August 23rd, 2013 by Sandy Dechert
We still don’t know how humans acquire Middle East Respiratory Syndrome (MERS, formerly known as “n-coronavirus”). The mortality rate among people treated for MERS is 65%, making it one of the most lethal coronaviruses identified to date.
However, scientists from the Ministry of Health of Saudi Arabia, the Center for Infection and Immunity of Columbia University, and EcoHealth Alliance have shown with molecular investigation the 100% identity of a betacoronavirus found in Egyptian tomb bats (Taphozous perforatus) with a human MERS CoV sequence.
From ARKIVE, an initiative of the charity WILDSCREEN: The Egyptian tomb bat is a fairly small bat, with fine, silky fur that is a mixture of dark brown and charcoal grey on the back, creamy grey on the underparts, and pale brown on the throat. The wings are dark brown in the centre and fade into a creamy colour at the tips. It has long, sharply-pointed ears with a mushroom-shaped tragus and tufts of hair behind each ear. Female Egyptian tomb bats are generally larger than the males. The Egyptian tomb bat has excellent eyesight and can spot prey from large distances, which, along with the long, narrow wings that allow it to fly rapidly, makes the Egyptian tomb bat a proficient hunter. Length: 9.4 – 11.2 cm, Tail length: 2 – 2.7 cm, Forearm length: 6.1 – 6.6 cm. Habitat: savannah.
Human-to-human transmission of the deadly MERS lung virus has been documented between patients and others in close contact (such as other hospital patients sharing rooms, family members, and medical personnel). However, the sources of infection for most patients remained unidentified until now.
The CDC’s Emerging Infectious Diseases journal just reported the new results online, ahead of print. The study team presented significant background:
“Bats are reservoirs of several viruses that can cause human disease, including rabies, Hendra, Nipah, Marburg, severe acute respiratory syndrome [SARS] CoV, and probably Ebola viruses. Cross-species transmission from bats to humans can be direct, through contact with infected bats or their excreta, or facilitated by intermediate hosts. Bat CoVs are typically host specific; however, MERS-related CoVs have reportedly been found in many bat families, including Vespertillionidae, Molosidae, Nyteridae, and now Emballonuridae (sheath-tailed bats) in Africa, the Americas, Asia, and Europe.”
Public health research has previously indicated that a very large number of MERS patients came from Saudi Arabia. In October 2012 and April 2013, the three agencies above went to three Saudi regions where MERS cases had been identified and collected thousands of samples from bat fecal pellets and rectal swab samples. (However, the October shipment of cryovials, inadvertently opened at U.S. Customs, sat at room temperature for 48 hours before transfer to Columbia University. At arrival there, all those samples had thawed.)
Nonetheless, PCR amplification of nucleic acid from a fecal pellet of one T. perforatus in the October shipment from Bisha revealed 100% nucleotide identity to human betacoronavirus cloned from a Bisha MERS patient. The bat samples had come from an abandoned date palm orchard within half a mile of the hardware store where the patient worked and less than five miles from his home.
W. Ian Lipkin, MD, Director of Columbia’s Center for Infection & Immunity and an internationally recognized authority on the use of molecular methods for pathogen discovery, led the study. Lipkin has also made important findings in AIDS, West Nile virus, and SARS research. Dr. Z.A. Memish, the first author, is deputy minister for public health, director of the WHO Collaborating Center for Mass Gathering Medicine in the Ministry of Health, and professor in the College of Medicine of Alfaisal University in Riyadh.
“Given the rarity of MERS CoV sequences detected by our survey,” the authors concluded, “and the broad distribution of MERS cases throughout the Middle East, we speculate that there are probably other hosts. Future work should investigate additional bat and other wildlife species and domestic animals for CoV infection and potential linkage to human disease.”
Two weeks ago, an international team of scientists reported in Lancet that they had tested the blood of various livestock, including cattle, sheep, goats, and dromedary (single-hump) camels from the Netherlands, Spain, Chile, and Oman. They found MERS antibodies in retired racing camels in Oman, which neighbors Saudi Arabia. Middle Eastern nations consume large amounts of camel meat, much of which is imported from African countries like Egypt. This lends further credence to a bat-camel-human viral linkage.
Seems as if anthrax may not be the only killer you could encounter in the tombs of Egypt’s long-dead pharoahs.
UPDATE: Two unrelated cases of MERS have occurred in the United States in the first half of May 2014.
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