autism and pertussis

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As you have probably heard, the US is in the midst of a widespread pertussis outbreak.

And closer to home, a school in Floyd County, Virginia has closed for a week because of an outbreak. (http://www.roanoke.com/news/breaking/wb/282367Pertussis ). Pertussis is the short name for Bordetella pertussis, the bacterium that causes whooping cough. As you have probably also heard, April is Autism awareness month. I have been planning to write a post on autism ever since a reader wrote to me about several bad experiences her son, who has high-functioning autism, has had when visiting medical offices. And while I still plan to write the post on how we view and treat individuals with disabilities, especially autism, I feel I must address this pertussis issue first.

Nonetheless, there is a relationship between the low rate of pertussis immunization in certain populations, and some myths about autism.

Pertussis (whooping cough) is a disease that is preventable with immunization. The vaccine available to prevent pertussis has gotten increasingly safe and effective over the last few decades. When I was first in practice, the vaccine was derived from the whole cells of the bacteria, and as such, had a fairly high rate of  complications, such as  high fever and pain and swelling. Because children receiving the pertussis vaccine were at the age when children are nauturally vulnerable to having seizures with high fevers (febrile seizures), the vaccine got a bad name for itself, in that it was thought by some people to cause seizures or epilepsy. This has been proven NOT to be the case. More recently, the vaccine uses more elegant means of isolating the appropriate components of the bacterium that are able to initiate an immune response, but have a much lower incidence of general side effects, yet it is highly effective in preventing disease. AND THERE IS NO EVIDENCE THAT IT CAN CAUSE AUTISM.

Infants receive their first SERIES of pertussis vaccinations at 2, 4, 6  and 15-18 months, in the same shot with the vaccinations for diptheria (D) and tetanus (T). That shot is called DTaP.  "aP" stands for "acellular pertussis" and tells you it is the new form of the vaccine. They get a booster at 4-6 years.  At 11-12 years they should have a booster with a shot known as Tdap, which has slightly different doses of the diptheria and pertussis components.

Resistance to infection improves with each additional shot  and may remain  incomplete until the entire initial series has been administered at 15-18 months.

Therefore children are at most risk to contract this disease if they are unimmunized (through parental choice or under two months of age) or they are partially immunized (before they have had their 4th DTaP shot). The disease itself is most severe in the youngest infants, who may require hospitalization, potentially mechanical ventilation (having a breathing tube in their throats and being attached to a machine to breathe for them) in the pediatric intensive care unit, and yes, some of them may die--this is usually from hypoxia (low oxygen levels in the blood) and/or apnea.

How do young infants contract this disease? A  letter written by the American Academy of Pediatrics among other medical organizations, to health care providers states:

Studies have indicated that 75%-83% of infant pertussis cases with a known source exposure were caused by an infected household member. Parents and siblings are the most common source, with 55% of cases in infants linked to an infected parent.

Therefore, it has become standard practice in many OB practices and delivery services to offer Tdap to women with newborns.

 It is strongly suggested that everyone be immunized against pertussis if they are going to be around a newborn, and its been at least 10 years since their last pertussis vaccine. Adults should obtain one dose of Tdap if they have never had one, especially if over the age of 65.

 I have seen many, many children with pertussis over my years practicing as a pediatric intensivist.

While older children and adults may present with a classic staccato cough followed by a "whoop" when they finally are able to take a breath, very small infants may present with a non-specific respiratory infection. Doctors can be helped to make the diagnosis by looking at the Complete Blood Count (CBC) in which the white blood cells WBCs--the cells that fight infection) are very high (in some cases I have seen as high as 70,000, where normal can be up to about 15,000) with a very high percentage of lymphocytes (the which cells we typically associate with viruses). In addition, the chest XRays are often characteristic, showing a "shaggy" appearance of the peri-hilar area (the area on either side of the middle of the chest, but not extending out too far).  However, most children do not show all the "classic signs" and the youngest children may show only evidence that they are ill with something affecting how they breathe. In most cases, the "clue" that this might be pertussis is that there is at least one adult in the family who has had a chronic cough, usually without fever, and may not seem all that sick from it.

 

The bottom line here after all this ranting, is that you should get your kids immunized if they have not been already, and you should encourage the adults with whom they associate frequently to get immunized. You cannot catch the disease from the immunization, it does NOT cause seizures, epilepsy or autism.

I have seen infants die of this disease (thankfully not here in Roanoke), and I am always extremely sad to think that such deaths could have been prevented by the simple act of immunization.

 As usual, I welcome your comments and concerns, your thoughts, questions and observations.

