The combination of two mosquito-borne viruses may lead to a stroke, according to a new study from the University of Liverpool. The team has been investigating the link between Zika and chikungunya infection and neurological disease.
These two mosquito-borne viruses, which are most prevalent in the tropics, are responsible for large outbreaks of rash and fever in places like Brazil and India.
Zika is known to cause brain damage in babies if expectant mothers are infected. According to the new findings, Zika also causes nervous system disease in adults.
The investigation was focused on 201 adults with new onset neurological disease, treated in Brazil during the 2015 Zika and 2016 chikungunya epidemics. The study is the largest of its kind to describe the neurological features of infection for several mosquito-borne viruses circulating at the same time.
The researchers found that each virus can cause a range of neurological problems. Zika was found to be more likely to cause Guillain-Barre syndrome, which is characterized by nerve damage in the arms and legs. Chikungunya is more likely to cause inflammation and swelling in the brain and spinal cord.
While stroke can be caused by either virus on its own, the analysis showed that patients infected with both were more susceptible to stroke.
“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,” said study co-author Dr. Suzannah Lant.
Patients were recruited over a two-year period at Hospital da Restauração in Recife in Brazil, and the experts conducted omprehensive PCR and antibody testing for viruses.
Of the 201 patients admitted with suspected neurological disease linked to Zika, chikungunya or both, 148 had confirmation of infection through lab testing. Approximately one-third of these individuals were found to be infected by more than one virus.
Among the stroke patients, about two-thirds had infection with more than one virus. There was evidence to suggest that stroke following Zika and chikungunya viral infection most often occurs in patients who already have risk factors, such as high blood pressure.
Study senior author Professor Tom Solomon is the director of the National Institute for Health Protection Research Unit in Emerging and Zoonotic Infections at the University of Liverpool.
“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,” said Professor Solomon. “We need to understand more about why some viruses trigger stroke, so that we can try and prevent this from happening in the future.”
The study is published in the journal Lancet Neurology.