Middle East respiratory syndrome (MERS), also known as camel flu, is a viral respiratory infection caused by the MERS-coronavirus (MERS-CoV).
The initial original source, bats, is one familiar to students of COVID-19. But camels might be a surprise.
MERS-CoV is a betacoronavirus derived from bats. Camels have been shown to have antibodies to MERS-CoV but the exact source of infection in camels has not been identified. Camels are believed to be involved in its spread to humans but it is unclear how. Spread between humans typically requires close contact with an infected person.A strain of MERS-CoV known as HCoV-EMC/2012 found in the first infected person in London in 2012 was found to have a 100% match to Egyptian tomb bats. A large outbreak occurred in South Korea in 2015. In January 2016, a larger outbreak of MERS among camels in Kenya was reported. As of February 5, 2016 more than 500 camels were said to have died of the disease. On February 12, 2016, the disease was reported to be MERS. As of February 12, 2016, there were no known human cases. Antibodies though were found in healthy humans in Kenya according to one study.
As of 2020 there is no specific vaccine or treatment for the disease; a number of antiviral medications were being studied. The World Health Organization recommends that those who come in contact with camels wash their hands frequently and do not touch sick camels and that camel-based food products be appropriately cooked. Treatments that help with the symptoms may be given to those infected.
About 36% of those who are diagnosed with the disease die from it. Source.
Further 2020 Update on American cases:
The Indiana patient traveled from Riyadh, Saudi Arabia, to London on April 24,  and then to Chicago by air. He took a bus to the Highland, Ind. area and went to Community Hospital in Munster, Ind. after falling ill. He was kept in isolation until he recovered. Source.
A second patient who also traveled from Saudi Arabia was reported in Orlando, Florida on 12 May 2014. Source.No one has died of MERS-CoV in the United States.
MERS-CoV, short for Middle East Respiratory Syndrome, is a type of coronavirus.
Since the first documented cases in spring 2012, MERS sickened at least 339 people in Saudi Arabia alone and killed nearly a third of them, according to the country's Ministry of Health.
As of April 16, 2014, the World Health Organisation has recorded 238 cases of the disease and 92 deaths globally.
The patient was a 27-year-old man who has been living in Riyadh, Saudi Arabia for the past four years. The patient had contact with a previously laboratory-confirmed case (his uncle) who died on April 19, and another laboratory-confirmed case (neighbor of his uncle) who is still under treatment in a hospital in Jeddah, Saudi Arabia. The patient became ill on April 22, returned to Egypt on April 25 and was laboratory-confirmed with MERS-CoV on April 26.
This "Indiana" patient flew to Chicago from Riyadh, Saudi Arabia, via London, then took a bus to northwest Indiana. He fell ill on April 27 and was hospitalized the next day. The patient is currently in a stable condition.
Researchers at the Center for Infection and Immunity at Columbia University’s Mailman School of Public Health, King Saud University, and EcoHealth Alliance extracted a live, infectious sample of MERS coronavirus (MERS-CoV) from two camels in Saudi Arabia. They found that this sample matched the virus found in humans on a genetic level.
As the New York Times has pointed,
The virus is thought to have originated in bats, but it is also widespread in camels. While it has not spread easily between humans, there have been outbreaks within families and in hospitals, where patients have infected paramedics, nurses and doctors.
Travelers to the Middle East have been warned to stay away from farm animals, and camels in particular. Camels are raised for meat and milk, for racing, and to haul goods. So-called beauty camels are kept as pets and entered in beauty contests.
Experts suspect that raw camel milk and meat transmit the virus.
As of the end of January 2020, 2519 cases have been reported worldwide, with 866 deaths.
Pangolins, or scaly anteaters, are mammals of the order Pholidota (from Ancient Greek φολῐ́ς, "horny scale"). The one extant family, Manidae, has three genera: Manis, Phataginus and Smutsia. Manis comprises the four species found in Asia, while Phataginus and Smutsia each include two species living in Sub-Saharan Africa.
The working theory of researchers in Guangzhou, China, was that SARS-CoV-2 had originated in bats and, prior to infecting humans, was circulating among pangolins. The illicit Chinese trade of pangolins for use in traditional Chinese medicine was suggested as a vector for human transmission. Researchers recently have implicated the pangolins as intermediate hosts in the ongoing coronavirus pandemic as the discovery of multiple lineages of pangolin coronavirus and their similarity to SARS-CoV-2 suggests that pangolins should be considered as possible hosts in the emergence of novel coronaviruses. However, further study was less conclusive on pangolins as the definitive source of (SARS-CoV-2), namely being the bridge that the virus used to jump from bats to humans, after it emerged that the 99% match did not actually refer to the entire genome, but to a specific site known as the receptor-binding domain (RBD). A whole-genome comparison found that the pangolin and human viruses share only 90.3% of their RNA. Ecologists worried that the early speculation about pangolins being the source may have led to mass slaughters, endangering the animals further, which was similar to what happened to civets during the SARS outbreak. Source.
By April 2020, the wet markets of Wuhan were open again.
A lesson learned is often not one recalled.
The danger awaits us all in the second wave of infections.