In a snapshot of MERS-CoV cases over the past year and an assessment of the global risk, the World Health Organization (WHO) said the epidemiology of the virus hasn't changed, but deep concerns persist about ongoing hospital-related outbreaks.
The report covers 189 lab-confirmed cases reported since the last report in July of 2017 through June of this year. The illnesses were in four countries: Saudi Arabia (182), Oman (3), the United Arab Emirates (3), and Malaysia (1).
Saudi Arabia over the past year reported six MERS-CoV (Middle East respiratory syndrome coronavirus) illness clusters, three of which occurred in healthcare settings. Hospital outbreaks are worrisome, because MERS-CoV symptoms are often nonspecific and healthcare personnel who aren't familiar with the disease can miss initial cases. Also, it's still unclear how the virus spreads in hospitals.
Maria Van Kerkhove, PhD, an epidemiologist who is the WHO's technical lead for MERS-CoV, said the report's findings are a reminder that the disease remains a global health threat. "This high threat respiratory pathogen has shown the potential to cause large outbreaks with substantial public health, security, and economic consequences," she told CIDRAP News.
Hospital exposures affected 12 health workers
Of 45 secondary cases reported to WHO over the past year, 17 were linked to healthcare transmission, including 12 health workers, as well as patients sharing rooms or wards with MERS-CoV patients and family visitors.
Hospital outbreaks occurred in the Al Jawf, Hafr Al Batin, and Riyadh regions.
Saudi Arabia has maintained progress since 2015 on testing all high-risk contacts in healthcare settings, regardless of symptoms, the WHO said, adding that steps have minimized the size of the outbreaks. However, it notes that improved compliance with infection prevention and control, especially observing contact precautions at all times, could further reduce or possibly eliminate healthcare-related cases.
Drivers of hospital spread still unclear
MERS-CoV seems to spread easily in healthcare facilities, unlike other community settings, and health officials still haven't been able to pinpoint what drives transmission. The topic is the focus of research collaborations, the WHO said.
Observational reports suggest transmission begins before cases are recognized and infection control steps are put in place. Also, investigations during outbreaks have found that aerosolizing procedures done in crowded emergency departments or other hospital wards may fuel human-to-human transmission and contaminate environments.
In hospitals, secondary cases had varied levels of contact with confirmed cases, ranging from direct contact, such as between health workers and patients, to no clear contact, such as only sharing a ward with infected patients.
In March 2017, the WHO held a meeting to weigh the role of environmental contamination, which resulted in a list of critical studies that need to be done, some of which are currently underway.
Overall picture remains the same
Since past updates, the epidemiology, transmission patterns, clinical presentation, and viral characteristics haven't changed, the WHO said. The primarily zoonotic virus is repeatedly infecting humans though direct or indirect with camels, with limited, nonsustained human-to-human transmission. Of 56 people thought to be exposed to the virus in the community last year, 37 (66.1%) had direct or indirect contact with camels.
The size and number of household clusters hasn't increased, the WHO notes.
The WHO said multisector investigations of community cases has improved, which has included testing of animals and herds linked to human cases and follow-up testing of human contacts of lab-confirmed cases.
About 75% of cases involved males, and the median age of patients over the past year is 54, similar to 52 for all cases reported to WHO since 2012.
Since the first human cases were detected, the WHO has received reports of 2,229 cases from 27 countries, mostly from Saudi Arabia, at least 791 of them fatal.
The WHO said its risk assessment hasn't changed since its last report. It emphasized that a person's activities and exposures while in the Middle East are most relevant for MERS-CoV, rather than just that an individual may have visited a particular country.
Movements between hospitals within and between countries can complicate the epidemiological picture, said the WHO, which also urges health officials to routinely order genetic sequencing of samples from confirmed patients to help clarify transmission sources and patterns.
The WHO said it expects more MERS cases to be reported from the Middle East, with occasional exported cases involving people who were exposed to camels or camel products or infected people, especially those in healthcare settings.
Aug 8 WHO global MERS-CoV summary and risk assessment