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Current time:0:00Total duration:5:15

Video transcript

here are three generations of a family let's say that one day the seven-year-old develops a little cough which soon turns into something much worse they have an audio clip with the COFF and I want you to pay special attention to the noise of what makes when he catches his breath so this boy's definitely having a coughing fit that's causing him to cough out the entire air content of his lungs but did you hear the noise he makes when he's finally able to take his breath it's the sort of whooping noise and well this is the signature noise that gives a disease whooping cough it's named whooping cough is also called pertussis because it's caused by an infection from a type of bacteria called Bordetella pertussis if we were to look at pertussis under a microscope we would see these rod-shaped bacteria like I'm drawing here and the bacteria infect the respiratory tract and releases toxins which cause damage and inflammation to the Airways and this damage causes mucus to build until the violent cough reflex is triggered and when breathing in after one of these fits air is traveling rapidly through swollen Airways and this is what generates that whooping noise now pertussis is highly contagious because it's transferred person to person through mucus travel it's containing live bacteria that's coughed or sneezed into the air so let's say that mom is close by like within three feet of her son she might breathe in the mucus trap --let's and become infected where droplets can be passed along by shared surfaces like a toy shared with this boy's sister she may pick up the bacteria on her hands and then rub her eyes and nose and introduce the bacteria into her body this is why coughing and sneezing into the elbow and so the hand and lots of hand-washing is so important it's also why health care workers treating the family will wear gowns gloves and masks to minimize cross-contamination between their patients but there's a particular stage during the infection where the disease is most contagious so let's get a timeline going to explore that and we'll start with the initial exposure to the bacteria typically there's about a week-long incubation period where the bacteria is in the respiratory tract and it's dividing and it's causing damage but there are no clinical symptoms present yet then the clinical symptoms present for about 12 weeks so I'm going to draw the entire clinical timeline to 12 weeks but actually the twelve weeks is divided into three stages the first stage is on the onset of the clinical symptoms - about two weeks it has this fancy name called the cat oral stage and the word cat oral literally means inflammation of the respiratory tract with increased secretions so the stage is appropriately named because the main clinical symptom that you see here is a runny nose with sneezing the small coffin a low-grade fever the symptoms make it hard to distinguish from a common cold but unfortunately it's this stage that pertussis is most contagious because the bacteria hasn't been killed by the immune system yet and so it's dividing to high numbers so each cough and each sneeze expels cool head bacteria into the air so the onset of symptoms an infected person should really stay away from others until at least twenty-one days by then the body's been able to generate antibodies against pertussis which tag it as a foreign invader needing to be killed by the immune system during the next two to eight weeks known as the paroxysmal stage most of the bacteria is dead so the disease isn't as contagious but the damage in the inflammation caused by the bacteria in the weeks leading up till now can cause extreme coughing fits and whooping noises like we talked about earlier and actually that's exactly how this stage gets its name a paroxysm is a fit or a reoccurrence of a symptom here it's coughing these coughing fits are absolutely exhausting and they're frequently followed by vomiting and other complications from the forcefulness of the cough but finally the convalescent stage is reached at weeks eight to twelve convalescence literally means recovery from an illness and that's exactly what the body is doing during this time the infections been cleared from the body and the body now needs to heal from the respiratory tract infection and damage over time the frequency and the intensity of the coughing will go away but it takes a really long time and it's the reason that some cultures call pertussis the 100 day cough even though I've clearly laid out these three clinical stages in reality the stages can be difficult to decipher depending on a few modifying factors and a modifying factor would be anything that changes the length or the severity of the disease so for example age let's say a two month old is infected infants may not have the energy after a coughing fit to breathe in strongly and get air rapidly in past swollen inflamed Airways so an infant may not food after a coughing fit adults may have coughing fits but they may not hope after because their Airways are larger and can handle being swollen a bit without drastically reducing air flow another modifying factor is immunization status let's say that grandma had a pertussis vaccine in the last ten years her body's primed for pertussis infection so if she becomes exposed her body can fight it faster and in a shorter amount of time the damage and the inflammation may not progress to the point where she has a whooping cough or any cough at all for the same reason of having the body primed previous exposure to pertussis can also be a modifying factor so for example if grandpa recently had a pertussis infection his body's primed to fight a reexpose for a second time and just like Grandma his coughing fits whooping and vomiting and other complications can be milder if they occurred all