Articles

Whooping Cough Epidemic

The Washington State Department of Health has released a statement stating that they are in the midst of a whooping cough epidemic, which will likely reach its highest levels in decades. So far this year there have been 640 cases, compared to 94 cases over the same time period last year. This is a dramatic increase. Whooping cough is a vaccine preventable disease, and so the resurgence of this infection raises questions about the efficacy of the vaccine program – specifically, to what extent is this increase due to vaccine refusal vs waning efficacy of the vaccine itself?

Background

Whooping cough is caused by the Bordetella pertussis bacterium (a Gram-negative, aerobic coccobacillus, for those who are interested), which produce a toxin that paralyzes respiratory cells and causes inflammation. The result begins like an ordinary upper respiratory infection (a common cold) but then develops into a severe cough which can last for weeks. The name of the disease, whooping cough, comes from the sound made by the sudden inhalation after a sustained cough. The disease can be severe at any age, but is especially pernicious in infants, in whom it can cause apnea, or brief pauses in breathing. In infants less than 1 year of age half will need to be hospitalized and 1 in 100 will die.

The pertussis bacterium was first isolated in 1906 by Belgian scientists Jules Bordet and Octave Gengou. In 1939 researchers at the Michigan Department of Public Health demonstrated the efficacy of a vaccine against Bodetella pertussis. The vaccine reduced the incidence of whooping cough from 15.1 to 2.3% and reduced the severity of the illness in those who contracted it. In 1948 the whole cell pertussis vaccine was combined with vaccines for diptheria and tetanus to make the DTP vaccine.

In the 1990s the DTP vaccine was replaced with the DTaP vaccine, which is still used. The whole cell pertussis component was replaced with a acellular vaccine. In the whole cell version the entire Bodetella pertussis bacterium is included in the vaccine in an inactivated state. The acellular vaccine contains only components of the bacterium. The change was made because the acellular vaccine has fewer side effects. However there was also unsubstantiated concerns about the risks of the whole cell pertussis vaccine that may have contributed to the decision to change. Both versions of the vaccine are effective, but some studies suggest that the acellular version provides less immunity than the prior whole cell vaccine. Today there is also the Tdap vaccine, which is intended as a booster vaccine for adolescents and adults.

Historically the introduction of the pertussis vaccine resulted in a 92% decrease in morbidity and 93% decrease in mortality from whooping cough.

The Return of Pertussis

Up until a few years ago pertussis was under good control in developed countries with a vaccine program. Pertussis has not known host outside of humans so it is even possible to achieve eradication. But in the last decade pertussis has been making a comeback. There is likely no single cause for this, but several can be identified.

There is evidence that the bacterium is evolving new strains that are less well covered by the DTaP vaccine. A recent study, for example, found that a new strain is emerging in Australia that is not well covered by the vaccine and is therefore spreading, because the existing strains are being selected against by the vaccine. The study also found that the older whole cell version of the vaccine produced wider coverage (better coverage for different strains) than the newer acellular vaccine. So it is possible that the return of pertussis is partly due to the narrowing of coverage that is allowing for the spread of newer strains.

To the extent that this is true it implies that we need to update the vaccine to cover the newer strains. This, however, may be only a temporary fix and still more strains may develop. Therefore we either need to chase new strains as they emerge, or we need to develop a pertussis vaccine that has broader antigen coverage, more similar to the older whole cell vaccine, but without the increased side effects.

Another contributing factor is the waning immunity provided by either infection or vaccination. Antibodies against pertussis do not last a life time, so adults who were either infected or vaccinated as children may have lost their immunity. They then provide a vector for the infection of young infants who are not yet old enough to be vaccinated. For this reason the CDC is recommending booster vaccines for teens and adults, especially health care workers and those exposed to young children.

Finally there are serious concerns about vaccine refusal as a contributor to the resurgence of whooping cough. Thanks to the anti-vaccine movement there is unsubstantiated fear about the safety of vaccines. In particular there are pockets of vaccine refusal resulting in a loss of herd immunity. Herd immunity results when enough of the population is immune so that an infectious disease cannot spread, so cases become isolated and do not cause an epidemic. Without herd immunity pertussis infections can spread through a population.

