Acute bronchitis is an acute respiratory infection in which cough, with or without phlegm, is a predominant feature. It becomes more obvious when the cough has set in for 5 or more days. The typical duration is 1-3 weeks. I wanted to review the causes and treatment of acute bronchitis and then go over Bordatella pertussis or what is called the “Whooping Cough”.
The most important issue when one has symptoms of bronchitis is to make sure it’s not pneumonia. A heart rate of <100 BPM, respiratory rate of <24, and a temperature of < 38 c (100.4 f), along with normal auscultation of the lungs makes pneumonia unlikely and a chest x-ray is not necessary. Fever (Temp 100.4 f or greater) is not typical for bronchitis unless it’s related to Influenza (The Flu) or there is underlying pneumonia. We are much more careful in the elderly and in patients with chronic lung disease, congestive heart failure, or immunosuppression because symptoms and signs can be atypical and the consequences of missing the diagnosis are much higher. The prevalence of pneumonia in the outpatient setting is about 5%.
About 90% of cases of bronchitis are caused by a virus. The most common virus isolated is Influenza (either A or B). Other notable viruses are parainfluenza and the respiratory syncytial virus (RSV). Viruses usually known for causing upper respiratory tract infections like coronavirus, adenovirus, and rhinovirus can also cause a lower respiratory tract infection (bronchitis). About 10% of bronchitis can be due to bacteria. The only 3 bacteria that have been proven to cause acute bronchitis are: 1) Bordatella pertussis, 2) Mycoplasma pneumoniae, and 3) Chlamydia pneumoniae (TWAR). Bacteria that can cause pneumonia like Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, and gram negative rods were once thought to cause bronchitis as well but this has never been proven. These organisms are involved, however, in acute exacerbation of chronic bronchitis (AECB) in patients with COPD (chronic obstructive pulmonary disease). Let’s review each of these 3 bugs to see when we should think about them in the setting of bronchitis. For this week let’s focus on Whooping Cough aka Tos Ferina (in Spanish).
Also known as “the 100 day cough” was a very common highly contagious childhood illness before the vaccine became available in the 1940’s. It would mainly affect children < age 10. The disease was characterized as a prolonged cough illness with one or more of the following: 1. an inspiratory “whoop”, 2. paroxysmal cough, or 3. post-tussive emesis (vomiting after coughing..gross!). There were 3 classic phases described and the condition would last up to 3 months. The first phase called the catarrhal phase was basically cold-like symptoms for about a week or 2. Then the 2nd phase would kick-in; the paroxysmal phase, which could last a few months. A paroxysmal cough is defined as a series of severe, vigorous coughs during a single expiration. This can sometimes be followed by an inspiratory “whooping” sound. The last phase is called the convalescent phase where things start to improve over a few weeks.
Here is the problem; since the 1980’s there has been an increase in the number of reported cases of pertussis. Of course, many cases (who knows how many) go undiagnosed and/or unreported but, for example, in 2010 there were 27,550 cases reported and in 2011 there were 18,719 cases reported. Worldwide, there are 30-50 million cases/year and 300,000 deaths. The biggest increase in reported cases has been in the 10-19 year old group and infants < 5 months old. The highest risk group that we are trying to protect is infants < 1 year old. More than 50% of infants < 1 year old will require hospitalization and some will die; we can prevent this from happening!
A study was done a few years ago that found that 10-20% of adults with a cough illness greater than 2-3 weeks in duration was due to pertussis. The problem is the illness in adults tends to be mild and usually has no clinical features that help distinguish it; the infection will typically last 4-6 weeks. In patients with a prior history of infection with pertussis or those that have been vaccinated, the classic pertussis symptoms may or may not be present. Immunity after immunization begins to wane after 3 years and is absent after 10-12 years. So prior infection or immunization may attenuate illness but neither confers lifelong immunity. Pertussis in people with “partial immunity” will resemble a mild viral bronchitis except that the cough may last longer (4-6 weeks).
