Middle East respiratory syndrome coronavirus infection

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Epidemiology and Demographics

• The Middle East respiratory syndrome coronavirus (MERS-CoV) was first reported to cause human infection in September 2012. In July 2013, the World Health Organization (WHO) International Health Regulations Emergency Committee determined that MERS-CoV did not meet criteria for a "public health emergency of international concern," but was nevertheless of "serious and great concern".

• As of September 20, 2013, a total of 130 cases from eight countries have been reported to WHO; 58 (45%) of these cases have been fatal. All cases have been directly or indirectly linked through travel to or residence in four countries: Saudi Arabia, Qatar, Jordan, and the United Arab Emirates (UAE).

• The median age of persons with confirmed MERS-CoV infection is 50 years (range: 2–94 years).

• The male-to-female ratio is 1.6 to 1.0.

• Twenty-three (18%) of the cases occurred in persons who were identified as health-care workers.

• Although most reported cases involved severe respiratory illness requiring hospitalization, at least 27 (21%) involved mild or no symptoms.

• Despite evidence of person-to-person transmission, the number of contacts infected by persons with confirmed infections appears to be limited. No cases have been reported in the United States, although 82 persons from 29 states have been tested for MERS-CoV infection.

Pathophysiology

Potential animal reservoirs and mechanism(s) of transmission of MERS-CoV to humans remain unclear. A zoonotic origin for MERS-CoV was initially suggested by high genetic similarity to bat coronaviruses , and some recent reports have described serologic data from camels and the identification of related viruses in bats. However, more epidemiologic data linking cases to infected animals are needed to determine if a particular species is a host, a source of human infection, or both.

History and Symptoms

The symptoms of MERS-CoV infection are:

• Fever (98%)
• Cough (83%)
• Shortness of breath (72%)
• Gastrointestinal symptoms
  • Diarrhea (26%)
  • Vomiting (21%

All but two patients (96%) had one or more chronic medical conditions, including diabetes (68%), hypertension (34%), heart disease (28%), and kidney disease (49%). Thirty-four (72%) had more than one chronic condition.

Diagnosis

CDC has changed its guidance to indicate that testing for MERS-CoV and other respiratory pathogens can be conducted simultaneously and that positive results for another respiratory pathogen should not necessarily preclude testing for MERS-CoV. Health-care providers in the United States should continue to evaluate patients for MERS-CoV infection if they develop fever and pneumonia or acute respiratory distress syndrome (ARDS) within 14 days after traveling from countries in or near the Arabian Peninsula. Providers also should evaluate patients for MERS-CoV infection if they have ARDS or fever and pneumonia, and have had close contact§ with a recent traveler from this area who has fever and acute respiratory illness.

CDC continues to recommend that clusters¶ of patients with severe acute respiratory illness (e.g., fever and pneumonia requiring hospitalization) be evaluated for common respiratory pathogens and reported to local and state public health departments. If the illnesses remain unexplained, particularly if the cluster includes health-care providers, testing for MERS-CoV should be considered, in consultation with state and local health departments. In this situation, testing should be considered even for patients without travel-related exposure.

Prevention

• Enhancing infection prevention and control awareness and measures is critical to prevent the possible spread of MERS‐CoV in health care facilities. Health‐care facilities that provide care for patients suspected or confirmed to be infected with MERS‐CoV infection should take appropriate measures to decrease the risk of transmission of the virus from an infected patient to other patients, health‐care workers and visitors. It is not always possible to identify patients with MERS‐CoV early because some have mild or unusual symptoms. For this reason, it is important that health‐care workers apply standard precautions consistently with all patients – regardless of their diagnosis – in all work practices all the time.
• Urgent investigations are required to better understand the transmission pattern of this virus. The most urgent include detailed outbreak investigations, case‐control studies to understand risk factors for infection, enhancing community studies and surveillance of community‐acquired pneumonia to assess whether significant numbers of mild cases resulting from human to human transmission are being missed, and identifying risk factors for infection in the hospital setting. Detailed information on the surveillance strategy and contact tracing would help understand limitations of current data.
• Although the immediate focus should be on clarifying the magnitude of the human‐to‐human transmission, no control will be possible until the transmission from the animal/environment source to humans is understood and interrupted. Based on current information, it is prudent for people at high risk of severe disease due to MERS‐CoV, including those with diabetes, chronic lung disease, pre‐existing renal failure, or those who are immunocompromised, to take appropriate precautions when visiting farms, barn areas or market environments where camels are present. These measures might include avoiding contact with camels, good hand hygiene, and avoiding drinking raw milk or eating food that may be contaminated with animal secretions or products unless they are properly washed, peeled, or cooked. For the general public, when visiting a farm or a barn, general hygiene measures, such as regular hand washing before and after touching animals, avoiding contact with sick animals, and following food hygiene practices, should be adhered to.
• WHO recommends increasing efforts to raise awareness of MERS among travelers going to and traveling from MERS‐affected countries but otherwise does not advise special screening at points of entry with regard to this event nor does WHO currently recommend the application of any travel or trade restrictions.