NOVEL INFECTIOUS DISEASES

Wednesday, March 16, 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.

Wednesday, January 20, 2016

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

Sunday, January 10, 2016

Will H5N6 Cause the Next Pandemic?

Influenza A(H5N6) is an emerging novel avian influenza that apparently derived from a reassortment of A(H5N1) with A(H6N6). H5N6 was first reported in domestic poultry in early 2014 from Laos, Vietnam, and China. Since then it has continued to be widely reported from domestic flocks in these countries (primarily China).

In April 2014, the first case of a human infected with the H5N6 influenza virus was reported from Sichuan Province in China. Since then, seven additional human cases have been reported, all from China. The most recent case was reported from Jieyang, Guangdong Province a few days ago. Of these eight cases, six have been reported by the World Health Organization (see links below).

Based on onset dates two of these cases occurred in 2014, four in 2015. Onset dates for the two most recent cases have not yet been reported. Among these cases are five males and three females. One of the females was pregnant. Her child was delivered by caesarian section and the woman is apparently still under treatment. Media reports indicate that the child was not infected. Ages range from 25 to 50 years old. Five the eight have died according to media reports.

Discussion

To date, there is no evidence of human-to-human transmission among these eight cases of H5N6. The fatality rate is high, but there are too few cases to project a fatality rate for a larger population of infected individuals. It is not known if subclinical cases of H5N6 are occurring. No asymptomatic cases have been reported and there are no reports of seroprevelance studies of H5N6 among humans.

As shown in the map below, these eight cases from the past two years are widely scattered over China. The map also depicts the location of reported H5N6 outbreaks in poultry flocks in southern China and northern Laos. Like the distribution of human cases, domestic flocks infected with H5N6 are widely scattered across a large area. The wide-spread geographic distribution of infected poultry along with the dispersed nature of human infections in this area suggests that more human cases are likely to be reported in the future. With such a large animal reservoir this influenza virus could reassort and become more easily transmitted to humans. Were H5N6 to pick up the ability to transit easily among humans, H5N6 could become a deadly pandemic virus.