In a recent study, a team of researchers argued that, contrary to what has been proposed, subclinical Bordetella pertussis colonization is an important cause of multiple sclerosis (MS). The study, “The potential role of subclinical Bordetella Pertussis colonization in the etiology of multiple sclerosis,” was published in the journal Immunobiology.
The bacteria Bordetella pertussis and its secreted toxin have been extensively used within the last 50 years as a potent adjuvant, or substance added to a vaccine to increase the body’s immune response to it. When co-administered with neural antigens, the bacteria induces neuropathology in experimental autoimmune encephalomyelitis, the key animal model for human MS.
Researchers now hypothesize that subclinical Bordetella pertussis nasopharyngeal colonization is not innocuous to hosts, and can actually behave as a human neuropathogen causing MS.
The team reviewed three epidemiological cases that offer evidence supporting their hypothesis. The first is the major MS-related epidemiologic phenomenon of the last century — the MS epidemic in the Faroe Islands during and immediately after World War II. According to the article, authors who studied the outbreak noted that “MS is the rare late outcome of a specific but unknown infectious disease of adolescence and young adulthood.”
The second evidence comes from epidemiological studies establishing that the world’s MS burden exhibits an equatorial gradient, so that the further a person moves from the equator, the greater is that person’s MS risk. Researchers propose that the heterogeneous global risks for MS parallel heterogeneous global Bordetella pertussis vaccination rates.
Finally, the third epidemiological case is U.S. government data indicating increased MS mortality among elementary and secondary school teachers (when compared with all other professional occupations), suggesting an increased risk for symptomatic and asymptomatic Bordetella pertussis infection.
Researchers concluded that these epidemiological cases indeed suggest there is a substantial probable cause for subclinical Bordetella pertussis colonization as a cause of MS. Since Bordetella pertussis is a frequent colonizer of the human nasopharynx, particularly in highly vaccinated populations, the team suggested that studies are warranted to investigate further MS development as a result of Bordetella pertussis colonization.