2012-08-30

The Return of Whooping Cough

The Return of Whooping Cough

In today's New England Journal of Medicine, one of the country's top experts in infectious diseases, James D. Cherry, MD, presents the fact that we are right now in the middle of the worst outbreak of whooping cough in 50 years.  There is so much whooping cough, or pertussis, around, that we are at levels approaching a full 1/3 of the rates seen before the pertussis vaccine was invented!

So what is pertussis, and what about our current epidemic?

Pertussis is an infection caused by a certain bacteria called Bordetella pertussis.  This bacteria infects mainly the lungs and airways (e.g., nose, throat).  The older you are, the milder the infection, so in young infants it can be quite dangerous.   

For infants less than 2 months of age, about 1 in 100 actually will not survive a bout of pertussis.  For infants ages 2-11 months old, the chance of dying from this infection is a bit less than 1 in 200.  For older children and adults, this infection causes mainly misery, death is quite rare from it.  

The main problem older children and adults have from pertussis is cough.  The cough is very persistent and can last several months.  In fact, in the article by Dr. Cherry, the claim is made that if an adolescent or adult is coughing for more than 3 weeks, the chance the cause is pertussis is 13-20%.  Screening a large number of adolescents and adults has found about 1-6% have had a recent case of pertussis.  Other problems it can cause the older child and adult include pneumonia, broken ribs from coughing, fainting, pneumonia, and insomnia.  Rarely it can cause seizures and dysfunction of the brain.

The number of people with pertussis is at a 50 year high, why?  One reason is that it is easier to test for it, and more doctors are aware that older kids and adults get it frequently.  So more tests are being done and more people found to have it.  

Another more troubling reason is that in an effort to make immunizations cause less fever and discomfort, the pertussis vaccine was weakened in the 1980's.  This was the move from whole cell to acellular pertussis vaccines.  The acellular variety is why the initial has a small "a" in it.   Immunizations to protect against pertussis are combined with tetanus and diphtheria vaccines.  The original version is DTP, the newer acellular version then is, DTaP.  The adult version is called TDaP.  Both are the acellular, weaker pertussis vaccine.

Yet another concern is that the pertussis bacteria, B. pertussis, is a clever enemy.  Even getting a full infection with this germ offers no or little immunity, you can get this illness over and over.  This is the main reason the immunizations for pertussis don't last very long.  After the first pertussis immunization, you are only protected for a few weeks.  After 5 such immunizations spanning the first 5 years of life, the immunization lasts only 7 or so years.  This is why the TDaP is being urged as a vaccine at age 12 and in adulthood.

Bottom Line
Whooping cough, or pertussis, is back.  We are in the midst of the biggest epidemic of it in 50 years.  Right now, up to 20% of all older children and adults with a cough lingering more than a couple of weeks have it.
This illness causes a lot of misery in older kids and adults, but is actually very dangerous to the life of infants.
What to do?  
  1. Make sure everyone in your entire family is up to date on pertussis immunization.
  2. If you have a cough lasting more than 2 weeks, the fact that a pertussis epidemic is on, means we are going to test for it more often.

Dr. Arthur Lavin




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