Airport screening for Ebola
BMJ 2014; 349 doi: https://doi.org/10.1136/bmj.g6202 (Published 14 October 2014) Cite this as: BMJ 2014;349:g6202
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Simon Howard believes that a reduction of 13% in the number of Ebola cases imported nto the UK would be relatively substantial. We do not disagree with this, but screening of passengers on arrival in the UK will not reduce the number of imported cases, as they have already arrived in this country. The key priority should be to ensure that people at risk of Ebola arriving in this country are informed about the action they need to take if they become ill in the 21 days following their arrival.
Competing interests: No competing interests
We endorse the sentiments expressed in the BMJ Editorial on Airport Screening for Ebola,1 which challenges the policy of enhanced screening as presently used. Whether applied to those exiting an affected area or arrivals, apart from being easily circumvented, temperature checks depending on currently deployed thermal scanning procedures in common use are the least reliable.
When using remote sensing infrared thermography, the most reliable estimate of body temperature is obtained when the probe is targeted at the ear and not the forehead or face; the most accurate reading accrues if the camera points to the side of the face and is at a short distance (about 1 m) from the hotspot in the ear. These findings stemmed from research carried out in Hong Kong during and following the SARS epidemic.2,3
It is hardly surprising therefore that a health care worker arriving in New York after caring for Ebola patients has complained bitterly about her detention and quarantine based on readings from a forehead scanner and a confusing array of other findings. This account was first published in the Dallas Morning News,4 and later generated much controversy in a host of print and other media worldwide. Under the circumstances, authorities who undertake or demand such screening should be made aware of the observations from Hong Kong.
We declare no conflicts of interest
CR Kumana, BMY Cheung, LS Chan
The University of Hong Kong
Correspondence may be addressed to CR Kumana (hrmekcr@hku.hk)
References
1. Mabey D, Stefan F, and Edmunds WJ. Airport Screening for Ebola (Editorial). BMJ 2014;349:g6202.
2. Chan LS, Cheung GTY, Lauder IJ, and Kumana CR. Screening for fever by remote sensing infrared thermographic camera. J Travel Med 2004; 11:273-9.
3. Chan LS, Lo JLF, Kumana CR, and Cheung BMY. Utility of infrared thermography for screening febrile subjects. Hong Kong Med J 2013; 19:109–15.
4. Kaci Hickox 2014. Her story: UTA grad isolated at New Jersey hospital in Ebola quarantine. Dallas Morning News 25 October 2014.
Competing interests: No competing interests
The implication that airport screening will make little difference seems to overlook that the fact that countries are knowingly bringing back nationals infected with Ebola for 'western' standards of health care which have shown to be inadequate. There would appear to be a case for placing members of staff in quarantine when working with patients infected with Ebola to reduce risk to co-workers and members of public. The international response has been slow but finally mobile facilities are being deployed in the source countries. It remains to be seen if these are overwhelmed.
Competing interests: No competing interests
While the enhanced port of entry screening is problematic, it appears many governments and agencies are keen to satisfy political pressures as citizens demand to see some action by their governments on their behalf. Being informed and observing the border screening measures calms fear, which is an outcome that government intend also to achieve.
Competing interests: No competing interests
Dr Cosford's comments are fine as far as they go. Is he also able to respond to the questions raised by me and others in the last few days? Some of the questions have legal implications.
Competing interests: No competing interests
The Ebola outbreak in West Africa is an unprecedented public health crisis, and has been described by the WHO as the 'most severe acute health emergency in modern times'.
As part of the UK response, Public Health England (PHE) has put in place enhanced entry screening for Ebola in passengers that Border Force officers identify as having travelled from Sierra Leone, Guinea and Liberia. This screening is already in place at Heathrow, and will shortly roll out to Gatwick and St Pancras (Eurostar).
The BMJ editorial of 14 October questions the number of people with active Ebola symptoms that will be detected as a result of UK entry screening. Due to the unprecedented nature of this outbreak, the impact of screening is difficult to quantify. However we recognise that because of the exit screening in place at airports in Sierra Leone, Guinea and Liberia, we do not anticipate identifying large numbers of people with active disease. Nevertheless, we do consider that enhanced entry screening acts as an extra level of safety and reassurance for the UK public.
