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Family 'cluster' shows MERS virus follows odd pattern

The grandfather got sick first, developing a fever, achiness, diarrhea and other vague but serious symptoms. Within a month, three male relatives were sick, too, with what’s been dubbed the MERS coronavirus. Two of the four men died.

The family’s case, described in the New England Journal of Medicine, shows some of the mysteries that public health officials are trying to solve as they grapple with the deadly new virus, which has killed more than half of its 49 known victims.  Where did it come from? And why does it so rarely pass from one person to another?

Wives, mothers and sisters all cared for the four men as they battled the infection, but none of them got ill.  Nor did any of the hospital workers who treated the patients -- even though they did not know at the time to take special precautions.

The family all lived in Riyadh, a big city, in a family compound of sorts. None had traveled much -- the first patient and two of his sons had gone to neighboring Bahrain six months before. The grandfather, aged 70, had a range of health complaints that made him vulnerable, including diabetes and high blood pressure.

He first started feeling ill on October 5, Dr. Ziad Memish of Al-Faisal University in Riyadh and colleagues report.

A week later he was in the hospital. Doctors had no idea they were dealing with a never-before-seen virus and barraged him with antibiotics. His 39-year-old son tended to him faithfully, doctors said, staying by his bedside for days. The patient, who is not named in the report, ended up on a ventilator and died October 23.

Five days later, the son showed up in the emergency room with a fever and coughing up blood. In October, a doctor’s first thought is when patients show up coughing, so he was treated with antiviral medications for influenza. It turns out these drugs are useless against the MERS coronavirus and the son died on November 2.

This man’s 16-year-old son become ill next and was admitted to the hospital on November 7. Doctors still had no clue about what they were dealing with, treated him with antivirals and antibiotics, and the teenager survived. His uncle -- son of the first patient -- also got sick and was hospitalized and also survived.

MERS is a relative of the severe acute respiratory syndrome (SARS) virus that spread globally from China in 2003, killed 775 people and infected close to 800 before it was stopped. It was eventually traced to an animal called a civet, a delicacy in China.

Scientists suspect MERS also comes from an animal, but they haven’t been able to find the source yet. SARS spread in what are known as clusters in which certain people seemed to be far more infectious than others. These “superspreaders” infected groups of health care workers or others they came into contact with.

MERS also appears to cause occasional clusters. A patient in France who died this week infected a person who shared his hospital room, and another so-called family cluster has been reported from Saudi Arabia.

In the case reported Wednesday, 28 family members lived in a large house divided into apartments in Riyadh.

“Aside from the four patients included in this report, no other family members had major respiratory symptoms or illness from September 2012 through April 2013,” Memish’s team wrote.

“This home is flanked by similar buildings on either side and is remote from any rural enterprises. There were no domestic animals in the immediate vicinity of the home, and the family did not keep pets. The only animal exposure occurred with Patient 4, who attended the slaughtering of a camel on October 24. No one had traveled out of Riyadh in the previous three months. “

When new diseases emerge, experts want to know every detail of how people lived and may have infected one another. This tells them whether am infection can pass casually, through the air, or whether close and intense contact is needed.

Right now, global health officials have warned hospitals to keep a close eye out for someone who might be infected with MERS. They’re told to take special, strict precautions in treating such a patient: wearing gowns, masks and gloves. Patients need to be kept isolated, so they don’t infect others. There’s no vaccine against MERS and no treatment, other than what’s called supportive care.

Everyone diagnosed so far has either lived in the Middle East, or traveled there recently.

The Riyadh family lived as many Saudi families do, Memish and colleagues reported. “All adult and adolescent male family members shared meals together and ate separately from female relations and their young children. The men also socialized and visited the local mosque together,” they wrote.

“After the onset of illness and before hospital admissions, each patient was cared for at home by family members; wives were the primary caregivers for the married men, and 16-year-old Patient 3 was cared for by his mother and sisters.“

But all these women stayed well, Memish reported. And none of the 24 health care workers who tended to the four sick men became infected.

So why weren’t any of the women in this particular family infected? The researchers don’t know. The good news, they say, is that MERS does not appear to be as easily transmitted as SARS was. But another study published Wednesday shows the incubation period may be as long as 12 days, meaning doctors will have to carefully watch anyone who comes into contact with a MERS patient.