced by the Chinese Centre for Disease Control on Saturday may explain why the Covid-19 virus was able to spread so quickly among passengers and crew on-board the Diamond Princess cruise ship, news.com.au reports.
"In addition to close contact and contact with respiratory secretions of patients, the virus can also be transmitted through the potential faecal-oral route," the CCDC said.
"This means that stool samples may contaminate hands, food, water, etc, and may cause infection by invading the oral cavity, respiratory mucosa, conjunctiva, etc. This virus has many routes of transmission, which can partially explain its strong transmission and fast transmission speed."
The agency recommended a number of measures to prevent faecal-oral transmission in epidemic areas, including drinking boiled water, avoiding raw food, frequent hand washing and disinfecting of surfaces, and preventing water and food contamination from patients' stool samples in medical facilities.
In 2003, a single patient with Sars — another coronavirus which binds to the same protein receptors as Covid-19 — was believed to be responsible for infecting up to 300 people in a Hong Kong housing complex through their diarrhoea after a "virus-laden aerosol plume" wafted through the building's air shafts.
In a separate study, the CDCC has also confirmed for the first time that the virus can be transmitted even when the infected person never shows any symptoms.
Researchers said the discovery that a 20-year-old woman from Wuhan infected five of her family members despite never becoming physically ill herself could mean "the prevention of Covid-19 infection would prove challenging".
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It comes after the World Health Organisation warned Friday that the window to stem the deadly coronavirus outbreak was shrinking, amid concern over a surge in cases with no clear link to China.
WHO chief Tedros Adhanom Ghebreyesus has for weeks insisted the low number of cases of Covid-19 outside the epicentre of the deadly outbreak in China's central Hubei province presented a "window of opportunity" to contain the international spread.
But as cases surged across the Middle East and in South Korea Friday, he cautioned for the first time that while "we are still in a phase where containment is possible … our window of opportunity is narrowing".
He warned that if countries did not quickly mobilise to fight the spread of the virus, "this outbreak could go in any direction. It could even be messy".
The outbreak which began in December has already killed more than 2200 people and infected more than 75,500 in China.