The evidence indicates that unvaccinated children are at higher risk of developing whooping cough than vaccinated children. Existing herd immunity is not sufficient to protect the unvaccinated, even in areas of high vaccine compliance. Further there is early evidence that whooping cough is spreading the most in counties that have a high vaccine refusal rate. The correlation between whooping cough and vaccine refusal needs to be studied in more detail, but certainly vaccine refusal is not helping and is contrary to the goal of increasing coverage to achieve herd immunity.

Conclusion

Historically controlled infections, like whooping cough, have the potential to make a comeback. There is a certain amount of complacence today toward diseases that are thought to be largely a thing of the past. However we are now experiencing a resurgence of some of these diseases, like whooping cough, and while the causes are complex and need to be teased apart, they are worsened by vaccine refusal which in turn is spawned by an anti-vaccine movement that is spreading misinformation and unwarranted fears.

With regard to the current whooping cough epidemic, the CDC has many specific recommendations for the public and health care workers. In short – vaccinate your children and get a booster.

 

Posted in: Vaccines

Leave a Comment (37) ↓

37 thoughts on “Whooping Cough Epidemic

  1. windriven says:

    “This, however, may be only a temporary fix and still more strains may develop.”

    All the more reason to approach the task as a mission of eradication as was done with small pox and nearly so with polio. We have the technology. What we lack is the will.

  2. _Arthur says:

    I fear there are discincentives for pharma company to research a new, better, vaccine.
    I understand that the immunity conferred by the pertussis vaccine wanes relatively rapidly, “a 2011 study by the CDC indicated that the duration of protection may only last three to six years”, according to Google.

  3. Epinephrine says:

    “All the more reason to approach the task as a mission of eradication as was done with small pox and nearly so with polio. We have the technology. What we lack is the will.”

    Smallpox eradication was incredibly expensive, and justified by the deadliness of smallpox. Polio hasn’t yet been eradicated despite a very lengthy campaign. We simply don’t have the resources to do eradication campaigns against all diseases. There are other ways to improve the effectiveness of the vaccine program; addition of new antigens (as was seen with Prevnar->Prevnar 13), use of adjuvants to promote better immune response and cross-reactivity, techniques to identify conserved proteins and the use of conjugates/adjuvants to direct an immune response against conserved antigens, and possibly the use of other routes of administration (e.g., intranasal influenza vaccines) which trigger immunity via a different route, and can result in better crossreactivity.

    I guess I just think it’d be far easier to develop a better vaccine, rather than trying to man a global effort to eradicate another disaease when we haven’t yet managed to eradicate polio, despite the advantage of using a live oral vaccine.

  4. DugganSC says:

    And didn’t a prior article indicate that eradication is a relatively futile goal because, for most of the eradicated diseases, the cases where it does spring up are the result of an infection resulting from the vaccination intersecting with weak immune systems? I’d think that would only happen with live cell vaccines (which are the exception rather than the rule), but if the prevention were the cause for even a miniscule percentage, that means that eradication can’t occur any more than applied violence ends violent conflicts.

    I wish I could remember which article that was and if it was in the article or in the comments. I’ll poke around and see what I can find.

  5. Epinephrine says:

    @DugganSC – The only human disease to have been eliminated is Smallpox. Despite being a live vaccine, smallpox vaccination couldn’t cause smallpox as the Orthopoxvirus used in the eradication effort was vaccinia, not variola.

    Polio has not been eradicated. Though it is true that there can be reversions to vriulence in the case of the live polio vaccine, polio has remained endemic in several areas. We could complete the polio eradication effort despite the possibility of vaccine-derived polio, but there are significant challenges in actually doing so, including the difficulty of maintaining a cold chain in some areas.

  6. DugganSC says:

    I am enlightened. Thank you. Also, thanks to Wikipedia, I also see what the “cold chain” is. I love learning new terminology.

    Nevertheless, it does look like a lack of childhood vaccination seems to be the culprit here. I’ll admit that I didn’t realize, either, that the period of protection was so short. Given the first shot is done in the first year and the second when they’re 10 (at least from what I gleaned from the schedule on the CDC site), aren’t we creating a pretty big gap there, given the vaccine is only shown to be effective for a few years?

