One expert: Bioterrorism might explain some MERS mysteries

The multiple “paradoxes” in the epidemiology of MERS-CoV suggest that bioterrorism may be a factor, Australian epidemiologist Raina MacIntyre, MB BS, PhD, argues in an article today in Environment Systems and Decisions. But a Canadian expert called the suggestion unlikely.

MacIntyre, head of the University of New South Wales’ School of Public Health and Community Medicine (SPHCM), says that many features of MERS-CoV (Middle East respiratory syndrome coronavirus) can’t be explained by known principles of epidemiology.

For example, MERS-CoV has lower transmissibility than SARS (severe acute respiratory syndrome), yet it has persisted in humans far longer than SARS did, which suggests ongoing introductions of the virus.

She cites several other paradoxes:

  • A hospital outbreak in Al-Ahsa, Saudi Arabia, had a classic epidemic pattern with some human-to-human transmission, but three different MERS-CoV strains were identified.
  • The virus was present in Saudi Arabia during several mass gatherings, including the Hajj, but no epidemic occurred.
  • The surge of MERS cases in Saudi Arabia in April and May of this year did not lead to epidemics in any other countries.
  • Camels are suspected as a source of human cases, but many case-patients had no history of contact with animals or other MERS patients.

A large proportion of undetected (asymptomatic or mild) human cases might explain these puzzles, but this possibility is not supported by surveillance so far, MacIntyre writes.

“A careful review of the paradoxes and inconsistencies in the epidemiology of MERS-CoV raises deliberate release as possible explanation,” she states.

But Allison McGeer, MD, a microbiologist and infection control expert at Mount Sinai Hospital in Toronto, said the hypothesis seems unlikely.

“I didn’t have time to read the article really carefully, but what I seem to understand is that she is arguing that because it’s sporadic there’s a possibility it is deliberate, and I guess that’s true,” McGeer told CIDRAP News.

“But it really just seems more likely that it’s sporadic and we don’t understand the source, and you could say that of any disease that has multiple introductions from an unknown source. They could all be deliberate, but generally they’re not.”

She said she has not heard anyone previously suggest seriously that MERS-CoV involves bioterrorism. “It seems to me that there’s not enough science behind it to make it really worth having a discussion about,” she commented.

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