Estimating Risk to Humans Exposed to Highly Pathogenic Avian Influenza Outbreaks in the United States, 2014–2017

Abstract

BackgroundIn the USA, poultry outbreaks of highly pathogenic avian influenza viruses (AI) caused by H5 and H7 viruses have raised concern about the risk of infections in humans. Based on data from Asian lineage H5 and H7 AI, which sporadically transmit from poultry to humans, CDC currently recommends active daily monitoring of persons exposed to H5 and H7 AI viruses, including those who wear personal protective equipment (PPE).MethodsPersons exposed to HPAI-infected birds or contaminated environments in the USA were actively monitored during exposure and for 10 days post-exposure for illness, during 2014–2017. Some exposed persons were monitored on-site by USDA or contract safety officers, company staff, or state health officials. State health department staff monitored people during the 10-day post-exposure period. Persons reporting any respiratory illness or conjunctivitis were swabbed for molecular influenza testing. Preliminary results are presented.ResultsFrom 2014 to 2017, 270 detections in poultry/wild birds were reported and at least 606 persons were potentially exposed to AI virus by exposure to birds, carcasses, or environment. Most exposed persons wore PPE. No human infections with AI viruses were detected.ConclusionThe risk of transmission of these H5 and H7 AI viruses to humans was low. These preliminary data offer evidence to change the recommendations for monitoring in persons exposed to these viruses. If final data support these findings, self-monitoring by workers with reporting to health departments if symptoms develop, rather than active monitoring by public health personnel, could be considered. However, it will be important to reconsider and update recommendations as the viruses evolve. Furthermore, risk of infection likely varies by exposure and those without PPE should be actively monitored.YearHPAI virusNo. of detections reportedEstimated no. birds destroyedNo. of persons exposedNo. HPAI positive/no. of ill and testedPercent ill of all exposed (95% exact binomial confidence interval)December 2014–June 2015H5N2 H5N8 H5N1 H5241 22 215,639,861 254,669 0103 56 3 2 1640/50 (0–0.02)2016H7N8 H5N21 1 42,600 0319 Missing0/20 Missing0 (0–0.01)2017H7N9 H5N22 1 127,956 0123 Missing0/1 Missing0 (0–0.03)Disclosures All authors: No reported disclosures.