California has seen a small number of cases (20-25) where children are being affected by a polio-like virus within the last year.
The five recent cases have also experienced partial paralysis in one or more arms and/or legs.
All five of these children have had medical treatment, but after six months, they still have poor limb function, according to the American Academy of Neurology.
Two of the children have tested positive for the enterovirus 68, but researchers have found no cause for the paralysis in the other three children.
Interview with CDC’s Director of Viral Diseases
Decoded Science recently had the privilege of speaking with Dr. Mark Pallansch, Director for the Division of Viral Diseases at the Center for Disease Control and Prevention, and we discussed the enterovirus situation in some detail.
Why Is the Enterovirus Confined to California?
We asked Dr. Pallansch why these cases have only been confined to California and he replied, “We don’t know that it is. Partly this is the background rate of AFP something approaching 1 per hundred thousand children under the age of 15; and that’s for all possible causes. The children reported from California are representing the subset of those one per one hundred thousand. That’s where we would expect the same rate to apply for the rest of the country and at this point in time because AFP is not reportable to the CDC we don’t know how many of those cases are investigated, as states aren’t required to report unless they suspect polio.”
What’s causing these cases? Medical experts don’t know for sure. Dr. Pallansch explained that there are a number of causes and we don’t know the full spectrum because two-thirds have no etiology, which is the biggest problem he says. Etiology is the study of causation or origination. In two-thirds of the cases in California, researchers simply cannot find the cause or origin of the illness.
Mutated Form of Polio?
It’s an enterovirus, like polio, and kids are getting paralyzed. How do we know this isn’t some mutated form of the polio virus?
We asked Dr. Pallansch about this issue, and he explains, “There is a standard protocol to rule out polio, including the clinical presentation, the epidemiological situation related to vaccine status, travel history for potential exposure, and laboratory testing. Because of the nature of the polio replication, some of the typical types of specimens like cerebral spinal fluid are not that sensitive to detecting polio. So that is where the recommendation is to collect fecal material because that is where the virus is shed in the highest quantity and for the longest period of time. In all the years of looking for polio there hasn’t been any mutated or unusual forms of polio, it’s just been the three serotypes. We don’t have that situation although since we characterize every virus globally we would indeed see if that were happening.”
Preventing Paralysis with Antivirals?
Antiviral medications can help stop the development of many viruses. I asked Dr. Pallansch whether antiviral medication could prevent paralysis in these cases? Dr. Pallansch explained,
“At least in the case of enterovirus it is too late to alter the clinical course. It largely depends on which virus. In some of the situations in where the virus is still actively replicating in the central nervous system it may limit the degree of paralysis. It probably would not stop clinical symptoms, but could limit paralysis.”
Enterovirus: Signs and Symptoms Before Paralysis
How can doctors (and parents) tell when their child is ill, and likely to experience paralysis due to the enterovirus? Decoded Science asked whether there were any specific signs and symptoms that doctors have been seen in the days prior to paralysis. Dr. Pallansch said,
“That is a very good question that we are working with the state of California to answer. We are trying to understand what common features occur in these cases. These cases of AFP have multiple causes, both infectious and non-infectious. So for any given person with AFP their clinical diagnosis can be one of many different diagnoses. Some would be expected to have a fever and some would not. So trying to find common characteristics is what we are trying to work with California to review.”
Enterovirus Paralysis Recovery
Can kids recover after becoming partially paralyzed in these cases? Dr. Pallansch also talked to us about the recovery rates after paralysis.
“It all varies tremendously on the diagnosis. For example the majority of AFP is due to guillain barre (GB) and recovery from GB is generally fairly good, but in polio cases, typically depending on age, only about a third of them would recover and at least two-thirds would have life-long paralysis. We don’t know if the children from California could recover; some of them had paralysis 60 days after the onset, which is a point of time beyond recovery.”
Transmitting the Enterovirus
The CDC says that the virus can live in water and if people drink it they can get sick. How long can the virus live in water? Dr. Pallansch explained that the virus can survive in water, but doesn’t actually replicate. Survival of the virus varies by temperature, so in cooler water the virus can survive longer. In warmer water it can only survive for a few weeks at most.
Survival of the virus can be measured in weeks and months in some water sources and how dirty the water is matters because the virus can stick to solids and therefore settles in the sentiment and dies there.
Clean, running water from a faucet tends to be safe, Dr. Pallansch explains because the water treatment facilities use chlorine to treat the water and chlorine kills the enterovirus very effectively.
The Enterovirus: Serious, but Rare
In conclusion, Dr. Pallansch tells us, “The general message is that this is a very uncommon condition and of course like any other significant serious disease, we are concerned. The issue on what causes these sporadic cases is something that’s been a subject of investigation in the past and we are indeed talking to California and what might be possible to investigate these cases further and that is up to the state of California.”
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