  7. windriven says:

    @Epinephrine and DugganSC

    “We simply don’t have the resources to do eradication campaigns against all diseases.”
    “I’ll admit that I didn’t realize, either, that the period of protection was so short.”

    To the first I’d suggest that we choose to allocate the resources in other ways. I would certainly agree that the resources are limited. It is a question of how those resources are allocated.

    To the second, it is hard enough getting people to vaccinate their children much less getting everyone re-vaccinated every 5 or so years. That coupled with the emergence of strains that are not well covered by the existing vaccine makes eradication seem attractive. If we don’t have the resources to eradicate now will we find it easier to allocate the resources later if a resurgent pertussis becomes an entrenched threat to infants worldwide?

    Cold chain – for those who don’t know (and like DugganSC, I didn’t and had to look it up) cold chain refers to the necessity of keeping live vaccines under refrigeration making it very difficult to vaccinate in remote areas.

  8. Quill says:

    In northern California’s affluent communities, there is a lot of anti-vaccination nonsense taken as truth and as a result a lot of children are not being vaccinated. In addition, the parents of these children aren’t getting booster shots. It will be interesting to see, in a tragic and very painful way, any comebacks of previously suppressed diseases in these communities where they have enormous resources to either learn from their mistakes or put even more money into anti-vax causes.

  9. Janet Camp says:

    That this is happening in Washington State doesn’t surprise me at all. I lived in two of any number of small New Age-y communities there over the last thirty years and both are plagued by woo. Both places are said to be “vortexes” of New Age philosophy–not even sure what this means other than it makes woo-people flock to these places where they set up numerous woo “practices”, “alternative” schools, studios, “healing” centers, spas, and the like. Needless to say, they tend to resist vaccination which takes only a signature on the school forms (that is even assuming most of these people’s kids are in the public schools). Bookstores and libraries in these towns are suffocating in woo-oriented literature and it is very easy to find MD’s who practice a wide variety of woo.

    There’s no reason to be secretive. These towns are Port Townsend and Langley (on Whidbey Island). Seattle and lots of other small towns are also woo-friendly, but these two are particularly known for it and attract such people from all over the country. Port Townsend, for example supports a food co-op that is the size of a Whole Foods Store in a town of 8,000 (it also draws on a wider population in surrounding Jefferson County–which is rural still). This co-op has a large “wellness” component while the town of Langley (on Whidbey), population less than 1,000, supports at least two shops that sell only woo potions.

    ——-

    About polio not being eradicated: No, but nearly so, and only remaining in pockets where refrigeration is difficult to maintain due to remoteness or in areas where vaccination fears based on falsely spread fears of racial/religious extermination are spread. It’s still a commendable record in my view as someone born into a pre-polio vax world.

  10. Linda Rosa says:

    Too bad that legal non-medical exemptions allow parents who don’t vaccinate to avoid child abuse charges and civil suits (i.e. regulation by litigation).

  11. windriven says:

    @Janet Camp

    “That this is happening in Washington State doesn’t surprise me at all.”

    Here is a statistic* that, as a WA state resident, shocked me:

    “Exemption rates vary widely, from less than 0.1% among kindergarteners in Mississippi to 6.2% among those in Washington State. Moreover, within Washington State, 2010–2011 exemption rates for K–12 students varied significantly by county, ranging from 1.2% to 25.4%.” Emphasis mine.

    Let’s see, less than 0.1% vaccination refusal at the epicenter of the bible belt and 6.2% in suave, cosmopolitan WA state. Maybe the Mississippians don’t think themselves smarter than their physicians.

    *Douglas S. Diekema, M.D., M.P.H., N Engl J Med 2012; 366:391-393February 2, 2012

  12. lilady says:

    We do have a problem with credulous parents who “opt out” of some or all vaccines, based on what is cranked out by “science” journalists at various notorious anti-vaccine websites.

