The growth in the number of enterovirus D68 (EV-D68) cases showed a possible sign of slowing today, with just 14 more confirmed, while Oregon joined the list of affected states, leaving only four states with no cases.
There were other hints today of a possible decline in the puzzling respiratory disease outbreak in children, including a comment from a physician in Kansas City, one of the first places affected by the outbreak, that cases have been slowly decreasing since early September.
The Centers for Disease Control and Prevention (CDC) reported today that 678 cases have now been confirmed, 14 more than yesterday. That's the smallest change this week, after increases of 36 cases yesterday and 34 on Oct 7. The CDC has been working through a backlog of respiratory samples from around the country and notes that changes in the daily numbers don't necessarily reflect changes in real time.
The outbreak began in August, striking children almost exclusively. The virus, previously fairly rare in the United States, usually causes only cold-like symptoms, but some children get seriously ill and struggle to breathe.
Five patients infected with the virus have died. The CDC has said the virus's role in the deaths is unclear, but New Jersey officials reported earlier this week that EV-D68 caused the death of a 4-year-old boy.
Neuro illness with limb weakness
Health officials also are trying to determine if EV-D68 is contributing to unexplained polio-like illnesses that have been reported recently in a number of children around the country. In an initial cluster of nine such cases in Denver, four tested positive for EV-D68.
In an update yesterday, the CDC said it had verified 17 cases in 12 states that meet its case definition of unexplained neurologic illness with limb weakness in children. A case is defined as acute onset of focal limb weakness on or after Aug 1, 2014, with a spinal cord lesion largely restricted to gray matter on magnetic resonance imaging (MRI).
The update didn't specify how many, if any, of the patients were infected with EV-D68.
"We are also in the process of verifying dozens of additional reports," the CDC said. "These investigations take time and are in the early stages." It said the number of cases is likely to rise.
Some polio-like illnesses have also been reported in Canadian children. Yesterday the Toronto Star reported that six children at the city's Hospital for Sick Children are suffering from muscle weakness linked to respiratory illness, and one of them has tested positive for EV-D68.
Another child has a rhinovirus, and test results were still awaited in two other cases, the story said. It noted that the hospital has had seven confirmed EV-D68 cases in the past few weeks.
Worse than 2009 H1N1?
Kansas City, Mo., was one of the first places to be hit by the EV-D68 outbreak. At a press conference today, Mary Anne Jackson, MD, an infectious disease expert at the Children's Mercy Hospital in Kansas City, said cases at the hospital peaked between Aug 21 and Sep 2 and have slowly declined since then.
"We had three times the number of kids in the ICU in August and September this year over last year, about 100 kids," Jackson said. She spoke at a press teleconference at IDWeek, the annual meeting of the Infectious Diseases Society of America (IDSA), the Society for Healthcare Epidemiology of America (SHEA), the HIV Medicine Association (HIVMA), and the Pediatric Infectious Diseases Society (PIDS).
She said the outbreak has featured "higher acuity and more beds occupied by children" than was true during the 2009 H1N1 influenza pandemic.
Although the cases have been described as mainly affecting children who have asthma or wheezing, Jackson said that's not true in all cases. She reported that about a third of the children had asthma, another third had a history of wheezing but were not on medication, and a third had no history of breathing problems.
Jackson also observed that the outbreak has been severe in the Midwest and less so on the East and West coasts.
As for a possible link between EV-D68 and neurologic illness, Jackson said, "We do not know if EV-D68 can cause a polio-like illness. I suspect there will be a number of different etiologies, and they more than likely won't all relate to EV-D68, if they do at all."
Another infectious disease physician at the press conference, Aaron Milstone, MD, of Johns Hopkins Children's Center in Baltimore, observed that EV-D68 is a non-polio enterovirus, and that enteroviruses can sometimes cause paralysis. He suggested it's possible that the neurologic cases in association with EV-D68 have come to light simply because there have been so many more EV-D68 cases than ever before, not because of any change in the virus.
CDC EV-D68 outbreak page
Oct 8 Toronto Star story