I was pleased to see that Mr. Richard Dowson, in his latest op/ed, has adopted a somewhat more nuanced view of the cause(s) of MS. There are however some aspects on which I [would like] to comment.
I shall only respond to a few remarks, refraining from comments on topics (such as the nature of leucocytes) which are of no consequence as far as this discussion is concerned.
Infectious mononucleosis (IM) is by far the most likely culprit as far as the cause of MS is concerned. Mr. Dowson tells us that one person in a group of MS sufferers has never had IM. How does he know that? As he himself tells us in his letter, IM is often asymptomatic, so we have no way of knowing whether this person had IM or not.
Mr. Dowson compares sunlight hours in southern Alberta and Nunavut and then leaps to the conclusion that vitamin D does not play a role in the pathogenesis of this disease.
On the contrary, there is an abundant literature on this subject, see reference (1) where we can read:
“The risk of MS was found to be 30% lower among women in the highest quintile [of vit D levels] compared with those in the lowest quintile. In the second study, conducted among young adults in the US military, vitamin D status was assessed by averaging multiple season-adjusted measures of 25-hydroxyvitamin D (25[OH]D). During an average of 5 years' follow-up, MS risk among healthy young adults with serum levels of 25(OH) vitamin D >100 nmol/l was about 60% lower than in individuals of the same age and sex with serum 25(OH) vitamin D levels <100 nmol/l.”
See also the excellent reviews (2, 3) as well as (4, 5 and 6)
MS is a multifactorial disease, one cannot extrapolate from a few simplistic observations to statements encompassing the entire pathophysiology.
Mr. Dowson writes: “The presence of a common pathogen may be more likely. It is noted that Saskatchewan Hutterites have near zero MS. They do not keep indoor pet dogs or cats.”
I will accept Mr. Dowson’s word for the keeping of cats and dogs but the situation is not as simple as he seems to think: Hutterites, keeping themselves to themselves as they do, is a genetically isolated population, and the role of genetics in the pathophysiology of MS should not be ignored.
We are told: “Multiple Sclerosis is rare in Sub-Saharan Africa.”
This may well be the case, but closer inspection of available data shows that things aren’t as simple and straightforward as they seem. Dogs, and in particular stray dogs (ie not vaccinated against CDV) are a common sight in some areas of South Africa. In reference (9) one reads: “85 percent of all pets in South Africa can be found in the townships surrounding the capital. The majority of people do not have the financial means for the veterinary care of their pet as well as for measures to prevent illness in the first place. Due to the animals mainly roaming the streets freely, preventable illnesses, such as canine distemper or pan leukopenia, can spread quickly…”
The prevalence of MS for the South African population as a whole is 3.5/100 000 (10), but white South Africans make up about 89% of people with MS (11). If dogs were the carriers of an agent causing MS one would expect the situation to be reversed.
One can also point to the situation in Mexico, which is home to the largest population of stray dogs in South America: between 15 and 18 million (12), yet the prevalence of MS in that country is only 8.1/100 000 population (9).
Mr. Dowson writes: “There does not appear to be a connection between Demyelination, the hallmark of MS, and EBV.”
This statement is wrong. I have previously given references and quotes to the contrary, here is one more link (7)
“Studies have shown that EBV can infect neurons directly or indirectly via infected B-lymphocytes, induce neuroinflammation and demyelination, promote the proliferation, degeneration, and necrosis of glial cells, promote proliferative disorders of B- and T-lymphocytes, and contribute to the occurrence and development of nervous system diseases, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis…”
Mr. Dowson writes: “The rates of EBV and low PR of MS in China [in comparison to Europe] is contradictory.” And “If EBV-1 was a culprit, MS prevalence in China would be like that in Europe.”
Why is it contradictory? We are talking about two genetically distinct populations.
Again, the influence of genetics and environment is not even mentioned.
Mr. Dowson informs us: “MS prevalence in the Western Pacific is 4.79 and 8.6 in Africa. These numbers do not seem to agree with the proposal. The numbers are not even similar.”
