She was, scientists concluded, that most problematic of patients: an asymptomatic carrier.

Asymptomatic carrier fish and contaminated water provide reservoirs for disease.

Concerns are rising after experts warned that asymptomatic carriers could cause new cases.

They also have a campaign for everyone to wear masks in public places to protect others, especially as there are so many asymptomatic carriers.

Some records show whether the isolates were obtained from symptomatic or asymptomatic carriers.

The doctors are on the lookout for any asymptomatic cases of cardiac arrhythmia or cardiomyopathy (enlarged heart) that could be of significance in young people.

Ministers believe that if passengers were tested only at airports on arrival then many asymptomatic cases would not be picked up.

The decree allows 1,000 spectators to attend football matches and reduces the period of quarantine for asymptomatic cases from 14 to ten days if they test negative.

That won't stop the spread of the disease but it should be sufficient to dramatically slow the rate of transmission, not least by identifying asymptomatic cases.

But there's a big question mark over whether these tests would actually detect asymptomatic infection.

Here, they will get a mild cold, more likely an asymptomatic infection, and be set for life.

Researchers said there were also lower rates of asymptomatic infection in the vaccinated groups.

Widely dispersed minor outbreaks of mild and asymptomatic infection would leave a core of fit and immune people to deal with more intense outbreaks.

Clinical manifestations range from asymptomatic infection to severe illness.

The film may not have any signs in an otherwise asymptomatic patient.

State media said that 43 of the new cases involved previously asymptomatic patients.

A clinical trial involving 500 symptomatic and asymptomatic patients found that it had sensitivity of over 97 per cent and 100 per cent specificity.

Asymptomatic patients who test positive are reportedly monitored and isolated, but not included in public statistics, though they are able to transmit the virus.

Public health experts advising the government have warned about a rise in untraceable clusters, spread by asymptomatic patients.