This article is about hand hygiene and immunology of babies. I’ve met a wide range of new parents, from those who don’t take their newborns outside for months to avoid getting them ill, to those parents who let their babies roll around in muck or refuse to vaccinate them. I have a bit of background story for why I felt the need to write about the importance of keeping your hands clean when you offer to carry a baby that isn’t yours.
A while back, I got to carry the two-month-old baby of a couple that I know in church. I know them relatively well so, I was elated to see the new baby. I have nieces and nephews, and many friends with babies but I have a bit of a phobia of carrying neonates; my mark for cuddles is about 3 to 5 months, so I felt confident enough to ask if I could carry her.
What happened after this was quite baffling to me and the spark behind the motivation to write this, as it set me a long trail of thought. As soon as I asked if I could carry the cute little baby, her parents had the most visceral reaction of shock and even confusion. Her dad shuffled and mumbled, and her mum’s eyes widened and she could barely disguise the dread. My initial thought was that they didn’t want her to cry, or maybe they didn’t want me to drop her?! Well, before I could come up with more excuses in my head for this slightly awkward encounter, her mother said “Ah well, I guess it fine. Let me grab some wipes for your hands!”
I did end up carrying her for a few seconds, then I gave her back to her dad. Mostly because I realised that she was tinier than the babies that I’m comfortable carrying, but also because I could tell that her parents were freaking out! I left that encounter bewildered and a little confused. As a doctor, who was made to endure many hours of handwashing tutorials in many forms (using antibacterial wipes and UV lighting, surgical prep etc)- I take pride in my hand hygiene. I always have antibacterial wipes in my bag, I wash my hands before and after using the toilet, before I eat, after I shake hands, and as soon as I come home from a commute on a bus or train. Side note: buses are petri dishes for bacteria and viruses (just saying).
Of course, the couple at church didn’t know this so they took cautionary measures to ensure that I wasn’t going to infect their baby. This got me thinking about my hand washing tutorials and immunology. It got me thinking about whether squeaky clean babies end up being healthy adults? Here are a few points that summarise the development of the immune system in humans from infancy to old age:
Immune responses are Innate or Adaptive:
The innate immune system is the first line of defense against pathogens. It is made up of neutrophils, monocytes, macrophages and dendritic cells. These cells develop and mature when a foetus is in utero, but are relatively immature and offer weak protection to newborns. These cells are especially immature in premature infants. In utero, babies receive IgG antibodies from the mother’s placenta- this provides protection from the baby during birth and up to three months afterwards.
After birth there is a sudden exposure to antigens, through the birth canal and as soon as their oral cavity, skin and respiratory linings make contact with the new world beyond the uterus. From this point on, there is continuous exposure to bacteria throughout their lifetime.
The immune system of newborns gradually matures during infancy. Breast milk provides passive immunity (IgG antibodies) from mother to child. This provides early protection against many infectious diseases experienced by the mother up to 20 – 30 years previously. Once this period passes, children become more vulnerable to infections; however the risks of contracting infections are reduced when the children are vaccinated, and at this point, their innate and adaptive immune systems are maturing.
Side note: This is why I personally find it ridiculous when parents don’t vaccinate their children! (I’ll cover this in a future blog post!)
Children are still susceptible to viral, bacterial and parasitic infections, and their immune systems still have to respond to these infections. These infections result in the development of the adaptive immune system and immunological memory- that is why most people only get chicken pox once, and adults get fewer infections! This memory persists till old age, but may fade as seen in the image below, which is a schematic of the immune response to influenza over the lifetime of an individual:
So it’s safe to say that a balance of general hygiene versus exposure to the environmental antigens is important for children, however, newborns should be especially protected because their immune systems are immature. My friends at church were right to ask me to wash my hands as their baby was just fresh out of the oven, and needed to be protected.
Image credits: vspa.com; the journal.ie; cnn.com; ancientorigins.net; huffingtonpost.com; healthlne.com; pixaby.com; ncbi.nlm.nih.gov/pmc/articles/PMC4707740/
Dr. Helen Zidon (MB BCh BAO LRCP SI) RCSI (Class of 2016)