According to research published on March 1, 2016, Zika virus might cause Guillain-Barré syndrome (GBS), a severe neurological disorder. Zika virus infection is associated with symptoms such as fever, rash, joint and muscle pain and conjunctivitis. The current Zika outbreak in Central and South America was followed by increased reports of cases of microcephaly and GBS, leading the World Health Organisation to declare it a global emergency.
The new study, published in The Lancet, analysed blood samples from 42 patients diagnosed with GBS during the Zika virus outbreak in French Polynesia between October 2013 and April 2014. The data suggests that if 100 000 people were infected with Zika virus, 24 would develop GBS.
Guillain-Barré syndrome is a disorder which affects the immune and nervous systems and is the leading cause of non-trauma-related paralysis. Symptoms develop rapidly and include weakness in the legs and arms, muscle weakness and pain. In about 20 - 30% of cases, severe GBS can lead to respiratory failure, and about 5% of patients die. GBS is usually triggered by an infection and can sometimes develop following infections of herpes, influenza or dengue virus. Across Europe and North America, GBS affects approximately 1-2 people out of 100 000 per year.
"This is the first study to look at a large number of patients who developed Guillain-Barré syndrome following Zika virus infection and provide evidence that Zika virus can cause GBS," says lead author Professor Arnaud Fontanet from the Institut Pasteur, Paris, France. "Most of the patients with GBS reported they had experienced symptoms of Zika virus infection on average six days before any neurological symptoms, and all carried Zika virus antibodies."
The aim of the study was to determine the link between Zika virus infection and GBS. Since French Polynesia is also prone to outbreaks of dengue virus, the researchers also wanted to see whether dengue virus was an additional risk factor for GBS.
Based on an attack rate for Zika virus of 66% in French Polynesia, the authors estimate that the risk of Guillain-Barré syndrome in the general population during the outbreak in French Polynesia is 0·24 per 1 000 Zika virus infections (or 24 people per 100 000 infections).
Professor Fontanet adds: "Although it is unknown whether attack rates of Zika virus epidemics will be as high in affected regions in Latin America than in the Pacific Islands, high numbers of cases of Guillain-Barré syndrome might be expected in the coming months as the result of this association. The results of our study support that Zika virus should be added to the list of infectious pathogens susceptible to cause Guillain-Barré syndrome."
Whether Zika will be proven to pose a greater threat in causing Guillain-Barré syndrome than its various flavivirus cousins remains to be determined.
- "Guillain-Barré Syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control study" - Frédéric Ghawché, MD et al. - The Lancet, March 2016 - DOI: 10.1016/S0140-6736(16)00562-6
- "Zika virus and Guillain-Barré syndrome: another viral cause to add to the list" - David W Smithemail, John Mackenzie - The Lancet, February 29, 2016 - DOI: 10.1016/S0140-6736(16)00564-X
Featured image: Zika virus prevention. Credit: PresidenciaRD (Flickr - CC)