The editorial highlights the incubation period of the Ebola virus of up to 21 days. One major aim of the screening process, not addressed in the editorial, is the opportunity to quickly identify anyone who might be at risk of developing Ebola at a later stage, and to provide targeted advice on what action they should take if they do develop symptoms. Those who are identified as being at particular risk will be actively followed up. Ensuring anyone at risk has rapid access to healthcare services is important not only for their own health but also to reduce the risk of transmission to others. We are in agreement with the authors that this is a key priority.
We fully acknowledge that even with exit screening in place in the affected countries of West Africa and this enhanced screening in the UK, no system can completely prevent a case of Ebola coming into the UK. However our intention is that these extra measures will help to decrease the critical time from symptom onset to diagnosis and isolation that is so important in reducing the risk of secondary transmission, if a case should arise in a returning traveller.
It is important to remember that the best way of halting the Ebola outbreak remains to control and contain the virus in the affected countries. In addition to our work here in the UK, PHE and other UK staff will continue to work on the frontline as part of the international effort to tackle Ebola in West Africa.
Competing interests: No competing interests
It is hard to disagree with the authors' substantial point that screening may be falsely reassuring and economically questionable. However, I question the validity of a number of assumptions in this paper.
I note that the authors use modelled data for their estimate of pick-up rate of Ebola cases following flights, including a duration of "direct flight from Freetown to London 6.42 hours".
There is no indication that the authors have considered that several factors are likely to increase the screening interval beyond the impractically precise 6.42 hours direct flight time, and even beyond the 13 hour-estimate for an indirect flight, and hence may increase the detection rate slightly:
1. Screening at West African airports takes place on arrival at the airport, or even en route to the airport, rather than at boarding.
2. Arrival screening will take place some time after the flight has landed, not at the point of landing.
I also find it hard to understand the authors' implied dismissal of a detection rate of 13% as an "insubstantial" fraction of cases, particularly given that the confidence interval reaches 21% and - for the reasons above - this is likely to represent an underestimate. Given the relatively small numbers of expected imported cases, and the relatively small number of NHS beds of the appropriate level, a reduction of up to a quarter in the expected number of imported cases seems relatively substantial (though perhaps not cost-effective).
Competing interests: No competing interests
Re: Airport screening for Ebola
The editorial points out of the probable lapse in airport screening for Ebola ( 1)
Currently, it is premature to assess the efficiency of such preventive measures, considering the unsuccessful screening programme introduced in Canada during the last SARS outbreaks in 2003.(2) Even if it is theoretically possible to have some cases of Ebola in the UK, could it be so devastating as in West Africa?
It is true that with an average mortality rate up to 60 %( 25 -90%) and with no effective vaccine or medicine to fight, Ebola makes a lethal and fearsome disease. Prevailing health system, culture, education, religion and socio-economic status can also play a crucial role in the transmission and prevention of infectious diseases such as Ebola. For instance, hepatitis B vaccination was made mandatory in Italy in 1991. A marked decline in the incidence of hepatitis B had started before the mandatory introduction of the vaccine. This can be attributed to an overall improvement in the health awareness of people, socio-economic status, demographic changes (smaller families), intensifying blood screening, better hygiene, changes in risky behaviour subsequent to anti-AIDS campaigns, and selection of universal precautions in all medical settings (3) In W. Africa a lot of unfavourable factors such as the local burial customs, which involve washing, touching and kissing of dead bodies before burial, lack of awareness, shortage of resources and poor health care system might have contributed to the worst ever outbreak.
In the UK/ Euro zone the situation is completely different and an outbreak of Ebola is most unlikely, even though sporadic cases with some casualties might occur.
References:
1.Airport screening for Ebola will it make a difference? David Mabey,Stefan Flasche, W John Edmunds. BMJ 2014;349:g6202
2.SARS airport screening ineffective , study says. BBC News, Dec 29,2004
3.Luisa Romanò, Sara Paladini, Alessandro R. Zanetti. Twenty years of universal vaccination against hepatitis B in Italy: achievements and challenges. Journal of public health research : Vol1, No 2 (2012)
Competing interests: No competing interests