Sunday, June 2, 2013

Potential Animal Reservoirs of the Novel Coronavirus MERS-CoV on the Arabian Peninsula

The first human infections of a novel coronavirus were identified in late of 2012. The coronavirus was later named hCoV-EMC based on genetic analysis at the Erasmus Medical Center [1].  More recently, the World Health Organization (WHO) has adopted the label MERS-CoV for hCoV-EMC [2].

As noted in a previous post,  at least 50+ MERS cases have been reported from eight countries; France, Jordan, Italy, Kingdom of Saudi Arabia, Qatar, Tunisia, United Arab Emirates, and the United Kingdom.

The nature of the transmission is uncertain, but some of these infections are occurring in hospital settings; several health care workers have been infected.  Four of these clusters, one from France, one from Italy, one from Tunisia, and one from the United Kingdom, occurred outside of the Middle East region. The index cases in all four of these clusters had previously visited countries within the Arabian Peninsula. The index cases of other clusters, as well as other individual isolated cases, were all apparently infected in the geographic area of the Arabian Peninsula.  These data suggest that the animal host for MERS-CoV is endemic on the Arabian Peninsula.  

MERS-CoV  is one of six known coronaviruses that infect humans [3]. The most well-known of these six  is SARS-CoV.  SARS-CoV infected more than 8000 people from 2002-2003. Although SARS-CoV was initial identified in palm civets, later research indicated that the Chinese horseshoe bat (Rhinolophus sinicus) was the most likely host organism with the civets acting as an intermediate amplification host [4].  The Chinese horseshoe bat (Rhinolophus sinicus) is one of approximately 77 bat species included in a single genus of Rhinolophus in the family RHINOLOPHIDAE.  

The Erasmus Medical Center researchers that initially identified hCoV-EMC (MERS-CoV) in 2012 noted that this novel coronavirus was most closely related to two coronaviruses found in vesper and pipistrelle bats (family VESPERTILIONIDAE). The researchers indicate that the closest match of hCoV-EMC is the coronavirus BtCoV-HKU5 from Japanese house bats (Pipistrellus abramus) [5].
The authors comment that “it is tempting to speculate that HCoV-EMC/2012 emerged from bats—either directly or via an intermediate animal host, possibly Pipistrellus bats. This bat species is known to be present in the Kingdom of Saudi Arabia and neighboring countries.” [6] 

The identification of the Chinese horseshoe bat (Rhinolophus sinicus) as a host reservoir for SARS-CoV and the discovery by the Erasmus Medical Center Team that MERS-CoV is related to coronaviruses found in the VESPERTILIONIDAE bat family provides a basis for considering bats as the host organism for MERS-CoV  in the Arabian Peninsula.

Because Saudi Arabia has reported the most MERS cases, and because it occupies a great percentage of the Arabian Peninsula, bat species in Saudi Arabia should be evaluated as potential hosts for this novel coronavirus. More than 30 species of bats have been identified in a 2003 report on the bats of Saudi Arabia by Abdulaziz Al-Agaili and Wikipedia [7]. A review of the geographic distribution of these species on the Arabian Peninsula, in comparison with bat species from Qatar, United Arab Emirates [8], and Jordan  [9] where other MERS cases have been reported, suggests that four species from three families, HIPPOSIDERIDAE, RHINOLOPHIDAE, and VESPERTILIONIDAE, should be considered as possible MES-CoV reservoirs in the region.

Four bat species, Asellia tridens, Otonycteris hemprichii, Pipistrellus kuhlii, and Rhinolophus clivosus  have  a sufficiently large geographic distribution on the Arabian Peninsula to be reservoir species  of MERS-CoV.  All of these species are from the sub order of Microchiroptera. These small bats are generally insectivorous but some leaf-nose bats in this suborder are known to eat fruit [10]. Pipistrellus arabicus and Pipistrellus ariel are not included in the potential list of hosts because of their limited geographic distribution on the Arabian Peninsula. 

Fruit eating bats, members of the sub order Megachiroptera, are known to be reservoir for diseases such as Ebola and Marburg hemorrhagic fever. The only fruit bats that are sporadically reported from the region are Rousettus aegyptiacus and Eidolon helvu, but they are not found in the eastern portion of the peninsula where many of the MERS cases have been reported. While fruit eating bats could be a reservoir, the other four Microchiroptera species are more likely candidates.  While a microbat species in the region may be the host reservoir, the possibility of intermediate hosts associated with date farming and consumption should not be discounted in the transmission of MERS-CoV.

Species Distribution Information

Asellia tridens

Otonycteris hemprichii

Pipistrellus kuhlii

Rhinolophus clivosus


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