What is Guillain-Barré Syndrome?
Guillain-Barré syndrome (GBS) is most often a rare post-infectious disease in which the immune system attacks the peripheral nervous system, the one that circulates information between the brain and the organs.
It is characterized, at first, by unusual sensations (tingling, tingling, feeling of cold) or the absence of sensitivity, as well as a feeling of weakness, fatigue and muscle cramps at rest, recalls the High Authority of health (HAS). The disease develops rapidly and its symptoms worsen within a few days, which can lead to paralysis of the limbs, damage to the chest muscles, and even impairment of the ability to speak and swallow.
In most cases, patients recover without sequelae within a few weeks. But, “even in the best health settings, 3% to 5% of patients die from complications of the disease, such as paralysis of the muscles of respiration, sepsis, pulmonary embolism or cardiac arrest”, summarizes the World Health Organization (WHO).
According to a 2021 report from the rare neuromuscular diseases sector (Filnemus), one of the twenty-three French national coordination structures for rare disease actors, its incidence rate increases with age, ranging from 0.6 per 100 000 per year in children to 2.7 per 100,000 per year in people aged 80 and over.
Why is the situation in Peru worrying?
On June 23, Peruvian health authorities issued an alert due to an abnormally high number of GBS cases. As of July 9, 191 cases have been detected since the start of the year, and four patients have died. However, this pathology requires very heavy care, “with 20% to 30% of admissions to intensive care”, specifies Mahmoud Zureik, professor of epidemiology and public health at the University of Versailles-Saint-Quentin-en -Yvelines. In 2022, the total number of intensive care beds was estimated at 1,200 by the Peruvian newspaper La Republica. “There is a fear of saturation of services,” confirms Nicolas Weiss, neurologist at Pitié-Salpétrière hospital in Paris.
On Sunday, July 9, the Peruvian Ministry of Health declared “a national level health emergency (…) for ninety days”. A decision that can be as health as political. “One of the reasons is also the fact that the Ministry of Health says they don’t have enough treatment for GBS,” Weiss said. Triggering the state of health emergency could allow them to access care or unlock WHO aid. Peruvian health authorities have not communicated since.
What can be the causes of the epidemic?
Very often, this inflammatory disease is a reaction to an infection. “In two thirds of cases the occurrence of Guillain-Barré syndrome is preceded within three weeks to a month by an acute viral or bacterial infectious episode, in particular infections of the respiratory or digestive tracts”, specified the French Agency for safety of health products (Afssaps) in a 2009 report. But the precise cause may remain unknown. “Sometimes we don’t know because we haven’t done the big studies, which are quite expensive, with large control groups”, regrets Professor Weiss.
Certain diseases are known to trigger it. Thus Covid-19, as a review of scientific literature from 2023 showed. Hospitalization for severe Covid even multiplies by eight the risks of developing GBS in the event of severe Covid. But this phenomenon remained “very marginal”, nuances the neurologist.
Other diseases can be the cause. French researchers thus showed in 2016 the causal link between infection with the Zika virus, characterized by flu-like symptoms, and the onset of GBS. They had observed an increase in hospitalizations due to this disease at the time of the Zika virus epidemic in French Polynesia, in 2013-2014.
In the case of Peru, dengue appears as an ideal suspect. The country has been facing its most serious epidemic since June since 1990. A situation caused by the passage in the spring of Cyclone Yaku, whose torrential rains attracted the tiger mosquito, the main vector of the disease. “In time, it might fit perfectly,” agrees Professor Zureik. But not everything fits. The epidemiologist notes the surprising geographical extent of current cases of GBS, while dengue is localized in the south of the country.
Other avenues are being considered. In 2019, the Latin American country had already been hit by a historic GBS epidemic. This had been caused by a bacterium transmitted by meat, Campylobacter jejuni, established a retrospective study of 2021. But between these different hypotheses, the incomplete communication of the Peruvian health authorities does not make it possible to decide, regrets Mahmoud Zureik. Dengue, Zika, unidentified virus, or bacteria…at this point, he repeats, “we don’t know.” Only certainty: the cause can only be recent, within six weeks at most before the onset of GBS.
Why do some people blame the Covid-19 vaccines?
Since the large-scale vaccination campaigns against Covid-19, anti-vaccine circles have seen every medical event as a side effect of injections. The Peruvian situation is no exception, the most active figures in this movement, who have been predicting the worst for two years, have established a link between this peak of GBS in Peru and vaccination in the country.
Guillain-Barré syndrome is a rare side effect of vaccines, especially those against the flu. Regarding those against Covid-19, the European Pharmacovigilance Risk Assessment Committee (PRAC) recognized, in September 2022, a link with the AstraZeneca vaccine. However, it remains very rare since it affects less than one person in 10,000, recalls the European Medicines Agency. A 2021 British study estimated that a “probable” link could be established for fifty-six cases of GBS out of over 85 million vaccinations.
In the case of the Pfizer vaccine, cases of GBS have been under observation by the National Agency for the Safety of Medicines since August 2021, but no link has ever been formally established, and recent scientific literature is rather reassuring. Finally, vaccination with AstraZeneca has only been marginal in Peru, and dates back two years now: difficult to see there the cause of an inflammatory reaction in 2023.