Middle East Respiratory Syndrome (MERS) virus investigation

The team, from Johns Hopkins and elsewhere, investigated the spread of the virus, or MERS CoV for short, in four local Saudi hospitals in May, and concluded that it is even more deadly than the related coronavirus responsible for the severe acute respiratory syndrome (SARS) outbreak in Toronto hospitals in 2003. The same team investigated that event, as well. Initially, 23 people in Saudi Arabia were infected with MERS at the time of the investigation, and 15 had died of the SARS-like virus. Saudi health officials now put the death toll at 32, with another 49 infected.

The experts, whose report on the outbreak is to be published in The New England Journal of Medicine online June 19, say that MERS is not only easily transmitted from patient to patient, but also from the transfer of sick patients to other hospitals.

Trish Perl, M.D., M.Sc., senior hospital epidemiologist for Johns Hopkins Medicine, a professor at the Johns Hopkins University School of Medicine, and a member of the team, says that swift action by local health officials to quickly monitor the situation and spread of the disease, supported by rapid detection, isolation and treatment of those infected, has largely helped stem the outbreak. Hospital staff also tightened infection control procedures, introducing more vigorous cleaning procedures with stronger disinfectants, and treating infected patients in private rooms, while wearing masks, gowns and gloves, and masking any other non-infected patients who are nearby.

Saudi health officials invited Perl, along with fellow infectious disease specialists Connie Price, M.D., from the University of Colorado in Denver, and Allison McGeer, M.D., from the University of Toronto in Canada, to assist the country with its investigation. Greeting the team upon their arrival was a dolly cart full of cartons of medical records, which the team reviewed in their hotel room. Additional data and blood samples collected after site visits to all four hospitals were later shared with colleagues at the Johns Hopkins University Bloomberg School of Public Health, and experts in viral genetics at the Wellcome Trust Sanger Institute in the United Kingdom.

Among the team's other major findings was that MERS, even with relatively fewer people infected than in the SARS outbreak, had a death rate many times higher than SARS, at 65 percent and 8 percent, respectively. However, experts caution that the MERS death rate may come down if more cases are identified, including among those with mild symptoms.

The time from viral exposure to the first signs of symptoms of coughing, shortness of breath, fever, or vomiting, was 5.2 days, while it took on average 7.6 days for the virus to spread from one person to the next.

Among the 23 infected initially, five were family members, two were health care workers, including a nurse who had worked with other nurses caring for infected patients, and an ICU physician who had cared for and been directly exposed to MERS patients.

Nine infected patients had received dialysis treatment at the same hospital, some at the same time. Another dialysis patient had been transferred between units at different hospitals, where others became infected. Eight other infected patients were transferred for care between facilities, which the research team believes led to additional exposures.

"The story of how this outbreak occurred and how this virus was transmitted became very clear once we started to lay out the evidence and saw that one infected patient had been in the hospital at the same time as another infected patient, and this patient was transferred to another hospital, where another patient became infected shortly thereafter," says Perl.

"Our investigation showed some surprising similarities between MERS and SARS. Both are very deadly viruses and easily transferred between people, and even between health care facilities," says Perl, who adds that some people, such as the original MERS dialysis patient, also inexplicably appear to transmit the infection faster than others. SARS has a similar history.

Epidemiologist and investigative team member Derek Cummings, Ph.D., an associate professor at the Bloomberg School of Public Health, says that knowing the MERS incubation and generation times are critical to halting future outbreaks because "it tells us how long we have to act" before someone exposed to the virus starts to show symptoms and when people they infect also start to show symptoms.

Perl points out that intense monitoring leads to early detection of those infected, which can then lead to immediate isolation (to protect others from becoming infected) and treatment. No cure exists for MERS, but infected people can be supported on mechanical ventilation, if needed, to help them breath, or offered fluids to lower fever. Perl says that early detection makes a difference, as three out of four died among those who were diagnosed while already ill and in hospital, while only three out of 19 died among those who were diagnosed early after admission to a hospital.

A rapid test to detect MERS is the next priority in containing future MERS outbreaks, Perl says, noting that medical experts also must determine what precautions are most important in preventing its spread, and what screening criteria need to be in place to prevent outbreaks from hospital-to-hospital patient transfers.

Other investigators in Saudi Arabia involved in the report include Abdullah Assiri, M.D.; Abdullah Al Rabeeah, M.D.; Zaki Alabdullatif, M.D.; Maher Assad, M.D.; Abdulmohsen Almulhim, M.D.; Hatem Makhdoom, Ph.D.; Hossam Madani, Ph.D.; Rafat Alhakeem, M.D.; Jaffar Al-Tawfig, M.D.; and Ziad Memish, M.D. Additional research support from the United Kingdom was provided by Matthew Cotton, Ph.D.; Simon Watson, Ph.D.; Paul Kellam, Ph.D.; and Alimuddin Zumla, M.D.