Mosquito-Borne Viruses Linked To Stroke

Zika and chikungunya mostly circulate in the tropics to cause large outbreaks of fever and rash in places like India and Brazil. Zika is known to cause brain damage in babies following infection during pregnancy, this report suggests that it can also cause nervous system disease in adults. 

This study is the largest of its kind to describe the neurological features of infection for several arboviruses circulating at the same time, involving 201 adults with new-onset neurological disease treated during the 2015 Zika and 2016 chikungunya epidemics. 

Findings show that each virus can cause a range of neurological problems: Zika was especially likely to cause Guillain-Barre syndrome; and chikungunya was more likely to cause inflammation and swelling in the brain and spinal cord. A stroke could be caused by either virus alone but was more likely to occur in those infected with the two viruses together. 

1410 patients were screened and 201 were recruited over a period of two years at the Hospital da Restauracao in Recife, Brazil; comprehensive PCR and antibody testing for viruses was carried out in Fiocruz Laboratories. Of the 201 admitted with suspected neurological disease linked to Zika, chikungunya or both 148 were confirmed to have an infection of which around one third had infection with more than one virus. 

The median age was 48 years old, just over half were female, and only around 10% had fully recovered at discharge with many experiencing ongoing issues such as weakness, seizures, and problems in brain function. Of the stroke patients, around two-thirds had an infection with more than one virus, and many had other stroke risk factors such as high blood pressure indicating that Zika and chikungunya viral infection may most often be seen in those who are already at high risk. 

"Zika infection most often causes a syndrome of rash and fever without many long-term consequences, but these neurological complications—although rare—can require intensive care support in hospital, often result in disability, and may cause death,” said Dr. Maria Lúcia Brito Ferreira, neurologist and head of the department at Hospital da Restauração, leading the Brazilian team.

"Our study highlights the potential effects of viral infection on the brain, with complications like stroke. This is relevant to Zika and chikungunya, but also to our understanding of other viruses, such as COVID-19, which is increasingly being linked to neurological complications,” Dr. Suzannah Lant, a Clinical Research Fellow at the University of Liverpool, who worked on the study explained. 

"Although the world's attention is currently focused on COVID-19, other viruses that recently emerged, such as Zika and chikungunya, are continuing to circulate and cause problems. We need to understand more about why some viruses trigger stroke, so that we can try and prevent this happening in the future,” said Senior author Professor Tom Solomon, Director of the National Institute for Health Research Health Protection Research Unit in Emerging and Zoonotic Infections at the University of Liverpool.