MERS-CoV summary and literature update – as of 31 May 2013

Since April 2012, there have been 50 laboratory-confirmed cases of human infection with Middle East respiratory syndrome coronavirus (MERS-CoV). Thirty of these cases have died. Local transmission from non-human exposures appears to have occurred in several countries in the Middle East, including Jordan, Qatar, Saudi Arabia and the United Arab Emirates (UAE). Cases have also been reported by three countries in Europe—France, Germany, and the United Kingdom (UK)—and by Tunisia, in North Africa. All the European and North African cases have had a direct or indirect connection to the Middle East. However, in France, the UK and Tunisia, there has also been limited local transmission among close contacts who had not been to the Middle East but had been in contact with a sick traveler recently returned from the Middle East. No case has been reported in Jordan since April 2012.

The most recent cases have occurred in Saudi Arabia and Tunisia. Two laboratory-confirmed cases and one probable case of MERS-CoV have been reported by Tunisia. In this family cluster, the index case, who was not laboratory confirmed, was a male Tunisian who traveled to Qatar in late March. He then left Qatar briefly, returning a few days later. He remained in Qatar for about 3 weeks before returning home to Tunisia. He became ill 5 days later and died after a week. He tested negative for MERS-CoV, but the quality of the specimen may have been poor. Two adult children, one who traveled to Tunisia from Qatar and one who lives in Tunisia and had not traveled, also became ill, with mild symptoms, and both tested positive for MERS-CoV.

Five new cases of MERS-CoV infection were reported by the Saudi Arabian Ministry of Health on 28 May 2013. The cases occurred in the eastern province of Saudi Arabia, but are not from the Al-Ahsa area. They range in age from 56 to 85 years, three were male, and three of these five patients have died. All were reported to have multiple co-morbid conditions and were admitted to hospital between 12-24 May, with pneumonia or respiratory symptoms. An official from the Ministry of Health has been quoted as saying that all were patients in the same hospital and that two had shared a hospital room. None of the patients have family contacts in Al-Ahsa. The Ministry of Health is continuing investigations to determine source of transmission in this cluster. An additional case, a 61-year-old man with chronic renal failure and other chronic diseases, was reported from Al-Ahsa on 29 May.

Thus far, all clusters of cases have occurred in a health care setting or among close family contacts. Human-to-human transmission has been documented on several occasions in which secondary cases had not traveled to affected areas and is strongly suspected in others. Transmission does not appear to have extended beyond these clusters into the larger community in any of the events. The mode of transmission has not been defined in any of the clusters.

Recent scientific papers published since the last update

A special supplement to the Eastern Mediterranean Health Journal on MERS-CoV contains papers arising from a meeting of experts in Cairo, Egypt, in January 2013. More information can be found using the links below.



Table of Contents:

http://applications.emro.who.int/emhj/v19/Supp1/EMHJ_2013_19_Supp1_Contents.pdf.



Articles:

http://www.emro.who.int/emhj-volume-19-2013/volume-19-supplement-1-coronavirus/volume-19-supplement-1-coronavirus.html.

French investigators have published a detailed description of two MERS cases recently reported to WHO. Key findings are that the initial patient’s clinical presentation was atypical, probably because of immunosuppression after renal transplantation, and that upper respiratory specimens can be falsely positive because of the low concentration of virus in specimens taken from the nasopharynx. The timing of transmission to a second patient in the same hospital room provided an estimated incubation time of between 9 and 12 days, based on exposure to the first patient.

Reference: Guery B, et al. Clinical features and viral diagnosis of two cases of infection with Middle East Respiratory Syndrome coronavirus: a report of nosocomial transmission. Lancet. Published online 29 May 2013.

http://dx.doi.org/10.1016/S0140-6736(13)60982-4.

http://download.thelancet.com/flatcontentassets/pdfs/S0140673613609824.pdf.



Investigators in Saudi Arabia have published results of investigations around a family cluster of MERS in Riyadh, which occurred in October and November 2012. The study authors suspect that human-to-human transmission occurred in the household. In addition to chest X-ray findings of pneumonia, the authors note lymphopenia in three of the four patients and renal failure in one. Also of note, gastrointestinal symptoms, including diarrhoea, were reported in three of the four.

Reference: Memish ZA, et al. Family cluster of Middle East Respiratory Syndrome coronavirus infections. New England Journal of Medicine. Published online 29 May 2013. DOI: 10.1056/NEJMoa1303729.

http://www.nejm.org/doi/pdf/10.1056/NEJMoa1303729.

Summary assessment

WHO’s assessment of the situation remains largely unchanged since the previous summary of 17 May.

The newest cases reported indicate that the source of infection, which has still not been determined, remains active in the Middle East and is present throughout a large area. The first case in Tunisia was likely infected in Qatar; however, this cannot be definitively shown without further investigation. Both the Tunisian and Qatari public health authorities are pursuing further investigations.

The appearance of cases in Europe and North Africa but not in other countries with frequent travel in and out of the Middle East is likely a result of differences in surveillance and testing. All Member States are encouraged to remind travelers returning from the affected area to seek medical attention if they develop a respiratory illness, and to test those who meet the profile described in the current surveillance recommendations posted on the WHO coronavirus website.

Human-to-human transmission has not been observed to persist beyond small clusters of individuals with close contact. However, it is likely that more sporadic cases with subsequent limited transmission will occur in the near future. The large number of cases with reported co-morbidities suggests that persons with underlying medical conditions may have increased susceptibility to infection. Health care facilities treating patients suspected of being infected with MERS-CoV should exercise appropriate infection control measures. Clinicians should be aware that MERS-CoV infection may present atypically, and initially without respiratory symptoms, in immunocompromised individuals.

Member States are reminded that lower respiratory specimens should be used for diagnosis in addition to nasopharyngeal swabs when they are available. If a nasopharyngeal swab tests negative, consider retesting using lower respiratory specimens such as sputum, endotracheal aspirate, or bronchoalveolar lavage. Clinicians should take care to follow strict infection prevention and control guidelines when collecting respiratory specimens of any kind. Recommendations on laboratory testing for novel coronavirus, including specimen collection and transportation, should be followed and can be found at:

http://www.who.int/csr/disease/coronavirus_infections/LaboratoryTestingNovelCoronavirus_21Dec12.pdf.