MERS is Widespread in Saudi Arabia

Middle East Respiratory Syndrome (MERS) has infected at least 1370 individuals (including asymptomatic cases) in Saudi Arabia since 2012 (e.g. ProMED link). Since mid-February 2016, Buraidah in Al Qassim region in Saudia Arabia has been experiencing a local MERS outbreak with 23 cases reported through March 16, 2016 (link). As of April 3, 2016 there have been an additional 11 cases reported, bringing the total cases reported from Buraidah by Saudi Arabia Ministry of Health to 34.  Many of these cases are a result of nosocomial infection, but perhaps as many as eight of these cases were community acquired infections with some individuals having contact with animals. Among these 34 cases, 17 have been reported as deaths so far. (see note)

While the Buraidah MERS outbreak has raised concerns, the 34 cases from Buraidah represented about 40% of all MERS cases reported from Saudi Arabia since January 1, 2016. The majority of MERS cases since January 1, 2016, about 49 cases, have been reported from numerous other locations around Saudi Arabia as shown in the map below. 

Since January 1, 2016, human MERS cases have been reported from at least 23 populated places scattered across Saudi Arabia. The widespread geographic distribution of these cases suggests that MERS has now become endemic in Saudi Arabia.

 Note: The total cases from Buraidah include a 60 year-old male who experienced symptom onset in Hail and was treated in the Buraidah hospital where he died (Case No 3. DON March 21,  2016)

The MERS Outbreak in Buraidah, Saudi Arabia, February - March 2016

Since late February, a Middle East Respiratory Syndrome (MERS) outbreak has been occurring in northcentral Saudi Arabia in Buraidah in the Al Qassim region. Through March 16, 2016, there have been 23 MERS cases reported from Buraidah by the Saudi Arabia Ministry of Health (SAMOH), include 6 females and 17 males, ranging in age from 22 to 84 years. Six of the cases are healthcare workers. Based on reports by the SAMOH, 11 of these individuals have died. Only five individuals have been reported to have recovered.

Constructing a preliminary timeline of Buraidah outbreak

Details are only available from the World Health Organization (WHO) for 18 of these cases prior to March 10, 2016. (link, link)

At least five of the cases reported by WHO appear to be community-acquired infections which suggest that MERS may be wide-spread in the Buraidah community. These individuals include a 40 year-old male (WHO 1670) who experienced symptoms on February 22 and was hospitalized the same day. It is not clear how this individual became infected. At least four other community-acquired infections also occurred. The first is a 42-year-old male (WHO 1658) who had symptoms on February 26 and was hospitalized on March 4 and is reported to have contact with animals. A 67-year-old female (WHO 1668) developed symptoms on February 28 and was hospitalized two days later on March 1. Investigations of exposure to known risk factors for this case are continuing. A 68 year-old female (WHO 1655) experienced symptom onset on March 2 and was hospitalized on March 5. Investigations of exposure to known risk factors prior to symptom onset is currently ongoing for this individual as well. The fifth individual is a 50-year-old male (WHO 1684) who experienced symptom onset on March 1 and was hospitalized the same day. He is reported by the SAMOH to have died.

Thirteen of the remaining WHO-reported MERS cases, including three healthcare workers, appear to be associated with the nosocomial outbreak at a hospital in Buraidah. The first healthcare worker developed symptoms on February 28 and the second on March 3. The third healthcare worker developed symptoms on March 6. This indicates that the coronavirus was present in the hospital prior to February 28.

According to the WHO report, eight of the confirmed cases were being hospitalized or treated in the Buraidah hospital starting as early as February 4 (seven had comorbidities and were possibly being treated for these conditions) and continuing through the start of the hospital outbreak. Three of these hospitalized cases initially tested negative for MERS; one on February 20, and two on February 24. Later all three of these individuals tested positive on March 4, indicating that these cases may have been infected after February 20.

This suggests that the possible index case for the hospital outbreak is the 40-year-old male (WHO 1670) who was experiencing symptoms on February 22 and was hospitalized on same day. He died on March 4. The other four community-acquired cases discussed above were hospitalized between March 1 and March 4, too late to have infected the first health care worker and some of the other hospitalized cases.

Between March 11 and March 16, the SAMOH identified five additional MERS cases from Buraidah. The WHO has not yet reported the details of these cases, but all least two or three of these cases appear to be part of the nosocomial outbreak.

Discussion

Although the details are unclear, community-acquired MERS infections are occurring in Buraidah  along with a nosocomial outbreak that originated after February 20 in a local hospital. In the Buraidah outbreak almost half of all of the reported fatalities (5 out of 11) are under 35 years in age. This is a high percentage. Of the previously reported MERS fatalities from Saudi Arabia only about 10% are under the age of 35.

