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Californians give a whoop – or I hope they do.

I’m certain by now many of our readers have come across news of the current pertussis, aka whooping cough, epidemic in California.  Beginning this February and accelerating dramatically through May and June, California has so far seen a ~500% increase in pertussis cases compared to last year, and only two days ago announced the death of a sixth baby from infection.  Public health officials in California are currently working to control its spread and determine the factors that allowed this outbreak to occur, unfortunately, at this time the available data is very rough.

The number of confirmed cases as of 6/30/2010 is growing rapidly (1,377), with an additional ~700 cases pending investigation.  General geographic location, ages, and ethnicity have been identified, and general vaccination rates and exemption rates are known, but other important demographic and epidemiologic data, including vaccination status of infected children and adults, has yet to be fully described.  Lack of data notwithstanding, I have read equally hasty stories and comments blaming the outbreak on vaccine refusal, a large immigrant population, an inadequate adult vaccination program, and normal cyclical variation in pertussis incidence, among other factors.  Finding where the system has broken down enough to allow this resurgence is exceedingly important, but in this situation pointing fingers is not as important as taking action.

Pertussis

A bit of background first.  Pertussis is a highly contagious infection of the respiratory tract by a bacteria Bordetella pertussis.  After an incubation period of 7-10 but up to 42 days, the disease progresses through three stages.  The catarrhal stage is often indistinguishable from the symptoms of the common cold, with runny nose, mild cough, and lasts 1-2 weeks.  During the second or “paroxysmal” stage infected people will have fits or “paroxysms” of uncontrollable rapid-fire coughing.  Examples can be seen here (caution, may be disturbing to watch). At the end of these paroxysms people take a large, rapid intake of breath through raw and often partially closed vocal cords, producing a high-pitched “whoop.”  The paroxysmal stage can last anywhere from 1-6 weeks.  The final stage is one of prolonged convalescence with a persistent dry cough lasting weeks to months (this is where pertussis got its other name, the “hundred day cough”).

A persistent cough isn’t the worst of pertussis.  60% of children under 6 months of age infected with pertussis need to be hospitalized, 5-10% get pneumonia, 1 in 125 have seizures, and 1 in 1000 suffer from an encephalopathy (inflammation of the brain) that frequently causes permanent brain damage.  And of course pertussis can kill.  Children under 3 months of age are at the greatest risk, and make up 84% of all pertussis related deaths.

Treatment is possible, but limited in utility.  Even though pertussis is bacterial and we have multiple antibiotics that reliably kill it, treatment after the first stage (when it becomes clear someone has more than a cold) only limits the ability of a person to spread it to others, it does not reduce the severity or length of the disease.  Once symptoms start, we are forced to ride out the illness.  Prevention is far better than treatment.  And speaking of prevention…

The Vaccine

The first vaccine to prevent pertussis was licensed in the US in the 1940s.  At that time we had an average yearly of 157 per 100,000 people, though this is likely to be a low-ball figure, given the state of medicine at the time and under-reporting.  From its release through the 1970s we saw a steady drop in cases from the pre-vaccination rate of 157 down to <1 infection per 100,000 people per year.  Though effective, the original vaccine had multiple side effects, including inducing a febrile seizure in 1 in 10,000 children.  These serious complications were enough to begin to undermine the public trust in the vaccine in the US, and to prompt several countries to stop pertussis immunization entirely.

In the 1980s and 90s several countries ceased or severely curtailed their use of DTP, including Japan, Sweden, and the UK.  Each of them saw a sharp and immediate rise in pertussis incidence to levels 10-100 times that of countries that continued to have high rates of vaccination with DTP.  This is a pattern we see repeated time and again when vaccines are withdrawn; it represents one of the best and most tragic demonstrations of vaccine efficacy you could ask for.

Effectiveness aside, the original DTP vaccine had legitimate problems, so a new vaccine was developed, tested, and eventually licensed for use.  By 1997 DTaP had fully replaced the original DTP vaccine.  Subsequent testing confirmed that it was just as effective as its predecessor, and induced significantly fewer side effects.  DTaP replaced DTP in the US before significant outbreaks could occur, and when instituted in countries that had stopped vaccination with DTP, quickly brought pertussis back under control.

DTaP, like all vaccines, continues to be studied, and is holding up very well to scrutiny.  Just this month, a self-controlled case series study in Pediatrics including 433,654 children and 7191 seizure events failed to find any significant association between DTaP and febrile seizures.