    Last year, in California, ten infants who were too young to have completed the primary DTaP series, died from pertussis, during the largest pertussis outbreak that California experienced in 52 years:

    http://www.cdc.gov/pertussis/outbreaks.html

    As a consequence of recent outbreaks and the problems associated with waning immunity to the pertussis component of the 3-antigen vaccine, a new diphtheria, tetanus, pertussis “booster” (Tdap) vaccine has been licensed and recommended for adolescents and for adults:

    http://www.immunize.org/vis/vis_td-tdap.asp

    (click to enlarge the Vaccine Information Sheet-my Adobe reader is giving me grief)

    The WHO had set a goal of eradicating polio and, but for political unrest in certain areas of the world, that goal would have been reached…

    http://www.polioeradication.org/

    There are weekly reports of YTD confirmed polio cases at that website, as well as topics dealing with the opportune time to switch from OPV to IPV, once eradication has been achieved.

  13. aeauooo says:

    To the best of my knowledge, pertussis has never been considered an eradicable disease.

    There are two reasons for this:

    1. The efficacy of the vaccine is limited.

    2. Limitations in case detection. People can be infected with B. pertussis, transmit the infection to others, yet have mild or atypical symptoms or even be asymptomatic.

    “Three indicators were considered to be of primary importance: an effective intervention is available to interrupt transmission of the agent; practical diagnostic tools with sufficient sensitivity and specificity are available to detect levels of infection that can lead to transmission; and humans are essential for the life-cycle of the agent, which has no other vertebrate reservoir and does not amplify in the environment.”
    The Principles of Disease Elimination and Eradication

    @ Janet Camp

    Don’t forget Vashon Island

  14. lilady says:

    @ Winddriven: Excellent post. May I add to your comment that only two states (Mississippi and West Virginia), do not permit “philosophical, personal belief and/or religious exemptions” for school entry. The other 48 states “permit” the *free-rider parents*, who rely on herd immunity to protect their children, to claim these exemptions.

  15. aeauooo says:

    @windriven

    “Let’s see, less than 0.1% vaccination refusal at the epicenter of the bible belt and 6.2% in suave, cosmopolitan WA state. Maybe the Mississippians don’t think themselves smarter than their physicians.”

    Mississippi and West Virginia are the only two states that allow neither religious nor philosophical exemptions to immunizations – only medical exemptions.

  16. Calli Arcale says:

    aeauooo:

    2. Limitations in case detection. People can be infected with B. pertussis, transmit the infection to others, yet have mild or atypical symptoms or even be asymptomatic.

    But that part is also true of polio, yet we stand on the verge of eliminating that. I think that’s where vaccination becomes important; if it’s possible for asymptomatic cases to be major carriers, then one cannot depend on quarantine. Only vaccination stands a chance.

    I don’t know how well vaccine efficacy compares between pertussis and polio.

  17. DugganSC says:

    If I’m reading the material right at http://sprojects.mmi.mcgill.ca/tropmed/disease/polio/vaccine.htm, it’s 99% effective after three doses and the live-virus version seems to be a lifelong innoculation while the dead-virus version is just a long time.

    Of course, searching for Polio vaccine efficacy also turns up http://www.whale.to/vaccines/kent.html where they claim that the vaccine caused the number of cases to spike when it was already on the decline due to “nature” and even notes the biggest increase in polio cases pre-vaccine was right after the pertussis vaccine was released. Also, a very bad explanation of herd immunity as “Vaccine recipients infect unvaccinated persons”…

    Lastly, http://www.ncbi.nlm.nih.gov/pubmed/7775883 states “Vaccine efficacy (VE) was 86% (95% CI: 39-97%) and 92% (95% CI: 64-98%) for 3 and 4 doses of OPV respectively.” and then notes that OPV should be producing 100% efficacy and speculates on what other variables may be influencing results.

    Frankly, the fact that pertussis vaccine has side effects, and worse ones with the more effective vaccine, probably would further sour people on including more vaccinations…

  18. lilady says:

    Is someone there to get my comment out of moderation? I *just knew* that I linked to too many articles about recent pertussis outbreaks, the recently licensed Tdap booster vaccine and the efforts of the WHO…to finally eradicate polio.

  19. Marco Rosaire Rossi says:

    I used to live in Washington state. I concur with the comments that there is a large woo-friendly population out there. Just outside of Seattle in the city of Kenmore, there is Bastyr University–founded by grandfather of alternative medicine John Bartholomew Bastyr. This man was a jack-of-all-craziness. At Bastyr, Naturopath students are not required to take any classes in statistics–they don’t even offer them–but are expected to take three years of homeopathy (hey, I wonder if the less work you do in the class, the better grade you get?) and several classes on naturopathic philosophy, professionalism, and business. In my opinion, any “medical” school that teaches business classes should be a fair warning sign for anyone. Alas, that is not the case. Students from the area and beyond are willing to pay the $30,573 a year in tuition and fees to a fraudulent education institution, so they can establish fraudulent healthcare practices.

