A deadly combination of two mosquito-borne viruses may be a trigger for stroke, new research published in the The Lancet Neurology has found.
From: The University of Liverpool
September 18, 2020 -- University of
Liverpool researchers and Brazilian collaborators have been investigating the
link between neurological disease and infection with the viruses Zika and
chikungunya. These viruses, which mostly circulate in the tropics, cause large
outbreaks of rash and fever in places like Brazil and India. Zika is widely
known to cause brain damage in babies following infection in pregnancy, but the
new research shows it can also cause nervous system disease in adults.
The study of 201 adults with new onset
neurological disease, treated in Brazil during the 2015Zika and 2016
chikungunya epidemics, is the largest of its kind to describe the neurological
features of infection for several arboviruses circulating at the same time.
The new research shows that each virus
can cause a range of neurological problems. Zika was especially likely to cause
Guillain-Barre syndrome, in which the nerves in the arms and legs are damaged.
Chikungunya was more likely to cause inflammation and swelling in the brain
(encephalitis) and spinal cord (myelitis). However, stroke, which could be
caused by either virus alone, was more likely to occur in patients infected
with the two viruses together.
Stroke occurs when one of the arteries
supplying blood to the brain becomes blocked. The risk of stroke is known to be
increased after some types of viral infection, like varicella zoster virus,
which causes chickenpox and shingles, and HIV. Stroke is also being recognised
increasingly as a complication of COVID-19. This has important implications for
the investigation and management of patients with viral infection, as well as
for understanding the mechanisms of disease.
In total 1410 patients were screened and
201 recruited over a two-year period at Hospital da Restauração in Recife,
Brazil. Comprehensive PCR and antibody testing for viruses was carried out in
Fiocruz laboratories.
Of the 201 patients admitted with
suspected neurological disease linked to Zika, chikungunya or both, 148 had
confirmation of infection on laboratory testing, around a third of whom had
infection with more than one virus.
The median age of patients was 48, and
just over half the patients were female. Only around 10% patients had fully
recovered at discharge, with many having ongoing issues like weakness,
seizures, and problems in brain function.
Of the stroke patients, who were aged 67
on average, around two thirds had infection with more than one virus. Many of
the people who had a stroke had other stroke risk factors, such as high blood
pressure, indicating that stroke following Zika and chikungunya viral infection
may most often be seen in those who are already high risk.
Dr Maria Lúcia Brito Ferreira,
neurologist and head of department at Hospital da Restauração, leading the Brazilian
team said: "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."
Dr Suzannah Lant, a Clinical Research
Fellow at the University of Liverpool, who worked on the study explained:
"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."
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 said: "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."
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