Whooping cough is caused by a bacteria called Bordetella pertussis, which lives only in human throats. Vaccine-induced immunity to B. pertussis wears off eventually, but for adults the bug usually produces nothing more than a very bad cough. In small children the cough, which comes in bouts or "paroxysms", can make someone literally breathless, and they usually have to take a quick deep breath or "whoop" at the end of the paroxysm -- thus the term "whooping cough". B. pertussis can be grown in culture, but it takes a few days and special culture media; it can also be detected by the polymerase chain reaction (PCR) test, which looks for the bacteria's genetic material and is much faster than culture.
The danger of whooping cough is that in small babies (usually under six months, definitely under two months, and especially ex-premies) the paroxysms may leave them not just breathless but without oxygen. Because of this danger we often have to intubate small babies and put them on ventilators until they get over the infection -- and this is made harder because the cough can be so forceful that a baby can cough the tube right out of the windpipe.
B. pertussis can be treated readily with several antibiotics, usually one of the macrolides (erythromycin, azithromycin, or clarithromycin), or trimethoprim and sulfamethoxazole (TMP-SMX). We usually treat everyone in the family at the same time when one family member is sick so that people don't pass the bug back and forth; we also treat anyone who has has close or prolonged contact with the sick patient, from children (and adults!) in the same classroom or day-care center to someone who sat next to the patient on an airliner for more than 4 hours. (If you have pertussis, you stop being contagious after 5 full days of antibiotics, although you may need a longer course of antibiotics for complete treatment.) We can also immunize against B. pertussis, which is much better since the treatment for an active infection takes a while to work, during which the coughing persists. Students (and teachers and other staff) who have pertussis should stay home from school until they have had at least 5 days of antibiotics; if they do not take antibiotics they need to stay away from school (and from small babies or their families) for 21 days after symptoms begin.
The first four doses of vaccine for whooping cough are given at 2, 4, 6, and 12-18 months of age. Unfortunately, although babies younger than 2 months can get whooping cough, the vaccine isn't effective before about 2 months. However, keeping older kids immune (the last dose of whooping cough vaccine is given at 5 years of age) helps prevent them from bringing the bug home from school. Immunity after vaccination seems to wear off after 5-10 years. Side effects of the previous vaccine prevented us from immunizing adults routinely. However, there are now two new vaccines, known as Tdap>. which combine a modified pertussis vaccine suitable for and effective in adults with the adult vaccines against tetanus and diphtheria. Although there is some debate among infectious-disease experts, many believe that someone who has full-blown B. pertussis infection will be immune to B. pertussis for life. The CDC and its Advisory Committee on Immunization Practices now recommend that everyone receive Tdap in their teens.
The whooping-cough vaccines are made from inactivated B. pertussis. For many years the vaccine was prepared from whole bacterial cells (killed chemically). This induced immunity quite well. However, it also produced many side effects, from fever (up to 103 or 104, and lasting 1-2 days) and pain at the injection site, to seizures (fortunately very rare). When I give whooping-cough vaccine I usually give Tylenol just before the shot and tell parents to continue giving Tylenol regularly for two days, whether or not the child seems to need it. The side effects of the whooping-cough vaccine are a definite problem, but I and most other pediatricians feel that the risk of having whooping cough far outweighs the risks of getting the vaccine. We are now starting to use vaccines from which the parts of the B. pertussis cells have been removed; in clinical trials these "acellular" vaccines seem to produce fewer side effects than the older vaccines -- although I still usually give Tylenol for two days with every dose of pertussis vaccine.
The whooping-cough vaccine is usually combined with the
diphtheria and
tetanus vaccines
and given as a single shot; this is often referred to as DTaP (the a stands
for "acellular"). We now have a single vaccine which combines
DTaP, the injectable
polio vaccine, and the
hepatitis
B vaccine into one shot; this can be given at ages 2, 4, and 6 months,
eliminating six pokes while still giving immunity to all five diseases.
The new Tdap vaccine (see above) is recommended for teenagers and for adults.
As always, ask your doctor for complete details.
Since the beginning of 2006 there have been at least 175 confirmed (by PCR
or by culture) or probable (by the definition of "probable" during a pertussis
outbreak, as defined by the
CDC
cases of pertussis in Kalamazoo County, Michigan, where I
practice and teach. (Contrast
this with 1976, when there were only 1,010 cases in the entire United States;
in the 1920's and 1930's there were up to 250,000 cases in the US per year and
up to 9,000 deaths.) Many of these cases have been in preteens and teenagers,
but there have been several infants with confirmed pertussis. (I have seen
and cared for a few myself.)
We have been seeing increasing numbers of patients with whooping cough over
the past few years. One reason may be that, with the wider use of the PCR
test, we are diagnosing B. pertussis infection in people who would
have been diagnosed with bad colds a few years ago. Since older children
and adults are usually not fully immune to B. pertussis even if they
were immunized as kids, there are always older kids and adults who carry the
bacteria and can give it to smaller children. (Remember that a baby may
not be completely immunized until after all of the first 3 doses.) Another
reason may be that, because of scares about side effects and especially about
seizures, many parents in the early 1990's avoided having their children
vaccinated -- which might explain why so many teens and young adults are
susceptible. (This may be hard to prove, but it would explain a few things.)
What can we do about this? For one thing, we can -- and, right now, we do --
treat anyone with a cough lasting more than 2 weeks as if they have pertussis.
We also give prophylactic antibiotics to anyone who has been in contact with
a possible pertussis patient. And we do this whether or not the
patient has been recently immunized; the patient may be able to fight off
the infection, but may be able to pass it on to someone who can't fight it
off (like a baby).
The other thing we -- actually, you -- can do is to make sure that your
children, and you yourself, are vaccinated against pertussis. As I mentioned
above, one reason why we are seeing more cases of whooping cough is that many
children have not been vaccinated. The risk of side effects from the vaccine
are much rarer than the risk of complications from full-blown whooping
cough.
For more information on whooping cough, see the
CDC page
on pertussis. Another useful source of information on whooping cough
is whoopingcough.net, maintained
by Douglas Jenkinson, MB ChB, an English family practitioner who has
considerable experience (both as clinician and as researcher) in the
diagnosis and treatment of whooping cough.
The Kalamazoo Pertussis Outbreak
Search the Office for:
Back to Dr. Reddy's Pediatric Office
on the Web
We welcome your comments
and questions.