Is My Child Contagious?

Some common childhood ailments and how and when they spread.

If the teacher sends home an email about an anonymous child (mine) who threw up in class yesterday, and now every single child in the class but one — plus both teachers — are out with the stomach flu, does it make you famous? Infamous more likely.

In our own defense, we were not the first family to come down with this thing, just the only ones to show it off in such a vivid manner. Now the whole school is apparently talking about the epidemic that took out a whole kindergarten class. Of course, it’s hard to hear the talk over the sound of that roaring train in the distance that’s probably coming right for them! A friend commented that misery loves company. You can tell he doesn’t have kids.

This is only the second or third time my poor 5-year-old has ever thrown up, which makes it all the more disorienting and awful for her to be doing so for more than 10 hours at a stretch. Poor thing! The first time it hit, I also had a small baby and so I called the doctor to see if there were any special precautions I could take. She informed me that you can’t catch stomach viruses just by being close to someone who has one, only by touching fecal matter from their diarrhea or vomit. This helped my paranoia about cuddling diminish, and my paranoia about hand-washing rise off the charts.

But at least I was informed and not going off superstitions that may have existed since the Middle Ages. If you, too, are wondering about the contagiousness of a particular illness in the interest of not spreading or catching anything this winter, here is a list of some common childhood ailments and how and when they are most spreadable:

Cold (Upper Respiratory Infection)

According to the American Academy of Allergy, Asthma, and Immunology, the average young child between ages 1 and 3 may get up to 12 colds a year. Telltale signs: a cough or a runny or stuffy nose.

Contagiousness: Colds are transmitted by touching your skin or environmental surfaces, such as door knobs and stair rails, that have cold germs on them and then touching your eyes or nose. They also spread when one inhales drops of mucus full of cold germs from the air when a contagious person coughs or sneezes.

When your child is feeling her worst (days three through five), she’s most contagious. But symptoms can last for up to two weeks, and while contagiousness decreases with symptoms, she’s contagious as long as she’s sick. Of course, you can’t quarantine her for days. So wash your hands frequently after touching her, and keep her away from other kids during the cold’s peak. And if the snot is green versus yellow? It doesn’t matter. All colds are contagious regardless of mucus color.

Ear Infection 

One of the most common childhood illnesses, it’s caused by bacteria settled behind the eardrum that cause a buildup of pressure in the middle ear canal.

Contagiousness: The good news is that unlike the colds that can lead to or accompany them, ear infections are not contagious, according to the American Academy of Pediatrics.

Vomiting and Diarrhea 

Sometimes accompanied by fever, these conditions are most often caused by viruses invading the intestinal tract. Vomiting usually ends after 24 to 48 hours, but diarrhea can last a week or more.

Contagiousness: Vomiting and diarrhea are spread by fecal bacteria, so wash your hands immediately after changing a diaper or cleaning vomit. If your child is throwing up, she is contagious from the first symptom until she feels completely better. With diarrhea or illnesses that involve both vomiting and diarrhea, contagiousness spans from the first symptom until stools are formed again. (If your baby wears a diaper, her stools should be firm enough so that they're not leaking.) The AAP also offers a handy list of do’s and don’ts if your child has diarrhea.


An infection of the lining of the eye and eyelids, it’s characterized by redness, itching or pain, and eye drainage.

Contagiousness: It’s one of the only illnesses a child can infect himself with. That’s right! If your child has pinkeye in one eye, all it takes to spread it to the other is rubbing. But how did he get it in the first place? From direct contact with the germs that cause it, either by touching an infected person or an object handled by an infected person (think bathroom towel). According to the Mayo Clinic, contagiousness generally lasts as long as the eye continues to tear and produce a discharge

Fifth Disease 

This viral infection, also known as Parvovirus B19 (or Parvo), infects immune cells, causing a rash and a low-grade fever. The classic description is a “slapped cheek” appearance with bright red cheeks and a lacy, non-raised rash on the body (see photo here).

Contagiousness: You can’t do anything to prevent spreading it or catching it. Kids who’ve been exposed may not show symptoms for up to two weeks, but they can be contagious for up to five days before showing symptoms. The most ironic part: According to the Center for Disease Control, by the time the red cheeks and rash appear, a child can no longer spread the infection. An important note here, it’s unlikely that adults will catch this illness, most are immune from childhood. But if they do, symptoms are way worse and may include, , arthritis and joint pain that lasts months to years!


A viral infection that causes fever and a red, bumpy, itchy rash, chickenpox can lead to skin infections and potentially life-threatening cases of pneumonia, sepsis, or meningitis.

Contagiousness: Even after vaccination, children still have a slight risk of catching chickenpox. The CDC says about 15 to 20 percent of vaccinated people could see another case of chickenpox, though it will be milder. If you’ve never had the pox before, and your child does, you’ll need to avoid touching her until her lesions are crusted over (this is hard, I know!), especially since the older the patient, the more severe the symptoms and potential complications, like Fifths. How long is your child contagious? From one to two days before the rash surfaces, until after all lesions are crusted over, says the CDC.

Strep Throat 

Symptoms of this bacterial infection include sore throat, fever, headache, decreased appetite, abdominal pain and nausea. To confirm that your child has strep, he’ll need a throat swab; results take about five minutes. If the test comes up negative, you can get a backup culture (office tests are wrong up to 6 percent of the time), which takes 48 to 72 hours for results. This way, there’s little risk of your child’s developing serious complications caused by untreated strep.

Contagiousness: Strep is spread by sneezes, coughs and sharing sippy cups. But knowing this likely won’t prevent your child from getting sick: The infection is contagious before symptoms appear. There is a way to prevent her from getting sick again, though. Strep likes to hang out on toothbrushes, so get her a new one 24 hours after she’s been on antibiotics — when she’s no longer contagious — so she won’t re-infect herself (horror!) The AAP recommends infected children stay home until they’ve been taking antibiotic treatment for at least 24 hours. 


Its name comes from the barking-dog or seal-like cough it causes. Croup is spread by a virus that attaches to the throat’s lining and causes the upper airway to swell. Fever usually accompanies it, and symptoms last for five to seven days. Croup is most common is small children, usually 5 and under with children 3 and younger showing the most severe symptoms, according to the Mayo Clinic.

Contagiousness: It’s contagious as long as fever and cough are present. While prednisone is helpful in decreasing symptoms’ severity, it doesn’t prevent your child from spreading the illness as long as he has symptoms. So keep him home until the “barking” subsides.


No matter the illness, keep your child home if she has a fever. It may seem harmless enough, but assume any fever is a symptom of a contagious condition. The Mayo Clinic also points out that a fevers seemingly help your body fend off infection. Viruses that cause fevers are contagious as long as the fever is above a 100.4 degrees reading rectally, according to AAP. Many parents take their sick child to daycare (understandably if they have to work) or birthday parties, but this is ill-advised because other kids can get sick.


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