That the current pertussis vaccine is effective is beyond any serious contention, and its safety profile is excellent, but it’s not perfect.  The immune response the vaccine generates is relatively weak, necessitating multiple doses at 2, 4, 6, 15-18 months and 4-6 years to generate an adequate response (this isn’t unique to the vaccine; natural pertussis infection isn’t capable of providing long-lasting immunity either), and protection wanes after 5-10 years.

These characteristics predispose the vaccine, when used exclusively in childhood, to leave a couple of populations susceptible to infection.  First, the children most at risk of death from pertussis, those under the age of 3 months, have little to no direct protection from the vaccine or from maternal antibodies; this population relies heavily on herd immunity for protection.  The second vulnerability is that since neither the childhood vaccine nor natural infection provides lasting immunity, adults can become repeatedly infected, and serve as the primary reservoir of disease.  This is grimly illustrated by the fact that infants are most frequently infected not by other children, but by their parents.

Of course, this has been known for some time, and the vaccination schedule isn’t focused exclusively on early childhood.  A late childhood booster dose of TDaP (a reformulation of DTaP) at 11-18 years has been recommended since 2005, and adults are supposed to receive TDaP once between the ages of 19-64 to address this very problem.  Unfortunately, these doses are infrequently given for a variety of reasons, creating vulnerable populations to act as reservoirs for pertussis.

Though I may wish to have a vaccine that is somewhat less burdensome to use, it’s hard to complain about the current pertussis vaccine’s safety record, and properly administered, it’s capable of controlling and preventing epidemics (some even optimistically speculate the possibility of eradication).  To be fully effective though, it requires the dedicated support of both public health officials and the community.

The California Epidemic

Without a doubt, the relatively high-maintenance vaccination schedule contributes to our inability to fully control pertussis, but even if we had a vaccine capable of inducing lifelong immunity from birth onward, we would still have sections of the population that remain vulnerable to infection.  An embarrassingly large fraction of our fellow citizens lack access to health care.  Some immigrant populations may not have had the benefit of a modern medical system and immunization before arriving in the US, and some again lack access to health care after arrival.  A relatively small number of people are unable to be vaccinated or are immunocompromised due to medical conditions.  Finally, there are people who utilize California’s notoriously lax Personal Belief Exemption (PBE) policy to opt out of vaccination.

To what degree each of these factors is to blame for the current epidemic is not yet clear.  While it is true that some of the counties with the highest attack rates also happen to be counties where PBEs are common and vaccination rates low, other counties with reasonable vaccination rates are also being heavily affected.  (The attack rates of individual California counties can be found here.)  We simply do not yet have the entire epidemiologic picture, and it appears likely that several, if not all of these factors are in play.  That doesn’t mean, however, that we don’t know what action needs to be taken.

The California Department of Public Health is approaching this problem in the right way by addressing all of these elements at once, educating the public and expanding their TDaP program (TDaP program FAQ here, CDPH’s current activities and news releases here, and local California public health services here), though I think they may need to be even more aggressive.  In particular, I’d like to see a heavy revision of California’s PBE policy to make PBEs more difficult to obtain.

At the beginning of this post I said that in this pertussis epidemic, pointing fingers isn’t as important as taking action; to some this may have sounded hasty, but I hope you now understand my rationale.  An increase in size of any of any vulnerable group pushes the population as a whole closer to that nebulous cliff where herd immunity can no longer prevent an outbreak from becoming an epidemic.  No matter what the underlying cause(s) turns out to be, the single best intervention to control the spread of the current epidemic is the same: Vaccination. There may be multiple reasons for an outbreak of pertussis… but in our society there really is no excuse for it.

Posted in: Science and Medicine

Leave a Comment (45) ↓

45 thoughts on “Californians give a whoop – or I hope they do.

  1. Smiles302 says:

    Did the old whooping cough vaccine need a top up?

    http://www.immunisation.ie/en/ChildhoodImmunisation/VaccinePreventableDiseases/WhoopingCough/

    As far as I can tell Ireland only vaccinates children under 5.

