Middle East respiratory syndrome coronavirus (MERS-CoV)
Middle East respiratory syndrome (MERS) is a viral respiratory disease caused by a novel coronavirus (Middle East respiratory syndrome coronavirus, or MERS-CoV) that was first identified in Saudi Arabia in 2012. Approximately 35% of reported patients with MERS-CoV infection have died. This may be an overestimate of the true mortality rate, as mild cases of MERS may be missed by existing surveillance systems and until more is known about the disease, the case fatality rates are counted only amongst the laboratory-confirmed cases. From 2012 through 30 November 2019, a total of 2494 laboratory- confirmed cases of MERS-CoV and 858 associated deaths were reported globally to WHO under the International Health regulations (IHR 2005). The total number of deaths includes the deaths that WHO is aware of to date through follow-up with affected member states.
Coronaviruses are a large family of viruses that can cause diseases ranging from the common cold to Severe Acute Respiratory Syndrome (SARS). Infection with MERS-CoV can cause severe disease resulting in high mortality. Humans are infected with MERS-CoV from direct or indirect contact with dromedary camels. MERS-CoV has demonstrated the ability to transmit between humans. Although most of human cases of MERS-CoV infections have been attributed to human-to-human infections in health care settings, current scientific evidence suggests that dromedary camels are a major reservoir host for MERS-CoV and an animal source of MERS infection in humans. However, the exact role of dromedaries in transmission of the virus and the exact route(s) of transmission are unknown.
The virus does not seem to pass easily from person to person unless there is close contact, such as occurs when providing unprotected care to a patient. Health care associated outbreaks have occurred in several countries, with the largest outbreaks seen in Saudi Arabia, United Arab Emirates, and the Republic of Korea.
Typical MERS symptoms include fever, cough and shortness of breath. Pneumonia is common, but not always present. Gastrointestinal symptoms, including diarrhoea, have also been reported. Some laboratory-confirmed cases of MERS-CoV infection are reported as asymptomatic, meaning that they do not have any clinical symptoms, yet they are positive for MERS-CoV infection following a laboratory test. Most of these asymptomatic cases have been detected following aggressive contact tracing of a laboratory-confirmed case.
Infection prevention and control measures are critical to prevent the possible spread of MERS-CoV in health care facilities. It is not always possible to identify patients with MERS-CoV infection early because like other respiratory infections, the early symptoms of MERS-CoV infection are non-specific. Early identification, case management, and isolation, together with appropriate infection prevention and control measures can prevent human-to-human transmission of MERS-CoV.
MERS-CoV appears to cause more severe disease in people with underlying chronic medical conditions such as diabetes mellitus, renal failure, chronic lung disease, and compromised immune systems. Therefore, people with these underlying medical conditions should avoid close unprotected contact with animals, particularly dromedary camels, when visiting farms, markets, or barn areas where the virus is known to be potentially circulating.
From 1 through 30 November 2019, the National IHR Focal Point of Saudi Arabia reported 10 additional cases of Middle East respiratory syndrome (MERS-CoV) infection and one associated deaths. On 5 December 2019, the National IHR Focal Point for Qatar reported three laboratory-confirmed cases of Middle East respiratory syndrome (MERS-CoV) infection to WHO. The first case-patient (case #1) was a 67-year-old female from Doha, Qatar. She developed fever, cough, shortness of breath and headache on 23 November 2019, and presented to a hospital on 25 November. The patient had underlying medical conditions, and died on 12 December 2019. The two contacts are a 50-year-old (case # 2) and a 32-year-old (case # 3), living in Doha.
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