February 12, 2016

expert comments on Guillain-Barré Syndrome and the Zika virus outbreak in central and South America

The Zika outbreak in Central and South America has been linked to microcephaly, a small head with limited brain development, in babies as well as Guillain-Barré Syndrome, an autoimmune disorder which brings about muscle weakness.

All our previous output on this subject can be seen here.

Dr Nathalie MacDermott, Clinical Research Fellow, Imperial College London, said:

“Guillain Barré syndrome (GBS) is an acute inflammatory condition which may occur a few weeks after certain bacterial and viral infections when the immune system attacks the sheaths covering peripheral nerves. Because of the damage to the nerve sheaths they are unable to conduct properly and this results in weakness of the corresponding muscles. The damage usually starts in the legs or feet causing weakness or altered sensation, it then moves upwards towards the chest. In its most severe form it can affect the nerves that supply muscles responsible for breathing, resulting in a person finding it difficult to breathe. In this case a patient will require ventilation in an intensive care unit. GBS has been associated with several bacterial and viral infections, one of the most commonly associated bacteria is Campylobacter jejuni which can cause diarrhoea. Several viruses such as Cytomegalovirus and Epstein-Barr virus have been associated with GBS and cases have been reported in association with Dengue viral infection.

“At present several South and Central American countries have reported an increased incidence of GBS which appears to have occurred in association with increasing numbers of Zika virus cases. In particular Brazil, Colombia, Venezuela and El Salvador have reported increased numbers of cases.  While the cases of GBS are confirmed and some patients report a febrile illness with rash prior to onset of GBS, the patients have not necessarily been confirmed to have Zika virus infection. Although the incidence of GBS has risen, the proportion of people developing GBS that might be associated with Zika infection, compared to the number of cases of Zika infection in these countries, remains small. Research is currently underway to determine if Zika is linked to GBS and if demonstrated will help determine the true proportion of cases of GBS in relation to the actual number of Zika infections.

“While if a link between Zika and GBS is demonstrated this will be concerning for people living in regions where Zika virus is present, the incidence of GBS remains small in comparison to the number of Zika cases and it must be remembered that many infections and other factors can result in GBS.”

Dr Peter Barlow, British Society for Immunology spokesperson, and Reader in Immunology & Infection, Edinburgh Napier University, said:

“Guillain-Barré syndrome is a condition that can occur when the natural immune response generated by an infection, such as a virus, damages nerve cells. It is generally quite rare but can cause paralysis and prolonged or permanent nerve damage. The exact cause of why Guillain-Barré syndrome is associated with infection still remains to be identified.

“It has been suggested that there is a link between Zika virus and Guillain-Barré syndrome, in addition to the ongoing concerns relating to congenital microcephaly when Zika virus infection occurs in pregnancy.

“While the link between Zika and Guillain-Barré syndrome has not yet been fully proven,  it is clear that the advice given by the WHO and CDC to prevent Zika infection should still be followed.  People living in, or travelling to, Zika affected areas should take careful measures to protect themselves against mosquito bites which could pass on the infection.  In the event that a firm link between Zika and Guillain-Barré syndrome is identified, this is the best and most appropriate way to prevent infection.”

Dr Andrew Freedman, Reader in Infectious Diseases and Honorary Consultant Physician, Cardiff University, said:

“Guillain-Barré Syndrome is an uncommon neurological condition in which the body’s own immune system attacks nerve cells, leading to varying degrees of muscle weakness and paralysis. There are around 1,000-1,500 cases in the UK each year. It is usually triggered by an infection which occurs days to weeks before the onset of the condition. There are a number of well recognised causes including Campylobacter, HIV and other viral infections, but in many cases it is not possible to determine exactly which infection caused it. The course is variable but most patients recover completely over a period of weeks to months.

“There is no definite proof as yet that Zika virus can cause Guillain-Barré Syndrome, but there does appear to be an increase in reported cases in the countries where Zika is spreading at present. Further studies will be required to confirm the link and, if so, the extent of the risk of developing it after catching infection with the Zika virus. However, four out of five people who catch Zika virus have no symptoms at all and the chance of developing Guillain-Barré Syndrome afterwards is likely to be very small.”

Declared interests

Dr Nathalie MacDermott: “I am a paediatrician. I am also undertaking a PhD in Ebola virus disease at Imperial College London funded by the Wellcome Trust.”

Dr Peter Barlow: “I have no conflicts of interest to declare.”

Dr Andrew Freedman: “I have no conflicts of interest to declare.”