Causes of severe cough in children

I believe that friends who have children at home must all know that children have the weakest constitution and are the most susceptible group. For example, if a child coughs frequently, parents must be worried. Children's organs have not yet grown and matured. Frequent severe coughing will make their organs feel uncomfortable and the children will be in great pain. Let's take a look at the causes of severe coughing in children.

The pathogen is Bordetella pertussis in the genus Bordetella, commonly known as Bordetella pertussis. There are four known species of Bordetella, including Bordetella pertussis, Bordetella parapertussis, Bordetella bronchiseptica and Bordetella avium. Bordetella avium generally does not cause disease in humans and only causes infection in birds.

Bordetella pertussis is about 1.0 to 1.5 μm long and 0.3 to 0.5 μm wide. It has a capsule, is non-motile, is Gram-negative, is aerobic, has no spores, and no flagella. It stains darker at both ends when stained with toluidine blue. Bacterial culture requires a large amount (15% to 25%) of fresh blood to reproduce well, so the colonies are often isolated using Abalone-King medium (i.e. blood, glycerol, and potatoes).

Bordetella pertussis grows slowly, and after 3 to 7 days in a humid environment at 35 to 37°C, a small, opaque colony grows. The initial colony is raised and smooth, and is of the smooth (S) type, also known as phase I bacteria. It has a consistent morphology, a capsule, strong virulence and antigenicity, and strong pathogenicity.

If the isolated colonies continue to be cultured in ordinary culture medium, the colonies will change from smooth type to rough (R) type, which is called phase IV bacteria. They have no capsule, lose virulence and antigenicity, and lose pathogenicity. Phase II and Phase III are intermediate transition types. Bordetella pertussis produces many toxic factors, five of which are known:

① Pertussis toxin (PT); a protein present in the cell wall of Bordetella pertussis, formerly known as leukocyte or lymphocyte proliferation promoting factor (LPE), histamine sensitizing factor (HSF), and insulin secretion active protein (IAP).

② Heat-resistant endotoxin (ET) can only be partially destroyed at 100℃ for 60 minutes and can only be inactivated at 180℃. This toxin can cause fever and coughing.

③ Heat-labile toxin (HLT): This toxin can destroy its toxic effect after heating at 55℃ for 30 minutes. The antibody against this toxin has no protective effect against Bordetella pertussis infection.

④Tracheal cytotoxin (TCT):

It can damage the host's respiratory ciliated epithelial cells, causing them to degenerate and necrotize.

⑤ Adenylate cyclase toxin (ACT): An enzyme present on the surface of Bordetella pertussis cells. After entering the phagocytes, this enzyme is activated by calmodulin, catalyzing the production of cAMP, interfering with phagocytosis, and inhibiting the chemotaxis of neutrophils and the bactericidal ability of phagocytes, allowing it to persist in infection.

From the above we can know some of the causes of severe coughing in children. If a child does have a severe cough, adults do not need to panic. Gently comfort the child, feed the child plenty of water, let the child receive care and attention, and then send the child to see a doctor in time. Paying attention to the child's physical health is a very important task for every parent.