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New Treatments for Respiratory Infections

Respiratory infections are the most common thing in pediatrics. Children experience about six respiratory infections per year. In daycare it’s not uncommon to have a mean of nine respiratory infections a year. So somewhere between 3-12 are normal and that’s probably one of the first things to recognize; is that normal children will have a lot of respiratory infections, and that’s one of the things that we get all the time, are children referred to us who are normal.

The last thing is the incredible faith in antibiotics. A lot of people give antibiotics … and there’s a lot of attention on this today, in fact so much so that I think in some cases people are not using antibiotics when they should. So this is just the way some people approach respiratory infections.

The common cold. The common cold; a lot of you write on charts, URI, upper respiratory illness or upper respiratory infection, but if you do that you’ve written too broad a category. And that can have both bacterial etiology and viral etiology, but if you use the term " common cold" and have criteria.

Then next, this is that there are two differences in pathogenesis in colds, two major differences. One of them is primary infections with rhinoviruses and coronaviruses, whereas colds with parainfluenza and respiratory syncytial virus are never - or virtually never - primary infections. A primary infection with RSV or parainfluenza is a more severe illness and is usually associated with fever and some other manifestations which we will talk about later. Whereas with rhinoviruses you can get a new rhinovirus every year and it can give you a cold.

The treatment of the cold - I’m going to come back and talk about treatment in general, but this is just one approach - when I ask about treatment with the medical students, I spend about ten minutes on it. First of all somebody will say vitamin C. And vitamin C doesn’t work prophylactically and it doesn’t work therapeutically. Although I’m sure there’s a lot of people in the room who take vitamin C. And the question is, why? Why are so many people hooked on it?

The next category is acute nasopharyngitis and here, again it’s an acute illness and usually a viral disease, but the main characteristics, again, same nasal symptomatology but there’s throat irritation and pharyngitis. If nasopharyngitis it means objective evidence of pharyngitis and most of these will have some degree of fever, greater than that that you would see in a common cold. Now with this you see some of the same viruses but you see different orders. The number one and two causes of nasopharyngitis are adenoviruses and enteroviruses. Adenoviruses …both of these in general have more pharyngeal symptomatology than nasal.

The next category is tonsillitis or pharyngitis. And here the key thing is no nasal symptomatology. Acute illness involving erythema of the tonsils and certain other manifestations, like enlarged follicles, exudate, ulcerative lesions, probably should add petechiae as well. And again, no nasal symptomatology. Now here you have a much bigger differential. Particularly people on the East Coast, if you talk about pharyngitis, they talk about group A strep much quicker. Whereas out here a lot of people are very laid back about group A strep disease. Nevertheless, our therapy is predominantly aimed at treating group A strep and preventing complications. But I think that to look at this, when you see a pharyngitis, you need to at least think beyond group A strep and also the viruses.

Now I want to go on and talk about three other illnesses with pharyngitis, all three of which you should be able to diagnose clinically. The first of these illness you should be able to diagnose clinically is herpangina. In herpangina, what you see are 1-2 mm ulcerative lesions. Where they are most marked is on the soft palate, but they are also on the anterior tonsillar pillars, tonsils, pharyngeal mucosa, posterior pharyngeal mucosa and that around the ulcers you may have a little bit of redness but you don’t have a whole diffuse red background that you would see in typical pharyngitis. Herpangina is caused by enteroviruses. Now you may get, on a test, a question on herpangina .

A self-limiting disease with fever and occasionally associated with aseptic meningitis or exanthem. This picture shows not too big individual lesions right here and about four lesions right here, 1-2 mm ulcerative lesions with a little redness around them but the rest of the background is not the bright red you would see with, for example, streptococcus tonsillitis.

Pharyngoconjunctival fever. This is a disease that almost always occurs in outbreaks but occasionally in the wintertime you will see isolated cases. There are two different mechanisms. In most cases when you have an outbreak, they are related to swimming. They are due to adenoviruses and the pathogenesis is the water in the pool or lake gets contaminated and the irritation of the water plus the virus causes infection in the eye. The infection gets transmitted through the lacrimal duct and you get pharyngitis.

