While we don't as yet have a proven causal link between Zika virus infection and an increase in Guillain-Barre syndrome, the evidence supporting that link continues to mount.
Other arboviruses (including Dengue, CHKV) have been linked to GBS, and about two years ago (see Zika, Dengue & Unusual Rates Of Guillain Barre Syndrome In French Polynesia) we began to get the first hints that Zika might as well.
Overnight the World Health Organization reported on two cases of GBS with confirmed Zika infection in the United States.
While 3,000 to 6,000 GBS occur each year in the United States, finding two cases out of a cohort of just a few hundred imported Zika cases is bound to raise some eyebrows, as the normal incidence is 1 or 2 per 100,000 (see CDC GBS Q&A)
This from the WHO.
On 10 March 2016, the National IHR Focal Point of the United States of America notified PAHO/WHO of 2 cases of Guillain-Barre syndrome (GBS) with confirmed Zika virus infection. Both cases are under investigation to determine whether they meet the Brighton Collaboration case definition for GBS.
Details of the cases
- The first case is an elderly male resident of the United States with recent travel to Central America. He developed an acute febrile illness shortly after returning to the U.S. and was subsequently hospitalized in January with progressive ascending weakness of the extremities and diminished reflexes. The patient tested positive for Zika virus infection by polymerase chain reaction (PCR). He improved following treatment and was ready to be discharged. However, he experienced a sudden subarachnoid haemorrhage due to a ruptured aneurysm and died.
- The second case is an adult male resident of Haiti who experienced an acute onset of facial weakness, difficulty swallowing, and numbness of fingers in early January. No antecedent illness was reported. A few days later, he travelled to the United States for additional medical care. Cerebrospinal fluid had elevated protein and normal white blood cells. Physical examination showed mild weakness and diminished reflexes. The patient tested positive for Zika virus infection by serology. He improved with intravenous immunoglobulin therapy and was discharged.
WHO risk assessmentTo date, a total of 9 countries or territories have reported an increased incidence of GBS and/or laboratory confirmation of Zika virus infection among GBS cases. This is the first time that a country with no vector borne transmission of Zika virus detects patients with concomitant GBS and Zika virus infection. These cases provide additional evidence of a possible causal relationship between Zika virus and GBS. Further investigations are needed to understand the implications of pre-existing dengue infections, together with recent Zika infections, in the pathogenesis of GBS.
It is likely that countries that are currently reporting autochthonous Zika virus transmission will face a rise in the number of GBS cases in the coming months. However, it is critical to ensure that in all these countries the reported increases in the incidence of GBS are the result of a real change rather than enhanced surveillance. WHO continues to monitor the epidemiological situation and conduct risk assessment based on the latest available information.(Continue . . .)
WHO adviceWHO recommends Member States affected or susceptible to Zika virus outbreaks to:
- monitor the incidence and trends of neurological disorders, especially GBS, to identify variations against their expected baseline values;
- develop and implement sufficient patient management protocols to manage the additional burden on health care facilities generated by a sudden increase in patients with Guillain-Barre Syndrome;
- raise awareness among health care workers and establish and/or strengthen links between public health services and clinicians in the public and private sectors.