We are not informed what the proposal is, but leaving that aside, how closely does Mr. Dowson expect the numbers to agree in populations so widely separated by geography, climate, environment and genetics?
We also read: “Almost everyone has EBV. Relatively speaking, almost no one has MS.” This statement is correct – but only as far as it goes, which is not really very far.
Before the days of the polio vaccine many people got infected by the polio virus, but only about 0.5% of infected people actually got the paralytic form of the disease. In Africa many people show radiographic or serologic evidence of having had tuberculosis, but have never had any symptoms whatsoever.
In other words, to paraphrase mr. Dowson, almost everyone has TB or polio but almost no-one has the disease.
Furthermore, considering that EBV has been shown to be a causative factor in the development of diseases like Burkitt’s lymphoma and other malignancies, the fact remains that these particular diseases are not as common as he seems to believe – they are still rare.
Mr. Dowson states: “EBV ‘like condition’ in dogs is associated with malignancies, not demyelination.”
Dogs apparently cannot get mononucleosis. See reference (8), where we can read: “This virus can indeed spread to dogs, and most often comes from exposure to a person with mono. That being said, the virus does not affect mononuclear cells in dogs. So technically, dogs can not get mono.”
Mr. Dowson states, quite correctly: “The Measles vaccine can prevent CDV.”
One would therefore expect that the measles vaccine, which is in widespread use in the first world, would protect against MS, but this is not the case (13).
In (14) we read: “A new study found that part of the Epstein-Barr virus mimics a protein made in the brain and spinal cord, leading the immune system to mistakenly attack the body’s nerve cells.”
Reference (15) informs us: “Exosomes From Subjects With Multiple Sclerosis Express EBV-Derived Proteins and Activate Monocyte-Derived Macrophages.”
In (16) we read: “Epstein-Barr virus is present in the brain of most cases of multiple sclerosis and may engage more than just B cells.”
A new trial targeting EBV (admittedly it was small with no control group) showed promise in treating MS (17).
And so one can go on quoting research papers discussing the role of EBV in MS.
Mr. Dowson, quoting Chuck Dinerstein, is correct in that EBV is necessary but not sufficient for MS to develop. This of course does not necessarily make CDV the sufficient agent for MS – as we have seen, this is a malady with a great many faces, none of them pretty, and although the jury is till out, some candidates seem more likely than others.
An important aspect of MS pathogenesis is the genetic aspect, which is often overlooked (18).
All good things must come to an end, as the saying goes. Since I have other demands on my time, this will be my last contribution to this discussion
1) https://pubmed.ncbi.nlm.nih.gov/24289836/
3) https://www.cureus.com/articles/72893-impact-of-vitamin-d-supplementation-on-multiple-sclerosis
4) https://www.frontiersin.org/articles/10.3389/fimmu.2020.00781/full
5) https://jamanetwork.com/journals/jamaneurology/fullarticle/1815002
6) https://journals.sagepub.com/doi/10.1177/1352458518815605
8) https://wagwalking.com/wellness/can-dogs-get-mononucleosis
9) https://welttierschutz.org/en/projects/strays-in-south-africa/
10) http://www.mult-sclerosis.org/prev_tab.html
11) http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0256-95742008000500024
13) https://pubmed.ncbi.nlm.nih.gov/2087249/
14) https://med.stanford.edu/news/all-news/2022/01/epstein-barr-virus-multiple-sclerosis.html
15) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8130999/
16) https://pubmed.ncbi.nlm.nih.gov/29394264/
18) https://www.thelancet.com/journals/laneur/article/PIIS1474-4422(10)70064-8/fulltext
Leon Retief
(Although the criteria for letters to the editor in our publications is capped at 900 words per submission, this over-wordage response has been allowed because it is a full response to both Part 1 and Part 2, rather than being split into two individual letters.)
The views and opinions expressed in this article are those of the author, and do not necessarily reflect the position of this publication.
