Coronavirus: eclipsed by Covid-19, Mers continues to kill

Despite low rates of person-to-person transmission, Mers cases remain deadly

Police officers check vehicles on the empty Ataturk Airport road on the road during 48-hour restrictions imposed to stem the spread of coronavirus in Ankara, Turkey. AFP

Shiite Muslim men carry a coffin to the Imam Ali Ibn Abi Talib mosque in Iraq's central shrine city of Najaf during a funeral procession, one of the very rare ceremonies still allowed in the city during the coronavirus pandemic. AFP

People walk past a damaged building depicting drawings alluding to the coronavirus and encouraging people to stay at home, in the rebel-held Idlib city, Syria. Reuters

A member of the Kurdish internal security forces stands in the middle of an empty road in the city of Qamishli in Syria's northeastern Hasakeh province a day after local authorities of the Kurdish-dominated northern part of war-torn Syria recorded its first death due to the coronavirus outbreak. AFP

A car drives past Le Bristol hotel in Beirut, Lebanon. One of the country's landmark hotels that has survived the country's bloody 15-year civil war is closing its doors due to a combination of an economic crisis and the global health threat of coronavirus. AP Photo

Workers from the Kuwait Ministry of Public Works paves a road near the capital as the Ministry takes the opportunity to repair and repave roads during the curfew hours. AFP

The empty Galata bridge in Istanbul, as Turkish government announced further restrictions to prevent the spread of coronavirus. AFP

Men sit outside a closed shop along a street in Erbil, the capital of the northern Iraqi Kurdish autonomous region. AFP

The empty Istiklal street in Istanbul, Turkey. EPA

An Iraqi Kurdish woman and her relative outside their home in Erbil, the capital of the northern Iraqi Kurdish autonomous region. AFP

The empty shore side of the Golden Horn, with the Metro bridge in the foreground and Unkapani bridge in the background, in Istanbul. AFP

A Palestinian groom, Rafeh Qassim, wears a mask as he sits in a car with his bride on their wedding day, in Ramallah in the Israeli-occupied West Bank. Reuters

A member of the security forces checks his new haircut, provided by a volunteer hairdresser, in the northern Iraqi city of Mosul. AFP

Lebanese bride and groom Joanna and Marc wearing protective masks designed as a national flag, pose for pictures during their wedding cermony attended only by close relatives amid the COVID-19 pandemic, at the Saint Georges church in the Hadath region, east of the capital Beirut. AFP

Palestinian security forces in the West Bank city of Hebron. EPA

Police officers check vehicles on the empty Kizilay Square in Ankara. AFP

A member of the medical staff at Moroccos's military field hospital in Nouaceur, South of Casablanca, inspects the beds as they prepare to receive patients of the coronavirus pandemic. AFP

A member of the medical staff at Moroccos's military field hospital in Nouaceur, South of Casablanca, checks a monitor as staff prepared to receive patients of the coronavirus pandemic. AFP

An employee of the Ankara Municipality staff feed pigeons in a park in Ankara. AFP

A man wearing a compulsory face mask observes his neighborhood from a hill during a health state of emergency and home confinement orders in Rabat, Morocco. AP Photo

A man paints outside his home while a woman wearing a face mask walks past during a health state of emergency and home confinement order in Rabat, Morocco. AP Photo

As the number of Covid-19 victims continues to climb globally, another related virus still causes fatalities years after it first emerged.

Figures released this month by the World Health Organisation show that five people died from Middle East Respiratory Syndrome in February, some eight years after it materialised in 2012.

Though tragic for its victims and their families, the overall death toll from Mers is far smaller than what might have been expected.

In 2013, the disease was branded “a threat to the entire world” by WHO’s then director-general, Dr Margaret Chan.

Since then, however, experts have been able to better understand its ability to spread between hosts, recognising that “sustained person-to-person transmission” was low.

“The coronavirus Covid-19 has the ability to cause disease and to be highly infectious,” said Dr Bharat Pankhania, a senior consultant in communicable disease control and senior clinical lecturer at the University of Exeter in the United Kingdom.

“Mers is different. If you get infected, it’s difficult to be infectious.”

Seven strains of coronaviruses are known to infect humans, with four leading to common cold symptoms largely restricted to the upper airways.

The other three - which can cause Covid-19, Mers and Severe Acute Respiratory Syndrome (Sars) - are more harmful because they affect lower airways, including the lungs, where they can cause pneumonia.

New WHO figures show there have been 871 fatalities from Mers since 2012, from a total of 2,538 infections.

Ten of the deaths occurred in the UAE, with additional victims also recorded in 20 other countries.

Meanwhile, between 2002 and 2004, Sars is known to have killed 774 people globally.

Key to the way these pathogens infect human cells are their spike proteins, which stand out from the main surface of the virus.

Spike proteins attach to receptor proteins on the surface of human cells and enable the virus to pass through the cell membrane.

Once inside, the virus takes over the cell’s machinery and starts producing multiple copies of itself, which then infect other cells.

Different coronaviruses have different spike proteins, and this affects which cells the viruses target.

Spike proteins on the coronaviruses that cause Covid-19 and Sars attach to a receptor called ACE2, found on cells in the lungs.

The Mers coronavirus, however, attaches instead to a receptor called DPP4, which is more prevalent on cells further down in the lung’s airways, so the virus must travel for longer to pass on the infection.

As a result, people need a larger dose of the Mers coronavirus to contract the disease. This helps explain why the virus does not spread so easily person-to-person.

Many cases of Mers are know to have begun with someone who works on a farm.

The infection can be caught from camels after sustained exposure, while person-to-person transmission happens mostly in hospitals.

Camels' ability to infect people is the chief cause behind continued new cases of Mers.

The differences in where cell receptors are distributed is also thought to explain why it, unlike Covid-19, infects and replicates in the intestines, where it can cause pain, vomiting and nausea.

“You need prolonged contact with an infected animal [to be infected with Mers],” said Dr Pankhania.

“If you’re unlucky [enough to be infected], any human will need prolonged contact to be infected [by you].”