Saturday, June 8, 2013

The spread of A(H7N9) by migratory birds

 Influenza A(H7N9) is a novel infectious bird flu strain that burst on the world's stage at the beginning of April 2013. Since then at least 132 individuals have been infected and more than 35 have died. [1]

In an article entitled Taiwan faces challenges on the emerging avian influenza A (H7N9) virus in China [2], researchers from Taiwan raise concerns over this novel influenza virus because it is a low path avian influenza virus (LPAI) in birds. This means that it does not kill off its avian hosts and is more difficult to detect in domesticated poultry and wild birds. The researchers note that after the closing the live poultry markets in Shanghai on April 5, the number of human cases caused by A(H7N9) virus dramatically decreased in that province. They speculate that A(H7N9) virus may spread silently in poultry in China and eventually spread globally through the migration of wild birds. They include a graphic depicting the geographic relation of humans cases in eastern portion of the People's Republic of China with the East Asian–Australasian migratory bird flyway.

The researchers in Taiwan have a right to be concerned. The only confirmed case of influenza A(H7N9) outside the mainland of the People's Republic of China was a Taiwanese national who worked in Suzhou, Jiangsu, where he was infected before returning to Taiwan.



Thursday, June 6, 2013

What is the actual count of MERS-CoV cases and the number of deaths?

With less than 60 MERS-CoV cases scattered around the world why is it so difficult for national and international public health agencies to report an accurate account of infected individuals including the number who died.

The World Health Organization charged with tracking health issues around the world reports that there have been 54 cases of MERS-CoV infection and 30 deaths. [1]

The CDC-USA reports a total of 55 cases and 30 deaths. [2]

A tabulation provided by the Virology Down Under blog identifies a total count of 55 cases and 33 deaths. [3]

FluTrackers identifies 55 cases but only 26 deaths in its list of cases. [4]

And through May 30, 2013, the ECDC reports a total of 49 cases with 27 deaths. [5]

This confusion over the number of MERS-CoV cases and how many deaths highlight the needs for one central, official, line list of cases that is publicly available on the internet.  Paramount in this case list is to distinguish between confirmed cases, probable cases, and suspected cases. Ideally, this line list would include cases that were previously reported as confirmed or probable, and then later identified as negative cases. This would alleviate much of the reporting and tabulation differences that occur when comparing case counts from different agencies and organizations.   

Tuesday, June 4, 2013

Confusing Information from Italy about the number of MERS-CoV Cases

Yesterday, the media from Italy reported that an additional 10 to 12 individuals were infected with the MERS-CoV, but the individuals were asymptomatic. These individuals reportedly included doctors and nurses. Today, a second round of testing on eight of these individuals produced negative results [1].  Based on the number of confirmed cases to date, MERS-CoV is a deadly disease. The presence or absence of asymptomatic or mild cases of MERS-CoV is an important component in understanding how this disease spreads. Hopefully, the confusion over the number of infected individuals and the MERS-CoV testing results will be cleared up soon by public health officials in Italy.

Monday, June 3, 2013

Map: MERS-CoV Clusters in Europe and North Africa, June 3, 2013

The announcement today of an additional 10-12 asymptomatic MERS cases in Florence, Italy, raises the specter of silent human-to-human transmission.  The map depicts the locations of clusters of confirmed and suspected MERS-CoV cases in Europe and North Africa.

An Expanding Cluster of MERS-CoV Cases in Italy

As of yesterday, three confirmed cases of MERS-CoV were reported in Italy.[1] Today, another 10+ asymptomatic cases have been reported by the media in Florence.[2-4] It is difficult to draw a conclusion from these media reports. 

Are these individuals actually positive for the MERS-CoV virus?

Is this a local coronavirus variant that is spreading from the initial index case in Italy?  

Does this indicate that MERS-CoV is actually a wide-spread coronavirus, a coronavirus with less virulence than expected?

More questions than answers now until official results are presented.

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


Map: MERS-CoV Outbreak, June 2, 2013

More than 50 MERS-CoV cases have been reported from eight countries as of June 2, 2013.  The index cases in the three European countries (France, Italy, and the United Kingdom) and Tunisia all contracted the virus when visiting countries on the Arabian Peninsula. The animal host for this coronavirus most likely originates on the Arabian Peninsula.

Saturday, June 1, 2013

Novel infectious diseases in the 21st Century

This blog will provide personal observations and speculations about current novel infectious diseases. When people contract an infectious disease for which they do not have any natural defense or immunity the disease is called a novel infectious disease.  Generally these infections are zoonoses [1], diseases that are transmitted between animal sources and humans.

In the past decade, a number of novel infectious diseases have erupted around the world including SARS, influenza A(H5N1) [bird flu], and the 2009 H1N1 pandemic virus. In the past 12-14 months, two new diseases have jumped to humans from unknown animal sources. 

 Since April of 2012, Middle East Respiratory Syndrome Coronavirus (MERS-CoV) has claimed the lives of at least 30 people and infected more than 20 others in eight different countries including France, Italy, Jordan, Kingdom of Saudi Arabia, Qatar, Tunisia, United Arab Emirates, and the United Kingdom [2]. In the past 60-90 days, avian influenza A(H7N9) [also known as bird flu] has infected more than 130 individuals in the People’s Republic of China and Taiwan [3]. 

Every novel infectious disease has the potential to grow into an epidemic and, from there, into a global pandemic. Every outbreak of a novel infectious disease needs to be monitored very closely.


[1] WHO zoonoses