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Border screening for infectious diseases has low detection rates
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Border screening for infectious diseases was ineffective, as evidenced by the widespread international transmission of severe acute respiratory syndrome in 2003 and influenza A(H1N1)pdm09 in 2009, according to recent findings published in Emerging Infectious Diseases.
“The intent of border screening is to detect possibly infectious persons at the border, either on entry to or exit from a country, so that they can be placed in isolation or prevented from traveling and spreading the disease elsewhere; however, this strategy is useful only if the intended goal is successfully achieved,” researchers wrote.
Researchers from Australia evaluated border-screening efforts during the 2009 influenza A(H1N1) virus pandemic and the 2003 severe acute respiratory syndrome (SARS) pandemic.
They found that border screening for A(H1N1)pdm09 was ineffective because people may be asymptomatic (eg, have no fever); therefore, many infected travelers went undetected. The border screening sensitivity and specificity for influenza infection was low. Infrared thermal image scanners are known for their low sensitivity, nevertheless, they were used to test for fever associated with A(H1N1)pdm09 at the borders of Singapore, Japan and Australia, according to the researchers.
In Singapore, only 15 of the first 116 international travelers infected with influenza A(H1N1)pdm09 were found during airport screenings. In Japan, only 6.6% of 151 influenza cases were identified during border screenings. In New South Wales, Australia, an estimated three out of 45 imported cases (6.7%) were identified through border screening, and in Auckland, New Zealand, four out of 69 cases (5.8%) were identified through border screening.
Similarly, border screening measures implemented in several countries during the SARS pandemic yielded low detection rates. In Australia, Canada and Singapore, no confirmed cases of SARS were detected through border screening. In Australia, infrared thermal image scanners were not used and four suspected/probable SARS cases were identified at the border, equaling 13.8% of the 29 cases of suspected/probable SARS detected in the country. Five people with suspected/probable SARs arrived in Canada during the screening period; each developed SARs symptoms after arriving in Canada, but none of these cases were detected at the border. Given the low prevalence of SARS infections among travelers, the researchers concluded the predictive value of border screening is zero and does not justify the public resources and costs required for implementation.
“We conclude that border screening should not be used,” they wrote. “Instead, the less costly measure of providing information to arriving travelers is recommended, together with effective communication with local clinicians and more effective disease control measures in the community.” – by Jen Byrne
Disclosure: The researchers report no relevant disclosures.
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