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Babies and Infection – Why does my baby keep getting sick?

Why does my baby keep getting sick!

Is there something wrong with my baby?  Should I be concerned?  Are there any ways to prevent this?  These are just a few of the many questions this article will attempt to explain.

Let us start with a little background on the immune system.

Simply speaking, the immune system is your body’s defense mechanism against foreign and infectious agents.  The immune system comprises of two main components – innate and adaptive.  Innate immunity can be thought of typically as your first line of defense, like the skin, mucous membranes and specific cells of the body such as neutrophils and macrophages.  Adaptive immunity can be compared to an elite group of special forces – lymphocytes (B and T cells), plasma cells and antigen presenting cells.  Plasma cells and B cells create antibodies for the immune system.  Innate and adaptive immunity together work hand in hand to protect the body from foreign and infectious agents.

From birth, the baby is immature in many ways.  As you may have already experienced, the baby has many milestones during the first couple of years in life.  It is remarkable to see your baby turn over on his/her back, crawl for the first time and eventually take the first steps in life around the first year.  The body is not only physically immature but also functionally immature.  Likewise, a baby’s immune system is also very immature at birth.  Not only is there a quantitative decrease in the number of cells that fight infection but the qualitative function of immune cells are also decreased.  In a study by Yost et. al. in Blood 2009, it is shown that there are decreased function of cells (such as neutrophils, macrophages, natural killer cells) involved in the response to infection.

If the baby’s immune system is so weak and immature, then what is protecting my baby?

Antibodies are also known as immunoglobulins.  They are created by plasma cells and memory B cells.  They help protect the body from infections by identifying and neutralizing the virus or bacteria by physically attaching to it.  At birth most of the antibodies in the baby come from the mother in the form of IgG – the only form that crosses the placenta from mother to child.  The graph below shows the immunoglobulin levels of an infant in the first year of life.

One can see from birth, the immunoglobulin levels of the newborn comes mainly from the mother in the form of IgG. Around 4~6 months, the level of immunity is at its lowest and reaches 60% of adult immune level by the first year.

As one can see from the graph, almost all of the immune protection IgG comes from the mother.  (What is also important to note is that levels of IgG from the mother is reduced in premature babies at birth.  Babies born at 32 weeks have around 50% of mother’s IgG while at 40 weeks it is 100%.  Infant with birth weight below 1,500 g have even lower levels. [1])   By 4~6 months, the mother’s immune boost fades away and the baby’s immune system is at its lowest point in his/her entire life.  During this time, the baby is most vulnerable to infectious agents – viral, bacterial and even fungal.  By the first year, the immune levels of the baby has risen to about 60% of the total adult levels.   Weak immune systems translates to babies getting infections more easily and extra attention to care and hygiene is needed.

Remarkably babies get few infections during the first couple months of life – this may be attributed to several factors such as immunoglobulin help from the mother, a more protective handling of the newborn during the first couple of months, breastfeeding and good hygiene practices reiterated by pediatricians who tell parents to wash your hands before touching the baby.

Why does it seem my baby is constantly sick?

As reasons explained above, the child has an immature immune system and is more vulnerable to infections than adults.  The baby can not fight infections as effectively and therefore their sick days are also prolonged.  Seasonal changes are also a contributing factor in bringing sickness to the child.  The body’s defense mechanism is weakened via environmental factors such as a cold and dry environment.  Seasonal allergies can create nasal congestion in some kids bringing forth secondary superimposed infection.

It seems there are more sick children during the winter time.  This is not because of the cold per se but the moisture in the air is very low and this causes the nasal cavities to dry up.  When this happens, the cilia in the nose cannot function properly and cannot rid of the impurities from the nasal cavities.  The mucosal layer is also dried up and this allows growth of germs leading to illness.  To remedy this, it is important to humidify the baby’s room during dry seasons – typically in late fall and winter.  Another effective way to help prevent colds is to use normal saline sprays for the nose everyday.  (Make sure it does not contain any medication.)  The key here is to have a clear and moist sinus at all times.  Keeping warm does help the body boost its immune system/response and thus bundling up when it is cold will also help prevent sickness.

During the cold, people tend to stay indoors and usually perform more activities inside.  This also increases the risk of getting a cold because where there is more people, there are more chances to meet people with a cold.  Naturally, children who are placed in daycare have the greatest exposure to germs.  An important mechanism to note is that the infectious period of a virus in most cases occur before the symptoms appear.  So it is difficult to isolate children who are sick from the healthy ones because visible symptoms appear later than the infectious period.  Kids cough on each other, hold hands, and touch each other toys and sometimes stick the same toys and hands in the mouth.  Viral and bacterial transmission occurs through the air and via hand to hand.  Although reputable daycare centers have strict sanitizing policy and try to clean their room as much as possible, it will be very difficult for the center to disinfect all the toys from germs.

