Autism and MMR (More Measles Rubbish)
June 8th, 2009
A reader sent me a comment from a parent of an autistic child. This parent had been told that their child’s “measles titre” was “five times normal”, which was offered as an explanation of why this child had autism.
I assume that this information was provided by some form of “health care practitioner”, most likely of the “alternative” genre. The parent’s comments made it clear that they had also been told that this “elevated titre” was due to the MMR vaccine.
Let’s deconstruct that argument.
Measles Titres - what are they?:
The “old school” way of doing measles antibody titres is the plaque reduction neutralisation (PRN) test. This involves adding serial dilutions of the patient’s serum to a virus solution and then putting the mixture on a lawn of cells. The greatest dilution (titre) that still gives a specified reduction in plaques (areas of viral infection) on the cell culture is the “antibody titre”. Previously, this was reported as the dilution itself (e.g. 1:64), but now the trend is to reference the results to the international standard anti-measles serum and report it as milli-International Units per milliliter (mIU/ml).
An easier (not to mention cheaper and faster) method is to use an enzyme-linked immunosorbent assay (ELISA) to measure the anti-measles antibody. This is a test that can be done in almost any clinical lab and requires no finicky cell cultures. Although the test is usually set up to give results as “immune”, “not immune” and “equivocal”, it can be quantified by using dilutions of the standard serum to set up a calibration curve.
The PRN test has been shown to be more sensitive to low levels of antibody (Cohen 2008) and it is probably more accurate, but both tests are “good enough” to give the answer most clinicians want: “Is this person immune to measles?”
The “normal value” of anti-measles antibody:
The whole idea of an anti-measles antibody titre being “five times normal” is a little weird. You see, the report from the lab will give the titre (if it is quantified - often it is not) and then state the level at which immunity is assured. What value the lab uses depends on which level of certainty they have chosen.
Studies have shown that an antibody level (titre) of 120 mIU/ml is sufficient to prevent clinical illness. This is often used by labs as the “rock-bottom” level for immunity. At this level, the patient will show some laboratory signs of measles infection (e.g. rising antibody levels) and may be able to transmit the disease to others (for a brief period) but won’t generally feel ill or develop a rash. Generally.
Because there is some debate about whether people at 120 mIU/ml are truly protected from measles, most labs set their “immune” point somewhere between 200 and 300 mIU/ml. This gives some margin for error.
However, these are not “normal values” except in the sense that anything below these levels is abnormal (if you want to be protected from measles). There is no upper “normal value”.
Let me say that again:
There is no upper value of “normal” for measles titres.
Baird et al (2008) should be an interesting read for those clinicians telling parents that their autistic children’s anti-measles antibody titre is “five times normal”. Not only did Baird et al show that there is no relationship between measles antibody titre and autism, but their data show the extreme range of antibody titres in both the “normal” and “autistic” population.
Baird et al looked at 90 “neurotypical” children born between 1 July 1990 and 31 December 1991 (average age 12 yrs at the time of the study) as their control group. The measles titres they measured in this group ranged from 25 to 6,300 mIU/ml (geometric mean - 890 mIU/ml). Even using a “normal” value of 300 mIU/ml, the highest of these “neurotypical” children was “twenty-one times normal”.
The antibody titres of the autistic children in the Baird et al study were not statistically different from the “neurotypical” controls (geometric mean - 870 mIU/ml).
Just to show that this wasn’t a fluke, LeBaron et al (2007) looked at measles antibody levels in kindergerten children (4 - 6 years) and at middle school children (10 - 12 years) before and after their second MMR vaccination. They found that the kndergarten children had a geometric mean antibody level of 1559 mIU/ml (over “five times normal”). The middle school children had a geometric mean of 757 mIU/ml prior to their “booster” MMR and 1672 mIU/ml after the second MMR.
The significance of “elevated” serum anti-measles antibody titres:
None.
Why do practitioners get quantitative anti-measles antibody titres for autistic children?:
I have no way of knowing for certain. All plausible explanations involve a “belief” that measles vaccine - more specifically, the MMR vaccine - can cause autism. This is a “belief” that is not, currently, supported by any credible data (Dr. Wakefield’s work having passed into the category of “non-credible” some time past). From talking with parents in my area, I have discovered that it is still a common practice (among the “alternative” autism practitioners) to obtain (and even follow) anti-measles antibody levels.
If the antibody levels are HIGH (which, as I have shown above is nonsense), the parents are told that the child has a “persistent vaccine-strain measles infection” (without, I might add, ever doing any testing to show that it was a vaccine strain). In my area, the common “treatments” are intravenous immunoglobulin (puzzling, since it has only moderate levels of anti-measles antibody - the child’s level is, presumably, much higher than normal), valcyclovir (puzzling, since it is absolutely ineffective against measles virus) and/or chelation (again, no possible effect against the measles vaccine). The “treatments”, I have found, vary from region to region, practitioner to practitioner and - apparently - day to day.
If the anti-measles antibody levels are LOW, a few parents have been told that the measles virus is suppressing the immune system and that “treatment” is indicated. In the few instances I have come across, the only treatment consistently not used was intravenous immunoglobulin - the only treatment that might have worked, were the diagnosis correct (which I doubt).
Summary:
The anti-measles antibody titre is being used in a nonsensical way to convince parents that their autistic children have persistent measles infections. This is nonsensical for two reasons - first, there is no indication that high anti-measles antibody titres are even associated with autism. And, secondly, the claim that a child’s anti-measles antibody titre is “five times normal” (or even “fifty times normal”) is nonsensical on its face, as there is no upper “normal” limit.
Parents who are told by a doctor that their child’s anti-measles antibody titre is “five times normal” should thank the doctor, firmly grasp their child’s hand and walk briskly from the office. This doctor does not understand how the anti-measles antibody titre works and should not be trusted with your child’s health care.
Prometheus
References:
Baird G, Pickles A, Simonof E, et al. Measles vaccination and antibody response in autism spectrum disorders. Arch. Dis. Child. 2008 Oct;93(10):832-7.
Cohen BJ, Doblas D, Andrews N. Comparison of plaque reduction neutralisation test (PRNT) and measles virus-specific IgG ELISA for assessing immunogenicity of measles vaccination. Vaccine 2008 Nov 25;26(50):6392-7.
LeBaron CW, Beeler J, Sullivan BJ, et al. Persistence of measles antibodies after 2 doses of measles vaccine in a postelimination environment. Arch. Pediatr. Adolesc. Med. 2007 Mar;161(3):294-301.
Filed under: Autism Practitioners, Autism Science, Critical Thinking | 26 Comments »