Unless you’ve been living under a rock (and even if you have) you can’t help but have noticed the headlines about all the viruses we’re seeing lately. Measles in Ohio – the largest outbreak in the US since 1996. Polio in Syria and Iraq – a resurgence of a once eradicated virus as war leads to a breakdown in the vaccination efforts. MERS – a second case reported in the US of a “new” zoonotic infection from the Middle-East.
There was a whole session devoted to these “emerging” infections at the recent Pediatric Academic Societies meeting in Vancouver. There are many lessons that we can take away from these events. Firstly, that the well-fought victories we have won against vaccine-preventable infections are actually more of a fragile truce. Given enough of a susceptible population many of these viruses are ready to recur. Measles is an obvious example: probably the most infectious disease known to man, and a plane ride away from ongoing outbreaks in Europe and Africa. One of the most embarrassing exports from my homeland of England has to be the disgraced Andrew Wakefield (I won’t do him the honor of calling him a “doctor”) who pedaled fabricated data to support his efforts to sell a “safe” measles vaccine to a fearful British public. But what about polio? For the first time in years we have seen a significant increase in cases worldwide, as the safety of those administering the vaccinations has been threatened by war. Even as India can now claim itself Polio-free for the first time, I’m starting to wonder if and when we might expect our first case of imported polio to the US from the northern African countries or the Middle East, as the vaccine delayers and refusers leave us with an increasingly vulnerable population.
Secondly, that the pathogens just keep on coming! The Middle Eastern Respiratory Syndrome virus is a coronavirus, only the sixth known to infect humans. It is entirely distinct from the SARS coronavirus, and we’re still trying to piece together exactly how humans are catching and spreading it. Thankfully human-to-human transmission seems to be inefficient, which is just as well as asymptomatic infection seems to be rare, and the mortality rate is about 40%! It’s just as well it has absolutely nothing in common with a virus that causes the common cold that could mean its transmission might become easier…oh, wait….never mind….
The third lesson I took away from the PAS meeting was just how adept we have become at chasing these infections down. Modern sequencing technologies allow us to send patient specimens from an outbreak of an unknown infection, and within a few days we can have a full-length genome sequence and a phylogenetic tree of its nearest and dearest. MERS was isolated in good old fashioned virus culture by a doctor in Saudi Arabia, then confirmed through collaborative efforts in the UK and Netherlands, and reported publicly through global mailing lists prior to publication. Infectious Disease doctors and epidemiologists are recognizing the ease of global spread of infection, especially novel infections, and the need to work together if we are to stay ahead of them.
But it’s not just exotic imports we have to worry about. The epidemiology of infections in the Americas is changing too. Florida has already become a place where Dengue fever can be picked up without the need for a passport, and as our climate changes that may change too. I saw three cases of imported Dengue in Connecticut last year, and all we need is the Aedes aegypti mosquito to set up shop here and our imported cases can become local! (Chronic Dengue in Connecticut, anyone?)
Just about the only positive thing to come out all of this, is that it’s pretty much guaranteed that my job will stay interesting for years to come.