  2. BillyJoe says:

    “The immune response the vaccine generates is relatively weak, necessitating multiple doses at 2, 4, 6, 15-18 months and 4-6 years to generate an adequate response”

    In Australia, it is 2, 4, 6 months; 4 years; 15 years

    I don’t know why the dose at 15-18 months is left out, but the booster at 15 years seems a good idea

  3. rork says:

    “In particular, I’d like to see a heavy revision of California’s PBE policy to make PBEs more difficult to obtain.” (PBE=Personal Belief Exemption)

    That’s easy to say. The details are problematic I think. It would not be the first time those issues are discussed.

    The “157″ sentence may be worth fixing, since it’s hard for reader to reconstruct.

  4. What really concerns me in reading reports of this and other recent outbreaks is that people do not take this infection seriously. Maybe because the name sounds a little funny it’s disarming but nobody should take pertussis lightly.

    I had the misfortune of contracting pertussis about 8 years ago through a series of events. I was in the ER being for an insect-sting reaction the treatment of which dulled my immune responses. Just over the curtain in the next bed there were three infected children from a religious community that does not vaccinate. I was later told by a pulblic health official that there was a particularly virulent strain circulating at the time. And I’ll admit, my vaccination was probably getting old. So a perfect storm there. When the paroxysmal stage hit me I was a wreck. I would cough until I blacked out. I spent af few days in hospital on oxygen and IV antibiotics. I had to take 2 months off of work and was useless to my family.

    The worst of it is that is has never really gone away. Even now if I get a respiratory infection the paroxysmal coughing returns (although much less severe) and ever since I had pertussis I seem much more vulnerable to respiratory infections. All of this happened in an otherwise very fit healthy man in his early thirties. I can’t imagine the suffering a small child would experience; it breaks my heart to even think about it.

    The moral of the story is to please vaccinate if you can. You don’t want you or a loved one get this.

  5. plurie says:

    Until 2005, there was no pertussis vaccine available in the US for anyone over the age of seven. Since then, the Tdap vaccine has been approved and recommended for routine use in preadolescents (ages 10-12), and for “catch up” vaccination of adolescents and adults up to age 64. Currently, the recommendation is for a single dose, but there may eventually be recommendations for periodic boosters (probably at 10 year intervals) and for vaccination of people aged 65 and older, but the data to support these recommendations do not (yet) exist.

    The DTaP vaccine is still used for infants and children up to age seven.

  6. windriven says:

    While it would be difficult to envision mandatory vaccinations in a free society, there is a long legal tradition of holding individuals responsible for their actions and negligent inaction. Outbreaks of pertussis, measles, mumps and other preventable diseases impose significant financial burdens on the communities in which they occur. Should not those who place their families and neighbors at risk by eschewing vaccinations bear the financial burden when their folly results in an eruption of disease?

    The rights that accrue in a free society include the right to do any number of stupid things. But with rights come responsibilities and with the abrogation of those responsibilities come consequences. Isn’t it time that we hold anti-vaccinationists, herbalists, chiroquacksters and naturopaths responsible when their nonsense leads to death, disease and disability?

  7. Pieter B says:

    I’m a Californian in my 60s. Where I work, there has been for the past couple of years “a thing going around” that some have dubbed the “100-day flu.” People are not really sick, but a minor persistent cough that lasts and lasts.

    Should I ask for a pertussis booster at my next physical?

  8. Kenneth says:

    I knew from my own reading and research that vaccination against pertussis had always been difficult, and I always considered that to be part of the nature of the pathogen in question. But I had no idea that pertussis was, please pardon my language, that persistent a pain in the ass. Until now I had no idea just how difficult a problem pertussis is and has been.

    Thank you very much for this information.

  9. borealys says:

    In Canada (or, rather in the two Canadian provinces where I’ve lived) we’re also required to get a booster at 14-16 years — when I got it, it was required for entry into grade 9 and was colloquially known as the “high school booster.” Interestingly, looking at the Quebec vaccination schedule, no adult dose is routinely recommended. I was required to get one at 24, along with an MMR booster, when I entered graduate school in a health care program (required by the university, not the government), and was recommended after that to get one every ten years or so since I work with children.
    Also interesting in the Quebec schedule we have a DTaP-Polio-Hib combined vaccine … is that common?

  10. wales says:

    While this post addresses some of the complex issues surrounding pertussis, it omits others. Examining the science is more informative than ranting about political rights for vaccine exemption.

    First, the pertussis component of DTaP is only about 85% effective against b. pertussis, according to the Infantrix and Daptacel vaccine pkg inserts.

