A four-year-old boy from Jerusalem, who has not been vaccinated against Polio, was diagnosed with the virus, marking the first case in Israel since 1988, the Health Ministry said on Sunday.
According to the statement, the ministry's Jerusalem bureau has opened an epidemiological investigation into the case and will be in close contact with the child and his family to provide specific instructions. At this stage the symptoms developed by the infected boy are unclear, though he has not been hospitalized. Based on the findings of the investigation, further recommendations will be given.
According to an infectious diseases expert, this is a significant incident. “The last time a clinical case of polio was diagnosed was in the 1980s, when a teacher from Or Akiva contracted polio under similar circumstances. While less dramatic than polio caused by a feral strain of the virus, which is hardly ever seen today, we do know that the vaccine strain can – at a chance of one in a million or more – undergo such a mutation.
Prof. Haggai Levin, Chairman of the Public Health Physicians’ Union, says “This is a very abnormal occurrence, and all the details matter: The results of this investigation, the strain, the vaccination coverage in the population of origin.
The case was found following the monitoring of sewage water
for the virus in the area – findings that occur from time to time, but have previously not led to a clinical case of illness. The outbreak of polio in 2013, which led to a national vaccination drive of nearly a million children – was based entirely on samples of the virus in the wastewater, indicating the presence and spread of the virus in Israel.
In that drive, close to a million children were vaccinated within about four months, many of them in loci where vaccination rates were low. Following this, the vaccination rate rose and Israel once again enjoyed herd immunity.
Polio disease, or Poliomyelitis in scientific terms, is
caused by infection with the poliovirus, generally transmitted from person to person via saliva or feces. The virus has three [known] strains and most of those infected develop no symptoms at all, or mild symptoms typical of many illnesses, such as fever, loss of appetite, sore throat, and weakness. Some 4-8 percent of those infected contract a mild case of meningitis, characterized by full spontaneous recovery within days. A fraction of cases – about one in a thousand people infected – will develop paralysis symptoms.
According to Israeli experts, in cases where paralysis
presents, the virus penetrates from the colon through the blood stream to the central nervous system. When the poliovirus attacks the nerves in charge of muscular movement in the spine, paralysis appears suddenly in one or more limb. The paralysis is sometimes accompanied by severe pain in the infected muscle.
The paralysis usually involves the lower limbs. A spontaneous improvement in the severity of the paralysis is possible in the months following the infection, but in over half of all cases, some degree of permanent weakness to full paralysis remains.
In addition, the penetration of the virus to the nervous
system may lead to respiratory failure, which is one of the most common and threatening complications of the disease.
The polio vaccine is administered in four doses – at age two months, four months, six months, and twelve months, and another booster shot is given as part of second-grade vaccinations around age
Until the age of one, the polio vaccine is administered as part of the “quintuple” vaccine which also includes inoculations against diphtheria, tetanus, pertussis (whooping cough) and hemophilus influenza.
At least two doses are needed to attain sufficient protection (over 90 percent) against the disease. Three doses
provide 95 percent protection, and four doses provide protection approaching 100 percent.