There is a lag time between being exposed to an infection and coming down with the disease. This time frame is called the incubation period.
The value of knowing
the incubation periods for common infections is that you can better gauge if you have “dodged a bullet” regarding something you or your child has come in contact with. Here are the incubation periods for some well-known childhood infections.
- common cold: 1 – 3 days
- conjunctivitis (“pink eye”): 1 – 3 days
- croup: 2 – 7 days
- fifth disease: 4 – 14 days
- hand/foot/mouth disease: 3 – 6 days
- herpes (“cold sores”): 2 – 12 days
- impetigo: 1 – 7 days
- Influenza: 1 – 4 days
- molluscum contagiosum: 1 week – 6 months
- mononucleosis: 4 – 6 weeks
- pertussis (“whooping cough”): 1 – 2 weeks
- pinworms: 2 – 6 weeks
- roseola: 5 – 12 days
- RSV: 2 – 8 days
- strep throat: 1 – 3 days
- viral gastroenteritis (“stomach flu”): 1 – 3 days
Strep throat is caused by a bacterial species called Streptococcus pyogenes. There are more than 100 types of strep based on their cell structure. Of these, a small number produce a toxin that can cause scarlet fever.
The symptoms of strep throat include fever, sore throat, headache, stomachache and fatigue. On examination, a child will typically have red and swollen tonsils with or without pus and swollen, tender lymph nodes where the neck meets the jaw. With scarlet fever strains, a child will develop additional findings: a red, strawberry-appearing tongue and a sandpapery or gooseflesh rash on the body. A week or so after the infection resolves, the skin on the child’s body may peel.
Before the development of antibiotics, scarlet fever was a deadly disease. As a result, some people (especially grandparents) may worry if they hear that a child has scarlet fever. Nowadays, scarlet fever is a different illness, and doctors just consider it a strep throat with a rash.
One fact about scarlet fever is very interesting. It appears that not only does a child have to be exposed to a certain strain of strep to develop scarlet fever, but his body has to react to the bacteria in such a way that the rash occurs. Although I have experienced hundreds of patients giving strep to their brothers and sisters, I have never had two cases of scarlet fever in the same family at the same time. This doesn’t mean it can’t happen, just that it’s quite rare.
When a newborn’s penis is circumcised, the head of the penis (glans) will be red and wet looking for 3 to 5 days. During the healing process, it’s common for the glans to develop small yellow patches. These areas are part of the healing process and do not mean the baby has an infected circumcision. (If you’ve ever had a cut inside your mouth, you’ll recall that it heals with a whitish or yellow patch rather than a tradition scab. The same thing happens to a circumcised penis.)
I’ve been practicing pediatrics for over 30 years, and I have never seen an infected circumcision. If this were to occur, the redness would extend from the glans to the shaft and then towards the baby’s body. If you see this, call your doctor right away.
Most children contract hand, foot and mouth syndrome before kindergarten. The infection is usually caused by a member of the Coxsackie virus family. It typically presents with fever, sore throat and small blisters on the palms and soles. Some strains of the virus also cause a red bumpy rash on the body. The treatment is the same as it is for most viral infections: rest, fluids and fever control.
When I see kids with hand, foot and mouth syndrome, parents usually ask two questions. (1) How long is the child contagious? (2) When can she go back to daycare or school? The answer to the first question surprises parents. They’re contagious for 2 to 3 weeks after they get sick. The answer to the second question surprises them even more. Kids can return to school as soon as they feel better. What? How can doctors send kids back to school when they’re still contagious? The rationale for this is simple. Up to 20% of children with hand, foot and mouth syndrome are asymptomatic. This means they contracted the virus and are spreading it to others even though they’re not sick themselves. That fact, combined with the long contagious period, means keeping kids home will have no impact on the spread of the disease. That’s why we send them back when they feel better.
At the time of birth, a baby’s umbilical cord has a shiny, off-white color. Over the next few days, the cord will dry out and turn a dark brown or black color. As this happens, the cord will shrink and often looks like a scab on the baby’s abdomen. In the past, the umbilical stump was coated with a blue dye after birth and parents were told to clean the area with rubbing alcohol at every diaper change. These recommendations were discontinued because they were found to increase the time it took for the cord to fall off. Nowadays, parents don’t need to do anything special other than keeping the stump from becoming irritated by the baby’s diaper and avoiding baths until the cord falls off.
A few things may happen that worry parents during the 7 to 10 days that it takes for the cord to fall off.
- The base of the cord may develop a gooey, greenish-yellow appearance. This is normal and not a cause for concern.
- The cord may smell bad. The reason the cord falls off is because it no longer has a blood supply, and the baby’s immune system is rejecting the dead tissue. If the stump became infected, the skin around the belly button would become red and swollen. If you think your baby’s umbilical stump is infected, you should see the doctor promptly.
- The cord may bleed a little before or after it falls off. If this happens, you can gently clean the excess blood with a cotton swab.
- A red, fleshy lump may appear after the cord falls off. This is called an umbilical granuloma. It’s not serious, but doctors treat the area with silver nitrate to make the lump fall off.
Lots of parents think that giving a child acetaminophen or ibuprofen prior to seeing the doctor will compromise the visit. This is not true. Fever reducing medicine won’t make it harder for the doctor to figure out what’s wrong. In fact, reducing a child’s fever usually makes it easier for the doctor because the child is more likely to cooperate if her temperature is lower during the visit.
The same thing is true for asthma medicine or any other drug your child is taking. Unless the doctor or nurse specifically tells you not to give a medicine before a visit, you should do what you can to control your child’s symptoms.
If you spend time outdoors with children, you’ll need to keep them safe from mosquitos, biting flies and ticks. For young infants, the best approach is to protect them with clothing or nets that cover their strollers. For older children, you’ll need an insect repellent to get the job done. DEET can be used with infants as young as 2 months, but the American Academy of Pediatrics (AAP) recommends not using products with more than 30% DEET: http://www.healthychildren.org/English/safety-prevention/at-play/Pages/Insect-Repellents.aspx. Lower concentrations of DEET work well, but last for shorter periods of time. A 10% concentration lasts for about two hours. I prefer an ingredient called picaridin because it works almost as well as DEET, but feels nicer on the skin. If you want a natural product, the soy-based repellent in Bite Blocker lasts about 90 minutes.
If you use a product containing DEET or picaridin, a lotion or pump spray is safer than an aerosol. Don’t apply it to your child’s hands and be careful to avoid the eyes, nose and mouth. It’s also a good idea to wash it off when you come inside.
You should not use products containing insect repellent and sunscreen. Instead, apply the sunscreen first, wait until it’s absorbed, and then apply the insect repellent. Keep in mind that sunscreen should be used liberally and reapplied every two hours. Bug sprays are applied sparingly and many should not be reapplied. Always read the instructions that come with the product you’re using.