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Human immune systems consist of both innate and adaptive immune systems. (1) Both immune systems are interconnected, and they must work collaboratively for any individual to develop appropriately and to prevent them from getting ill from various infectious diseases. (1)
Both innate immunity and adaptive immunity require time to expand their presence through their production in the immune organs and time to mature. Any issues with the production or maturation process of the immune systems can result in various disorders such as allergy, immune deficiency, or immune dysregulation. (2)
Infants under the age of 3 months are rapidly building up their immunity by ramping up their production of immune cells and the creation of “memory” in their adaptive immunes systems through various exposures to their environment. During this period, the child is very vulnerable to serious bacterial infections such as those caused by group B streptococcus (GBS) and E. coli. (3)
Common Infectious Diseases Among Children
Common infectious diseases affecting children include bronchiolitis, pneumonia, urinary tract infection, sinusitis, skin infection, gastroenteritis, and acute otitis media, (4) among others. Most of these infections are viral, and only a small portion are caused by bacteria.
While most viral infections have no specific antidote, there are often steps that you can take to decrease the risk of infection. Many bacterial infections, if identified in time, can be treated with antibiotics.
Some serious childhood viral illnesses can be prevented by routine vaccination. Here are a few common illnesses along with their treatment and prevention strategies:
1. Common colds
Common colds (upper respiratory infection, URI) are one of the most common and frequent childhood illnesses. (5) URIs commonly affect children under the age of two. Some reports showed that children, on average, can get 8–14 URIs annually within the first 2 years of their lives. (6)
The cause of URIs is generally viral in origin with no specific treatment. Such respiratory illnesses tend to be caused by a variety of viral infections, and children can get them repeatedly throughout their childhood.
Symptoms include run-the-mill cough, congestion, runny nose, fever, and sore throat. The symptoms may last for 10–14 days and generally worsen at 4–5 days into the illness.
Whenever the child has a URI, supportive therapy with a lot of TLC (tender loving care) to ensure the child is breathing comfortably without retraction is recommended.
Up to 10% of children with prolonged URI symptoms can have sinusitis, and about 5% of children with URI and prolonged fever may have a concurrent urinary tract infection (UTI), which is treatable with antibiotics. (6)
Self-care measures include frequent hand washing and ensuring distancing with ill peers. It is also important to continue to have good fluid intake and output (urination at a minimum of every 6 hours).
When to see a doctor:
When the child’s symptoms persist beyond 2 weeks or the fever persists beyond 5 days, the child should be brought to the doctor for re-evaluation.
Note: Symptom-relief medications such as decongestants, mucolytic agents, and antitussives should not be given to children under the age of 10–12 as they can cause more harm than good.
2. Stomach flu
Stomach flu, medically referred to as acute gastroenteritis (AGE), (7) is typically a viral infection that causes inflammation of the stomach lining. This condition can affect people of all ages, presents mild symptoms, and is self-resolving.
Different viral strains can trigger gastroenteritis, but adenoviruses, rotaviruses, and astroviruses infect toddlers and young children more than the others. Norovirus, on the other hand, equally targets children and adults. (8)
Symptoms include nausea, vomiting, watery diarrhea, headache, fever, chills, and stomach ache. (7)
Most of the causes of AGE are viral in nature; thus, antibiotics would not be very effective. Even if the AGE is caused by bacteria, watchful monitoring would be preferred instead of antibiotic treatment. The mainstay treatment for AGE is hydration (9) and supportive care.
Note: Antibiotics can often prolong the illness by destroying the normal bacterial flora in the gut by causing more diarrhea and gastrointestinal upset. (10) In rare cases, antibiotics can open up the bacterial wall, which can lead to the release of toxins that can cause more serious illnesses such as hemolytic uremic syndrome.
Preventive measures for AGE are frequent hand washing, (9) ensuring meals are coming from reputable sources, and limiting the child from having close contact with ill peers.
3. Pink eye
Pink eye, commonly known as infectious conjunctivitis, is characterized by inflammation of the conjunctiva (the white part of the eye) and the inner eyelids. It is a common eye infection among children.
Pink eye can be the result of viruses, bacteria, or allergy. (11) When a child has pink eye, it is imperative to differentiate the cause. Bacterial conjunctivitis usually has a more purulent discharge and tends to be unilateral rather than bilateral.
