Polio case reported in New York, first in the US since 2013

Health officials in the US have confirmed a case of polio, the first in nearly a decade in the country, in an unvaccinated man. The last known case was in 2013.

Results of lab tests have confirmed revertant polio Sabin type 2 virus in the 20-year-old man, a resident of Rockland County, according to a joint statement from officials at Rockland County, New York state department.

The infection was transmitted from someone who received the oral polio vaccine, which has not been administered in the US since 2000. As per the officials, the virus may have originated outside the US, where the oral vaccine is still administered.

Citing a public health official close to the investigation and not authorised to speak on the record, The Washington Post reported that the young man had travelled to Poland and Hungary this year and was hospitalised in June.

He was initially diagnosed with a possible case of acute flaccid myelitis, caused by inflammation of the spinal cord that results in severe muscle weakness and paralysis.

In the US, only the inactivated polio vaccine (IPV) has been given since 2000, suggesting that the virus may have originated in a location outside of the US where OPV is administered, since revertant strains cannot emerge from inactivated vaccines, the statement said.

"Based on what we know about this case, and polio in general, the Department of Health strongly recommends that unvaccinated individuals get vaccinated or boosted with the FDA-approved IPV polio vaccine as soon as possible," said Dr. Mary T. Bassett, State Health Commissioner, in the statement.

Due to the success of the vaccine, which was introduced in 1955 in the US, polio cases were cut dramatically in the late 1950s and early 1960s, with the last naturally occurring cases of polio in the country in 1979.

More recent polio cases were not wild strains, with the last known case in the US recorded by the Centers for Disease Control and Prevention (CDC) in 2013.

A viral disease that can affect the nervous system and cause muscle weakness, the polio virus typically enters the body through the mouth, usually from hands contaminated with faecal matter of an infected person. Respiratory and oral-to-oral transmission through saliva may also occur.

Polio is very contagious, and a person can spread the virus even if they aren't sick. Symptoms, which can be mild and flu-like (fatigue, fever, headache, stiffness, muscle pain, vomiting), can take up to 30 days to appear, during which time an infected individual can be shedding virus to others. Though rare, some polio cases can result in paralysis or death.

"The polio vaccine is safe and effective, protecting against this potentially debilitating disease," Bassett said.

The health officials have advised medical practitioners and healthcare providers to be vigilant for additional cases.

While those already vaccinated are considered to be at lower risk, individuals who are unvaccinated, including those who are pregnant, those who have not completed their polio vaccine series previously, should get vaccinated. Individuals who are already vaccinated but are at risk of exposure should receive a booster, the officials said.