Middle East respiratory syndrome (MERS)

Part of the Communicable Disease Control Manual

Chapter last reviewed and updated in February 2015.

Contents


Epidemiology in New Zealand

An outbreak of Middle East respiratory syndrome (MERS) began in the Arabian Peninsula in 2012. This coronavirus strain had not previously been detected in humans or animals. The disease has demonstrated a high mortality rate and is caused by a new coronavirus, termed MERS coronavirus (MERS-CoV). No cases of MERS have been diagnosed in New Zealand.

It is likely that the virus has come from an animal source. Experimental evidence identifies dromedary camels as the primary reservoir of MERS-CoV; many of the human cases reported to date have had close contact with camels. There are also limited reports that MERS-CoV has been detected in bats.

Most cases have occurred in the Middle East region, and all cases outside the Middle East have had a direct or indirect travel link with the Middle East. There has been no reported sustained person-to-person transmission of MERS-CoV. However, in some instances MERS-CoV has been transmitted to close contacts, including health care workers.

Case definition

Clinical description

Most confirmed cases have presented with, or later developed, acute, serious respiratory illness. Typical symptoms have included fever, coughing and breathing difficulties. Some cases have also presented with gastro-intestinal symptoms (vomiting or diarrhoea). Asymptomatic cases and cases with only mild flu-like symptoms have also been reported.

Most of the severe cases have occurred in people with underlying co-morbidities, particularly type II diabetes. Reported cases have also been more common in the middle-aged and elderly populations. The case fatality rate is higher in patients who are immunocompromised and elderly or who demonstrate significant co-morbidities.

Laboratory test for diagnosis

Laboratory confirmation requires molecular diagnostic testing, including either a positive PCR on at least two specific genomic targets or a single positive target with sequencing on a second.

While PCR testing for MERS-CoV may be undertaken in any PC2 laboratory, positive samples should be sent to Institute of Environmental Science and Research (ESR) for confirmatory testing.

The laboratory should be notified about the referral and samples should be transported in accordance with current regulatory requirements. Please refer to the Annex for the procedure for shipping respiratory samples.

For further information on testing, refer to Laboratory Testing for Middle East Respiratory Syndrome Coronavirus (PDF, 285 KB) on the WHO website

Case definitions for MERS-CoV

Suspected case (under investigation)

A suspected case is a person who has an acute febrile respiratory illness with clinical, radiological or histopathological evidence of pulmonary parenchymal disease (eg, pneumonia or acute respiratory distress syndrome)[1] and either:

  • has a history of residence in, or travel to, the Arabian Peninsula[2] or neighbouring countries within 14 days before onset of illness or
  • has had close contact with a probable or confirmed case within 14 days before onset of illness[3] or
  • is a member of a cluster of patients with severe acute respiratory illness of unknown aetiology in which MERS-CoV is being evaluated.

Probable case

A probable case is a person:

  • with an acute febrile respiratory illness with clinical, radiological or histopathological evidence of pulmonary parenchymal disease (eg, pneumonia or acute respiratory distress syndrome) and
  • for whom there is no possibility of laboratory confirmation for MERS-CoV because either the patient or samples are not available for testing and
  • who has had close contact with a laboratory-confirmed case.

Confirmed case

A confirmed case is a person with laboratory confirmation of infection with MERS‑CoV.

Spread of infection

Incubation period

The incubation period of infection has not yet been fully determined but is likely to be from 2–14 days (most commonly 5 days). This timeframe is based on what is known about other coronaviruses and the MERS-CoV cases in which exposures are known.

Mode of transmission

The mode of transmission of MERS-CoV has not yet been fully determined. Some cases have involved a strong history of exposure to camels or camel products (eg, milk). However, many cases have had no history of exposure to camels or other animals. A considerable proportion of MERS-CoV cases have been part of clusters in which limited, non-sustained, human-to-human transmission has occurred.

Period of communicability

The period of communicability of MERS-CoV has not yet been fully determined. Isolation precautions should be continued until 24 hours after the resolution of symptoms.

Notification procedure

The attending medical practitioner and laboratory should immediately notify any suspected case to the local medical officer of health. The medical officer of health should inform the Office of the Director of Public Health by phone and email.

Any contacts of a probable or confirmed case should also be reported to the local medical officer of health.

Management of case

Investigation

Any suspected cases (and/or family members) should be interviewed within the first 24–48 hours of the investigation to collect basic demographic, clinical and epidemiological information.

For further information on case investigation, refer to the WHO guidelines for investigation of cases of human infection with Middle East Respiratory Syndrome Coronavirus (PDF, 351 KB) on the WHO website.

Ensure laboratory confirmation has been attempted.

