Polio case confirmed in New York State, medics told to look for more

Polio virus, illustration. Each viral particle consists of a protein coat around the nucleus containing the RNA genetic material. This virus infects children and causes polio or infantile paralysis.

Roger Harris/Scientific Photo Library | Scientific Photo Library | Getty Images

On Thursday, the New York State Department of Health confirmed a case of polio, the first known case of infection in the US in nearly a decade.

A resident of Rockland County, a New York City suburb, tested positive for polio, according to the state health department. The Centers for Disease Control and Prevention confirmed the infection.

Health care providers should look for additional cases of polio, state health officials said. The chain of infections that led to the New York case is believed to have originated outside the US. There have been no cases of polio in the US since 1979, according to the CDC.

The strain of polio that infected the man, known as revertant Sabin virus type 2, suggests the chain of infection began with someone who received the oral polio vaccine, according to the state health department. The oral polio vaccine contains a weak strain of the virus that is still able to replicate, meaning that people who get it can transmit the virus to others.

The oral polio vaccine is no longer being introduced in the U.S., suggesting the chain of transmission began abroad, according to New York City health officials. In the United States, an inactivated polio vaccine is used, which is given as a shot in the leg or arm. This vaccine uses a non-replicating strain of the virus, so people who receive it cannot transmit the virus to others.

The CDC recommends that all children receive the polio vaccine. New York State requires all children to be vaccinated before they start school.

Polio is highly contagious and often begins with flu-like symptoms such as fatigue, fever, headache, muscle pain, vomiting, and stiffness. It can take up to 30 days for symptoms to develop, meaning that people who have not yet become ill can still transmit the virus to others.

In rare cases, polio can cause paralysis and death. The virus caused widespread fear in the 1940s, when vaccines were not yet available: more than 35,000 people become disabled every year due to polio, according to the CDC. At the time, many parents were afraid to let their children play outside during the summer when the transmission of the virus was at its peak.

However, a successful national vaccination campaign from the 1950s to the 1960s dramatically reduced infections. By 1979 the US was polio free.

United Kingdom declared a national incident in late June after the discovery of polio in several sewage samples in London. Wastewater samples in the UK have tested positive for a strain of the virus used in vaccines.

CNBC Health & Science

Read the latest CNBC Global Health Review: