May 29, 2013 (CIDRAP News) – Another Saudi Arabian has been infected with the Middle East respiratory syndrome coronavirus (MERS-CoV), while six others whose illnesses were previously announced have died, Saudi Arabian authorities and the World Health Organization announced today.
The latest reports raise the unofficial MERS-CoV tally to 50 cases with 30 deaths, for a case-fatality rate of 60%.
Also today, two medical journals published reports on MERS-CoV case clusters in France and Saudi Arabia, which reinforced the view that the virus does not spread very easily from person to person and suggested that its incubation period is as long as 12 days.
In a brief statement, the Saudi Arabian Ministry of Health (MOH) said the latest case is in a "new Saudi citizen," age 61, who has chronic diseases that include kidney failure. The statement said he lives in the Al-Ahsa region but did not say whether his case is related to the hospital-centered case cluster that began there in April.
The MOH also announced the deaths of three patients, aged 60, 58, and 24, whose cases were reported previously and who were hospitalized about a month ago. It said they all had chronic kidney failure and other diseases, but gave no other details.
Earlier today, the WHO reported the deaths of three other MERS-CoV patients, who apparently were among the five new cases that were reported by the Saudi MOH yesterday. The WHO said all five patients are from eastern Saudi Arabia but not from Al-Ahsa.
The five patients—three men and two women—were all older than 50 and had pre-existing health problems. The WHO described those who died as:
- A 56-year-old man who became ill on May 12 and died May 20
- A 77-year-old man who fell ill on May 19 and succumbed on the 26th
- A 73-year-old man who got sick on May 18 and died on the 26th
The other two patients are an 85-year-old woman who became ill May 17 and is in critical condition and a 76-year-old woman who had her first symptoms May 24 and was discharged from a hospital on May 27, the WHO reported.
The agency also confirmed yesterday's reports of the deaths of an 81-year-old woman from Al-Ahsa and the man who became France's first MERS-CoV patient.
The WHO listed the global MERS-CoV count as 49 cases with 27 deaths. Today's MOH statement apparently increases that to 50 cases with 30 deaths.
The journal reports published today focus on the two MERS-CoV cases that recently surfaced in France and a family cluster of four cases in Saudi Arabia last October and November.
Writing in The Lancet, a French team reported on the man who fell ill after returning to France from Dubai and the man who contracted MERS-CoV after sharing a hospital room with him.
The index patient, age 64, got sick with fever, chills, and diarrhea on Apr 22, 5 days after returning from his travels. He was hospitalized Apr 23, and 3 days later he experienced dyspnea and cough. After being transferred to other hospitals twice and being treated with extracorporeal membrane oxygenation (ECMO), he died on May 28.
The second patient, a 51-year-old, was hospitalized on Apr 26 for left arm deep venous thrombosis; he shared a room with the index patient in a Valenciennes hospital from Apr 26 to 29. The two beds were 1.5 meters apart, and because the first patient's MERS-CoV infection was not yet known, he wore no mask, and the second patient, staff, and visitors used no protective equipment. Despite this, no cases were found among other contacts of the two patients.
The second patient was released from the hospital on Apr 30, but on May 8 he sought treatment for asthenia, myalgia, and cough, and was sent to the Lille University Teaching Hospital, because by then the index patient's case was known.
The 51-year-old's case was confirmed on May 11, and he suffered respiratory failure the next day. He was treated with ECMO, and his respiratory status has improved since May 26, the report says.
The authors say the cases are clinically very similar to the only other two MERS-CoV cases that have been described in detail so far, with rapid decline in blood oxygen leading to mechanical ventilation and ECMO. Soon after intensive care admission, both patients suffered renal failure, necessitating hemodialysis.
The timeline of the two cases suggests that the virus's incubation period could be 9 to 12 days, which is "at the high end" of the 1- to 9-day period suggested by two secondary cases in the United Kingdom and of the 2- to 10-day period for SARS (severe acute respiratory syndrome, caused by another coronavirus), the report says. The finding implies that contacts of patients may need to be quarantined up to 12 days to rule out infection, it adds.
The authors found that the MERS-CoV load was high in samples from the lower respiratory tract but almost undetectable in the upper respiratory tract. They judge that this may make the virus less transmissible, but serologic studies are needed to better assess transmissibility. Also, they say the finding suggests that samples from the lower respiratory tract should be used for diagnostic testing, especially in the early clinical stages.
Exactly how the virus spread between the two patients remains unclear, but as with SARS, transmission through large droplets is the most likely route, the report says. But it also notes that the index patient's diarrhea—a condition that occurred in SARS patients as well—might have contaminated the environment.
Saudi case cluster
The Saudi Arabian family cluster is described in a report released today by the New England Journal of Medicine. It involved four cases, with two deaths, in a household of 28 people in Riyadh.
The first patient, a 70-year-old retired soldier with diabetes and heart disease, fell ill on Oct 5, was hospitalized 4 days later, and died on Oct 23. His oldest son, a 39-year-old factory worker who smoked and had reactive airway disease but no previous hospitalizations, got sick on Oct 24 and died Nov 2 after a few days of hospitalization in intensive care.
The third patient was a previously healthy 16-year-old boy and a son of patient 2. He became ill on Nov 3 and was hospitalized Nov 7. His illness was mild; he improved and was released from the hospital on Nov. 11.
The fourth patient was the 31-year-old son of the elderly man and younger brother of patient 2. A smoker with no other preexisting illnesses, he fell ill on Nov 4 and was hospitalized 2 days later. He was released on Nov 14.
MERS-CoV was retrospecitvley confirmed by polymerase chain reaction in patients 1, 2, and 4, the report says. But for the 16-year-old, mild illness precluded obtaining lower respiratory tract samples for testing, and the virus was not found in upper tract samples.
Although 28 family members lived in the patients' household, and the patients received care from other family members before they were hospitalized, no one else in the family had any major respiratory illness from September 2012 through April 2013.
As for possible animal exposures, the family had no pets and there were no domestic animals nearby. The only patient who had any animal exposure was the 31-year-old, who attended a camel slaughtering on Oct 24.
While it's impossible to exclude a common source of infection for all four cases, it appears that the second patient caught the infection from his father, the article says. The third and fourth patients might have caught the virus from either the older man or the second patient. Why the cases occurred only in men remains unexplained, the authors note.
They also comment that female caregivers in the family had repeated close contact with the patients before they were hospitalized, but did not visit them often after their admission. None of the women got sick, whereas two male family members who attended the older man before and during his hospitalization did get the virus.
The findings "may suggest that there is a reduced risk of disease transmission during the early stages of infection with MERS-CoV," the authors observe.
In other observations, the authors say three of the four patients had gastrointestinal symptoms, including anorexia, abdominal pain, and diarrhea, which may have important implications for hospital infection control measures and contact isolation.
May 29 WHO statement
May 29 Saudi MOH statement
Guery B, Poissy J, el Mansouf L, et al. Clinical features and viral diagnosis of two cases of infection with Middle East Respiratory Syndrome coronavirus: a report of nosocomial transmission Lancet 2013; early online publication May 29 [Full text]
Memish ZA, Zumia AI, Al-Hakeem RF, et al. Family cluster of Middle East respiratory syndrome coronavirus infections. N Engl J Med 2013; early online publication May 29 [Abstract]