    A substantial number of whooping cough cases derive from b. parapertussis rather than b. pertussis. The b. pertussis vaccine is ineffective against b. parapertussis. “Since differential diagnosis of B. pertussis and B. parapertussis does not affect the course of treatment, it is rarely performed in clinical settings. The CDC does not list B. parapertussis as reportable, but a few epidemiological studies have reported the percentage of whooping cough cases caused by B. parapertussis to be from 1% to 98%, most commonly 4–40%. Although B. parapertussis appears to contribute substantially to disease, whooping cough vaccines are solely derived from B. pertussis. Clinical and experimental data indicate that whooping cough vaccines are very efficacious against B. pertussis but not against B. parapertussis, however, a mechanistic understanding of this phenomenon has not been described.” http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006989

    Another paper suggests that high rates of b. pertussis vaccination leads to increased incidence of b. parapertussis. “Despite decades of worldwide pertussis vaccination, whooping cough is re-emerging in highly vaccinated countries. A rise in non-vaccine alleles coincident with widespread vaccination has been documented for Bordetella pertussis leading some authors to propose that vaccine-driven epitope-evolution in B. pertussis is one factor—among several others—that may contribute to whooping cough re-emergence in humans. However, it is not clear how Bordetella parapertussis—the other major aetiological agent of human whooping cough—might respond to the selective pressure exerted by large-scale pertussis vaccination. Here, we postulate that the widespread and long-term use of acellular subunit pertussis vaccines creates hosts that are more favourable for B. parapertussis.” http://rspb.royalsocietypublishing.org/content/277/1690/2017.full

    A 2000 report on pertussis in the Netherlands ruled out decreases in vaccine coverage as a factor in the reemergence of pertussis, instead proposing adaptation of b. pertussis to the vaccine as the cause “In some countries with highly vaccinated populations such as Australia, Canada, and The Netherlands, pertussis has reemerged. Such a phenomenon may have been caused by changes in the accuracy of notifications, decreases in vaccine coverage, or changes in vaccine quality. These possibilities have been excluded for The Netherlands, and we have proposed another possible cause: adaptation of B. pertussis to the vaccine. http://www.cdc.gov/ncidod/eid/vol7no3_supp/mooi.htm

    Complicated. Will pharmaceutical companies fund studies that might shed further light on these issues?

  11. Todd W. says:

    Dr. Albietz,

    Great article and good background on pertussis and the vaccine.

    @Brian the Coyote

    Gotta agree that people’s impression of pertussis tends to be that it is relatively benign. I can see how people think of it as “just a really bad cough”. Then you have people like Meryl Dorey claiming that people don’t die from pertussis (and if you’re reading this, Dorey, why don’t you try telling that to the parents of the 6 babies that died in California). There needs to be a better education campaign about this disease.

    @borealys

    no adult dose is routinely recommended

    That has been the way in the U.S., as well. Normally, adults were given the DT vaccine, but that appears to be changing as we realize more and more that adults are the vectors for pertussis transmission.

    I’ve got an appointment coming up to finish my Hep A and Hep B series. This is a reminder that I need to ask them to have my vaccination records available to review what I’m missing and what boosters are coming up.

  12. Jann Bellamy says:

    @windriven:
    “Isn’t it time that we hold anti-vaccinationists, herbalists, chiroquacksters and naturopaths responsible when their nonsense leads to death, disease and disability?”

    I have a couple of posts on these issues coming up soon if they pass muster with the SBM editors. Must finish writing them first though.

  13. pedsnurse says:

    thanks for the great article, I agree “Finding where the system has broken down enough to allow this resurgence is exceedingly important, but in this situation pointing fingers is not as important as taking action”. I read a post on another skeptics site that was quick to point the finger at the anti-vaccine camp. I agree that until all the data is in, action/vaccination/education is the key to curtailing this awful epidemic. BTW I worked for many years in the pediatric intensive care environment and saw first hand what pertussis does to these susceptible infants.

  14. Joe says:

    Thanks for a great post.

  15. jre says:

    This is an excellent post, information-rich and scrupulously fair.
    Please do more of the same!

    I became aware of the link between vaccine refusal and pertussis rates in 2002, when Arthur Allen wrote about Boulder’s Shining Mountain Waldorf School and its role in making Boulder one of the nation’s pertussis hot spots.

    As it turns out, Boulder is not alone. Where you find a Waldorf school, you you are likely to find pertussis. Thank you, Rudolf Steiner. Thanks a lot.

