Situation at a glance 

On 26 June 2023, the National Center for Epidemiology, Prevention, and Disease Control (CDC) of Peru issued an epidemiological alert due to an unusual increase in Guillain-Barré Syndrome (GBS) cases in different regions of the country. According to historical data (excluding the 2019 outbreak), the average monthly number of GBS cases registered is less than 20 suspected cases per month nationwide. However, between 10 June – 15 July 2023, 130 suspected cases1 of GBS have been reported. Out of these cases, 44 have been confirmed. 2,3 This increase in the number of observed cases is higher than expected. 

The Presidency of the Republic of Peru in early July 2023, declared a national health emergency due to the unusual increase and enhanced the implementation of public health responses. To date, the potential cause of the unexpected GBS incidence remains under investigation.

WHO advises Member States to maintain the ongoing monitoring of the incidence and trends of neurological disorders, especially GBS, to identify variations against their expected baseline values and implement protocols for improved patient management. By closely observing and tracking these conditions, countries can effectively respond to any changes and ensure appropriate measures are in place to address potential public health concerns.

Description of the situation

Between epidemiological weeks 1 and 28 (until 15 July 2023), a total of 231 suspected GBS cases were reported in Peru as defined by the National Center for Epidemiology, Prevention, and Disease Control (CDC) Technical Health Standard for Epidemiological Surveillance and Laboratory Diagnosis for GBS1 in 20 of the country’s 24 departments. Fifty-six percent of the cases (130 cases) were reported between epidemiological weeks 23 (10 June 2023) and 28 (15 July 2023).  Since the start of the year, the highest number of GBS cases were recorded in seven of the country’s 24 departments: Lima and Callao (75 cases), La Libertad (39), Piura (21), Lambayeque (20), Cajamarca (17), Junín (12), and Cusco (10). As of 15 July 2023, 100 cases have been confirmed to be compatible with GBS 2,3, including four deaths (Case Fatality Rate (CFR) 1.7%).

The age group most affected were adults ≥ 30 years (158 cases) while children under 17 years of age accounted for 19% of the cases (44 cases). More than half of the reported cases (133; 57.6%) were males.

The preliminary clinical manifestations of the 130 cases reported between epidemiological weeks 23 (10 July 2023) and 28 (15 July 2023) include gastrointestinal infection, respiratory infection and fever. In addition, 72.3% of these cases (94 cases) presented with upward progression of paralysis as neurological manifestation, with other cases presenting with some type of sequelae.  

Samples were collected from the cases according to the technical health standard for epidemiological surveillance and laboratory diagnosis of GBS in Peru. Between epidemiological weeks 23 and 28, 22 samples were collected of which 14 (63%) were positive for Campylobacter jejuni (one of the most common risk factors for GBS) in samples from the departments of La Libertad (5 cases), Lima (4), Piura (3), Cusco (1) and Lambayeque (1), with the sample from Lambayeque further characterised as genotype Campylobacter jejuni sequence type (ST)2993. 

Epidemiology of the disease

Guillain-Barré Syndrome (GBS) is a rare neurological disorder of variable clinical severity, including fatal outcomes. It is the most common form of acute flaccid paralysis worldwide and is characterized by motor weakness, areflexia (absence of muscle reflexes), sensory abnormalities, and elevated protein levels in cerebrospinal fluid (cytoalbuminologic dissociation). Most often, an upper respiratory or gastrointestinal illness typically precedes GBS. 

There is currently no known cure for GBS. However, people with GBS need supportive treatment, sometimes in intensive care and follow-up. Most treatments available can help manage the symptoms, support the recovery process, and potentially shorten the duration of the illness. Although most cases, even the most serious ones, fully recover, they can produce almost total paralysis. Campylobacter jejuni infection is the most frequently identified precipitant and usually is associated with the acute motor axonal neuropathy form of GBS. While this syndrome is more common in adults and in males, people of all ages can be affected.

In 2019, Peru reported an unprecedented outbreak of GBS that affected several regions of the country, with almost 700 reported cases (incidence: 1.2/100,000 inhabitants). From the clinical-epidemiological characteristics and the study of the identified agents, it was concluded that the outbreak was associated with the presence of the Campylobacter jejuni sequence type (ST) 2993 genotype. In addition, during the year 2020, a total of 448 cases were reported nationally with a weekly average of 11 cases; in 2021, a total of 210 cases were reported with a weekly average of four cases. Similarly, in 2022, there were 225 cases reported with a consistent weekly average of four cases.

Figure 1. Guillain Barré Syndrome case trends in Peru 2021, 2022 and 2023 (Epidemiological week 28)

Source: National Center for Epidemiology, Prevention and Disease Control (CDC) Peru-Peru. The situation of Guillain Barré syndrome -Peru, 2023 (Epidemiological Week 28)

Public health response

The National Center for Epidemiology, Prevention, and Disease Control (CDC) of Peru of the Ministry of Health issued an epidemiological alert on 26 June 2023 and has maintained monitoring of the situation through a GBS Situation Room.

On 8 July 2023, the Presidency of the Republic of Peru declared a national health emergency due to the unusual increase in cases of GBS. The decree provides: 

  • The implementation of an action plan that includes financing for the provision of strategic resources in health, including the acquisition of 7000 human immunoglobulins as part of the treatment of patients with Guillain Barré syndrome, promoting recovery, and preventing complications associated with the disorder. 
  • Intensification of surveillance, prevention, and response actions to possible cases. 
  • Communication of risk to health professionals and issuance of key messages to the population to adopt preventive measures. 
  • Advice, information, and guidance on Guillain Barré syndrome to health professionals and the general population.  

WHO is supporting the health authorities of Peru in the management of this event.

WHO risk assessment

Guillain-Barré syndrome is a rare condition, and while it is more common in adults and males, people of all ages can be affected. The cause of it is not fully understood, but most cases follow an infection with a virus or bacteria. This leads the immune system to attack the body itself. Infection with the bacteria Campylobacter jejuni, which causes gastroenteritis, is one of the most common risk factors for GBS. People can also develop GBS after having the flu or other viral infections, including cytomegalovirus, Epstein-Barr virus, and the Zika virus. In rare instances, vaccinations may increase the risk of people getting GBS, but the likelihood of this occurring is extremely low. Studies show that people are much more likely to get GBS from infections such as the flu than from the vaccine given to prevent the infection, in this case, the flu vaccine. Occasionally, surgery can trigger GBS.

To date, the potential cause of the reported increase in GBS incidence in Peru remains under investigation as Campylobacter jejuni infection was confirmed by the laboratory in 63% of GBS cases from 22 samples tested since epidemiological week 23. In 2019, Peru reported an unprecedented outbreak of Guillain-Barré Syndrome that affected several regions of the country, which was concluded to be associated with the presence of the Campylobacter jejuni ST2993 genotype.

Further investigations are needed to identify the possible causes associated with the increase. So far, no association has been found with the current dengue outbreak, and Zika virus transmission is currently low in the country. Additionally, there have been no reports of a similar surge in cases in other countries of the Americas.