The last of these is primary herpetic stomatitis. This occurs almost always with the exposure of a child, after the transplacental antibody from the mother disappears and the child is exposed to a parent who is shedding herpes, with or without a cold sore. And the child usually somewhere between 16 and 18 months has the primary disease.

Now we are going to switch and talk about middle and lower respiratory tract infections. The first illness is laryngitis and this is probably the least studied and the least understood illness, and it is usually …the organisms that cause laryngitis in older people and young people usually cause one of the croup syndromes.

Now to talk about upper airway obstructive diseases. The basic thing here is inspiratory obstruction, difficulty getting air in. Before we go and talk about the infectious causes, we need to mention allergic. Acute angioneurotic edema of the epiglottis can give you marked inspiratory obstruction, and in fact can cause death and looks like epiglottitis. But you need to know this because obviously your treatment is different. The other thing is; be aware of mechanical problems. Masses can make viral infections worse.

Okay, with that background, first is epiglottitis and if I could see I would ask how many of you have seen epiglottitis. But we are in a new era and thanks to H. influenza type B vaccine this disease has virtually disappeared. Invariably this disease in children is caused by H. influenza type B. The age grouping is 2-7 years, but there are occasional cases in older people. You have rapid onset and progression so that you can have a child that is totally well and ten hours later is dead. So very rapid. They have initial sore throat followed by dysphasia, drooling, retching, difficulty breathing, a voice that is not hoarse and there is no croupy cough.

Okay, the next category is laryngotracheitis. I’m going to go through this and then come back and say something about therapy. Usual age is six months to three years, but there is overlap with that for epiglottitis. It’s a highly seasonal disease, fall, winter and spring and relatively slow onset. Starting out like a cold with coryza and cough.

The next category, which I mentioned before, is laryngotracheal bronchitis or laryngotracheal pneumonitis. Now laryngotracheal bronchitis, this is wrong, written incorrectly so often in textbooks and in the literature and it is a relatively rare disease. It can be caused … it is really a viral infection with parainfluenza I and III particularly, and influenza A but most commonly it is what’s been called bacterial tracheitis.

The next category is spasmodic croup. Again, this was well described in the late 1940’s and 1950’s and it is, I think, confused. Every single therapy study, including one study that I did a long time ago, in not separating, not recognizing two different diseases. There is spasmodic croup from laryngotracheitis. And I forgot to say, with laryngotracheitis when people look at the pathology in the subglottic area that you see damage to the cilia, the epithelial cells.

Lastly, steroids; most recommendations today is that steroids benefit croup, which is assuming laryngotracheitis. But when you read the papers you realize that they are a combination of laryngotracheitis and spasmodic croup. This issue has been going on for about 30 years and the therapy that’s most commonly used is one dose of dexamethasone, 0.6 mg/kg. Yet I think that is probably not good treatment, but if you are asked the question you can put it down.

Now to switch over to bronchiolitis. This again is a … there is a lot of difficulty historically, and also confusing the illness, the clinical illness and etiologic agents. Because people use RSV and bronchiolitis interchangeably. And of course RSV can give you pneumonia or can give you bronchiolitis or can give you combinations of the two. You also have a primary infection and then in some people you get repeated expiratory distress syndrome, which are called bronchiolitis or called infectious asthma.

The other illness, in general they are linked together - and it’s probably correct - because when you try to study the pathogenesis of RSV infections in those who have bronchiolitis, it turns out that this is predominantly a host response to an infectious agent and what is doing the damage is resulting from T-cells and from specific cytokine liberation.

Now as far as treatment, here I’ve given you the same list to go through as we did with croup. Bronchiolitis; these children are hypoxic so they need oxygen. The next thing is mist and with bronchiolitis there is usually an unrecognized interstitial pneumonia as well, and excess fluid, either as hydration or by mist is detrimental.