MERS is another disease with no cure or vaccine--can scientists get ahead while there's still time?
Do you remember MERS? That’s right, the Middle East Respiratory Syndrome Coronavirus infection (MERS or MERS Co-V). It may seem like a disease of the past now, but there was a time only months ago that we had similar if not equally overreactive fears about whether the disease–which was spreading primarily in the Middle East–could spread through the United States.
In fact, there were a few cases of MERS in the U.S. in May. The CDC told Americans that: “In this interconnected world we live in, we expected MERS Co-V to make it to the United States.” And though the virus is a very different disease from Ebola, it similarly transmits between humans only via direct contact–making health care workers the most at risk. And like Ebola, there is no vaccine or cure.
Right before MERS slipped off our collective radars only to be replaced by the deadly Ebola virus one continent over, the World Health Organization (WHO) reported in July that it had received reports of 837 laboratory-confirmed cases of infection with MERS-CoV including at least 291 related deaths.
So, why is no one talking about MERS right now? Cases and deaths appear to have leveled off for now, which is leading researchers–who are very much still paying attention to the disease–to believe that perhaps it’s seasonal, like the flu. “It appears we are dropping out of MERS season,” says study author Darryl Falzarano, of the National Institute of Allergy and Infectious Diseases (NIAID). “It could be happening again in the spring. It’s possible that MERS could be more chronic, and Ebola is more sporadic.”
In a recent paper, a team of National Institutes of Health (NIH) scientists, including Falzarano, report that they’ve concluded that marmosets are the best animal model for testing potential treatments for MERS. The team has tested its fair share of critters, starting with small rodents like hamsters and ferrets, and eventually landing on another type of money called the rhesus macaques.
The trouble with finding the right animal is that viruses react differently depending on the host, and sometimes the cells won’t accept the virus, making testing useless. Though the rhesus macaques were able to contract MERS, their symptoms only grew to that of a humans’ mild to moderate symptoms, which is not as critical for testing as severe.
Now, the finding–published in the journal PLoS Pathogens– is by no means groundbreaking. But it highlights just how difficult and time consuming it can be to develop a drug or vaccine for an uncommon virus. One of the primary topics of debate during the current Ebola outbreak is whether experimental drugs should be used. The two now-recovered American Ebola patients received an experimental drug called ZMapp, and WHO is in the process of developing guidelines for how such treatments should be used. But the inconvenient truth is that even if a drug for Ebola is available, and most manufacturers only have limited amounts, we really have no idea whether they could work. It might just be too late for this outbreak.
But what about MERS?
“You cannot expect magic bullet types of cures off the bat,” says study author Vincent Munster, chief of the Virus Ecology Unit at NIAID. “The viruses we work with are really niche viruses, so there’s not a lot of interest from pharmaceutical companies. But I think this outbreak could propel some recent developments and vaccines.”
There are currently drugs and vaccines in the pipeline undergoing testing for MERS, and like in the current outbreak, they could be considered for last-ditch efforts. Scientists are not just studying how to develop methods to treat MERS, but they’re also trying to determine how it transmits from what appear to be camels, to people, plus whether or not there’s potential it could become airborne. The hope is that as our world continues to become more and more connected, there will emerge an incentive to develop and produce treatments for deadly diseases that we still don’t fully understand.
Thankfully, it appears we have some time when it comes to MERS–at least until spring.