Identifying and Treating Whooping Cough

We recently wrote on here about the comeback of measles. Well, there’s another infectious disease from days of yore that is clawing its way back into the limelight. And that’s pertussis, AKA “whooping cough.” Even though it sounds like something from Oregon Trail, it’s real, and its hanging around.

Just like Holly Hunter’s character in Raising Arizona, we all know how important the “Dip-Tet” is. “Dip-tet” is how they used to refer to the vaccine that prevents pertussis. Nowadays, the shot combines the vaccines for diptheria, tetanus, and pertussis, and is administered to kids at age 6-8 weeks of life with four doses administered over the first two years.  

The crazy thing is that this vaccine is only thought to confer immunity for around three to six years. This is great for the babies getting the shot, since they are the ones who are most susceptible to serious complications (and even death, yikes) from pertussis. The vaccines are often referred to as DTaP for infants and babies. Preteens, teens, and adults get a version that is called Tdap. 

Before the introduction of the vaccine in the 1940s, as many as 200,000 poor souls contracted pertussis in the US each year.  With widespread vaccination, this was reduced to around 10,000 cases per year by the 1960s. In the 1980s though, things took a turn for the worse.  And we aren’t just talking about New Coke, people. Pertussis started making a comeback with some years having tens of thousands of cases. (This peaked in 2012 when there were 48,277 cases reported in the US.)

In 2012, CDC began recommending that pregnant women receive a booster of pertussis vaccine (in the form of Tdap). As you would imagine, most adult women who become pregnant are no longer immune to pertussis. By getting vaccinated, they develop antibodies that pass to their unborn child. If the parents are given boosters, it also decreases the likelihood that the child could be exposed to an occult infection from them.  So any adult who has not had a booster should get one at least two weeks before meeting baby. This recommendation is supported by the American College of Obstetricians and Gynecologists and the American College of Nurse-Midwives, healthcare professionals who specialize in caring for pregnant women, as well as the American Academy of Pediatrics and the American Academy of Family Physicians

When are the Symptoms of Pertussis / Whooping Cough?

The infection begins with what is called the catarrhal phase. This looks essentially like the common cold with runny nose, cough, and low-grade fever. After 1-2 weeks, the infection progresses to what’s called the paroxysmal phase. This phase is characterized by severe paroxysms (or bursts) of numerous, rapid coughs.  This can be followed by a sharp inspiration leading to a “whooping” sound. Often these fits can lead to vomiting, and severe exhaustion.  Yet between the episodes, the patient may appear completely normal, which can lead to delays in diagnosis. This paroxysmal phase can last anywhere from one to six weeks, and then the infection moves to what is called the convalescent phase – a gradual recovery over two to three weeks.

One of the things that makes diagnosis tricky is that adolescents and adults who have been immunized can still get the infection, but display milder symptoms. They may not have the classic inspiratory whoop. Clinicians should consider pertussis in anyone presenting with at least two weeks of cough. Having said that, there are some clues that make the diagnosis more likely. In adults with a cough of less than eight weeks, vomiting or a “whoop” after a bout of coughing, should be considered suggestive of pertussis. If coughing is not occurring in severe bouts, or if there is fever, than the diagnosis is less likely. 

How Can You Be Tested for Pertussis?

The CDC recommends only testing patients in whom there is a high clinical suspicion of pertussis. And they do not recommending testing asymptomatic contacts of the patient.

A highly sensitive test called PCR can be done on a swab that is inserted into the posterior nasal cavity. Ideally this should be performed within three weeks of the onset of cough in order to properly detect the bacteria. Because the test can produce false positives, the CDC only recommends testing patients in whom there is a high degree of clinical suspicion.  A culture can be sent as well, but the results take longer and it is less accurate after two weeks of illness.

Should I Be Treated for Pertussis?

The decision to treat a suspected case of pertussis is based more on clinical suspicion than actual testing. 

In adults, with a cough of less than 8 weeks:

  • Severe paroxysms of coughing followed by whoop suggest pertussis
  • Vomiting after bouts of coughing suggests pertussis
  • Fever suggest another cause other than pertussis
  • If the coughing is not occurring in severe bouts, or paroxysms, it is probably not pertussis

In children,

  • Vomiting after coughing should raise the suspicion of pertussis
  • If there are severe paroxysms of cough or whooping, then pertussis should be considered

How Is Pertussis Treated?

Interestingly, most adolescents and adults will clear a pertussis infection even if it is not treated with antibiotics. However, due to the public health implications, treatment for pertussis is typically initiated immediately upon the suspicion of the disease, rather than wait for laboratory results. 

Close contacts of a patient with pertussis should also be treated regardless of symptoms. This is called post-exposure prophylaxis. (A close contact is considered face-to-face exposure within three feet, or contact with the patient’s secretions.) Contacts who are asymptomatic need not be tested. 

Patients who are symptomatic should avoid contact with children (especially infants) until they have completed five days of antibiotics. The typical treatment for suspected pertussis is a “Z-pack”, or a five-day course of azithromycin or other macrolide antibiotic.