Middle East respiratory syndrome coronavirus

The Middle East Respiratory Syndrome coronavirus, also termed EMC/2012, is positive-sense, single-stranded RNA novel species of the genus Betacoronavirus. 

Scientific name: Middle East respiratory syndrome coronavirus

Rank: Species

Higher classification: Betacoronavirus

Middle East Respiratory Syndrome (MERS) is an illness caused by a virus (more specifically, a coronavirus) called Middle East Respiratory Syndrome Coronavirus (MERS-CoV). MERS affects the respiratory system (lungs and breathing tubes). Most MERS patients developed severe acute respiratory illness with symptoms of fever, cough and shortness of breath. About 3-4 out of every 10 patients reported with MERS have died.

Health officials first reported the disease in Saudi Arabia in September 2012. Through retrospective investigations, health officials later identified that the first known cases of MERS occurred in Jordan in April 2012. So far, all cases of MERS have been linked to countries in and near the Arabian Peninsula.

MERS-CoV has spread from ill people to others through close contact, such as caring for or living with an infected person.MERS can affect anyone. MERS patients have ranged in age from younger than 1 to 99 years old.

Symptoms & Complications

Most people confirmed to have MERS-CoV infection have had severe acute respiratory illness with symptoms of:

fever

cough

shortness of breath

Some people also had gastrointestinal symptoms including diarrhea and nausea/vomiting. For many people with MERS,

 more severe complications followed, such as pneumonia and kidney failure. About 3-4 out of every 10 people reported with MERS have died. Most of the people who died had an underlying medical condition. Some infected people had mild symptoms (such as cold-like symptoms) or no symptoms at all; they recovered.

Based on what researchers know so far, people with pre-existing medical conditions (also called comorbidities) may be more likely to become infected with MERS-CoV, or have a severe case. Pre-existing conditions from reported cases for which we have information have included diabetes; cancer; and chronic lung, heart, and kidney disease. Individuals with weakened immune systems are also at higher risk for getting MERS or having a severe case.

Based on information we have to date, the incubation period for MERS (time between when a person is exposed to MERS-CoV and when they start to have symptoms) is usually about 5 or 6 days, but can range from 2-14 days

Clinical Presentation

A wide clinical spectrum of MERS-CoV infection has been reported ranging from asymptomatic infection to acute upper respiratory illness, and rapidly progressive pneumonitis, respiratory failure, septic shock and multi-organ failure resulting in death. Most MERS-CoV cases have been reported in adults (median age approximately 50 years, male predominance), although children and adults of all ages have been infected (range 0 to 99 years). Most hospitalized MERS-CoV patients have had chronic co-morbidities. Among confirmed MERS-CoV cases reported to date, the case fatality proportion is approximately 35%.

Limited clinical data for MERS-CoV patients are available; most published clinical information to date is from critically ill patients. At hospital admission, common signs and symptoms include fever, chills/rigors, headache, non-productive cough, dyspnea, and myalgia. Other symptoms can include sore throat, coryza, nausea and vomiting, dizziness, sputum production, diarrhea, vomiting, and abdominal pain. Atypical presentations including mild respiratory illness without fever and diarrheal illness preceding development of pneumonia have been reported. Patients who progress to requiring admission to an intensive care unit (ICU) often have a history of a febrile upper respiratory tract illness with rapid progression to pneumonia within a week of illness onset.

Clinical Course

The median incubation period for secondary cases associated with limited human-to-human transmission is approximately 5 days (range 2-14 days). In MERS-CoV patients, the median time from illness onset to hospitalization is approximately 4 days. In critically ill patients, the median time from onset to intensive care unit (ICU) admission is approximately 5 days, and median time from onset to death is approximately 12 days. In one series of 12 ICU patients, the median duration of mechanical ventilation was 16 days, and median ICU length of stay was 30 days, with 58% mortality at 90 days. Radiographic findings may include unilateral or bilateral patchy densities or opacities, interstitial infiltrates, consolidation, and pleural effusions. Rapid progression to acute respiratory failure, acute respiratory distress syndrome (ARDS), refractory hypoxemia, and extrapulmonary complications (acute kidney injury requiring renal replacement therapy, hypotension requiring vasopressors, hepatic inflammation, septic shock) has been reported.

Transmission

MERS-CoV, like other coronaviruses, is thought to spread from an infected person’s respiratory secretions, such as through coughing. However, the precise ways the virus spreads are not currently well understood.

Person-to-person spread of MERS-CoV, usually after close contact, such as caring for or living with an infected person, has been well documented. Infected people have spread MERS-CoV to others in healthcare settings, such as hospitals. Researchers studying MERS have not seen any ongoing spreading of MERS-CoV in the community.

All reported cases have been linked to countries in and near the Arabian Peninsula. Most infected people either lived in the Arabian Peninsula or recently traveled from the Arabian Peninsula before they became ill. A few people became infected with MERS-CoV after having close contact with an infected person who had recently traveled from the Arabian Peninsula.

Public health agencies continue to investigate clusters of cases in several countries to better understand how MERS-CoV spreads from person to person.

 Risk  factors for MERS

1) Recent Travelers from the Arabian Peninsula

If you develop a fever and symptoms of respiratory illness, such as cough or shortness of breath, within 14 days after traveling from countries in or near the Arabian Peninsula, you should call ahead to a healthcare provider and mention your recent travel. While sick, stay home from work or school and delay future travel to reduce the possibility of spreading illness to others.

