Beware: Mosquito-borne diseases like Zika, Chikungunya may trigger stroke and more

Vector borne diseases are a bane for tropical countries. Disease causing mosquitoes cause many outbreaks in such countries every rainy season, most of which come with their own complications. Now, according to a new study, a deadly combination of two mosquito-borne viruses may be a trigger for stroke. This was published in the The Lancet Neurology. 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.

Neurological impact of vector borne diseases

The study of 201 adults with new onset neurological disease, treated in Brazil during the 2015 Zika 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 risk increases with viral infections

Stroke occurs when one of the arteries supplying blood to the brain becomes blocked. The risk of stroke is known to go up after some types of viral infection, like varicella zoster virus, which causes chickenpox and shingles, and HIV. It 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, according to researchers.

Recovery seen in only 10 per cent patients

In total 1410 patients were screened and 201 recruited over a two-year period at Hospital da Restauração in Recife, Brazil, for the purpose of the study. 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 per cent patients had fully recovered at discharge, with many having ongoing issues like weakness, seizures, and problems in brain function.

Underlying conditions increase risk of stroke

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.