The increase in cases has been happening since 2014, with the number of cases spiking in August and September, she said in a news briefing with reporters. "We recommend seeking medical care right away if you or your child develop sudden weakness of the arms and legs". "Most AFM cases occur in the late summer and fall, ." which she referred to as "seasonal clustering".
Since 2014, 386 cases have been confirmed, the CDC said on Tuesday.
"As a parent myself I understand what it's like to be scared for your child", Messonnier said.
AFM may be caused by other viruses, including enterovirus, environmental toxins and a condition in which the body's immune system attacks and destroys tissue that it mistakes for foreign material, Messonnier said: "This is a mystery so far, and we haven't solved it yet, so we have to be thinking broadly".
Federal health officials released the updated numbers on Tuesday, and said they still had no idea what was causing the spike in AFM cases or why kids were getting it in the first place. Officials said it's too early to know whether the total cases for 2018 will surpass those previous years. No one finding can explain all the cases, she said.
The cause is a mystery but the CDC and other officials have ruled out polio and West Nile virus.
In some individuals, health officials have determined that the condition was from infection with a type of virus that causes severe respiratory illness.
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In a country where cricket is heavily politicised, Marshall also briefed the president, prime minister and sports minister. They were laid following more than a year of ACU focus on Sri Lanka's 2017 ODI series against Zimbabwe.
Still, because this is a "pretty dramatic disease", Messonnier said, health officials want to raise awareness about the symptoms to ensure parents seek medical care immediately if their children show a sudden onset of weakness in their arms and legs.
She said that CDC has tested every stool specimen from AFM patients.
The illness affects the patient's spinal cord. All recent Minnesota cases have been in children under 10 years old and all were hospitalized.
The CDC says disease prevention steps should be followed, including staying up to date on vaccines, washing hands and using mosquito repellant.
The CDC referred calls to individual state health departments.
The CDC will determine whether the suspected cases in Maryland are AFM based on clinical information and lab tests, a spokeswoman for the state health department said in an email.
Kate Fowlie, a spokeswoman for the CDC, said in an email that many states are voluntarily reporting their data on the disease and that "many parents are coming forward to tell their stories".