Value of having 700 staff check arriving passengers for fever questioned

The prospect of an Ebola case hitting densely populated Hong Kong has left the city on edge since the massive outbreak in West Africa began earlier this year. But for 700 Hongkongers, keeping infectious diseases at bay has been part of daily life for the past 11 years.

That's how many staff the Health Department devotes to screening people passing through the city's 11 immigration entry points.

They have screened travellers' temperatures since the severe acute respiratory syndrome (Sars) outbreak killed 299 people in 2003. But the Ebola outbreak has put the spotlight on the effectiveness of border health checks; one of the scientists who discovered Ebola last week questioned whether screening every traveller was really worth it.

"Widespread screening [of arrivals] in airports is not that effective, to be honest," said Professor Peter Piot, director of the London School of Hygiene and Tropical Medicine. Screening departing passengers in the three worst affected countries - Guinea, Liberia and Sierra Leone - would be more cost effective in fighting the outbreak, which has killed almost 5,000 people.

Hong Kong's airport health checks have been stepped up since last month. Passengers arriving from Ebola-hit countries, or those who have visited an affected area in the last 21 days, have to fill in a health questionnaire upon arrival. The airport also tightened temperature screenings, lowering the fever threshold to 37.5 degrees Celsius. For Ebola, a temperature of 38.6 degrees Celsius or higher is considered significant.

As of Thursday, 10 days after the questionnaire was launched, 139 passengers had completed the forms. No arriving passengers reported Ebola symptoms.

Yet even the best temperature screening measures could miss up to 20 per cent of Ebola patients who had a fever, said a report by the European Centre for Disease Prevention and Control. The equipment used can give false negatives or false positives.