Infection onset A scanning electron microscope-derived image of Campylobacter jejuni, which triggers about 30% of cases of Guillain–Barré syndrome Two-thirds of people with Guillain–Barré syndrome have experienced an infection before the onset of the condition. Most commonly, these are episodes of gastroenteritis or a respiratory tract infection. In many cases, the exact nature of the infection can be confirmed. Approximately 30% of cases are provoked by Campylobacter jejuni bacteria, which cause diarrhea. A further 10% are attributable to cytomegalovirus (CMV, HHV-5). Despite this, only very few people with Campylobacter or CMV infections develop Guillain–Barré syndrome (0.25–0.65 per 1000 and 0.6–2.2 per 1000 episodes, respectively). The strain of Campylobacter involved may determine the risk of GBS; different forms of the bacteria have different lipopolysaccharides on their surface, and some may induce illness (see below) while others will not. Links between other infections and GBS are less certain. Two other herpes viruses (Epstein–Barr virus/HHV-4 and varicella zoster virus/HHV-3) and the bacterium Mycoplasma pneumoniae have been associated with GBS. GBS is known to occur after influenza, and influenza vaccination has been demonstrated to be associated with a reduced risk. The tropical flaviviral infections dengue fever and Zika virus have also been associated with episodes of GBS. Previous hepatitis E virus infection has been found to be more common in people with GBS. Vaccine onset An increased incidence of Guillain–Barré syndrome followed influenza immunization that followed the 1976 swine flu outbreak (H1N1 A/NJ/76); 8.8 cases per million (0.0088 per 1000) recipients developed it as a complication. GBS cases occurred in 362 patients during the 6 weeks after influenza vaccination of 45 million persons, an 8.8-fold increase over normal rates. The 1976 swine flu vaccination-induced GBS was an outlier; small increases in incidence have been observed in subsequent vaccination campaigns, but not to the same extent. The 2009 flu pandemic vaccine against pandemic swine flu virus H1N1/PDM09 did not cause a significant increase in cases. In fact, "studies found a small increase of approximately 1 case per million vaccines above the baseline rate, which is similar to that observed after administration of seasonal influenza vaccines over the past several years." The benefits to the population as a whole of vaccination in preventing influenza outweigh the small risks to individuals of that group of GBS after vaccination. Natural influenza infection is a stronger risk factor for the development of GBS than is influenza vaccination and the vaccination reduced the risk of GBS overall by lowering the risk of catching influenza. In the United States, GBS after seasonal influenza vaccination is listed on the federal government's vaccine injury table. On March 24, 2021, after reviewing several post-marketing observational studies, where an increased risk of Guillain–Barré syndrome was observed after 42 days following vaccination with the Zoster vaccine Shingrix, the FDA required safety label changes from the manufacturer GlaxoSmithKline to include warnings for risk of Guillain–Barré syndrome. COVID-19 related GBS has been reported in association with COVID-19, and may be a potential neurological complication of the disease. GBS has been reported as a very rare side effect of the Janssen and the Oxford–AstraZeneca COVID-19 vaccine for COVID-19. The incidence of GBS following the vaccination with the Oxford-AstraZeneca vaccine is reportedly lower than the incidence of GBS following a COVID-19 infection. COVID-19 has been reported as causing peripheral neuropathy and more recently some evidence of aggravation of autoimmune disorders including GBS. Some studies are now finding Parkinson's Disease is more common in infection survivors. Drug induced Zimelidine, an antidepressant, had a very favorable safety profile but as a result of rare case reports of Guillain–Barré syndrome was withdrawn from the market.
complications of Campylobacteriosis
complications of Shigellosis
complications of Cholera
complications of Lemierre's syndrome
complications of Typhus
complications of Amoebiasis
complications of Gonorrhea
complications of Helicobacter pylori