In a profile of MERS-CoV activity in Saudi Arabia since Jan 12, the country has reported 75 cases, including 10 from two small hospital clusters and 11 from two household clusters, the World Health Organization (WHO) said today.
The most recent MERS-CoV (Middle East respiratory syndrome coronavirus) cluster involves a household in Najran, which an assistant Saudi health minister reported in a May 31 post to ProMED Mail, the online reporting system of the International Society for Infectious Diseases. Since then, one more related illness was reported, raising the number of people infected in the cluster to eight, according to the WHO's report today.
Maria Van Kerkhove, PhD, an epidemiologist who is the WHO's technical lead for MERS-CoV, said experts are seeing the same clinical patterns with MERS-CoV, including milder symptoms in people who have secondary infections. "However, as you can see from the mortality reported, MERS is incredibly deadly, and it's important that we continue to push forward the development of MERS-specific therapeutics and vaccines," she said.
Household clusters in Najran and Jeddah
The source of the cluster is believed to be camels at the index patient's home, the WHO said. The first patient is a 45-year-old man whose symptoms began on May 17. The other seven patients are all men ages 19 to 52 years old with illness onsets that range from May 22 to May 29. Only one, the first patient, had been exposed to camels. None of the men have died, and the WHO said no related infections have been reported in healthcare workers.
"This cluster is still under investigation at the time of writing," the WHO said. Najran is in far southern Saudi Arabia.
Meanwhile, the other cluster involves three people in Jeddah who were sick in March: a 56-year-old man whose exposure to the virus is still under investigation and two women, ages 67 and 41.
MERS-CoV doesn't spread easily from person to person, but close unprotected contact can contribute to the spread of the virus, and similar clusters have been reported before.
Van Kerkhove said in the latest cluster of household contacts from Najran, the secondary cases were infected through close unprotected contact while caring for their family member.
Hospital clusters in Hafr Albatin and Riyadh
The two hospital outbreaks occurred earlier this year, one in early February involving four people in Hafr Albatin in north central Saudi Arabia and one in late February and early March involving six patients at a facility in Riyadh. In each instance, the index patients are men for whom the source of the virus hasn't been determined. Both died from their infections.
In the Hafr Albatin cluster, the three other cases involved health workers who had asymptomatic infections. In the Riyadh event, the five other cases apparently involved other patients, all of whom had symptoms. Two died from their illnesses.
MERS-CoV appears to spread more easily in hospital settings, where early symptoms aren't always identified, because the symptoms can be nonspecific. In the past the virus has sparked large hospital-related outbreaks, mostly in Saudi Arabia, but also in South Korea. However, in Saudi Arabia, improvements in infection prevention and control have steadily decreased the size of the hospital outbreaks.
Saudi Arabia daily reporting update
Aside from the Najran household cluster, details about other MERS-CoV activity has been unclear since the middle of May when Saudi Arabia's health ministry began revamping its website. The ministry hasn't posted any daily update since about May 15.
According to today's WHO report, during the reporting lapse the country, as of May 31, has only reported two additional cases to the WHO that aren't related to the Najran household cluster. They include a 71-year-old man from Taif who got sick in May after contact with camels and died on May 24. The other case involves a 56-year-old man from Najran who began having symptoms on May 26 and whose exposure to the virus is still under investigation. Van Kerhhove said Saudi Arabia has been regular and timely with reporting its lab-confirmed MERS-CoV cases to the WHO.
Of the 75 cases the WHO covered in its report today, 24 patients had contact with camels or consumed camel products, 20 had no contact with camels, and 31 had exposure that is still under investigation. Twenty-three people died from their infections.
The WHO said the latest cases don't change its overall risk assessment of the virus and that it expects more cases to be reported from the Middle East, along with illnesses exported to other countries by people who were exposed to camels or to patients sick with MERS-CoV in health settings.
The latest illnesses boost the global number of reported MERS-CoV cases since September 2012 to 2,220, including 790 deaths, the WHO said. Of the total, 1,844 are from Saudi Arabia.
Jun 18 WHO statement
May 31 CIDRAP News story "Cluster of MERS illnesses reported in Saudi family"