  16. wales says:

    Over 5 hours for moderation on a day without much comment activity, that’s long even by sbm standards…….

  17. wales says:

    ps: the “available data” link in para 1 is broken. Please fix, I’d like to see that. thx.

  18. wales says:

    While I’m waiting for my comment of 7 hours ago to appear, I thought I’d offer some more information about the persistence of pertussis infections despite very high vaccination coverage rates. I would appreciate any comments from sbm bloggers on this paper I found (JA, MC, anyone?).

    Quoting a 2009 paper “The reemergence of pertussis has been attributed to various factors, including increased awareness, improved diagnostics, decreased vaccination coverage, suboptimal vaccines, waning vaccine-induced immunity, and pathogen adaptation. Pathogen adaptation is supported by several observations.”

    In the past few decades, more virulent b. pertussis strains (ptxP3) have emerged, replacing older strains (ptxP1), apparently as a result of high vaccination coverage rates. In the Netherlands, ptxP1 was entirely replaced by ptxP3 from 1989-2004. “The replacement of ptxP1 strains by ptxP3 strains in recent times is a global phenomenon because it has been observed in 11 countries representing 4 continents: Asia, Europe, and North and South America. Notably, ptxP3 strains were not observed in Africa.”

    “Ptx causes leukocytosis in humans by inhibiting egression of leukocytes from the vasculature, and high levels of leukocytosis are associated with an increased mortality rate in infants due to pulmonary hypertension. Thus, the invasion of ptxP3 strains may result in increased illness and death. Consistent with this assumption, we found that the emergence of ptxP3 strains in the Netherlands was associated with increased incidence of hospitalizations and deaths and increased lethality.”

    “An important issue is whether vaccination has selected for the ptxP3 strains. Several lines of evidence support this contention. First, ptxP3 strains were not found in the prevaccination era. Furthermore, although ptxP3 strains were found in high frequencies in vaccinated populations in the 1990’s, they were not detected in Senegal, where vaccination was introduced in 1987. Several studies have provided evidence that increased host immunity may select for higher virulence.”

    “We propose that the crucial event, which shifted the competitive balance between ptxP1 and ptxP3 strains, was the removal by vaccination of immunologically naïve infants as the major source for transmission, selecting for strains, which are more efficiently transmitted by primed [vaccinated] hosts.”

    Bordetella pertussis Strains with Increased Toxin Production Associated with Pertussis Resurgence. FR Mooi et al, Emergining Infectious Diseases, Vol. 15, No. 8, August 2009

  19. borealys says:

    @Todd W.

    “Normally, adults were given the DT vaccine, but that appears to be changing as we realize more and more that adults are the vectors for pertussis transmission.”

    We don’t even have that here. No recommended vaccines at all, not even a flu shot, between the ages of 16 and 60 on the Health and Social Services schedule.

    I can get boosters free at my local public health clinic regardless, because of what I do for a living … or, at least, I’ve gotten one booster that way in the past. (A third dose of MMR — very unusual according to the nurse. The R portion hadn’t taken, and no one could find me a single-dose rubella shot.)

  20. wales says:

    It’s worth another shot here.

    A substantial number of whooping cough cases derive from b. parapertussis rather than b. pertussis. The b. pertussis vaccine is ineffective against b. parapertussis. “Since differential diagnosis of B. pertussis and B. parapertussis does not affect the course of treatment, it is rarely performed in clinical settings. The CDC does not list B. parapertussis as reportable, but a few epidemiological studies have reported the percentage of whooping cough cases caused by B. parapertussis to be from 1% to 98%, most commonly 4–40%. Although B. parapertussis appears to contribute substantially to disease, whooping cough vaccines are solely derived from B. pertussis. Clinical and experimental data indicate that whooping cough vaccines are very efficacious against B. pertussis but not against B. parapertussis, however, a mechanistic understanding of this phenomenon has not been described.” http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006989

  21. wales says:

    One more comment.