So how do we diagnose pertussis? When should we consider it? Here is what the CDC and the WHO (World Health Organization) recommend. In the setting of an outbreak or known close contact to a confirmed case of pertussis, if you have a cough that’s lasted 2 or more weeks you need to be treated for presumed pertussis infection. The other criteria would be: a cough illness lasting 2 weeks without apparent cause and one of the following: 1) paroxysmal coughing, 2) inspiratory whoop, or 3) post-tussive emesis. Other subtle clues can be the incubation period. The typical incubation for a viral bronchitis is 1-3 days; for pertussis, it’s more like 7-10 days or up to 3 weeks. Other clues may be a worsening of symptoms at night and episodes of sweating between bouts of paroxysmal coughing attacks. The cough also tends to be non-productive (dry; there is no “purulent sputum”).
So if we are going to treat you for presumed pertussis we need to do a nasopharyngeal swab or aspiration to do both a culture and PCR test (polymerase chain reaction). If it’s been more than 4 weeks, the only useful test is serology (anti-pertussis toxin IgG) as long as you have not been vaccinated within the prior year. Regardless, we initiate treatment immediately with an antibiotic. The antibiotic of choice is the famous “ZPAK” (azithromycin); it’s a 5 day course. If you can’t do a ZPAK, the other choices are BIAXIN x 7 days or BACTRIM DS x 14 days. Now here is the thing; the antibiotic will only work to shorten the duration of the illness if you catch it within 7-10 days. Well most people don’t come in until 2-4 weeks of having the cough because, again, it’s generally a mild illness. It’s still worth it to take the antibiotic, though, because it is thought to help limit the spread of the infection. So the antibiotic will generally not make you feel any better or help you recover faster, it will just help limit spreading it to others so you would have done your service to the community. Remember, you’re looking at a 4-6 week duration of illness with or without antibiotics unless if you catch it within a week to 10 days which is difficult. The current recommendation is to offer antibiotics in cases of suspected pertussis when symptoms have been present for 4 weeks or less. If you are a health care worker, pregnant woman, or you work or care for infants, the recommendation is to take an antibiotic for symptoms up to 8 weeks in duration. You are considered contagious until you have completed the 5 day course of antibiotic.
So the best approach is really to try and prevent it by means of vaccination. Infant vaccinations (DTaP) is a series of 5 shots: 2mths, 4mths, 6mths, 15-18mths, and 4-6 yrs. The capital letters means it has a higher dose of it. The D = Diphtheria, T = Tetanus toxoid, aP = acellular pertussis. The new guideline is that all adolescents and adults now need a booster with what’s called Tdap (we use brand name ADACEL). Initially it was recommended for adults 19-64 and now it’s also for ages 65 and up and also pregnant women. The Tdap should be given regardless of when your last Td (tetanus toxoid) was. People who should come running in to get their Tdap’s now are: adults with close contacts with infants < 1 year old. This would be families with new infants, grandparents, childcare providers, healthcare providers, and pregnant women. Since it looks like this vaccine doesn’t last that long, in the future, we may be doing this one every 10 years. For a review of the updated immunization schedule check here.
Finally, post-exposure prophylaxis is recommended. Say you were exposed to someone who has a confirmed case and their cough has been present for 21 days or less, you should take an antibiotic (ZPAK) to prevent from getting the illness. This is regardless of whether or not you’ve been vaccinated. Post-exposure vaccination will not prevent you from getting sick.
Bottom Line: Most cases of bronchitis are due to a viral infection although it is frustrating because the course lasts longer than the usual common cold. Let me know if you know for a fact you’ve been exposed to pertussis or you have a cough that’s lasted 2 weeks or more with these severe paroxysmal coughing attacks where you cough a bunch of times without being able to breathe. Otherwise, we should all check our vaccination history and make sure you’ve had your Tdap booster, not just the Td booster.
Next time, we’ll discuss those other 2 bugs and also treatment…