During the allergy season, children who get constantly congested have greater risk for secondary infection because their sinuses cannot drain and blocked sinuses can cause virus and bacteria to grow out of control.  Because of the congestion, these children also tend to breathe through their mouths which can further bring opportunities of sickness.  If chronic mouth breathing is suspected, a trip to a pediatrician is needed.  Constant mouth breathing is not normal.  Breathing through the nose is very important in that it not only opens the doorway to smell but in respiration, it humidifies the air and filters the air before it gets into the lungs.

What can I do to reduce the amount of colds and protect my baby from infection?

The answer to the difficult question is simple –  avoid sick people, practice good hygiene, get the necessary vaccinations, have good nutrition, drink plenty of fluids and give breast milk for the first year of life!

Avoiding sick people means to not take your baby to hospital visits unless he/she is the patient. Nosocomial infections are very serious and there are lots of nasty diseases lurking in the hospital. If your child does become sick, it is etiquette towards others to take your child out of school or daycare. Furthermore it is in the best interest of the child to recover and rest from the illness rather than risk superimposing and worsen illness by keeping the child in daycare or school.  There are some who believe that the child should be exposed to as many colds when they are young so that the child’s immune system will be built up.  While it does hold some truth, there are so many variations of the cold virus, one can theoretically be sick for their entire lifetime.  This is the very reason why there are no vaccinations for the common cold.  At the very least a child less than one year should avoid daycare and good hygiene must be practiced.
There are situations where daycare is the only option.  In this case choosing a good daycare center or home daycare with strict hygienic policies and well trained teachers is a must.  Daycare is good for social interactions and one has just to decide on priorities.  With this said, it would be best to not send the child to daycare before age 2.  The reasoning behind this is that the baby’s immune system is physically and functionally immature especially during the first year of life.  In addition, most of the vaccinations will also be over by age 2 until the child enters kindergarten.

Practicing good hygiene means to wash your hands frequently. Believe it or not there is hand washing guidelines that are followed by all doctors before they perform surgery. It is particularly important to wash between the fingers. This can be easily achieved by simply interlocking the fingers and rubbing them back and forth with soap and water. Many people tend to neglect the area between the fingers and only wash their hands in a closed position.

At the very least one should wash his/her hands before touching the baby. Baby proofing your home against household germs will also help against sickness – especially gastrointestinal sickness.

Keeping your child’s vaccinations up to date is very important in protecting your baby from potentially lethal diseases which are proven to effective.  Caretakers and parents surrounding the child should also have their vaccinations up to date.  The concept of “herd immunity” is a very important in describing how vaccinations not only help protect yourself but also protect those few who aren’t vaccinated for one reason or another.  Vaccinations are effective for a vast majority of the public, but there are also some people who do not create antibodies against the vaccine and leave them vulnerable to the disease.  This is where herd immunity defines the importance of vaccination for all people.  Have you lately been vaccinated against the whooping cough (Tdap vaccine) and the flu?

Breastfeeding will bolster the child immune’s system greatly because mother’s breast milk contains immunoglobulins.  During the periods where the mother is sick, it is particularly beneficial to feed the baby with breast milk because the mother creates antibodies against the infection.  Those antibodies are also transferred to the milk and to the baby when fed.  The American Academy of Pediatrics strongly recommends exclusive breastfeeding for the first six months of life and that breastfeeding continue on for at least 12 months.  Not only that, “skin to skin” bonding between the mother and child naturally bolster the immune system of the baby and also to the mother.

Do I need to worry whether my child has more serious immune defects?

Children with serious immune deficiencies typically have either a characteristic clinical pattern or clinical feature associated with the disease.  They typically have a more systemic manifestations such as systemic bacterial infections, multiple bacterial infections within a year, infections occurring at unusual sites, infections with out of the ordinary pathogens and common infections that are more severe than usual.  However, these manifestations are very rare and your pediatrician should be able to determine whether immune defects are present by physical examination and blood chemistry.

References and additional readings:

[1] Kliegman, R., et. al. Nelson textbook of Pediatrics, 19th Ed. PA:  Elsevier, 2011

  1. Helen
    June 29, 2016 at 3:09 pm

    Love the article…really good, to the point explanation.

  2. Seven
    September 25, 2018 at 3:44 am

    Thank you for this article – Puts my mind at ease a bit!

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