    Another paper suggests that high rates of b. pertussis vaccination leads to increased incidence of b. parapertussis. “Despite decades of worldwide pertussis vaccination, whooping cough is re-emerging in highly vaccinated countries. A rise in non-vaccine alleles coincident with widespread vaccination has been documented for Bordetella pertussis leading some authors to propose that vaccine-driven epitope-evolution in B. pertussis is one factor—among several others—that may contribute to whooping cough re-emergence in humans. However, it is not clear how Bordetella parapertussis—the other major aetiological agent of human whooping cough—might respond to the selective pressure exerted by large-scale pertussis vaccination. Here, we postulate that the widespread and long-term use of acellular subunit pertussis vaccines creates hosts that are more favourable for B. parapertussis.” http://rspb.royalsocietypublishing.org/content/277/1690/2017.full

  22. Mark Crislip says:

    re: wales

    Both are interesting. As parallels, the peumococcal vaccine in kids has shifted the strains causing disease and, temporarily lead to a decrease in pneumococcal pcn resistance.

    HIV is subject in some patients to evolving to escape the immune system.

    The interaction of vaccines on populations is always more complicated and interesting that one could imagine and often with unanticipated ecologic consequences.

    Still, a world with the vaccine is better than one without.

  23. windriven says:

    “An important issue is whether vaccination has selected for the ptxP3 strains. Several lines of evidence support this contention.”.

    Also Sprach Darwin. The genes and plexes that evolve rapidly enough to adapt to their changing environment survive.

  24. TsuDhoNimh says:

    The only way to protect infants is to create a buffer layer of vaccinated people around them. All adults that will be caring for a baby, and all siblings and playmates of the siblings should be vaccinated.

    In Phoenix we often found that granny was the source of infection … her immunity had waned, she had a long-lasting but low-level cough and the baby got infected.

  25. wales says:

    One other nitpicking item. JA states that “The number of confirmed cases as of 6/30/2010 is growing rapidly (1,377), with an additional ~700 cases pending investigation. “
    According to this

    http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5926a5.htm

    the 1,377 cases “either met the Council of State and Territorial Epidemiologists definitions for confirmed or probable pertussis or had an acute cough illness and Bordetella pertussis–specific nucleic acid detected by polymerase chain reaction from nasopharyngeal specimens”

    So what percentage of the 1,377 are “probable” and what percentage are “laboratory confirmed”? My point being that until laboratory confirmed (not easy, according to the CDC’s pink book) how do we know these cases are not b. parapertussis cases (no vaccine) rather than b. pertussis?

  26. TsuDhoNimh says:

    Wales;
    Part of the difficulty of the vaccine production when they started in the 20s or so was that there weren’t as many nifty tools to figure out which parts were antigenic and which caused the nasty reactions.

    Killed-cell vaccines are from the stone age of disease prevention. Compare them to the much-maligned HepB vaccine that contains a single protein from the viral coat that can induce immunity.

    Adding a new strain to the current vaccine is always possible. If ptxP3 emerges as a problem … add it.

    If B. parapertussis is also causing a problem, add it.

  27. wales says:

    b. parapertussis has been around a loooong time. http://www.jpeds.com/article/S0022-3476%2846%2980170-7/abstract

  28. wales says:

    Let’s get the disease confirmation right before we move on to more vaccines http://query.nytimes.com/gst/fullpage.html?res=9501e7db1f30f931a15752c0a9619c8b63&sec=health&spon=&pagewanted=1

  29. wales says:

    The matter of disease confirmation is key to whether or not there is an actual pertussis epidemic occurring. The CDC says the 1,377 cases through June 30 were either 1) confirmed (Does this means by bacteriological culture or pcr?); 2) probable, or 3) confirmed by pcr. The NY Times article cited above discusses how inaccurate pcr can be and has been in many instances. According to the CDC’s Pink Book, no pcr test has been approved by the FDA, there are no standardized protocols, reagents or reporting formats for pcr, and pcr should be used in conjunction with culture, not in place of it. The “gold standard” diagnostic test of bacteriological culture is time consuming and difficult, but the most accurate. JA, any data on how many of the cases have been confirmed by culture? Thx.

  30. wales says:

    Just curious about why the focus on California. “The CDC said June 19 that 5,120 cases of pertussis had been reported nationwide. Although that number was less than the 6,326 reported at the same time last year, several states reported significant increases in pertussis activity, including Texas (1,154 cases), Ohio (523 cases), Michigan (380 cases) and Arizona (163 cases). In addition, the South Carolina Department of Health and Environmental Council issued a public health advisory June 8, saying reported pertussis cases were above an epidemic threshold.” http://www.aafp.org/online/en/home/publications/news/news-now/health-of-the-public/20100706pertussis-spikes.html

    What are the vaccination exemption laws in these other states? In Texas, the pertussis incidence per 100,000 is higher than that in California.

