Human Infection with Highly Pathogenic Avian Influenza A(H7N9) Virus, China

Abstract

The recent increase in zoonotic avian influenza A(H7N9) disease in China is a cause of public health concern. Most of the A(H7N9) viruses previously reported have been of low pathogenicity. We report the fatal case of a patient in China who was infected with an A(H7N9) virus having a polybasic amino acid sequence at its hemagglutinin cleavage site (PEVPKRKRTAR/GL), a sequence suggestive of high pathogenicity in birds. Its neuraminidase also had R292K, an amino acid change known to be associated with neuraminidase inhibitor resistance. Both of these molecular features might have contributed to the patient's adverse clinical outcome. The patient had a history of exposure to sick and dying poultry, and his close contacts had no evidence of A(H7N9) disease, suggesting human-to-human transmission did not occur. Enhanced surveillance is needed to determine whether this highly pathogenic avian influenza A(H7N9) virus will continue to spread.

Keywords: CMV reactivation; China; H7N9; HPAI; R292K mutation; acute respiratory distress syndrome; antimicrobial resistance; chickens; hemagglutinin; highly pathogenic avian influenza; hypoxia; influenza; neuraminidase; oseltamivir resistance; poultry; viral pneumonia; zoonoses.

Figure 1

Clinical course of 56-year-old man with diabetes and hypertension infected with highly pathogenic avian influenza A(H7N9) virus, China, 2017. CT, computed tomography; ECMO, extracorporeal membrane oxygenation; ICU, intensive care unit; MDR, multidrug resistant; NAI, neuraminidase inhibitor; POCT, point-of-care test.

Figure 2

Chest and brain imaging of 56-year-old man infected with highly pathogenic avian influenza A(H7N9) virus, China, 2017: radiograph imaging of chest at day 7 (A) and day 40 (D); computed tomographic scans of the chest (B) and the brain (C) at day 30.

Figure 3

Kinetics of viral load, oxygenation index, and HI antibody titers in 56-year-old man infected with highly pathogenic avian influenza A(H7N9) virus, China, 2017. Arrows indicate the days HI titers and viral titers in serum were acquired. HI, hemagglutination inhibition; neg, negative.

Figure 4

Phylogenetic analysis of the hemagglutinin gene of highly pathogenic avian influenza A(H7N9) viruses in Guangdong Province, China, and reference viruses. Maximum likelihood trees were constructed with PhyML by using the general time reversible plus gamma distribution plus proportion of invariable sites model. Node support was estimated by the SH-like aLRT method, and values >0.8 are shown. Virus clades A, B, and C—previously defined as W2-A, W2-B, and W2-C (5)—are labeled. A/Guangdong/17SF006/2017 (from a 56-year-old man), A/Guangdong/17SF003/2016, A/Taiwan/1/2017, and environmental isolates are underlined. Scale bar indicates nucleotide substitutions per site.