  • It is recommended that both upper and lower respiratory tract specimens be collected whenever possible.
  • Respiratory samples – including upper respiratory tract viral swabs, nasopharyngeal swabs and aspirates, sputum, endotracheal aspirate, bronchoalveolar lavage fluid, lung biopsies and postmortem tissues – are suitable for testing for MERS-CoV.
  • Even after the initial detection of the virus, continued sampling and testing will add to current knowledge about the duration of virus shedding and are strongly encouraged.

For WHO recommendations on laboratory testing for MERS-CoV, refer to Laboratory Testing for Middle East Respiratory Syndrome Coronavirus (PDF, 285 KB) on the WHO website.

Restriction

The use of standard precautions in conjunction with contact and airborne precautions is recommended for suspected, probable or confirmed cases until the transmission characteristics of MERS-CoV are better understood.[4]

In general, where cases do not meet the definition of a probable or confirmed case after investigation, standard, contact and droplet precautions should be applied. The exception is when respiratory samples are being taken, in which case airborne precautions are also required.

Transmission-based precautions should include:

  • placement of suspected, confirmed and probable cases in an airborne infection isolation (negative pressure) room if available or, as a minimum, a single room with a closed door
  • standard precautions, including wearing a mask and eye protection (goggles or a face shield) and an apron or gown
  • additional contact and airborne precautions, including wearing a P2/N95 respirator and strictly adhering to hand hygiene.

If it is necessary to transfer the patient outside the airborne infection isolation room, the patient should wear a surgical mask while they are being transferred and follow respiratory hygiene and cough etiquette. They should also be encouraged to perform hand hygiene.

Treatment

Consult an infectious diseases physician.

Counselling

Advise the case and their caregivers of the nature of the infection and what is known of its mode of transmission.

Management of contacts

Definition

Close contact includes:

  • anyone who provided care for the patient, including a health care worker or family member, or who had other similarly close physical contact
  • anyone who stayed at the same place as (eg, lived with or visited) a probable or confirmed case while the case was ill
  • where a case has travelled on an aeroplane, any passenger seated in the same row as the case or up to two rows in front of or behind the case and any crew member who has had prolonged interaction with the case.

Investigation

Close contacts of probable and confirmed cases should be identified and monitored for up to 14 days for the onset of respiratory symptoms, and tested for MERS-CoV infection if respiratory symptoms develop (regardless of the severity of illness).

Restriction

Quarantine of asymptomatic contacts is not required as current evidence shows limited human-to-human transmission of MERS-CoV. Current evidence does not show that the disease is transmissible in the pre-symptomatic or early symptomatic stages.[5]

Prophylaxis

Nil.

Counselling

Advise all contacts of the estimated incubation period and typical symptoms of MERS‑CoV infection. Encourage them to contact their local public health unit and seek early medical attention if symptoms develop.

Other control measures

Identification of source

Check for other cases in the community.

Disinfection

Clean and disinfect surfaces and articles soiled with respiratory secretions or faeces, using a product with antiviral activity. For further details, see Appendix 1: Disinfection.

Health education

Consider a media release and direct communication with local health professionals to encourage prompt reporting of symptoms and to provide advice (for both the public and health professionals).

Reporting

Public health units should enter cases into EpiSurv, using the Generic Case Report Form. If entering a case directly on the EpiSurv website then choose Middle East Respiratory Syndrome.

Any change in a case status (eg, case confirmation, death or de-notification) should also be immediately reported and updated in EpiSurv.

WHO will be notified of probable and confirmed cases through the National Focal Point for International Health Regulations (ie, the Office of the Director of Public Health, Ministry of Health).

If a cluster of cases occurs, contact the Ministry of Health Communicable Diseases Team and outbreak liaison staff at the Institute of Environmental Science and Research. Also complete the Outbreak Report Form.

References and further information


[1]    Immune-compromised patients may not present with typical or severe symptoms.

[2]    Countries of the Arabian Peninsula and immediate surrounding areas are: Bahrain, Iraq, Iran, Israel, Jordan, Kuwait, Lebanon, Oman, Palestinian territories, Qatar, Saudi Arabia, Syria, the United Arab Emirates (UAE) and Yemen. Transiting through an international airport (<24 hours’ stay, remaining within the airport) on the Arabian Peninsula is not considered to be a risk factor for infection.

[3]    Close contact includes:

  • anyone who provided care for the patient, including a health care worker or family member, or who had other similarly close physical contact
  • anyone who stayed at the same place as (eg, lived with or visited) a probable or confirmed case while the case was ill
  • where a case has travelled on an aeroplane, any passenger seated in the same row as the case or up to two rows in front of or behind the case, and any crew member who has had prolonged interaction with the ill person.

[4]    Please refer also to guidance from the US Centers for Disease Control and Prevention.

[5]    Refer to the Rapid advice note on home care (PDF, 130 KB) on the WHO website.

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