    Regarding exemptions in California, “Looking at the 20 California counties with whooping cough rates above the state average of about 4 cases per 100,000 people, it’s a draw. Ten of those counties have more kids than the average state personal-belief exemption rate. Ten have fewer.”
    http://californiawatch.org/watchblog/role-personal-belief-vaccine-waivers-whooping-cough-mixed-bag#comment-2623

    Also, does anyone know why the CDC’s Pink Book appendix stopped reporting pertussis mortality rates after 2005, when they appeared to begin a steep rise?

  31. Sid Offit says:

    @Dr. Albietz

    natural pertussis infection isn’t capable of providing long-lasting immunity either), and protection wanes after 5-10 years.

    I had to check if you really were a doctor after the above bit of nonsense

    http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1000647
    Our results support a period of natural immunity that is, on average, long-lasting (at least 30 years) but inherently variable.

  32. weing says:

    “natural pertussis infection isn’t capable of providing long-lasting immunity either), and protection wanes after 5-10 years.”

    I wonder if this may be due to the use of antibiotics during the infection. Their use earlier during the infection may eradicate the bacteria too quickly and lead to lower titers of antibodies. If used later during the infection, the titers may be higher. Just a hypothesis. I don’t know if anyone has looked into this.

  33. tmac57 says:

    NPR did a story on this today ( http://www.npr.org/blogs/health/2010/07/26/128774343/calif-docs-struggle-to-keep-up-with-the-need-for-whooping-cough-vaccine ). They report that doctors may not be supplying as many vaccines due to financial considerations:
    “About half of family doctors and pediatricians who responded to nationwide survey said they had delayed buying some vaccines financial reasons, according to data published in Pediatrics in late 2008. A CDC analysis, published in 2009, concludes that most pediatrics practices either just break even or lose money in providing vaccinations.”
    There is an accompanying audio link there as well.

  34. BillyJoe says:

    “About half of family doctors and pediatricians who responded to nationwide survey said they had delayed buying some vaccines financial reasons…”

    In Australia, vaccines are supplied free to doctors who supply it free to their patients through their private practices (where there is, of course, a consult fee) or through community health centres (where there isn’t even a consult fee).

  35. BillyJoe says:

    Dr. Albietz said:
    “natural pertussis infection isn’t capable of providing long-lasting immunity either), and protection wanes after 5-10 years.”

    Sid Offit blew off:
    “I had to check if you really were a doctor after the above bit of nonsense….Our results support a period of natural immunity that is, on average, long-lasting (at least 30 years) but inherently variable.”

    What Dr Albietz really said:
    “The immune response the vaccine generates is relatively weak, necessitating multiple doses at 2, 4, 6, 15-18 months and 4-6 years to generate an adequate response (this isn’t unique to the vaccine; natural pertussis infection isn’t capable of providing long-lasting immunity either), and protection wanes after 5-10 years.”

    In other words, he did not say that protection after natural infection wanes after 5-10 years, he said that the protection after vaccination wanes after 5-10 years.

    In any case, a review of the published data reveals the following:
    http://www.ncbi.nlm.nih.gov/pubmed/15876927
    “A review of the published data on duration of immunity reveals estimates that infection-acquired immunity against pertussis disease wanes after 4-20 years

    One raw raspberry for Sid Offit :D

  36. Rober White says:

    Hi

    Good information in this post and I think the lack of data notwithstanding, I have read equally hasty stories and comments blaming the outbreak on vaccine refusal, a large immigrant population, an inadequate adult vaccination program, and normal cyclical variation in pertussis incidence, among other factors.

    Nail fungus

  37. Sid Offit says:

    @Billy Joe

    You’re right, I did misinterpret the doctor, but I think you’d have to admit Albietz’s horribly constructed sentence contributed to the confusion. As to what he actually said:

    natural pertussis infection isn’t capable of providing long-lasting immunity either

    I’d call “at least 30 years” of protection long-lasting although I guess long-lasting could mean anything to anyone

    Also see Google book’s

    Preventive medicine and hygiene By Milton Joseph Rosenau, George Chandler Whipple, John William Trask, Thomas William Salmon P226

    for the pre-vaccine era’s take on the length of natural immunity and read the study to which I linked for a discussion of the limits surrounding the 4-20 year study. And isn’t 20 years long-lasting?