Symptoms of infectious conjunctivitis include a clear or purulent eye discharge, red injection to the conjunctiva, eye irritation, (12) and sensitivity to sunlight. The child generally does not appear ill except for having pink eye.
If the cause of pink eye is bacterial, antibiotic drops or ointment will be effective. If the cause is an allergy, drops such as pentanol would alleviate the symptoms. Unfortunately, a good portion of conjunctivitis is viral in origin, and, like many viral illnesses, you must let it run its course.
Since the transmission of pink eye tends to be from close contact and droplets, the best prevention method is to ensure good personal hygiene along with frequent hand washing. (12) Children should get in the habit of not sharing any hygiene product such as towels, goggles, or face cover to prevent transmission.
4. Hand, foot, and mouth disease
Hand, foot, and mouth disease is a common viral illness (13) affecting children below the age of 5. The infection usually involves the hands, feet, mouth, and sometimes the genitals and buttocks. (13)
The most common virus that causes this disease is coxsackievirus. (13)
The symptoms are generalized lesions that spread from head to toe, mostly affecting the hand, foot, and mouth.
Differentiating hand, foot, and mouth disease from more concerning lesions such as chickenpox is very important. One of the big things to consider is that chickenpox lesions start centrally and then spread to the periphery. The lesion of the hand foot and mouth is mostly localized in the hand, foot, and mouth itself.
Treatment is generally focused on the symptoms with an emphasis on hydration.
For oral pain, an ice popsicle is generally a good way to numb the sores and increase hydration at the same time. Pharmacological treatment such as Carafate and magic mouthwash can often take care of the oral symptoms.
The lesion itself is typically not harmful, but on rare occasions, the lesion can spread to the child’s liver and central nervous systems, causing severe complications.
The most common complications are associated with secondary skin infection from excessive manipulation of the lesions and/or oral lesions that prevent the child from having adequate intake.
Note: If the child is on magic mouthwash for oral pain relief, make sure the child can swish and spit. Otherwise, lidocaine must be removed as part of the ingredient to prevent unnecessary complications.
Just like for any viral illness, ensuring good hygiene practice (13) and distancing from the ill child are effective prevention measures.
5. Whooping cough
Whooping cough, or pertussis, is a respiratory tract infection that can be easily transmitted from person to person.
When the infected person coughs or sneezes, respiratory droplets carrying the infectious pathogen are released into the air. People who breathe in these droplets end up getting infected as well. Plus, these droplets contaminate the surrounding surfaces, which can spread the infection to those who touch them.
This highly contagious illness can take a turn for the worse if not treated properly and can lead to serious complications such as pneumonia. It is particularly life threatening for infants. (14)
Bordetella pertussis is the name of the bacteria that cause pertussis or whooping cough. (14) Whooping cough is one of the childhood diseases preventable through vaccination.
Interesting fact: Due to the advent of vaccination technology and safety concerns, most children born after the 90s have been receiving acellular DTaP vaccine rather than whole-cell DTP vaccine. Due to this change, although the vaccination is safer, protection against pertussis is not as strong; thus, we can see a small resurgent of the illness in children. (15)
Whooping cough generally has four stages: the incubation (asymptomatic period, 5–10 days), catarrhal stage (looks like the common colds, 1–2 weeks), paroxysmal stage (strong coughing fits that can last up to 10 weeks), and final convalescent stage (cough lessens with slow and gradual recovery). A patient with whooping cough is most infectious during the catarrhal and early paroxysmal stages.
Symptoms of pertussis can differ from child to child. As its name suggests, the characteristic symptom of this condition is a cough that produces a “whoop” sound. But this is generally absent in infants younger than 2 years old.
Children with pertussis usually suffer from a mild cough, low-grade fever, and runny nose, whereas babies may develop apnea or a brief cessation of breathing.
Macrolide antibiotics such as azithromycin will kill the causative bacteria. (16) The treatment can shorten the course and prevent the spread of the illness. The treatment is only effective when the antibiotic is initiated in the early catarrhal stage.
The best prevention method is none other than getting the pertussis vaccinations on time and practicing good hygiene.
Measles is one of the most contagious viral (rubeola virus) infectious illnesses with a high transmission rate via aerosolization. (17)
Unfortunately, not every country in the world has the robust medical system as the United States does, and due to the lack of vaccination in those regions of the world, measles still affects a good portion of the pediatric population around the world (especially among the poor nations).
