Thursday, June 18, 2015

Eurosurveillance: China’s Imported MERS Case




# 10,228


While we’ve not been getting much news on China’s sole MERS case, involving a Korean businessman who was supposedly under quarantine but elected to travel , we get details today from a Rapid Communications article published in the ECDC’s Eurosurveillance Journal.

Unlike in Korea, no secondary cases have been reported in China, and their index patient is reportedly improving and will be released from isolation when he is no longer shown to be shedding the virus.

Because of the length and amount of detail in this report, I’ve only excerpted the abstract and part of the discussion.  The entire report is interesting and well worth reading in its entirety. Of particularly interest is the variability (in term of quantity, location, and duration) of viral shedding with this patient which are discussed under Laboratory Findings and at the end of the report. 



Rapid communications

Imported case of MERS-CoV infection identified in China, May 2015: detection and lesson learned

J Wu1,2,3, L Yi3,4, L Zou1,2, H Zhong1,2, L Liang1,2, T Song1,2, Y Song1,2, J Su1,2, C Ke ()1,2

At the end of May 2015, an imported case of Middle East respiratory syndrome coronavirus (MERS-CoV) infection was confirmed in China. The patient is in a stable condition and is still undergoing treatment. In this report, we summarise the preliminary findings for this imported case and the results of contact tracing. We identified 78 close contacts and after 14 days of monitoring and isolation, none of the contacts presented symptoms and all tested negative for MERS-CoV.




Laboratory findings

MERS-CoV RNA was detected over eight days after fever onset, in serum samples, but only in the first four days in throat swabs. Sputum was collected and the result of the test was positive for MERS-CoV from Day 7 when pneumonia was detected. We tested two faecal samples and obtained positive results on Day 10 and 15. Sample collection and testing are still ongoing.





The increased number of countries outside the Arabian Peninsula affected by MERS-CoV highlights the need for enhanced awareness on the presence of the virus in travellers with fever from countries with ongoing epidemics. During our investigation, we observed sometimes people preferred not to disclose their history of exposure to a MERS case because of insufficient knowledge on the disease and its associated risks, or on the public health actions around it. Education of the public about MERS-CoV including symptoms, transmission modes, infection and prevention measures and risks, are critical to prevent the possible spread of MERS-CoV.

In this study, MERS-CoV RNA was detected in throat swabs only in the first two days of sampling after hospitalisation (four days after fever onset), while increased viral loads were observed in sputum seven days after fever onset when pneumonia was detected. This was consistent with previous studies that recommend that lower respiratory tract samples be given a high priority for MERS-CoV diagnosis especially in patients presenting late in their disease course with lower respiratory involvement [8,9]. We also obtained positive results when we tested stool and serum samples.


Due to the possibility of viral shedding, comprehensive precautions for healthcare workers managing probable or confirmed MERS cases, are important. So far, data on MERS-CoV shedding were very rare and have shown different MERS-CoV detection profiles [10-12]. The complete viral load profiles from a large number of patients are essential for establishing infection control measures and their necessary duration.


This can also be used to monitor possible early signs of virus change: the apparent deep respiratory tract tropism of MERS-CoV in this patient was an indication that the virus causing the large cluster in South Korea did not behave differently, as concluded from the initial sequence data (data not shown). Subtle changes in the virus-host interaction that would lead to increased replication in the upper respiratory tract could potentially lead to much more efficient transmission.


Therefore, detailed virological monitoring, in addition to case and contact investigations, is crucial for monitoring evolution of emerging infectious diseases.

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