Tabatha Vassey struggles to put her son to bed each night for fear that he will not wake up in the morning.

Two weeks ago, her son’s best friend, Eli Waller, age 4, died in his sleep. Health officials determined that the cause of death was the enterovirus 68. Eli had shown no signs of illness as he went to bed the night he died.

Vassey’s son, however, did exhibit symptoms of the virus. At the time of his friend’s death, Vassey’s son, whose name has been withheld per Vassey’s request, was in intensive care battling the respiratory effects of an enterovirus infection.

Her son appeared to come down with a cold on September 19 and within two days he was lethargic and wheezing. She said his breathing “sounded like a freight train.” He was admitted to the hospital shortly after when his oxygen levels were discovered to be way too low.

Vassey says she and her son have been targeted for some of the blame for Eli’s death. Her own son is still struggling to recover and his breathing has not improved.

She is waiting on tests to confirm if the virus is present or not.

Eli’s story is scary, but rare, health officials say. The CDC reports that enterovirus infections are quite common in the United States. Each year sees a range of strains of the virus circulate, with some strains being more present in some years than in others. The CDC’s records indicate that this year is presenting more cases of the enterovirus 68 strain than usual.

So far 43 states have confirmed the presence of the virus and another three are pending confirmation. At least four deaths are thought to be connected to the virus. Two dozen children who have tested positive for the virus have also shown signs of paralysis.

The CDC says that these types of complications are very rare. Most people who contract the virus exhibit signs of a cold and heal without medical intervention. The virus is known to pass through coughing and sneezing and standard hygiene practices are recommended to protect against infection.