It is not clear if the nosocomial MERS outbreak in Buraidah has been contained.

The Geography of MERS

Since 2012, the World Health Organization (WHO) has been notified of 1626 laboratory-confirmed cases of Middle East Respiratory Virus Syndrome (MERS) as of January 7, 2016 (link). These cases have been reported from 26 countries as shown on the map and table below. Cases have been reported from most continents: North America, Africa, Europe, and Asia. No cases have been yet been reported from South America, Australia, or the sparsely inhabited Antarctica. More than 75% of these cases have been reported from Saudi Arabia. 

Countries Reporting MERS infections to WHO

 

Worldwide count of MERS cases  

The earliest cases of MERS in 2012 were geographically associated with countries in the Middle East. Numerous cases in Saudi Arabia are reported as “primary cases”, autochthonous cases, which have been infected from local animal hosts. Current research indicates that camel populations on the Arabian Peninsula are a reservoir for this coronavirus, although there may be other intermediate animal hosts as well. 

The map above only shows countries that have officially reported MERS cases to WHO, not the countries where the individual cases were initially infected. A review of the published case reports indicates local infections from animal sources has only occurred in countries on or adjacent to the Arabian Peninsula as shown in the map below. Although the MERS jump from animals to human appears to be occurring only in a small geographic region in the Middle East, this coronavirus is very infectious. Many infections on the Arabian Peninsula and elsewhere are reported to have occurred from human-to-human contact or by transmission within a healthcare facility. 

Secondary cases of infections have occurred in health care facilities in Saudi Arabia, South Korea, and other countries. The large number of MERS infections among healthcare workers, healthcare facility patients, and patient visitors is a strong indication of the infectious nature of this coronavirus. According to published information, at least 240 reported MERS cases were healthcare workers.

Last year in South Korea, 185 cases of MERS were sparked by a single infected individual who traveled to South Korea from the Middle East. The infections spread primarily though hospitals. The nature of infectious transmission in health care settings is not clear. Human-to-human airborne transmission has been proposed for pneumonia-infected “superspreaders” in South Korea (link), but human-to- fomite-to-human transmission seems to occur frequently as well. 

Because of the nature of international travel and the infectious nature of this coronavirus MERS, cases have been reported from 26 countries around the world in less than four years. We can expect more MERS cases to be infected in the Middle East and to be reported from more countries in the future. 

Countries on the Arabian Peninsula reporting autochthonous cases of MERS 

Case Details from the Current MERS Outbreak in Riyadh Saudi Arabia, August 2015

The current outbreak in Riyadh started mid-July when a 56-year-old man became infected with Middle East Respiratory Syndrome coronavirus (MERS). This individual had frequent contacts with camels and consumed raw camel milk. This man infected his 52-year-old wife, his 53-year-old brother, and 30-year old son. The index case and his wife are reported to have died.

Almost 120 cases have been confirmed during this MERS outbreak in Riyadh through August 28, 2015.  As in other MERS outbreaks, more males then females are infected, about 61%. The males range in age from 2-109 years old with a median age of 61. The females range in age from 25 to 98 with a median age of 58.

The fatality rate for this outbreak is about 25%, with similar death percentages for both males and females. However the fatality statistics could change because the Saudi Arabia Ministry of Health is reporting that there are at least 50 cases still under treatment.

In this outbreak, most of the infections had been contracted by either visiting or being treated in a hospital with current MERS patients. A few cases are reported to have contact with confirmed MERS patients possibly outside of a healthcare setting. Information on family clusters is not available. It is difficult to assess the extent of family clusters, since that information is not generally available. 

Besides the initial family cluster in this outbreak, one other possible family cluster can be proposed from the data. A 56-year-old female experienced symptom onset on August 7, with her death reported on August 17. The World Health Organization reports that a 28-year-old female had contact with this woman and became symptomatic on August 12. A third individual, a two-year-old boy, also had contact with this woman and became symptomatic on August 12 as well. The boy is reported by the Saudi Arabia Ministry of Health to have recovered. Speculating, this cluster would seem to be a result of a daughter and a grandson interacting with the 56-year-old grandparent.

Healthcare workers represent about 11% of all infected individuals in this current outbreak.  This is similar to the overall percentage of healthcare workers infected with MERS in Riyadh since 2012. About 10% of all of MERS cases reported from Riyadh since 2012 were healthcare workers.

The epidemiological similarities among various MERS outbreaks should begin to provide a framework for understanding and controlling this disease in the future.