  38. BillyJoe says:

    Sid,

    Yes, the bracketed bit should have come at the end of the sentence. However, if you go off half cocked, you can expect to be taken down.

    20 years is not bad but, considering the vaccines are given in the first 5 years of life, that makes you vulnerable again at age 25. Which is about when you start having kids. Even 30 years protection isn’t great by that reckoning.

    In Australia, in addition to the booster at age 15-17, parents of young children are offered a free vaccine and granparents are encouraged to get it as well (though it’s not free for them as yet)

  39. Sid Offit – your link says “A recent review by Wendelboe et al. [21] of the handful of published studies on duration of immunity suggested estimates in the range 7–20 years for naturally acquired immunity and 4–12 years for vaccine-induced immunity against disease. The wide range in estimates may be due to a combination of differences in study methodology and pertussis epidemiology in different countries.

    You cite a paper published less than a year ago that suggests the natural immunity of some or much of the population (data collected from England and Wales), is longer lasting (30+ years). But they also note that a reasonable percent of the population looses immunity quickly.

    “many individuals will lose immunity quickly and some never at all. If we consider the time taken for 25% of the population to lose immunity, estimates of the average duration of immunity between 50 and 80 years would predict that this lies in the range 14–23 years (see Figure 6). Moreover, more than 10% of the population would have lost immunity within 10 years.”

    This is interesting, but it hardly seems adequate to support your above snark “I had to check if you really were a doctor after the above bit of nonsense”.

  40. tmac57 says:

    I have to agree with micheleinmichigan here.Sid Offit’s shot at Dr Albietz was gratuitous given the tone of the article.

  41. wales says:

    Those of you interested in the pertussis outbreak might find this informative. I know pertussis is grossly underreported, but I did not realize the degree to which this is true.

    A 2005 paper by noted UCLA pertussis researcher J. Cherry states that “the incidence of reported disease has been reduced, but the circulation of b. pertussis has continued in the overall population in a manner similar to that which occurred in the prevaccine era. Data generated during the last 15 years suggest that the circulation of b. pertussis in occurring in adolescents and adults and is manifest by prolonged cough illnesses, which most often go unrecognized as pertussis.” The paper suggests “a total yearly adolescent and adult pertussis burden of between about 800,000 and 3.3 million in the US”. That translates to stupendous underreporting of pertussis.

    The paper concludes, among other things, that “The epidemiology of reported pertussis is different from the epidemiology of b. pertussis infection. The modest increase in reported pertussis in the US since 1984 is is mainly the result of increased awareness of b. pertussis illness and also the use of many vaccines that were less efficacious than DTP vaccines of the past.” PEDIATRICS Vol. 115 No. 5 May 2005, pp. 1422-1427 (doi:10.1542/peds.2004-2648)

  42. wales says:

    Does anyone have any information about why there is a disproportionately larger number of pertussis incidence and mortality in individuals of Hispanic ethnicity? In a June, 2010 bulletin the CDPH says that “Since 1998, more than 80 percent of the infants in California who have died from pertussis have been Hispanic.” All 7 California deaths this year were latino infants.

    “Infants have the highest burden of pertussis disease. Hispanics are overrepresented in pertussis cases, and the reason remains unclear. Immunization coverage did not seem to play a role and no differences in socioeconomic risk factors were found in Hispanic children, including family size and household contacts, with the exception of higher Medicaid coverage. Future studies and immunization policies for the prevention of pertussis should target the elimination of this disparity.”www.txpeds.org/u/documents/castagnini_pertussis1.ppt

    This does partially explain why CA and TX have high pertussis incidence. Of course infants and young children are more likely to be taken to a physician or hospital for persistent coughing and thus more likely to appear on the radar, while large numbers of adolescents and adults walk around infected without seeking medical assistance (per the 2005 Cherry paper).

    “Pertussis incidence was 74% higher in Hispanic infants than in infants of other ethnicities throughout the 1990s despite comparable childhood immunization rates.” http://the-medical-dictionary.com/pertussis_article_3.htm

    I would appreciate any info.

  43. wales says:

    since the texas pediatrics society article I cited on July 30 has been “moved”, here’s another one with similar findings. perhaps this one will disappear as well…..

    http://journals.lww.com/pidj/pages/articleviewer.aspx?year=2003&issue=07000&article=00012&type=abstract

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