At this time we have no other convincing explanation for the spike in these two conditions than the Zika virus.
But while the WHO isn't ready to pass judgment on precisely what's to blame, (it specifies only "possible association with Zika virus") by citing Guillan Barre Syndrome, a debilitating neurological disorder, it has elevated our awareness of the threat posed by it.
GBS, an autoimmune disease, puts everyone, potentially, at risk - males and females, pregnant or not, and there's nothing we can do to make sure any particular case of Zika infection doesn't turn into GBS.
Thousands of babies born with malformed heads have deservedly captured media attention, but the less-mentioned GBS poses a unique challenge that is magnified in the developing world, where lack of access to medical treatments that can make a difference will likely prove lethal.
GBS hits all the criteria for a modern medical odyssey: It is
mysterious in origin, requires some detective work, it carries the risk of death, it requires prolonged intensive care, it strains families, it can ruin finances, and in some cases it leads to lasting loss of function -- paralysis.
Diagnosing and treating GBS demands a high degree of medical expertise backed up by the full spectrum of services available in the modern health care system. Even in the United States, GBS is one of the more dramatic and systemically taxing conditions we treat.
I treat GBS at the Shepherd Center in Atlanta, a specialty neurorehabilitation hospital. While GBS is normally rare -- affecting less than 2 people per 100,000 in any given year in the United States -- a variety of insults to the body can kick it off, including a number of viruses.
Through studies of the bacteria campylobacter jejuni, a frequent culprit in food poisoning that can also cause GBS, we know that the antibodies our immune systems generate to fight off this bug sometimes go on to attack the cell surfaces of our own peripheral nerves, damaging them to the point they can stop working. That causes paralysis, sensory loss and pain.
People will often come into my care completely paralyzed from GBS, as if they had a high cervical spinal cord injury, but in the moment it can seem even worse, as GBS can paralyze the facial muscles as well, limiting communication. They sometimes require a ventilator, and may need one for such prolonged periods that we will outfit them with portable ventilators that we attach to electric wheelchairs.
The medical regimen is advanced. Getting the right diagnosis to distinguish GBS from other causes of paralysis requires that we study cerebrospinal fluid obtained via spinal tap, as well as the results of electrical muscle and nerve tests.
Treatment calls for intravenous immunoglobulin, a product distilled from thousands of individual blood donations, or plasma exchange, which requires placing a large catheter in the neck or groin to retrieve the blood that we filter through a plasmapheresis machine to remove antibodies and other factors causing immune inflammation. Patients undergo the process every other day for 10 days. These are expensive treatments. Some patients need both.
The time and cost of treatment is a stretch even in the U.S. medical system. GBS cases stand out for their intensive use of resources, like a month of ICU care.
Survivors may require hospital-based rehabilitation for two months, followed by many months of outpatient rehabilitation. It's not so simple to get up once you've got GBS, even as your strength comes back, your blood pressure may suddenly crash.
Recovery usually takes over six months, with most people walking by that point. About 10% of people will suffer a lasting disability even after they've recovered.
That's the scenario in the United States. In many South American countries, where GBS rates appear to be rising, the kinds of resources I've described aren't available. GBS will be much more deadly, and more people there will suffer long term disabilities.
Earlier this week I joined Alberto Zambrano on a BBC radio program focusing on Zika. He's a physician based in Caracas, Venezuela's capital city, and teaches public health at the Central University of Venezuela. Zambrano made the GBS threat quite clear
"We lack the IVIG, the plasmapheresis machines and the laboratory re-agents for us to properly tackle this as well as the infrastructure. ... And this illness affects mostly in rural areas and in growing urban areas. We would need a lot of help in order for us to properly tackle this epidemic, particularly in Venezuela."
The WHO has put a spotlight on the need for thorough research into the link between Zika and diseases like microcephaly and GBS, the need for thorough mosquito control programs and related education campaigns, as well as the need for better diagnostics.
It will help coordinate
research efforts and the efforts mounted by individual national public health agencies. But GBS and microcephaly are already straining threadbare health systems throughout Latin America.
This is a slow-moving disaster spread across a vast geography. It's unlike earthquakes and tsunamis; the world is better accustomed to responding to those kinds of disasters in coordinated humanitarian relief campaigns.
The WHO's next priority? Coordinating global philanthropies and developed nations in mounting an international humanitarian relief campaign piggybacking on existing health systems.
We must shore up key medical and rehabilitative services in the affected nations now.