    I have a friend out in Olympia, WA who hides the fact that she got her daughter vaccinated from some people out of fear of judgment and scorn. Thankfully, she got her vaccinated against whooping cough–along with everything else. In my view, she really is a rare ray of rational light in a vast dark cave of foolishness and nonsense.

  20. aeauooo says:

    @DugganSC

    Regarding the http://www.whale.to article (The Polio Vaccine Myth, Christopher Kent, 2000. The Chiropractic Journal):

    “In 1942, the epidemic of the first half of the century subsided, and there were fewer than 5,000 cases of polio in the United States. Around 1948, the number of polio cases began to soar. Interestingly, this is about the time the pertussis vaccine appeared on the public health scene.”

    First, improved sanitation changed the epidemiology of polio. Polio had previously been a disease of infancy; a time when babies were partially protected against paralytic polio from maternal poliovirus antibodies. With improved sanitation, children become infected when they no longer had maternal antibodies, which resulted in epidemics of paralytic polio.

    Second, there were no polio vaccines before the Salk vaccine, which was first trialed in 1954.

    “The risk of contracting polio from the live virus vaccine is greater than the risk of acquiring the disease from naturally occurring viruses.”

    There is a 1 in 2.4 million dose risk of vaccine-associated paralytic polio (VAPP) from oral polio vaccine (OPV). OPV is no longer used in the U.S. because the risk of VAPP outweighs the risk of infection with wild polio virus.

    That is not the case in countries where polio is still endemic, which is why OPV is still used in developing countries.

  21. aeauooo says:

    @Calli Arcale

    “I don’t know how well vaccine efficacy compares between pertussis and polio.”

    You are correct; most people infected with poliovirus do not develop paralytic polio.

    One of the reasons that polio was determined to be eradicable is that oral polio vaccine is highly effective.

    Acellular pertussis vaccines are about 85% effective.

    Also, unlike immunity to pertussis, immunity to polio does not wane.

  22. aeauooo says:

    Correction: I misread “Interestingly, this is about the time the pertussis vaccine appeared on the public health scene.”

    Post hoc ergo propter hoc.

  23. aeauooo says:

    More from Kent 2000:

    “A chilling legacy of the live polio vaccine may be the virus associated with AIDS. Edward Hooper’s book “The River: A Journey to the Source of HIV and AIDS” suggests that AIDS may be the result of a live virus polio vaccine administered in Africa in the 1950s.”

    Worobey, M., Santiago, M. L., Keele, B. F., Ndjango, J-B. N., Joy, J. B., Labama, B. L., et al. (2004). Origin of AIDS: Contaminated polio vaccine theory refuted. Nature, 428(6985).

    Rizzo, P., Matker, C., Powers, A., Setlak, P., Heeney, J. L., Ratner, H., Carbone, M. (2001). No Evidence of HIV and SIV Sequences in Two Separate Lots of Polio Vaccines Used in the First U.S. Polio Vaccine Campaign. Virology 287(1).

  24. DugganSC says:

    @aeauooo:
    Not my beliefs in that article. I was just listing it because it came up among the top three results for “polio vaccine efficacy” on Google so I figured I’d mention it since we’ll probably be dealing with people who use Google as their main information source and believe everything they read off of there.

  25. aeauooo says:

    Google is a great way to find vaccine misinformation.

