Publishing in The Lancet journal a group of researchers have analysed data from a previous outbreak of Zika virus in French Polynesia and report that of 42 patients diagnosed with Guillain-Barré syndrome at the time, all showed signs of an immune response against Zika whereas only half of those in a control group did.
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Dr Peter Barlow, British Society for Immunology spokesperson, and Reader in Immunology & Infection, Edinburgh Napier University, said:
“This study provides evidence to suggest a causal link between Zika virus infection and Guillain-Barre syndrome in French Polynesia. However, there is still a significant amount of work to be undertaken before the same conclusions can be extended to the Zika outbreak in South America, where local population factors may also play a role.
“Because the patient group that was analysed in this study is relatively small, the exact link between Zika and Guillain-Barre syndrome remains inconclusive. The authors also had to consider their findings in the context of Dengue virus infection circulating in the local population, which is another viral infection associated with Guillain-Barre.
“However, the evidence that links Zika virus with Guillain-Barre syndrome is now substantially more compelling.”
Prof. Jimmy Whitworth, Professor of International Public Health, London School of Hygiene & Tropical Medicine, said:
“This paper provides compelling evidence of the link between Guillain-Barré syndrome and Zika virus infection during the outbreak in French Polynesia in 2013. Guillain-Barré syndrome is a rare neurological complication seen after a variety of bacterial and viral infections (such as Campylobacter and cytomegalovirus) and occurs all around the world. From previous experience we know that one person in 2,000-4,000 of those who have had one of these infections will develop Guillain-Barré syndrome, which is an abnormal immune response to the infection. It usually occurs 2-8 weeks after an infection.
“In this paper, the authors calculate that Guillain-Barré syndrome occurred at about the same frequency after Zika virus infections as is seen with other infections. However, the condition seems to have developed sooner after infection, on average less than one week, than is seen with other infections. The affected patients are reported to have recovered quicker too. The authors found no signal that previous dengue infection was associated with the development of Guillain-Barré syndrome.
“If the experience of Zika virus infection in Latin America is similar to that seen in French Polynesia, we can expect to see about 2-5 cases of Guillain-Barré syndrome for every 10,000 people who get infected. This has implications for health care in countries with a Zika virus epidemic as a proportion of those affected with Guillain-Barré syndrome will need breathing support on a ventilator for a while, and some cases do not recover fully from the syndrome and are left with disability.”
Dr Jeremy Farrar, Director of the Wellcome Trust, said:
“This study provides the most compelling evidence to date of a causative link between Zika virus infection and the serious neurological condition Guillain-Barré syndrome. The increase in reported cases of Guillain-Barré in Brazil and other South American countries seems to suggest that a similar situation may be occurring in the current outbreak, although the link here is yet to be proven definitively.
“The scale of the crisis unfolding in Latin America has taken us all by surprise, and we should be prepared for further unforeseen complications of Zika virus infection to emerge in the coming weeks and months. What’s important now is that the global community comes together to focus research efforts on the many unanswered questions about the virus, and to share this information rapidly so that the knowledge gained can benefit patients as quickly as possible.”
‘Guillain-Barré Syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control study’ by Van-Mai Cao-Lormeau et al. published in The Lancet on Monday 29 February 2016.
Dr Peter Barlow: Peter has no interests to declare.
Prof. Jimmy Whitworth: Jimmy Whitworth directs the ERAES programme (Enhancing Research Activity in Epidemic Situations) at the London School of Hygiene & Tropical Medicine which is supported by the Wellcome Trust to provide funding for urgent research during outbreaks.
Dr Jeremy Farrar: The Wellcome Trust part-funded this work.