Arboviral Encephalitis

Arboviral encephalitis is an inflammation of the brain caused by arthropod-borne viruses, known as arboviruses.

A common example is the West Nile virus, an enveloped positive-strand RNA virus, primarily transmitted by mosquitoes.

When an infected mosquito bites, it injects the virus into the skin, where the virus enters dendritic cells through receptor-mediated endocytosis.

It first replicates locally, then spreads to nearby lymph nodes, and later enters the bloodstream.

Once in the blood, the virus can travel to various organs, including the brain.

Here, the virus crosses the blood-brain barrier through several mechanisms.

It may do so by directly infecting the endothelial cells, by disrupting the tight junctions, or by being transported via infected immune cells.

After crossing the blood-brain barrier, the virus replicates inside neurons, triggering strong inflammation and the release of pro-inflammatory cytokines.

The combined effects of viral cytotoxicity and immune responses lead to neuronal loss and inflammation in the brain, causing encephalitis.