Guillain-Barré Syndrome Triggers and Pathophysiology

Primary Infectious Triggers

Mycoplasma pneumoniae is another bacterial trigger, though less extensively investigated than C. jejuni, according to the American Academy of Neurology 1
Haemophilus influenzae has been associated with GBS but remains less well-characterized, as reported by the American Academy of Neurology 1
Cytomegalovirus and Epstein-Barr virus typically precede the demyelinating and sensorimotor forms of GBS, as stated by the American Academy of Neurology 1
Zika virus caused a 20-fold increase in GBS cases during the 2013-2014 French Polynesia outbreak, though only ~2 in 10,000 infected patients develop GBS, according to the Centers for Disease Control and Prevention 1
SARS-CoV-2 has been associated with GBS, with 77-80% showing demyelinating electrophysiological subtype, as reported by the World Health Organization 1
Chikungunya and dengue viruses (transmitted by Aedes mosquitoes) have been associated with surges in GBS cases, according to the World Health Organization 1
Enterovirus infection was linked to a GBS outbreak in Peru in 2018, as stated by the Pan American Health Organization 1

Polymorphisms in the TNF gene (encoding tumor necrosis factor) and MBL2 gene (encoding mannose-binding protein C) have been associated with GBS susceptibility, as reported by the National Institute of Neurological Disorders and Stroke 1
These genetic variations may influence the patient's susceptibility to producing cross-reactive antibodies, according to the National Institute of Neurological Disorders and Stroke 1
Poor nutritional status and malnutrition alter dysfunctional immune responses implicated in autoimmune disease pathogenesis, as stated by the National Institutes of Health 1

Despite widespread exposure to triggering infections, only a small fraction develop GBS: only 1 in 1,000-5,000 patients with C. jejuni infection develop GBS within the subsequent 2 months, according to the Centers for Disease Control and Prevention 1
One factor determining this low risk is the requirement for carbohydrate mimicry, which is not present in all C. jejuni strains, as reported by the World Health Organization 1
Emerging disease hotspots: Regions at lower latitudes (sub-Saharan Africa, parts of Asia) where wild animals and arthropod vectors reside are at particular risk for new outbreaks of GBS due to vector-borne diseases, according to the World Health Organization 1

Approximately two-thirds of patients with Guillain-Barré Syndrome report symptoms of an infectious disease within 4 weeks preceding the onset of weakness 2
Upper respiratory tract infections are the most common antecedent events (22-53% of cases) in Europe, North America, South America, and parts of Asia 2
Respiratory infections are even more common in pediatric GBS cases (50-70%) 2
In some regions like India and Bangladesh, gastroenteritis is the most frequent preceding event (36-47%) 2
Campylobacter jejuni is the most frequently identified trigger worldwide, accounting for 30-32% of cases in most regions, up to 60-70% in some areas 2

The primary mechanism involves structural similarities between microbial components and peripheral nerve tissues, with molecular mimicry being the key pathophysiological mechanism 3
The infection triggers an autoimmune response that causes demyelination and axonal degeneration of peripheral nerves and nerve roots 2

AIDP is the most common subtype in Europe and North America (83-90% of GBS cases) 4
In Asia, AIDP remains common but with regional variations (34-80% of GBS cases) 5, 4
The distribution of GBS subtypes correlates with the prevalence of specific infectious triggers in different regions 2

Polymorphisms in genes like TNF and MBL2 have been associated with GBS susceptibility 3
Poor nutritional status and malnutrition may alter immune responses implicated in GBS pathogenesis 3
Despite widespread exposure to triggering infections, only a small fraction develop GBS (e.g., only 1 in 1,000-5,000 patients with C. jejuni infection develop GBS) 3

In countries where C. jejuni infection is more common, approximately 80% of patients present with severe GBS (disability score >2) compared to 40-60% in regions where AIDP is more prevalent 2

AIDP is strongly associated with viral triggers, though the specific viral pathogens differ from those typically associated with Campylobacter jejuni infection, as noted by the American Academy of Neurology 6, 7

In Europe and North America, upper respiratory tract infections (predominantly viral) are the most common antecedent events in AIDP-predominant regions, with AIDP comprising 83-90% of all GBS cases, according to the European Academy of Neurology 8, 9
In pediatric populations, respiratory infections precede 50-70% of pediatric GBS cases, as reported by the American Academy of Pediatrics 9
Regional variation exists, with AIDP representing only 22-46% of cases in India and Bangladesh where gastroenteritis (often C. jejuni) predominates as the antecedent event, as noted by the World Health Organization 8, 9

Treatment for both AIDP and AMAN remains the same, with both responding to intravenous immunoglobulin or plasma exchange, so the distinction does not alter acute management, as recommended by the American College of Physicians 6