The virus responsible for measles is morbillivirus, which is largely active during the winter and spring months. It is mostly prevalent among children and can easily be transmitted through direct contact with discharge from the nose and throat.
Symptoms of measles include running a high temperature, nasal discharge, cough, skin rash, small white spots with a bluish-white mouth, and red and watery eyes.
Thanks to the highly effective MMR vaccine and successful vaccination program in this country, this scary disease is rarely seen nowadays. In the United States, the outbreak tends to take place among the unvaccinated population.
As with most viral illnesses, there is no cure for measles. However, with some vitamin A-deficient children (mostly in poor nations), increased intake of vitamin A may help decrease the severity of the illness.
Before the invention of the highly effective MMR vaccination, children in the United States would get respiratory complications from the illness. In rare cases, the affected children may suffer from Subacute sclerosing panencephalitis (SSPE), a severe form of brain complications 7–10 years after recovering from the initial illness. (17)
Chickenpox (varicella) is a highly contagious skin infection that is quite common during childhood. It is characterized by the development of generalized vesicles all over the body.
Chickenpox is caused by a variant of the herpes virus known as the varicella-zoster virus (VZV). (18)
Symptoms of chickenpox generally include severely itchy skin rash or lesions that may appear all over the body or be localized to certain areas, low fever, feeling unwell or malaise, and general discomfort. (18)
Treatment for chickenpox is the same as for other viral infections, which is prevention through timely vaccination and management through supportive care. (19)
Most individuals get only one episode of chickenpox and then stay immune from it for the rest of their lives. Thus, before vaccination was widely available, it was commonly accepted that when a child becomes infected with the illness, the parents host a “chickenpox party” to infect all those attending to create herd immunity.
After the widespread use of the varicella vaccine, this practice is no longer endorsed given that the varicella virus can remain dormant inside of the child’s nerves and can cause shingles later in life when it is reactivated.
The skin lesions caused by chickenpox are quite itchy, and scratching them can further rupture the skin and give rise to secondary bacterial infections, (19) which may even lead to generalized cellulitis. The viral infection can also attach to the child’s liver, brain, and other organs, which can result in systemic complications.
Ringworm is a fungal infection of the skin and in medical terms is known as tinea infection. The fungal species that can cause the disease varies depending on the transmitting agents and host.
Ringworm is caused by the overgrowth of certain fungi called dermatophytes. Dermatophytes live naturally on the surface of the skin and feed on dead skin cells without causing any harm. But if allowed to overgrow, they trigger superficial skin infections such as ringworm. (20)
The tinea infection tends to cause a rash with a raised border and a central scaly appearance. The lesion tends to be very itchy.
The location of infection would determine the treatment plan and can be oral or topical. Infection on the scalp or nail bed requires oral antifungal agents. Topical antifungal ointment would be very effective with fungal infections elsewhere in the body. (21)
The best prevention method is to observe good hygiene practices and to avoid sharing any hygiene products among peers.
Bronchiolitis is inflammation of the lower respiratory tract from an infection of any sort. The illness tends to affect children aged 2 and younger, and like every other viral illness, it is treated with supportive care. (22)
The most common cause is the respiratory syncytial virus (RSV). (22)
Symptoms of bronchiolitis start off resembling those of the common cold, such as fever, cough, runny or blocked nose, and diminished appetite, which are taken as the first signs of the infection.
It is important to practice good hand hygiene and isolate the ill child as much as possible. The subset of preterm infants with a history of chronic lung infection is more prone to any infection in comparison to their peers. These patients qualify for palivizumab, a vaccination against RSV, to reduce the risk of bronchiolitis within the first 2 years of their life. (22)
Children affected by bronchiolitis tend to suffer from respiratory difficulty, and, in some more severe cases, require admission to hospital for respiratory support. (22)
10. Strep throat
Streptococcal pharyngitis (strep throat) is one of the bacterial causes of throat infection among older children. (23)
Strep throat is a respiratory infection caused by group A streptococcus bacteria. (23) These bacteria are present in the nasal secretions and saliva of the infected person and can easily spread to others through direct or indirect contact.
Sneezing or coughing projects the infected droplets into the environment, which end up being inhaled by those in the vicinity or landing on surrounding objects. The pathogen can enter your system through direct inhalation or through indirect contact.