    Bean, S. J. (2011). Emerging and continuing trends in vaccine opposition website content. Vaccine, 29(10),.
    http://www.ncbi.nlm.nih.gov/pubmed/21238571

    Betsch, C., Renkewitz, F., Betsch, T., & Ulshöfer, C. (2010). The influence of vaccine-critical websites on perceiving vaccination risks. Journal of Health Psychology, 15(3).
    http://www.ncbi.nlm.nih.gov/pubmed/20348365

    Chatterjee, A. (2003). Vaccine and immunization resources of the World Wide Web. Clinical Infectious Diseases, 36(3).
    http://cid.oxfordjournals.org/content/36/3/355.long

    Davies, P., Chapman, S., Leask, J. (2002). Antivaccination activists on the world wide web. Archives of Disease in Childhood, 87(1).
    http://www.ncbi.nlm.nih.gov/pubmed/12089115

    Kata, A. (2010). A postmodern Pandora’s box: anti-vaccination misinformation on the Internet. Vaccine, 28(7).
    http://www.ncbi.nlm.nih.gov/pubmed/20045099

    Wolfe, R. M., Sharp, L. K., Lipsky, M. S. (2002). Content and design attributes of antivaccination web sites. Journal of the American Medical Association, 287(24).
    http://www.ncbi.nlm.nih.gov/pubmed/12076221

    Zimmerman, R. K., Wolfe, R. M., Fox, D. E., Fox, J. R., Norwalk, M. P., Troy, J. A., Sharp, L. K. (2005). Vaccine criticism on the World Wide Web. Journal of Medical Internet Research, 7(2).
    http://www.ncbi.nlm.nih.gov/pubmed/15998608

  26. nybgrus says:

    @dugganSC:

    Anything from whale.to is wrong. And anything that isn’t wrong there isn’t worth trying to find. You can, for all useful purposes, completely discount everything from that site.

  27. Chris says:

    Now, nybgrus, there is one page that many are proud to be mentioned on:
    http://www.whale.to/a/pharma_gang.html

    ;-)

  28. It’s happening in my neck of the woods too, unfortunately.

  29. nybgrus says:

    the basic layout and formatting of those pages make my eyes hurt.

    Why is it that nut-bag websites are always put together in such a way as to make sane people incapable of reading them comfortably?

  30. DugganSC says:

    ^_^ So I suppose that I shouldn’t go start distributing these links, claiming that they must be right because I got them off of http://www.sciencebasedmedicine.org?

    No, as I stated before, I knew that one was dead wrong. The horrible twisting of the definition of “herd immunity” if nothing else.

  31. Earthman says:

    Lets not forget the Jenny McCarthy body count

    http://www.jennymccarthybodycount.com/Jenny_McCarthy_Body_Count/Home.html

    and What’s the Harm

    http://whatstheharm.net/

    People are gathering good evidence as to the harm of the anti-vaccinators (and other CAM woo) – lets make sure we use the info and spread it far and wide.

  32. Earthman says:

    On a parallel track ( I hope), we have a weekly television debate program over in the UK called Question Time. In it a panel of people, usually a mix of politicians and journalists with the odd celebrity thrown in now and again. They are asked questions from the studio audience of which they have no prior knowledge. It can be quite entertaining.

    Last year there was a huge row in the media as the BBC wanted to invite an extreme right winger of the British National Party onto the debate. The opposition was that someone with such offensive racist views should not be given a national forum. As it happened, when he did get onto the debate the population at large could finally see just how stupid his ideas were, because they were so stupid, idiotic, and way outside any rational person’s beliefs. The popularity of his party fell like a stone, and many people finally realised what an idiot this man was.

    I put it to you, for discussion, that extreme views, idiotic views, should sometimes be given wide coverage, in a debate-like forum on national media, so that it can be seen by the general population just how wacky those views are. Rather than give publicity to woo, it could even have the opposite effect. Of course you need a good, honest, intelligent, independent person running the discussion who can be firm but fair with both sides.

    Any ideas?

  33. Narad says:

    Anything from whale.to is wrong. And anything that isn’t wrong there isn’t worth trying to find. You can, for all useful purposes, completely discount everything from that site.

    I present you with the Kavanagh debunking of Mercola’s claim about Bernard Greenberg.

  34. lilady says:

    Duggan SC: Why are you relying on an old (1993) citation from PubMed? Here is the CDC Pink Book website for all vaccine-preventable-diseases and the vaccines that are licensed in the United States:

    http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/polio.pdf

    I think you will find a short history of Polio endemic outbreaks here in the United States, both before and after the development and licensing of the Salk and Sabin Vaccines.

    Your cited of any article from whale.to indicates that you haven’t looked at reputable sources on the internet.

Comments are closed.