A few unexplained medical cases are enough to put the sanitary authorities on alert. This is a commendable precaution that may one day save the world from a major epidemic. On the other hand, spreading the fear of a non-existent threat can also do a lot of harm.
When a mysterious disease strikes people – such as recently in California, where twenty children have fallen victim to an unknown infection leading to paralysis – a team of doctors and epidemiologists steps in. Do you remember the Epidemic of Fear? The idea is to find the culprit before it has a chance to spread.
The investigation usually begins with disturbing medical reports: the Ministry of Health then learns about the growing number of patients visiting the clinic for specific reasons. Then the relevant authorities themselves have to assess whether the observations of doctors really indicate an increase in the incidence or whether the medical community has been subjected to a certain delusion. The story of Californian children is a typical example: the symptoms that occurred in young patients were not a surprise to the pediatricians. The fear was caused by the larger than usual scale of the problem.
Nonpoly Acute Flaccid Palsy, more commonly known as AFP, is a disease that many doctors have seen in their office, and its causes may be several. “A patient with AFP happens on average once every five years,” said Keith Van Haren, of Stanford University, a neuroscientist who has been tasked with solving the California disease. – Five cases at the same time are indeed an anomaly.
Yet it is more difficult to prove that something is an anomaly than to simply observe it. According to data from the World Health Organization, AFP affects one in 100 thousand. children a year. The incidence rates for the United States are unknown, but it is estimated that of 7,7 million Californians under the age of 15, 20 cases of AFP a year may not be a sufficient reason to raise the alarm. However, the final risk assessment is related to the determination of whether the reported cases are related in some way and whether they occurred in relative geographical proximity. If specialists see any relationship between infections, and the media join the case, we can expect further alarming reports.
“You see what you want to see,” says Daniel Feikin, head of the infectious disease epidemiological unit at the Center for Disease Control and Prevention. Doctors usually do not report cases of non-polypsis in children as they are under no obligation to do so. Now that they are oversensitive about this, they will certainly disseminate data on this subject. The difficulty will be to distinguish an increase in morbidity from an increase in reporting.
Another challenge is figuring out which cases should be counted. With a precise definition of the disease, it would prevent unrelated cases that could mislead the scientific community from being included in the statistics. Van Haren reports that at the moment the working definition for Californian childhood conditions is “paralysis with confirmed damage to motor neurons in the anterior horn of the spinal cord.” Already from this brief description, it is clear why the disease has been defined as “polio-like”. It is not enough to say that the Californian children were paralyzed. In fact, many health problems can cause paralysis: Guillain-Barré syndrome causes limb paresis in children, and transverse myelitis has similar effects. Yet polio reveals a number of features that distinguish it from a number of others.
The polio virus, or Heine-Medina disease virus, enters the body via the fecal-oral route. The infection occurs as a result of contact of the mouth with hands contaminated with feces or by drinking dirty water. Because in as much as 95 percent. In cases of viral infection, there are no symptoms whatsoever, and polio victims usually have no reason to suspect that they have come into contact with dangerous microbes at all. That is why the possible paralysis seems so surprising to the environment. In some patients, polio leads to a series of flu-like symptoms that have been observed in California patients. Only a small percentage of infections will lead to an attack by the virus on the central nervous system.
The polio virus contains proteins on its surface that match proteins belonging to nerve cells as precisely “as a lock key”. Damages the neurons responsible for controlling the muscles in the arms and legs – the so-called motor neurons or motor neurons in front of the spinal cord. It causes limb paresis, although the patient retains sensation in them because polio does not affect the sensory nerves. These symptoms – paralysis in combination with a slight reduction in sensation in the limbs or complete preservation of sensation – make it possible to rule out a number of causes other than Heine-Medin disease in the case of California illnesses, notes John Modlin, a polio doctor at the Bill Foundation. and Melinda Gates. Herpes simplex and chickenpox viruses can cause childhood paralysis on rare occasions, but in these cases patients lose feeling in the extremities. It will be the same with the Guillain-Barry syndrome.
However, since polio has been eradicated in practice in the United States, and California children have been vaccinated against the disease, suspicion has fallen on other members of the enterovirus family, including the Heine-Medin disease virus. By relying only on symptoms, doctors are able to clear out some germs. Many enteroviruses have protein ‘keys’ matched to other parts of the central nervous system. For example, dreaded in Asia and many other parts of the world, enterovirus 71 can impair respiratory or cardiovascular function by attacking the nerves that make the heart work or breathe properly. Californian children weren’t affected by this kind of problem.
However, although doctors have such indications, it is not possible to say with certainty what caused the paralysis without confirming the presence of the virus in the central nervous system. This is a difficult task, considering that enteroviruses are only a few days, sometimes even hours, in the spinal fluid. If a patient does not go to the hospital immediately after registering the first signs of weakening, doctors may still look for the microbes responsible for the development of the disease elsewhere in the body. Enteroviruses can be traced in oral and nasal secretions for 10 days, and in stools for several weeks.
Two paralyzed children showed the presence of enterovirus 68, also from the polio family, in a nasal discharge. (…) Which, however, does not prejudge the matter, because enteroviruses may have been present in the body, although they did not cause the paralysis. On the other hand, the allegations against the targeted microbe seem justified. Modlin, a specialist in enteroviruses of international fame, is ready to bet that, at least in these two cases of paralysis, we already know its cause. Moreover, it is possible to imagine a situation where enterovirus 68 is responsible for paresis in these two children, while the remaining patients fell ill for other reasons.
At the moment, however, an answer should be found especially to one question: if there is a pathogen responsible for paralysis in California, do we have reason to fear an epidemic? Were the other children in danger? The issue seems so serious that it has alerted Washington, where Senator Barbara Boxer is now demanding a separate investigation into the matter.
If you believe the specialists studying California cases, there is no basis at this stage to claim that we are on the brink of an epidemic. Children affected by paralysis had no contact with each other. Doctors are now trying to find out if there is something that connects little patients – travel or contact with the same animals. If it was enterovirus to blame, the chances of spreading the disease are minimal.
Apart from the poliovirus and enterovirus 71, few pathogens in this family are shown to cause epidemics. The Californian outbreak was probably caused by a tragic and unusual accumulation of cases that medicine would describe as “rare.”
Tekst: Brian palmer