           

 

Recent Comments

Thanks, Amy for your comment. I would love to hear from some of the parents out there, both for and against vaccines, or those with questions about pertussis, or other vaccine-preventable diseases such as measles, chicken pox, and influenza. As our world becomes increasingly small, due to ease and frequency of travel, we have to worry also about rates of disease and immunization in other countries. So... there is much to keep us busy thinking about and working, like yourself, to educate families so they can make the best possible decisions on behalf of their children.

As a general pediatrician I have the honor of talking daily to parents about vaccinations. Vaccines are strange in that they are one of the few medical "procedures" that we do that requires parental consent to take a risk (albeit very small) with a healthy child to prevent something that may or may not happen.

The angst that this creates for some families is large. It requires a leap of faith and "trust" in the "system" in a country that was founded on independant decision making and autonomy....

Hum, no wonder this becomes contentious. While I respect my family's thought processes and freedom to choose, in my heart of hearts, I feel that not vaccinating is a fundamentally a selfish decision. It can only work and be safe if all other families assume a risk for their children. The rate of vaccination, however, teeters on the threshold of herd immunity for some diseases, as we see with the pertussis outbreaks and measles outbreaks. Additionally, families who chose not to vaccinate also tend to congregate with each other due to other social beliefs and conditions.

I was gladdened last week by a sick visit in my office. A mom brought in her 5 or 6 month old with a cough and was worried about pertussis. I do not think that the child had pertussis. However, it is exactly when this healthy respect for the disease and understanding of its transmission reaches the concerns of families, can the rate of vaccination increase. I spent some time with mom talking about pertussis, how it is spread, who has it, and why I did not think her child had it. I hope that her interactions with her girlfriends and social contacts will spread beyond what I was able to do in my office that day.

Thanks, Dr. Muelenaer. Yes herd immunity is incrediblly important and has been helpful in fighting, on a community or societal level, many communicable diseases. I had the opportunity to participate in the development and licensure of the first vaccine useful in infants against what used to be the most common cause of bacterial meningitis in infants--Hib. I was able to track the incidence of this disease over time from licensure of the vaccine in the mid-80's and could watch as the disease in the community diminished, and fewer individuals became infected, even if they themselves were not being immunized. Every percentage point improvement in immunization rates translates into a BIGGER percentage decrease in disease prevalence once we exceed the tipping point of decrease for that particular communicable disease.

As a pediatric intensivist, I was able to watch some diseases caused by Hib decrease to the point of non-existence--to a point that we no longer see the life-threatening forms of Hib infection such as meningitis and epiglottitis (where the top of the airway closes off). Seeing this first hand, helps me to appreciate the true value of immunization--for every individual as well as for our community and society at large.

Dr Ackerman and I are of the same generation of physicians. I have practiced general pediatrics, pediatric pulmonology, and pediatric critical care. I have had similar experiences during my career. In the early 80s I had the opportunity to test one of the first monitors that measured oxygen through the skin. We had an infant in our ICU with pertussis and thought we would try it out. Most of us had seen babies turn blue during paroxysms of cough, witnessed seizures associated with these episodes, but had no idea how low the oxygen levels were. Watching the baby was frightening, but watching the numbers on the monitor was worse. While a normal oxygen level is 80-100 mmHg, we saw levels drop into the 30s & 40s, levels at which brain injury can occur.

It is critical that we look upon immunization of our children as part of our responsibility as members of society. Although I usually do not use Wikipedia as a medical reference, this link will carry you to a concise discussion about herd immunity: http://en.wikipedia.org/wiki/Herd_immunity The article begins with, " Herd immunity (or community immunity) describes a form of immunity that occurs when the vaccination of a significant portion of a population (or herd) provides a measure of protection for individuals who have not developed immunity.[1] Herd immunity theory proposes that, in contagious diseases that are transmitted from individual to individual, chains of infection are likely to be disrupted when large numbers of a population are immune or less susceptible to the disease. The greater the proportion of individuals who are resistant, the smaller the probability that a susceptible individual will come into contact with an infectious individual.[2]"

Pertussis is a deadly, preventable disease, and I encourage those who decide not to immunize their children to reconsider their positions based upon sound public health research, not anecdotal postings on the internet.

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About Dr. Ackerman

Alice Ackerman, MD, MBA, FAAP, FCCM is the Chair of the Department of Pediatrics at Carilion Clinic and Professor and Founding Chair of Pediatrics at the Virginia Tech Carilion School of Medicine. Dr. Ackerman is recognized nationally as an expert in pediatric critical care.

She has been at Carilion Clinic since June of 2007. Her primary goals are to enhance the health care of children in the Roanoke Valley and Southwest Virginia, and is actively working to do this both as physician in chief of the children's hospital, as well as through involvement with many state-wide initiatives.

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