2) Close Contacts of an Ill Traveler from the Arabian Peninsula

If you have had close contact with someone within 14 days after they traveled from a country in or near the Arabian Peninsula and the traveler has/had fever and symptoms of respiratory illness, such as cough or shortness of breath, you should monitor your health for 14 days, starting from the day you were last exposed to the ill person.

If you develop fever and symptoms of respiratory illness, such as cough or shortness of breath, you should call ahead to a healthcare provider and mention your recent contact with the traveler. While sick, stay home from work or school and delay future travel to reduce the possibility of spreading illness to others.

3) Close Contacts of a Confirmed Case of MERS

If you have had close contact with someone who has a confirmed MERS-CoV infection, you should contact a healthcare provider for an evaluation. Your healthcare provider may request laboratory testing and outline additional recommendations, depending on the findings of your evaluation and whether you have symptoms. You most likely will be asked to monitor your health for 14 days, starting from the day you were last exposed to the ill person. Watch for these symptoms:

Fever. Take your temperature twice a day.

Coughing

Shortness of breath

Other early symptoms to watch for are chills, body aches, sore throat, headache, diarrhea, nausea/vomiting, and runny nose.

If you develop symptoms, call ahead to your healthcare provider as soon as possible and tell him or her about your possible exposure to MERS-CoV so the office can take steps to keep other people from getting infected. Ask your healthcare provider to call the local or state health department.

4) Healthcare Personnel Not Using Recommended Infection-Control Precautions

Healthcare personnel should adhere to recommended infection control measures, including standard, contact, and airborne precautions, while managing symptomatic close contacts, patients under investigation, and patients who have probable or confirmed MERS-CoV infections. Recommended infection control precautions should also be utilized when collecting specimens.

Healthcare personnel who had close contact with a confirmed case of MERS while the case was ill, if not using recommended infection control precautions (e.g. appropriate use of personal protective equipment), are at increased risk of developing MERS-CoV infection and should be evaluated and monitored by a healthcare professional with a higher index of suspicion..

5) People with Exposure to Camels

MERS-CoV has been found in some camels, and some MERS patients have reported contact with camels. However, we do not know exactly how people become infected with MERS-CoV—many people with MERS have had close contact with a person sick with MERS.

The World Health Organization has posted a general precaution for anyone visiting farms, markets, barns, or other places where animals are present. Travelers should practice general hygiene measures, including regular handwashing before and after touching animals, and avoid contact with sick animals. Travelers should also avoid consumption of raw or undercooked animal products.The World Health Organization considers certain groups to be at high risk for severe MERS; these groups include people with diabetes, kidney failure, or chronic lung disease and people who have weakened immune systems. The World Health Organization recommends that these groups take
additional precautions:

1. Avoid contact with camels
2. Do not drink raw camel milk or raw camel urine
3. Do not eat undercooked meat, particularly camel meat

* Countries considered in the Arabian Peninsula and neighboring include: Bahrain; Iraq; Iran; Israel, the West Bank, and Gaza; Jordan; Kuwait; Lebanon; Oman; Qatar; Saudi Arabia; Syria; the United Arab Emirates (UAE); and Yemen.

** Close contact is defined as

•  being within approximately 6 feet (2 meters) or within the room or care area for a prolonged period of time (e.g., healthcare personnel, household members) while not wearing recommended personal protective equipment (i.e., gowns, gloves, respirator, eye protection) 

•  having direct contact with infectious secretions (e.g., being coughed on) while not wearing recommended personal protective equipment (i.e., gowns, gloves, respirator, eye protection.

Laboratory Findings

At admission may include leukopenia,lymphopenia,thrombocytopenia, and elevated lactate dehydrogenase levels. Co-infection with other respiratory viruses and a few cases of co-infection with community-acquired bacteria at admission has been reported; nosocomial bacterial and fungal infections have been reported in mechanically-ventilated patients. MERS-CoV virus can be detected with higher viral load and longer duration in the lower respiratory tract compared to the upper respiratory tract, and has been detected in feces, serum, and urine. However, very limited data are available on the duration of respiratory and extrapulmonary MERS-CoV shedding.

Prevention

Currently, there is no vaccine to prevent MERS-CoV infection. The U.S. National Institutes of Health is exploring the possibility of developing one.

CDC routinely advises that people help protect themselves from respiratory illnesses by taking everyday preventive actions:

1. Wash your hands often with soap and waterfor 20 seconds, and help young children do the same. If soap and water are not available, use an alcohol-based hand sanitizer.
   
2. Cover your nose and mouth with a tissue when you cough or sneeze, then throw the tissue in the trash.
3. Avoid touching your eyes, nose and mouth with unwashed hands.
4. Avoid personal contact, such as kissing, or sharing cups or eating utensils, with sick people.
5. Clean and disinfect frequently touched surfaces and objects, such as doorknobs.

Treatment

There is no specific antiviral treatment recommended for MERS-CoV infection. Individuals with MERS can seek medical care to help relieve symptoms. For severe cases, current treatment includes care to support vital organ functions.

REFRENCE

http://www.nbcnews.com/storyline/mers-mystery/what-mers-other-questions-about-mers-outbreak-n370531

http://www.cdc.gov/coronavirus/mers/hcp.html