;Resize=(1200,627)&impolicy=perceptual&quality=mediumHigh&hash=409c578113e65729cca5a178f566b12e18c0c40bfdb91756c527b65aa726989d "Mysterious accumulation of Guillain-Barré syndrome in Peru – what we know")
Guillain-Barré syndrome (GBS), which has affected 180 people in Peru since January, is not a new phenomenon. On the contrary: On average, one to two out of 100,000 people worldwide contract the mysterious paralysis every year. However, the number of cases in Peru is currently significantly higher than one would expect – the reason for this is not yet known.
The country has declared a health emergency because of the unusual number of sick people, which is actually a little less dramatic than it sounds. With this administrative act, however, the state can take better measures to combat the disease, for example specifically monitoring its spread or making medicines available to the sick.
Researchers have been observing for some time that GBS occurs more frequently from time to time. Peru also recorded a significant, very unusual increase in the number of cases in 2019. Such clusters are probably related to the most important cause of Guillain-Barré syndrome: Most cases of GBS are caused by a previous infection. Experts estimate that around 60 to 80 percent of diseases are caused by viruses or bacteria.
Many viruses and bacteria can cause Guillain-Barré syndrome
In fact, a whole list of pathogens is known that can trigger the very rare but serious disease. Among the viruses, the cytomegalovirus (CMV) and the Epstein-Barr virus, which causes glandular fever, and HIV are responsible for many GBS cases. In addition, some tropical diseases can also trigger GBS, including the West Nile virus, which is also spreading in Germany, Sars-CoV-2 and, in recent years, the Zika virus in particular. Individual GBS cases have also occurred after vaccinations, for example with the live vaccine against yellow fever and vector vaccines against Covid-19.
From some bacterial pathogens such as Mycoplasma pneumoniae are also known to be associated with GBS. However, the bacterium is particularly important Campylobacter jejuni , one of the most important causes of gastrointestinal infections worldwide. GBS occurs about 100 times more frequently in people infected with this pathogen than in the general population. A major outbreak of GBS in Peru in 2019, with nearly 700 cases, was also suspected to be linked to the bacterium.
The paralysis that is typical of Guillain-Barré syndrome usually begins a few days to weeks after the initial infection with numbness and tingling in the hands, later there are incoordination and paralysis that can affect different parts of the body.
An autoimmune reaction damages the nerves
Damage to the nerve cells is behind the symptoms. As a result, they can only poorly transmit signals to the muscles. Everything indicates that the immune system itself is responsible for this – Guillain-Barré syndrome is an autoimmune disease in which immune cells attack the body’s own tissue in an excessive reaction. In this case, the myelin sheaths that insulate the processes of nerve cells, as well as the nerve cells themselves.
The cause of the autoimmune disease is a process known as molecular mimicry. The components of the pathogen resemble endogenous molecules. Thus generates the immune response Campylobacter jejuni Antibodies that also react to cell membrane components known as gangliosides, which are particularly common in nerve cells. It is not yet known in detail which proteins in viruses trigger the process and which endogenous molecules it then targets – just as little is known about why some people develop GBS but not the vast majority.
GBS varies in severity depending on the extent of the damage. In severe cases, the paralysis also extends to the respiratory muscles and patients need to be ventilated. Most of those affected recover, but a portion of them, about ten percent, have permanent nerve problems. The number of people dying from the disease varies widely, ranging from 1 percent to 13 percent; in Peru, four people have died from it so far.
The exact cause may remain unknown
Differences in the pathogen proteins and thus also in the body’s own target molecule could possibly also explain that there are different forms of Guillain-Barré syndrome:
on the one hand, acute inflammatory demyelinating polyradiculoneuropathy (AIDP), in which immune cells attack the coating of nerve cell processes, and on the other hand, acute motor axonal neuropathy (AMAN), in which the nerve processes themselves are attacked. There seems to be a connection with the pathogen.
The latter form occurs more frequently after infection with Campylobacter jejuni while people who develop GBS after Zika or Covid-19 prefer to train AIDP.
If Guillain-Barré syndrome is recognized in time, it is easily curable
If the disease is recognized in time, it can usually be cured. Therapy is often with intravenous immunoglobulin (IVIG), an antibody preparation made from donated blood that is used to treat a wide range of inflammatory and autoimmune diseases. Peru has also ordered large quantities of immunoglobulin to treat GBS sufferers.
The cause behind the current accumulation of Guillain-Barré syndrome in Peru is still unclear – and given the large number of pathogens associated with GBS, it is also very difficult to find out. The accumulation itself could indicate an epidemic pathogen and the GBS subtype could provide further information, as could epidemiological data and surveys of those affected.
However, you may never really know for sure: Many of the infections that can result in Guillain-Barré syndrome are comparatively mild, not least the gastrointestinal infections caused by Campylobacter. Even with the great Peruvian GBS outbreak of 2019, the trigger has not been clarified to this day – although there are indications of the bacterium, it cannot be proven afterwards.