Indirect contact involves touching a contaminated surface, which will transfer the bacteria to your hands, and then using the same hands to touch your nose, eyes, or mouth, which will further transfer the bacteria into your body.
Children affected by this illness usually experience a sore throat without a cough, and, from time to time, they may report systemic symptoms such as fever, abdominal pain, rash, and headache. (24)
The detection testing rapid strep swab is very sensitive, and treatment is antibiotics (oral or IM). Strep throat should be treated promptly within the first 10 days of onset to prevent rheumatic fever and heart complications. (24)
Treatment for strep throat would not prevent the development of kidney complications (poststreptococcal glomerulonephritis, PSGN).
For the most part, strep pharyngitis is a rapid-onset illness and tends to self-resolve with or without treatment, but in some incidents, it can cause, kidney, and heart complications due to its subsequent immune reaction.
Treatment for Infectious Diseases
Treatment for infectious disease depends on the infectious agents. Treatment for bacterial illnesses is antibiotics and treatment for fungal infections is their respective antifungals.
However, virus infections tend not to have any effective antivirals, especially against any of the common childhood illnesses.
Preventive Self-Care Measures
Observe the following measures to prevent children from getting infectious diseases:
- Good hygiene should be practiced by both the caretaker and child.
- Isolate the ill child as much as you can to prevent the spread of the illness.
- Have the child acquire the recommended vaccination promptly.
In terms of prevention, good hygiene practice and hand washing for both the child and the caretaker are key to preventing any infections transmission.
In the height of the COVID pandemic, 3 large school districts across the nation have initiated the 3 W policy in school (wash hand, wear a mask, and watchful distance). The study revealed that by simply following these 3 rules, all three school districts have essentially 0 transmissions of COVID within the school district. (25)
This study and policy change have demonstrated the effectiveness of good hygiene practice and the importance of isolating the ill patient. Finally, obtaining the vaccination promptly will reduce the chance of getting serious illness and reduce the transmission of any infectious illness.
When to See a Doctor
If the child is under the age of 3 months, always have a low threshold to bring your child for evaluation if any signs and symptoms of infectious illness are present.
A child under the age of 3 months having a fever at or above 100.4°F should be taken to the hospital for immediate evaluation. As a pediatric hospitalist, this is the one thing that I emphasize on my discharge teaching before sending any patient home.
In other incidents, if a child has prolonged illness for more than 5 days and is not getting better, shows signs of respiratory distress, and has poor oral intake, bring your child back in immediately for evaluation.
Most-Asked Questions About Infectious Diseases
At what age is the immunity system of a human being fully developed?
The immune system grows rapidly within the first 3–6 months after birth and continues to mature and expand throughout a person’s life to ensure their well-being. A child’s immune system generally matures to its adult level around 7–8-years of age, right before puberty.
How effective are vaccines against infectious diseases?
Many vaccines are extremely effective in preventing communicable illnesses. For instance, MMR and varicella vaccinations are over 95% effective.
The flu vaccine is a yearly vaccination program for any individual 6 months or older. Although the efficacy of flu shot varies from year to year, the shot itself tends to reduce the chance for any individual from suffering from a severe form of the illness.
Otherwise, many of the formerly known common childhood infectious illnesses, such as epiglottis from H. influenzae or severe gastroenteritis caused by rotaviruses, have been virtually eliminated due to the successful vaccination program in this country. Other vaccines such as Hib and PCV13 are essential in reducing the rate of childhood meningitis and epiglottis to a minimum.
Also, I would like to make an endorsement that the COVID vaccine and all the reputable vaccines are well tested and highly effective even against every variant. I urge you to strongly consider the vaccine if you have not gotten it yet.
What infectious diseases are more common in neonates?
Neonates under the age of 3 months are immunodeficient due to their immature immune systems. They are very prone to serious bacterial infections and should be treated very differently if they have any signs of systemic illness.
Children under the age of 3 months also lack clinical signs to indicate the severity of their illness.
There are a lot of other bacterial and viral infections that can affect the child. Some of these common illnesses can be effectively prevented by vaccination such as influenza.
With the COVID pandemic starting to affect more and more of the younger population, I urge you to strongly consider the vaccination for yourself and your child if they are available. If done so, the COVID infection can turn into another vaccination-preventable disease, and the world return to normalcy.