SMITHTOWN, N.Y. (CBSNewYork/AP) — Officials on eastern Long Island are reporting an outbreak of whooping cough, also known as pertussis.

Thirteen students in three schools in Smithtown have been confirmed with the contagious bacterial infection.

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Health officials in Suffolk County said Tuesday they had alerted area pediatricians and had given advice to school officials on how to control the outbreak.

Suffolk County Health Department Spokesperson Grace Kelly-McGovern spoke with WCBS 880 Tuesday and called pertussis “very contagious.”

“Most people will recover from the pertussis. It’s mostly a concern for infants who don’t have the immunization or full immunization,” she said.

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Pertussis causes an uncontrollable, violent cough lasting several weeks or even months. It may begin with cold-like symptoms or a dry cough that progresses to episodes of severe coughing. It is spread from person to person.

Officials said all of the Smithtown students had been immunized, helping to reduce the severity of their illness.

“There is immunization that most children receive, which would probably mean…these children — from what I’ve learned — they are having milder symptoms than if they hadn’t been immunized,” Kelly-McGovern said.

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(TM and Copyright 2011 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2011 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)