It’s all over the headlines: Enterovirus D-68 (EV-D68) is making kids sick in what appear to be unprecedented numbers. It might be causing paralysis — or maybe not. It may have infected some adults.

But EV-D68 is nothing compared to the viral killer that really concerns Dr. Paul Checchia of Texas Children’s Hospital, who treats sick kids all day long.

“Hysterical — that’s the way I describe it,” Checchia said about the reaction to EV-D68.

Every year, respiratory syncytial virus or RSV sends 75,000 to 125,000 children to the hospital and kills as many as 200 every year, numbers that are a little fuzzy because hospitals are not required to report deaths from RSV. Last year, influenza killed at least 105 kids. No deaths from EV-D68, which has been linked to several hundred illnesses nationwide, have been reported.

“Enterovirus must have a really good PR agent because it is getting all the press and there is no real need for it,” Checchia told NBC News. “It is a significant respiratory pathogen, but it is not really different from a lot of other respiratory pathogens out there.”

Most of the seriously affected children appear to have underlying lung diseases, such as asthma, or a neurological disease, and these children are at high risk from many viruses.

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RSV infects almost everyone by the time they turn 2. It causes a very bad cold in most, but in a few, especially newborns, it can bring on very severe disease. RSV kills between 66,000 and 199,000 children annually worldwide, most of them in developing countries, where the population is more vulnerable and supportive care less available.

Checchia believes many more U.S. babies die from RSV and it’s just never reported. Adults also can catch RSV, and it kills 10,000 elderly Americans every year, according to the Centers for Disease Control and Prevention.

“Enterovirus must have a really good PR agent because it is getting all the press."

"By the time we are adults it usually is just a really, really, really bad cold,” Checchia said. “If there has ever been a time when you have gone through an entire box of tissues because of the drainage, then you probably had RSV.”

Hundreds of viruses can cause classic cold-like symptoms. There’s EV-D68 and RSV, but also rhinoviruses, adenoviruses, metapneumoviruses and influenza. RSV is in a family of viruses called paramyxoviruses. There are also coronaviruses, relatives of the bugs that cause SARS and MERS.

In 2009, a rhinovirus caused an unusual outbreak that sent at least 500 kids to the hospital in Philadelphia. In 2006, adenovirus 21 was found to be causing severe disease. In the case of adenovirus, it was a new test that allowed doctors to figure out what was going on.

Many of the viruses can cause non-respiratory symptoms, including sometimes deadly inflammation around the heart, and paralysis. EV-D68 has been suspected of causing paralysis before, and last week the CDC asked doctors to keep an eye out for mysterious paralysis because four out of eight children in Colorado with paralysis or muscle weakness also tested positive for EV-D68.

The latest count -- 443 cases of EV-D68 in 40 states.

Most cases of severe respiratory disease are never diagnosed, mostly because the treatment is the same for all of them: simple supportive care. There’s no specific drug for most viruses, although flu is an exception —Tamiflu and Relenza can help treat symptoms.

RSV can be prevented with a drug called palivizumab. It’s a monoclonal antibody, an engineered version of an immune system protein, and it’s approved for use in high-risk infants and children.

“If there has ever been a time when you have gone through an entire box of tissues because of the drainage, then you probably had RSV.”

Checchia says one reason to test sick children is to identify an outbreak. Another is so that patients with the same virus can be kept together in the hospital and away from children who are not infected with it.

Enterovirus D-68 is generating attention because the pattern of infections is unusual, says Dr. Anthony Fauci of the National Institute of Allergy and Infectious Diseases. “It isn’t that often that you get this wide an outbreak of enterovirus D-68,” Fauci told NBC. “RSV is always there and people get used to it.”

Whatever might be causing the sickness, parents should be on the lookout for one big symptom, both Fauci and Checchia say: trouble breathing.

“Little babies, we don’t ask them to do a lot,’ Checchia said. “We ask them to eat, to sleep, to breathe and go to bathroom. If they can’t breathe, that is the time when you need to see a pediatrician.”