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Paradigm Shift Intervention Monitoring
Nosocomial H7N9 Sequences at Tuen Mun
The above translation from the Centre for Health Protection (CHP) Department of Health December 8 Epi update indicates the recent H7N9 case lives in northwestern Shenzhen (see map), which is also the location of the Fuyong People’s Hospital where the case initially sought treatment for chronic diabetes and cardiac problems. After discharge, he traveled from Shenzhen to Tuen Mun Hospital (TMH) on December 3 where he was admitted for treatment for his chronic conditions. Three days later, on December 6 he developed a fever and was tested for H7N9, which was confirmed. Thus, the development of flu-like symptoms three days after admission is consistent with nosocomial transmission.
The possibility of H7N9 nosocomial transmission is increased by the prior treatment of the first confirmed H7N9 case (36M) at the same hospital. A sample collected by the CHP on November 30 was the source of a complete sequence, A/Hong Kong/5942/2013 (HK/5492), which was released at GISAID on December 4.
A similar turn-around time for the second confirmed case, would produce a public sequence on December 9, which would address the issue of nosocomial transmission, because the recent sequence was novel and easily distinguished from recent H7N9 sequences from a case in Zhejiang Province (A/Zhejiang/22/2013 and A/Zhejiang/DTID-ZJU10/2013 - see map) as well as an August case in Huizhou (see map), which produced the A/Guangdong/1/2013 (GD/1) sequence.
Both sets of sequences from cases in southern China were easily distinguished from the northern China sequences, which were similar to the poultry and human H7N9 sequences from the spring. The southern China sequences had internal genes which were most closely related to H9N2 sequences circulating in southern China (largely from Hong Kong). GD/1 had four such internal gene segments (PB2, PB1, PA, NS),
HK/5942 was easily distinguished from GD/1 because the Hong Kong sequence had an additional gene segments (NP), which matched H9N2 Hong Kong sequences, and two additional gene segments (PB1 and PA) matched southern China lineages that were distinct from those found in GD/1. Thus, these significant differences between GD/1 and HK/5942 strongly suggest that H7N9 in chickens in distinct regions of Shenzhen would have easily distinguished sequences.
The Hong Kong index case (36F) was employed at a resident in the Palatial Coast complex, which is 5 miles south of TMH (see map) suggesting that the market in Shenzhen that she visited to buy a chicken was near the Hong Kong border. In contrast, the chicken that the second case ate was likely from northwestern Shenzhen, and H7N9 from these two regions would be distinct.
In contrast, if the second case was infected after admission to TMH and that infection was linked to the prior admission of the index case, the two sequences would be closely related in all 8 gene segments.
Therefore, the prompt release of the full sequence from the recent Hong Kong case would be useful.